Patent Publication Number: US-2005139213-A1

Title: Physiological object displays

Description:
This application is a divisional application of copending application Ser. No. 10/054,069, filed Jan. 22, 2002, which is a continuation-in-part of U.S. Ser. No. 09/706,512, filed Nov. 3, 2000, now U.S. Pat. No. 6,743,172, which is a divisional application of U.S. Ser. No. 09/020,472, filed Feb. 9, 1998, now U.S. Pat. No. 6,234,963, which claims priority to Provisional Patent Application Ser. No. 60/071,510, filed on Jan. 14, 1998. This application claims priority under 35 U.S.C. §120 to Provisional Patent Application Ser. No. 60/263,861, filed on Jan. 23, 2001. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to display systems for displaying complex medical information to a physician. More specifically, the invention relates to hardware, software and object displays for displaying complex physiological information to physicians in unique graphical display formats in real time.  
     BACKGROUND OF THE INVENTION  
      Medical display systems provide information to physicians in a clinical setting. Typical display systems provide data in the form of numbers and one-dimensional signal waveforms that must be assessed, in real time, by the attending physician. Alarms are sometimes included with such systems to warn the physician of an unsafe condition, e.g., a number exceeds a recommended value. In the field of anesthesiology, for example, the anesthesiologist must monitor the patient&#39;s condition and at the same time (i) recognize problems, (ii) identify the cause of the problems, and (iii) take corrective action during the administration of the anesthesia. An error in judgment can be fatal.  
      Physiologic data displays of the patient&#39;s condition play a central role in allowing surgeons and anesthesiologists to observe problem states in their patients and deduce the most likely causes of the problem state during surgery, thus allowing expeditious treatment. As one might predict, 63 percent of the reported incidents in the Australian Incident Monitoring Study (AIMS) database were considered detectable with standard data monitors and potentially avoidable. Others have attempted to address these problems, but with only limited success.  
      For example, Cole, et. al. has developed a set of objects to display the respiratory physiology of intensive care unit (ICU) patients on ventilators. This set of displays integrates information from the patient, the ventilator, rate of breathing, volume of breathing, and percent oxygen inspired. Using information from object displays, ICU physicians made faster and more accurate interpretations of data than when they used alphanumeric displays. Cole published one study that compared how physicians performed data interpretation using tabular data vs. printed graphical data. However, Cole&#39;s work did not utilize all of the methods being leveraged in aviation and nuclear power to involve a system for receiving analog data channels and driving real-time graphical displays on a medical monitor.  
      Ohmeda, a company that makes anesthesia machines, manufacturers the Modulus CD machine which has an option for displaying data in a graphical way. The display has been referred to as a glyph. Physiologic data is mapped onto the shape of a hexagon. Six data channels generate the six sides of the hexagon. Although this display is graphical, the alphanumeric information of the display predominates. There is no obvious rational for why the physiologic data is assigned a side of the hexagon. Moreover, symmetric changes to the different signs of this geometric shape are very hard for individuals to differentiate. Overall, information displays that show the quantitative (data value), qualitative (high, low, normal zones for the parameter), temporal (trending and change over time), and relational (manner in which multiple parameters relate to disease states that need treatment) information that clinicians need in an intuitive manner are lacking.  
      The physiologic parameters that relate to oxygen transportation are central to medical assessment of any patient&#39;s well being. A review of the physiological parameters of interest and their importance in medical decision making that are represented in the informational display of this application, follows:  
      Blood adequacy: In the surgical and postoperative settings, decisions regarding the need for blood transfusion normally are guided by hemoglobin (Hb) or hematocrit levels (Hct). Hematocrit is typically defined as the percentage by volume of packed red blood cells following centrifugation of a blood sample. If the hemoglobin level per deciliter of blood in the patient is high, the physician can infer that the patient has sufficient capacity to carry oxygen to the tissue. During an operation this value is often used as a trigger, i.e. if the value falls below a certain point, additional blood is given to the patient. While these parameters provide an indication of the arterial oxygen content of the blood, they provide no information on the total amount of oxygen transported (or “offered”) to the tissues, or on the oxygen content of blood coming from the tissues.  
      For example, it has been shown that low postoperative hematocrit may be associated with postoperative ischemia in patients with generalized atherosclerosis. Though a number of researchers have attempted to define a critical Hct level, most authorities would agree that an empirical automatic transfusion trigger, whether based on Hb or Hct, should be avoided and that red cell transfusions should be tailored to the individual patient. The transfusion trigger, therefore, should be activated by the patient&#39;s own response to anemia rather than any predetermined value.  
      Tissue oxygenation: This is, in part, due to the fact that a number of parameters are important in determining how well the patient&#39;s tissues are actually oxygenated. In this regard, the patient&#39;s cardiac output is also an important factor in correlating hemoglobin levels with tissue oxygenation states. Cardiac output or CO is defined as the volume of blood ejected by the left ventricle of the heart into the aorta per unit of time (ml/min) and can be measured with thermodilution techniques. For example, if a patient has internal bleeding, the concentration of hemoglobin in the blood might be normal, but the total volume of blood will be low. Accordingly, simply measuring the amount of hemoglobin in the blood without measuring other parameters such as cardiac output is not always sufficient for estimating the actual oxygenation state of the patient.  
      More specifically the oxygenation status of the tissues is reflected by the oxygen supply/demand relationship of those tissues i.e., the relationship of total oxygen transport (DO 2 ) to total oxygen consumption (VO 2 ). Hemoglobin is oxygenated to oxyhemoglobin in the pulmonary capillaries and then carried by the cardiac output to the tissues, where the oxygen is consumed. As oxyhemoglobin releases oxygen to the tissues, the partial pressure of oxygen (PO 2 ) decreases until sufficient oxygen has been released to meet the oxygen consumption (VO 2 ). Although there have been advances in methods of determining the oxygenation status of certain organ beds (e.g., gut tonometry; near infrared spectroscopy) these methods are difficult to apply in the clinical setting. Therefore, the use of parameters that reflect the oxygenation status of the blood coming from the tissues i.e., the partial pressure of oxygen in the mixed venous blood (PvO 2 ; also known as the mixed venous blood oxygen tension) or mixed venous blood oxyhemoglobin saturation (SvO 2 ) has become a generally accepted practice for evaluating the global oxygenation status of the tissues.  
      Unfortunately, relatively invasive techniques are necessary to provide more accurate tissue oxygenation levels. In this respect, direct measurement of the oxygenation state of a patient&#39;s mixed venous blood during surgery may be made using pulmonary artery catheterization. To fully assess whole body oxygen transport and delivery, one catheter (a flow directed pulmonary artery [PA] catheter) is placed in the patient&#39;s pulmonary artery and another in a peripheral artery. Blood samples are then drawn from each catheter to determine the pulmonary artery and arterial blood oxygen levels. As previously discussed, cardiac output may also be determined using the PA catheter. The physician then infers how well the patient&#39;s tissue is oxygenated directly from the measured oxygen content of the blood samples.  
      While these procedures have proven to be relatively accurate, they are also extremely invasive. For example, use of devices such as the Swan-Ganz® thermodilution catheter (Baxter International, Santa Ana, Calif.) can lead to an increased risk of infection, pulmonary artery bleeding, pneumothorax and other complications. Further, because of the risk and cost associated with PA catheters, their use in surgical patients is restricted to high-risk or high-blood-loss procedures (e.g., cardiac surgery, liver transplant, radical surgery for malignancies) and high-risk patients (e.g., patients who are elderly, diabetic, or have atherosclerotic disease).  
      Among other variables, determination of the oxygenation status of the tissues should include assessment of the amount of blood being pumped toward the tissues (CO) and the oxygen content of that (arterial) blood (CaO 2 ). The product of these variables may then be used to provide a measure of total oxygen transport (DO 2 ). Currently, assessment of DO 2  requires the use of the invasive monitoring equipment described above. Accordingly, determination of DO 2  is not possible in the majority of surgical cases. However, in the intensive care unit (ICU), invasive monitoring tends to be a part of the routine management of patients; thus, DO 2  determinations are obtained more readily in this population.  
      Partial pressure of oxygen in the mixed venous blood or mixed venous blood oxygen tension (PvO 2 ) is another important parameter that may be determined using a PA catheter. Because of the equilibrium that exists between the partial pressure of oxygen (PO 2 ) in the venous blood and tissue, a physician can infer the tissue oxygenation state of the patient. More specifically, as arterial blood passes through the tissues, a partial pressure gradient exists between the PO 2  of the blood in the arteriole passing through the tissue and the tissue itself. Due to this oxygen pressure gradient, oxygen is released from hemoglobin in the red blood cells and also from solution in the plasma; the released O 2  then diffuses into the tissue. The PO 2  of the blood issuing from the venous end of the capillary cylinder (PvO 2 ) will generally be a close reflection of the PO 2  at the distal (venous) end of the tissue through which the capillary passes.  
      Closely related to the mixed venous blood oxygen tension (PvO 2 ) is the mixed venous blood oxyhemoglobin saturation (SvO 2 ) which is expressed as the percentage of the available hemoglobin bound to oxygen. Typically, oxyhemoglobin disassociation curves are plotted using SO 2  values vs. PO 2  values. As the partial pressure of oxygen (PO 2 ) decreases in the blood (i.e. as it goes through a capillary) there is a corresponding decrease in the oxygen saturation of hemoglobin (SO 2 ). While arterial values of PO 2  and SO 2  are in the neighborhood of 95 mm Hg and 97% respectively, mixed venous oxygen values (PvO 2 , SvO 2 ) are on the order of 45 mm Hg and 75% respectively. As such SvO 2 , like PvO 2 , is indicative of the global tissue oxygenation status. Unfortunately, like PvO 2 , it is only measurable using relatively invasive measures.  
      Another rather informative parameter with respect to patient oxygenation is deliverable oxygen (dDO 2 ). dDO 2  is the amount of the oxygen transported to the tissues (DO 2 ) that is able to be delivered to the tissues (i.e. consumed by the tissues) before the PvO 2  (and by implication the global tissue oxygen tension) falls below a certain value. For instance the dDO 2 (40) is the amount of oxygen that can be delivered to the tissues (consumed by the tissues) before PvO 2  is 40 mm Hg while dDO 2 (35) is the amount consumed before the PvO 2  falls to 35 mm Hg.)  
      Additional relevant parameters may be determined non-invasively. For instance, whole body oxygen consumption (VO 2 ) can be calculated from the difference between inspired and mixed expired oxygen and the minute volume of ventilation. Cardiac output may also be non-invasively inferred by measuring arterial blood pressure instead of relying on thermodilution catheters. For example, Kraiden et al. (U.S. Pat. No. 5,183,051, incorporated herein by reference) use a blood pressure monitor to continuously measure arterial blood pressure. These data are then converted into a pulse contour curve waveform. From this waveform, Kraiden et al. calculate the patient&#39;s cardiac output.  
      Regardless of how individual parameters are obtained, those skilled in the art will appreciate that various well established relationships allow additional parameters to be derived. For instance, the Fick equation (Fick, A. Wurzburg,  Physikalisch edizinische Gesellschaft  Sitzungsbericht 16 (1870)) relates the arterial oxygen concentration, venous oxygen concentration and cardiac output to the total oxygen consumption of a patient and can be written as: 
 
(CaO 2 −CvO 2 )×CO=VO 2  
 
 where CaO 2  is the arterial oxygen content, CvO 2  is the venous oxygen content, CO is the cardiac output and VO 2  represents whole body oxygen consumption. 
 
      While the non-invasive derivation of such parameters is helpful in the clinical setting, a more determinative “transfusion trigger” would clearly be beneficial. If PvO 2  or DO 2  is accepted as a reasonable indicator of patient safety, the question of what constitutes a “safe” level of these parameters arises. Though data exists on critical oxygen delivery levels in animal models, there is little to indicate what a critical PvO 2  might be in the clinical situation. The available data indicate that the level is extremely variable. For instance, in patients about to undergo cardiopulmonary bypass, critical PvO 2  varied between about 30 mm Hg and 45 nm Hg where the latter value is well within the range of values found in normal, fit patients. Safe DO 2  values exhibit similar variability.  
      For practical purposes a PvO 2  value of 35 mm Hg or more may be considered to indicate that overall tissue oxygen supply is adequate, but this is implicit on the assumption of an intact and functioning vasomotor system. Similarly, the accurate determination of DO 2  depends on an intact circulatory system. During surgery it is necessary to maintain a wide margin of safety and probably best to pick a transfusion trigger (whether DO 2 , PvO 2 , SvO 2  or some derivation thereof) at which the patient is obviously in good condition as far as oxygen dynamics are concerned. In practice, only certain patients will be monitored with a pulmonary artery catheter. Accordingly, the above parameters will not be available for all patients leaving the majority to be monitored with the imperfect, and often dangerous, trigger of Hb concentration.  
      Efforts to resolve these problems in the past have not proven entirely successful. For example, Faithfull et al. ( Oxygen Transport to Tissue XVI , Ed. M. Hogan, Plenum Press, 1994, pp. 41-49) describe a model to derive the oxygenation status of tissue under various conditions. However, the model is merely a static simulation allowing an operator to gauge what effect changing various cardiovascular or physical parameters will have on tissue oxygenation. No provisions are made for continuous data acquisition and evaluation to provide a dynamic representation of what may actually be occurring. Accordingly, the model cannot be used to provide real-time measurements of a patient&#39;s tissue oxygenation under changing clinical conditions.  
      Just as tissue oxygenation physiology has been reviewed, ventilation (the movement of air and medical gases in and out of the lung) and oxygenation (the loading of red cell hemoglobin with oxygen in the lung) are critical processes that impact on tissue oxygenation. Thus, what is needed in the art are relatively non-invasive systems for intuitively displaying physiological information to a physician. The emodiments system described below provide such a system to improve a physician&#39;s interpretation of patient data (in the areas of ventilation, oxygenation and perfusion). Other aspects of the invention will become apparent in the description that follows.  
      U.S. Pat. No. 6,234,963 is hereby incorporated by reference.  Nunn&#39;s Applied Respiratory Physiology,  4 th  Ed., J. F. Nunn, is also hereby incorporated by reference.  
     SUMMARY OF THE INVENTION  
      The present invention relates to systems and methods for obtaining physiological information from patients and displaying that information in an intuitive and logical format to a physician. The intuitive format may be termed a medical process diagram or object display because physicians reading the displayed information can quickly perceive the importance of changing patient values.  
      Research in applied human factors has focused on using graphical displays in high-risk environments similar to the operating room (e.g., nuclear power control rooms and airplane cockpits and flight decks) to reduce human error. The success of medical process diagrams appears to be a function of how well the operator&#39;s cognitive needs are illustrated and mapped into the graphical elements of the display. Using accepted task-analysis methods, a system was developed describing how medical doctors interpret oxygen-transport physiological data to diagnose pathological states and subsequently take appropriate corrective action for their patients. In an effort to make the voluminous data that doctors need to interpret more informative, a set of physiological object displays has been developed.  
      The object displays of the present invention have been developed to illustrate: 1) the relationships of data to other data; 2) data in context; 3) a frame of reference for the data; 4) the rate of change information for the data; and, 5) event information. Specifically, a system has been developed for presenting and relating cardiac, vascular, hemodynamic, cardiopulmonary, ventilator state, lung airway resistance, oxygenation and oxygen-transport physiology to doctors. The system uses data acquisition hardware, a computer, physiological parameter calculation software and object display software.  
      Unfortunately, current display systems that present physiologic data to physicians in critical care or other medical settings force the physicians to perform a great deal of cognitive work to interpret that data. Interpreting data in this manner has been shown to be more likely to introduce human error. In contrast, the display systems described below utilize visual memory cues and perceptual diagrams to map complex data graphically and in an intuitive manner for physicians and other medical personnel. These data maps are then displayed to match the mental model physicians use to interpret various physiological parameters. Because the system receives analog signals from the patient and thereafter calculates several physiological quantities, patient data is used to drive the display in real-time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an overview of the oxygen cycle;  
       FIG. 2  shows one embodiment of the extended heart object;  
       FIG. 3  is a flowchart illustrating one method that may be used to update the extended heart object;  
       FIG. 4  shows one embodiment of the vascular circuit object;  
       FIG. 5  shows another embodiment of the vascular circuit object, a split RV and LV version;  
       FIG. 6  is a flowchart illustrating one method that may be used to update the vascular circuit objects;  
       FIG. 7  shows one embodiment of the cardiopulmonary bypass object;  
       FIG. 8  is a flowchart of one method that may be used to update the cardiopulmonary bypass object;  
       FIG. 9  shows one embodiment of the ventilator state object;  
       FIG. 10  is a flowchart of one method that may be used to update the ventilator state object;  
       FIG. 11  shows one embodiment of a mixed ventilator/lung object;  
       FIG. 12  shows another embodiment of the mixed ventilator/lung object;  
       FIG. 13  shows another embodiment of the mixed ventilator object;  
       FIG. 14  shows one method of updating the mixed ventilator/lung object;  
       FIG. 15  shows one embodiment of an oxygenation object;  
       FIG. 16  is a flowchart of one method of updating the oxygenation object;  
       FIG. 17  is a schematic diagram illustrating one system for collecting, processing and displaying various physiological parameters;  
       FIG. 18  is a schematic diagram of one embodiment that can be used to run the present system; and,  
       FIG. 19  is a flowchart detailing a software scheme that may be used to run the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      I. Hardware System  
       FIG. 17  illustrates a system  310  constructed according to an embodiment of the invention. A series of probes  312  are connected to various monitoring activities associated with the patient  314 , e.g., a heart rate probe  12   a . These probes are well known and typically generate analog signals  316  representative of the monitored activity. The signals  316  are converted through well-known A/D devices  318  in a data conversion module  320  to generate digital data corresponding to the analog signals  16 . This data is made available on a data bus  322 .  
      A processing module  324  processes data on the bus  322  to generate usable quantitative measures of patient activity as well as to compare and create object displays that, for example: (1) relate certain data relative to other data; (2) present data in context; (3) relate data to a frame of reference; (4) determine the rate of change information in the data; and/or (5) to present event information.  
      One embodiment of the module  324  thus includes a plurality of data processing sections  326   a - 326   c  that analyze and/or quantify the data being input from the probe  312 . For example, one section  326   a , connected in the data chain to probe  312   a , processes data on the bus  322  to provide a representation of heart rate in the form of a digital word. As the patient&#39;s heart rate changes, so does the digital word. A memory module  328  is used to store selected data, such as the digital word corresponding to heart rate, so that the module  324  contains a record and a current value of the patient&#39;s heart rate activity. The memory  328  also stores information, such as nominal values from which to compare data to a frame of reference, or such as extreme values representative of desired patient thresholds. The display driver section  330 , connected to sections  326   a - 326   c , can thus command the display of the heart rate data in context on the display  332 , and/or relative to frame of reference data within the memory  328 .  
      The data from the sections  326   a - 326   c  can also be compared to other data or related to stored thresholds within the assessment module  334 . By way of example, data corresponding to probe  312   a  can be compared relative to probe  312   b  through a process of digital division within the module  334 . The driver  330  can in turn command the display of this related data on the display  332 . In another example, the assessment module  334  can compare other data to stored data within the memory  328 ; and a warning event can be displayed on the display  332  if the comparison exceeds a set threshold.  
      Those skilled in the pertinent technology should appreciate that certain probes  312  may have self-contained A/D conversion capability and data manipulation. Furthermore, such probes can easily be connected directly to the assessment module  334  and memory  328  by known techniques.  
      The system  310  is controlled by inputs at a user interface  336 , such as a keyboard, and the display driver  330  formats data into various object formats on the display  332 . Accordingly, by commanding selected processes within the assessment module  334 —such as comparison of certain data with other data—such data can be automatically displayed on the display  332  in the desired object format. The particular object displays, according to the invention, are described below. These object displays can be displayed simultaneously on different or the same display and thus sufficient probes are required to collect the associated data.  
       FIG. 18  shows a representative computer system  455  that may be used in conjunction with the system  310  of  FIG. 17 . System  455  can be operated in a stand-alone configuration or as part of a network of computer systems. The system  455  can be an integrated system that collects data from the patient and presents processed data to a display for viewing by a physician or other medical personnel.  
      The computer system  455  includes various software executed in conjunction with an operating system, for instance any of the Windows software available from the MICROSOFT Corporation, on a computer  460 . Other embodiments may use a different operational environment or a different computer or both.  
      In an alternate embodiment of the invention, computer  460  can be connected via a wide area network (WAN) connection to other physicians or hospitals. A WAN connection to other medical institutions enables a real-time review of the patient&#39;s progress during surgery or in the intensive care unit.  
      Referring again to  FIG. 18 , one embodiment of the computer  460  includes an Intel Pentium or similar microprocessor running at 128 MHz and 128 Kilobytes (Kb) of RAM memory (not shown). The system  455  includes a storage device  465 , such as a hard disk drive connected to the processor  470 . The hard drive  465  is optional in a network configuration, i.e., the workstation uses a hard disk or other storage device in a file server. If the computer  460  is used in the stand-alone configuration, the hard drive  465  is preferably 2.0 Gb or more. However, the system is not limited to particular types of computer equipment. Any computer equipment that can run the display system described herein is anticipated to function within the scope of this invention.  
      The computer  460  is integrated with a group of computer peripherals, and is connected to a VGA (video graphics array) display standard, or a color video monitor, which provides the display output of the system  455 . The display  475  may be a 15, 17 or 19 inch monitor running at (1024×768) pixels with (65,536) colors. A keyboard  480  that is compatible with IBM AT type computers may be connected to the computer  460 . A pointing device  485 , such as a two or three button mouse can also connect to the computer  460 . Reference to use of the mouse is not meant to preclude use of another type of pointing device.  
      A printer  490  may be connected to provide a way to produce hard-copy output, such as printouts for file records. In one configuration, a backup device  495 , such as a Jumbo (2 Gb) cartridge tape back-up unit, available from Colorado Memory Systems, is preferably connected to the computer  460 .  
      In an alternate embodiment of a stand-alone configuration, or as one of the workstations of a network configuration, the system  455  may include a portable computer, such as a laptop or notebook computer or other computers available from a variety of vendors. The portable computer (not shown) is equipped with components similar to that described in conjunction with computer  460 .  
      It will be understood by one skilled in the technology that a programmed computer can also be implemented completely or partially with custom circuitry. Therefore, the chosen implementation should not be considered restrictive in any matter.  
      II. Software  
      Many different ways of implementing the software of the present invention will be known to skilled technologists. For example, programming languages such as (Labview, C++, Basic, Cobol, Fortran or Modula-2) can be used to integrate the features of the present invention into one software package. An alternative method of illustrating the software of the present invention is to use a spreadsheet program to collect and determine the PvO 2  or other data of a patient in real-time. This method is described in detail below.  
      As discussed above, the systems and methods of the present invention collect data from a patient and determine various physiological parameters of a patient in real-time. Software is used to direct this process. Those skilled in the art will appreciate that the desired parameters may be derived and displayed using various software structures written in any one of a number of languages.  
      Referring now to  FIG. 19 , the process is begun when a start signal is transmitted by the user to the system at start state  500 . The start signal can be a keystroke of mouse command that initiates the software to begin collecting data. After receiving the start command at state  500 , arterial pressure data is collected from a patient at state  502 . Arterial pressure data may be collected by hooking a patient up to an arterial pressure monitor as is well known.  
      Once data have been collected from a patient at state  502 , a “data in range” decision is made at decision state  504 . At this stage, the software compares the data collected at state  502  with known appropriate ranges for arterial pressure values. Appropriate ranges for arterial pressure data are, for example, between 70/40 and 250/140.  
      If data collected at process state  502  are not within the range programmed in decision state  504 , or if the arterial pressure wave is abnormal, an error/exception handling routine is begun at state  506 . The error handling routine at state  506  loops the software back to process state  502  to re-collect the arterial pressure data. In this manner, false arterial pressure data readings will not be passed to the rest of the program. If the data collected at process state  502  are in the appropriate range at decision state  504 , the software pointer moves to process state  508  that contains instructions for collecting arterial data. Preferably the collected data will include patient temperature, arterial pH, hemoglobin levels, PaO 2  and PaCO 2 . Moreover, the data is preferably generated by an attached blood chemistry monitor which may provide information on the patient&#39;s blood gas levels, acid-base status and hematology status. In such embodiments the data is collected by receiving data streams via the serial connection from the blood chemistry monitor into the computer. Alternatively, the relevant values may be obtained from accessing data that is manually input from the keyboard.  
      As described previously, the blood chemistry monitor continually samples arterial blood from the patient preferably determining several properties of the patient&#39;s blood from each sample. Data corresponding to each of the properties taken from the blood chemistry monitor at process state  508  are checked so that they are in range at decision state  510 . An appropriate range for the pH is 7.15 to 7.65. An appropriate range for the hemoglobin level is from 0 to 16 g/dL. An appropriate range for the PaO 2  is from 50 mm Hg to 650 mm Hg while an appropriate range for the PCO 2  is from 15 mm Hg to 75 mm Hg.  
      If data are not within the appropriate ranges for each specific variable at decision state  510 , an error/exception handling routine at state  512  is begun. The error/exception handling routine at state  512  independently analyzes variables collected at state  508  to determine whether it is in range. If selected variables collected at state  508  are not within the appropriate range, the error/exception handling routine  512  loops a software pointer back to state  508  so that accurate data can be collected. If the selected data are in range at decision box  510 , the software then derives the CaO 2  value along with the cardiac output (CO) from the previously obtained arterial pressure data at state  514 .  
      As discussed, cardiac output can be derived from arterial pressure measurements by any number of methods. For example, the Modelflow system from TNO Biomedical can derive a cardiac output value in real-time from an arterial pressure signal. Other methods, as discussed above, could also be used at process step  514  to determine cardiac output. Once a cardiac output value has been determined at process step  514 , the patient&#39;s total oxygen transport (DO 2 ) may be derived at process step  515 . As previously discussed the total oxygen transport is the product of the cardiac output and the arterial blood oxygen content. This parameter may optionally be displayed and, as indicated by decision state  517 , the program terminated if the software has received a stop command. However, if the software has not received a keyboard or mouse input to stop collecting data at decision state  517 , a pointer directs the program to process state  516  to derive further parameters. Specifically, process state  516  relates to the measurement or input of the patient&#39;s VO 2 .  
      The patient&#39;s VO 2  can be calculated using the methods previously described measured by hooking the patient up to a suitable ventilator and measuring his oxygen uptake through a system such as the Physioflex discussed above or using a number of other devices such as systems manufactured by Sensormedics and Puritan Bennett. By determining the amount of oxygen inspired and expired, the ventilator may be used to calculate the total amount of oxygen absorbed by the patient. After the patient&#39;s VO 2  value has been determined at process step  516 , these variables are applied to the Fick equation at state  518  to provide a real time CvO 2 . The Fick equation is provided above.  
      Once the CvO 2  is known, mixed venous oxyhemoglobin saturation (SvO 2 ) and the mixed venous oxygen tension (PvO 2 ) can be derived at state  520 . As previously explained, values for mixed venous pH and PCO 2  are assumed to have a constant (but alterable) relation to arterial pH and PaCO 2  respectively and these are used, along with other variables, in the Kelman equations to define the position of the oxyhemoglobin dissociation curve. Alternatively, algorithms can be derived to calculate these values. Knowing the Hb concentration, a PvO 2  is derived that then provides a total CvO 2  (which includes contributions from Hb, plasma and PFC) equal to the CvO 2  determined from the Fick equation. If the CvO 2  value will not “fit” the Fick equation, another PvO 2  value is chosen. This process is repeated until the Fick equation balances and the true PvO 2  is known.  
      Those skilled in the art will appreciate that the same equations and algorithms may be used to derive, and optionally display, the mixed venous blood oxyhemoglobin saturation SvO 2 . That is, SvO 2  is closely related to PvO 2  and may easily be derived from the oxygen-hemoglobin dissociation curve using conventional techniques. It will further be appreciated that, as with PvO 2 , SvO 2  may be used to monitor the patient&#39;s oxygenation state and as an intervention trigger if so desired by the clinician. As discussed above, mixed venous blood oxyhemoglobin saturation may be used alone in this capacity or, more preferably, in concert with the other derived parameters.  
      After deriving values for PvO 2 , SvO 2  or both, the value or values may be displayed on the computer display at step  522 . If the software has not received a keyboard or mouse input to stop collecting data at decision state  524 , a pointer loops the program back to process state  502  to begin collecting arterial pressure data again. In this manner, a real-time data loop continues so that the patient&#39;s mixed venous blood oxygen tension (PvO 2 ) or saturation (SvO 2 ) is constantly updated and displayed on the computer at state  522 . If the software has received a stop command from a keyboard or mouse input at decision state  524 , then a finish routine  526  is begun.  
      III. Calculating Physiological Values  
      The following system can utilize a large Microsoft EXCEL® spreadsheet to collect information from the patient and display the desired physiological parameters. Before receiving real-time inputs of cardiovascular and oxygenation variables, a number of oxygenation constants may be entered into the system. These constants preferably include the patient&#39;s estimated blood volume, oxygen solubility in plasma and the oxygen content of 1 g of saturated oxyhemoglobin. The oxygenation constants are then stored in the computer&#39;s memory for use in later calculations.  
      TABLE 1 shows commands from part of a Microsoft EXCEL® spreadsheet that collects a patient&#39;s data and derives the value of the desired oxygenation parameters. The program is initialized by assigning names to various oxygenation constants that are to be used throughout the software. In the embodiment shown, oxygenation constants corresponding to blood volume (BV), oxygen solubility in a perfluorocarbon emulsion (O 2 SOL), specific gravity of any perfluorocarbon emulsion (SGPFOB), intravascular half-life of a perfluorocarbon emulsion (HL), weight/volume of a perfluorocarbon emulsion (CONC), barometric pressure at sea level (BARO), milliliters oxygen per gram of saturated hemoglobin (HbO) and milliliters of oxygen per 100 ml plasma per 100 mm of mercury (PIO) are all entered. The constants relating to perfluorocarbons would be entered in the event that fluorocarbon blood substitutes were going to be administered to the patient.  
      An example of starting values for Kelman constants, a subset of the oxygenation constants, is also shown in TABLE 1. These starting values are used in later calculations to derive the patient&#39;s mixed venous oxygenation state or other desired parameters such as mixed venous blood oxyhemoglobin saturation. As with the other oxygenation constants the Kelman constants are also assigned names as shown in TABLE 1.  
                   TABLE 1                          ASSUMPTIONS:   VALUES AT START:               Blood Volume (ml/kg) - BV    70       O 2  solubility in PFB (ml/dl @37 deg C.) - O2SOL    52.7       Specific Gravity of PFOB - SGPFOB    1.92       Intravascular half-life of Oxygent HT   = ½ Life of Oxygent       (hours) - HL       Wgt/Vol of PFOB emulsion/100 - CONC    0.6       Barometric Pressure @ sea level - BARO   760       Ml O2 per gram saturated Hb - HbO    1.34       Ml O2 per 100 ml plasma per 100 mm Hg - HIO    0.3               KELMAN CONSTANTS:   VALUES AT START               Ka1   = −8.5322289 * 1000       Ka2   = 2.121401 * 1000       Ka3   = −6.7073989 * 10       Ka4   = 9.3596087 * 100000       Ka5   = −3.1346258 * 10000       Ka6   = 2.3961674 * 1000       Ka7   −67.104406                  
 
      After the oxygenation constants, including the Kelman constants, have been assigned names, real time inputs from the arterial pressure lines and blood chemistry monitor may be initialized and begin providing data. As shown in TABLE 2, the system depicted in this embodiment derives or receives data relating to the arterial oxyhemoglobin saturation percentage (SaO 2 ). In particular, saturation percentages are derived from arterial data for oxygen tension (PaO 2 ), pH (pHa), carbon dioxide tension (PaCO 2 ) and body temperature (TEMP). If desired by the clinician, the present invention provides for the real-time display of SvO 2  values (as derived from calculated PvO 2 , pHv, PvCO 2  and temperature) to be used for the monitoring of the patient&#39;s tissue oxygenation status. As previously discussed, values for PvCO 2  and pHv are related, by a fixed amount, to those of PaCO 2  and pHa respectively as determined by algorithms. Cardiac output (CO) is also input as is VO 2 .  
      When Hb concentration, arterial blood gas and acid/base parameters are entered (automatically or manually) into the program, the O 2  delivery and consumption variables for both red cell containing Hb and for the plasma phase may be determined. Those variables relating to PFC (in the case of blood substitutes) or Hb based oxygen carrier can also be determined.  
      Numerical values useful for the calculation of CaO 2  relate to Hb concentration, arterial oxygen tension (PaO 2 ), arterial carbon dioxide tension (PaCO 2 ), arterial pH (pHa) and body temperature. The position of the oxygen-hemoglobin dissociation curve is calculated using the Kelman equations, which are input as oxygenation constants in the program. These calculations produce a curve that, over the physiological range of O 2  tensions, is indistinguishable from the parent curve proposed by Severinghaus ( J. Appl. Physiol.  1966, 21: 1108-1116) incorporated herein by reference. Iteration may be used to calculate a PvO 2  (via SvO 2 ) that results in the required mixed venous oxygen contents in Hb, plasma and fluorocarbon to satisfy the Fick equation.  
                   TABLE 2                       INPUTS:   AT START:                  Hemoglobin (Gm/dl) - Hb    6       Arterial Oxyhemoglobin saturation (%) - SaO2       Calculated Arterial Oxyhemoglobin saturation (%) -    = 100 * (SPaO2 * (SPaO2 * (SPaO2 * (SPaO2 + Ka3) + Ka2) +       SaO2CALC   Ka1))/(SPaO2 * (SPaO2 * (         Active Input Value for SaO2 - SaO2USED   = IF(SaO2&lt;&gt;O, SaO2, SaO2CALC)       Mixed venous blood oxyhemoglobin saturation (%) - SvO2       Calculated Mixed venous blood oxyhemoglobin saturation -    = 100 * (SPvO2 * (SPvO2 * (SPvO2 * (SPvO2 + Ka3) + Ka2) +       SVO2CALC   Ka1))/SPvO2 * (SPvO2 * (S         Active Input Value for SvO2 - SvO2USED   = IF(SvO2&lt;&gt;O, SvO2, SvO2CALC)       Arterial Oxygen Partial Pressure (mm Hg) - PaO2   100       Calculated ‘standardized’ PaO2 - SPaO2   = PaO2 * 10{circumflex over ( )}((0.024 * (37 − TEMPUSED) + (0.4 * (pHaUSED − 7.4)) +           (0.06 * (LOG10(40         Active Input Value for PaSO2 - PaSO2USED   = IF(PaO2&lt;&gt;O, PaO2, SPaO2)       Arterial pH - pHa       Normal Arterial pH - pHaNORM    7.4       Active Input Arterial pH - pHaUSED   = IF(pHa&lt;&gt;O, pHa, pHaNORM)       Arterial PCO2 - PaCO2       Normal PaCO2 - PaCO2NORM   40       Active Input Arterial PCO2 - PaCO2USED   = IF(PaCO2&lt;&gt;O, PaCO2, PaCO2NORM)       Body Temp C - TEMP       Normal Body Temp C - TEMPNORM   37       Active Input Body Temp C - TEMPUSED   = IF(TEMP&lt;&gt;O, TEMP, TEMPNORM)       Mixed Venous Oxygen Partial Pressure (mm Hg) - PvO2   40.6819722973629       Calculated ‘standardized’ PvO2 - SPvO2   = PvO2 * 10{circumflex over ( )}((0.024 * (37 − TEMPUSED)) + (0.4 * (pHvUSED − 7.4)) +           (0.06 * (LOG10(4         Mixed Venous pH - pHv       Normal Venous pH    7.4       Active Input Mixed Venous pH - pHvUSED   = IF(pHv&lt;&gt;O, pHv, pHvNORM)       Mixed Venous PCO2 - PvCO2       Normal Mixed Venous PCO2 - PvCO2NORM   40       Active Input Mixed Venous PCO2 - PvCO2USED   = IF(PvCO2&lt;&gt;O, PvCO2, PvCO2NORM)       Cardiac Output (l/mm) - CO   = ((14 − Hemoglobin (gm/dl) * CO Response to 1 gram of           Hb Depletion) + 5       CO Response to 1 gr Hb depletion - COCHG    0.7       Intravascular Oxygent HT Dose(ml/kg) - PFB       Time Adj. Intravascular Oxygent HT Conc(ml/kg) - TAPFB       Patient&#39;s Weight (kg) - kg   70       Total O2 Consumption (ml/min/kg) - VO2KG    3       Calculated Blood Volume (ml) - CBV   = BV * kg       Calc input Total O2 Consumption (ml/min/kg) - VO2   = kg * VO2KG                  
 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
               
               
                 DESCRIPTION: 
                 CALCULATIONS: 
               
               
                   
               
             
            
               
                 Arterial O2 Content in Hemoglobin (ml/dl) - CaO2Hb = 
                 ((Hb * HbO * SaO2USED)/100) 
               
               
                 Arterial O2 Content in Plasma (ml/dl) - CaO2Pl = 
                 ((PaO2 * PlO)/100) 
               
               
                 Arterial O2 Content in PFB (ml/dl) - CaO2PFB = 
                 ((PFB * kg * CONC)/SGPFOB)/(kg * BV * 0.01) * ((O2SOL * PaO2)/(100 * BARO 
               
               
                 Arterial Oxygen Content (ml/dl) - CaO2 = 
                 (CaO2Hb + CaO2Pl + CaO2PFB) 
               
               
                 Mixed Venous O2 Content in Hemoglobin (ml/dl) - CvO2Hb = 
                 ((Hb * HbO * SvO2USED)/100) 
               
               
                 Mixed Venous O2 Content in Plasma (ml/dl) - CvO2Pl = 
                 ((PvO2 * PlO)/100) 
               
               
                 Mixed Venous O2 Content in PFB (ml/dl) - CvO2PFB = 
                 ((PFB * kg * CONC)/SGPFOB)/(kg * BV * 0.01) * ((O2SOL * PvO2)/(100 * BARO 
               
               
                 Mixed Venous Oxygen Content (ml/dl) - CvO2SUM = 
                 (CvO2Hb + CvO2Pl + CvO2PFB) 
               
               
                 Mixed Venous Oxygen Content (ml/dl) - CvO2 = 
                 IF(CVO2SUM &gt; O, (CVO2SUM), CvO2CALC2) 
               
               
                 Mixed Venous O2 Content (ml/dl) - CvO2CALC2 = 
                 CaO2 − (VO2/(CO * 10)) 
               
               
                 Percent of VO2 provided from plasma = 
                 (O 2  Used From Plasma/Active Input Total O 2  Consumption) * 100 
               
               
                 Percent VO2 provided by PFB = 
                 100 * (O 2  Used From Perflubron/Active Input Total O 2  Consumption) 
               
               
                 Percent of VO2 provided by plasma and PFB = 
                 100 * ((O 2  Used From Plasma + O 2  Used From Perflubron/Active Inpu   
               
               
                   
               
            
           
         
       
     
                         TABLE 4                       DESCRIPTION:   OUTPUTS:                  Total Oxygen Transport (ml/min) - TDO2 =   CaO2 * CO * 10       O2 Transport in Hemoglobin (ml/min) - DO2Hb =   (CaO2Hb) * CO * 10       O2 Transport in plasma (ml/min) - DO2Pl =   CaO2Pl * CO * 10       O2 Transport in Perflubron (ml/min) - DO2PFB =   CaO2PFB * CO * 10       Calc Total O2 Consumption (ml/min) - VO2CALC =   (CaO2 − CvO2) * CO * 10       Active Input Total O2 Consumption (ml/min) - VO2USED =   IF(VO2&lt;&gt;O, VO2, VO2CALC)       Oxygen Used from Hemoglobin (ml/min) - VO2Hb =   (CaO2Hb − CvO2Hb) * CO * 10       Oxygen Used from Plasma (ml/min) - VO2Pl =   (CaO2Pl − CvO2Pl) * (CO * 10)       Oxygen Used from Perflubron (ml/min) - VO2PFB =   (CaO2PFB − CvO2PFB) * (CO * 10)       Total Oxygen Extraction Coefficient - OEC =   (CaO2 − CvO2)/CaO2       Hemoglobin Oxygen Extraction Coefficient - HOEC =   (SaO2USED − SvO2USED)/SaO2USED                    
 Based on the numerical values provided, the program calculates oxygenation parameters such as PvO 2  and SvO 2  in real time, as shown in TABLE 2. These values are then fed into the display system described below to generate perceptual diagrams. These diagrams are then used by the physician to determine, for example, when to alter the patient&#39;s clinical management. 
 
      TABLE 3 and TABLE 4 show additional information that may be provided by the instant invention further demonstrating its utility and adaptability. More specifically, TABLE 3 provides various oxygenation values that may be calculated using the methods disclosed herein while TABLE 4 provides other indices of oxygen consumption and oxygen delivery that are useful in optimizing patient treatment.  
      A closer examination of TABLE 3 shows that the system of the present invention may be used to provide the individual oxygen content of different constituents in a mixed oxygen carrying system. In particular, TABLE 3 provides calculations that give the arterial or venous oxygen content of circulating hemoglobin, plasma or blood substitute respectively.  
      TABLE 4 illustrates that the present invention may also be used to provide real-time information regarding oxygen consumption and delivery. As mentioned previously, Hb or Hct measurements are not a suitable reflection of tissue oxygenation. This is mainly because they only give an indication of the potential arterial O 2  content (CaO 2 ), without providing information about the total oxygen transport (DO 2 ) to the tissues where it is to be used. However as seen in TABLE 4 the instant invention solves this problem by providing on line oxygen transport information which is derived based on CaO 2  and cardiac output (CO).  
      Currently cardiac output is measured using thermodilution, and CaO 2  is calculated typically by measuring the arterial oxyhemoglobin saturation (SaO 2 ) and hemoglobin levels, and inserting these values into the following equation: CaO 2 =([Hb]×1.34×SaO 2 )+(PaO 2 ×0.003), where [Hb]=hemoglobin concentration (in g/dL); 1.34=the amount of oxygen carried per gram of fully saturated hemoglobin; PaO 2 =the arterial oxygen tension; and 0.003 is the amount of oxygen carried by the plasma (per deciliter per mm Hg of oxygen tension).  
      The present invention combines the continuous cardiac output algorithm with the Kelman equations to provide the position of the oxygen hemoglobin dissociation curve. Using on-line and off-line inputs of body temperature, hemoglobin, and arterial blood gases, the present invention is able to trend DO 2  on a continuous basis. The factors used to determine DO 2  are displayed along with their product; thus, the etiology of a decrease in DO 2  (inadequate cardiac output, anemia, or hypoxia) would be readily apparent to the physician, decisions regarding the appropriate interventions could be made expeditiously, and the results of treatment would be evident and easily followed.  
      More particularly, preferred embodiments of the invention are used to provide and display real-time DO 2 , arterial blood gases, hemoglobin concentration and CO (and all other hemodynamic data already discussed such as BP, heart rate, systemic vascular resistance, rate pressure product and cardiac work). As shown in TABLE 3, such embodiments can also provide separate readouts of contributions of Hb, plasma and PFC (if in circulation) to DO 2 . That is, the oxygen contributions of each component may be accurately monitored and adjusted throughout any therapeutic regimen. Such data would be particularly useful in both the OR and ICU for providing a safety cushion with respect to the oxygenation of the patient.  
      The importance of maximizing DO 2  for certain patients in the ICU has been underscored by recent studies. The present invention may also be used for determining when such intervention is indicated and to provide the data necessary for achieving the desired results. Once DO 2  is known it is possible to calculate the maximum O 2  consumption (VO 2 ) that could be supported for a certain chosen (and alterable) PvO 2 . As previously discussed, this value may be termed deliverable oxygen (dDO 2 ). For instance, a PvO 2  of 36 mm Hg might be chosen for a healthy 25 year old patient, where as a PvO 2  of 42 mm Hg or higher might be needed for an older patient with widespread arteriosclerosis or evidence of coronary atheroma or myocardial ischemia. Oxygen consumption under anesthesia is variable, but almost always lies in the range of 1.5 to 2.5 ml/kg/min. If the supportable VO 2 , at the chosen PvO 2 , was well above this range all would be well and no intervention would be necessary. The closer the supportable VO 2  to the normal VO 2  range the earlier intervention could be considered.  
      This relationship could be used to provide a single value, based on deliverable oxygen (dDO 2 ) vs. oxygen consumption (VO 2 ), that would simplify patient care. As previously explained, dDO 2  is the amount of oxygen transported to the tissue that is able to be delivered before the partial venous oxygen pressure (PvO 2 ) and, by implication, tissue oxygenation tension falls below a defined level. Thus, if it is desired that the PvO 2  value not fall below 40 (this number is variable for different patients depending on their general medical condition) then DO 2  (and by implication dDO 2 ) must be maintained at sufficient levels.  
      The supply/demand ratio (dDO 2 /VO 2 ) for a selected PvO 2  can be used to provide a single value showing that the amount of oxygen being administered is sufficient to maintain the desired oxygenation state. For example, if it is known that the dDO 2  required to maintain a PvO 2  of 40 is, say, 300 ml/min and the measured (VO 2 ) is 200 ml/min then the patient is being supplied with enough oxygen for his needs. That is, the supply/demand ratio is 300 ml/min÷200 ml/min or 1.5. A supply/demand ratio of 1 would imply that the PvO 2  (or other selected parameter i.e. SvO 2 ) was at the selected trigger value (here 40 mm Hg). Conversely, if the dDO 2  (deliverable oxygen) is 200 ml/min and the VO 2  (oxygen consumption) is 300 ml/min then the ratio is 0.66 and the patient is not receiving sufficient oxygen (i.e., the PvO 2  will be less than 40). Continuous monitoring and display of this ratio will allow the clinician to observe the value approaching unity and intervene appropriately.  
      A. Ventilator Data  
      Data concerning ventilator state information can be derived from most standard ventilators. For example, many ventilators have a standard RS232 serial port, where most data can be collected in either digital or analog form which can then be used to create the ventilator object displays which would display this information in a more intuitive manner. In other embodiments, ventilator&#39;s displays could include information, collected from arterial line sensors, concerning blood gases, pH, hemoglobin values and hemodynamic information such as heart rate, blood pressure, cardiac output and SVR. This data could be integrated with the patient&#39;s airway pressure and various compliance data and the system could be integrated to recommend tidal volume, PEEP, RR settings and FiO 2  adjustments to a desired oxygenation/ventilation target based upon this information. In the alternative, the ventilator could be peripherally managed by a computer system and act as a gateway for the distribution to computer information systems (“CIS”) and/or hospital information system (“HIS”) systems.  
                              Ventilator Inputs:                         cmH 2 O                                 Low   High   Max                                                     1.   PAP:   peak airway pressure   15   60   120           2.   P L P:   plateau pressure   15       120       3.   MAP:   mean airway pressure   15       120       4.   PEEP:   positive end expiratory   0   30   100               pressure       5.   RR:   respiratory rate/breathing   5       150   (min)               frequency       6.   I:E:   inspiratory to expiratory               (time ratio) (I time %)   10       80               (pause time %)   0       30       7.   TV I :   tidal volume inspiration   0       2000   ml       8.   TV E :   tidal volume expiration   0       2000   ml       9.   MV D :   minute ventilation delivered   0       20   l/min       10.   MV E :   minute ventilation expired       11.   ETCO 2 :   end tidal CO 2     10       80       12.   FiO 2 :   fraction inspired oxygen   21       100%       13.   Pa O 2 :   partial pressure oxygen       14.   C:   compliance       15.   EEF:   end expiratory flow                  
 
 IV. Object Displays 
 
      As discussed above, the computer system  455  of  FIG. 18  includes software and systems for displaying medical process diagrams relating the values derived or calculated above. The display system collects physiological values and creates object displays that are presented to the physician or other medical personnel. Although some of the data may be derived by reading raw analog or digital data from a patient monitor or other device, some of the values may be read from calculated data such as shown in TABLES 1-4 above.  
      The system might sample the data at 300 times per second, and update the display every 1 to 2 seconds. However, the system may be capable of higher sampling and display updates to provide the most up to date and accurate data.  
      As discussed above, the perceptual diagrams comprise a series of data objects representing physiological processes in the body. Examples of these data objects include an extended heart object, vascular circuit objects, cardiopulmonary bypass objects, ventilator state objects, mixed ventilator/lung objects and oxygenation objects.  
      These objects, as discussed below, can be displayed alone or together to provide a perceptual diagram.  
       FIG. 1  represents a conceptual overview  2  of the interrelationship of various factors of the oxygen cycle.  FIG. 1  demonstrates that ventilation, oxygenation and perfusion interrelate with the control (brain) and metabolism. The various factors are all interconnected and each factor influences the other factors.  FIG. 1  demonstrates that metabolism and control each affect one another and both metabolism and control affect ventilation, oxygenation and perfusion.  
      A. Extended Heart Object  
       FIG. 2  is an extended heart object display generally noted at  4 . The extended heart object display  4 , like the human heart, is divided into four chambers: a right atrium (“RA”) metaphor  6 ; a right ventricle (“RV”) metaphor  8 ; the left atrium (“LA”) metaphor  10 ; and, the left ventricle (“LV”) metaphor  12 . As with all of the object displays, the extended heart object  4  and portions thereof may be displayed in black and white, in color or both and various meanings can be assigned to whether the object or portion are displayed in black and white or in color (when medical standards exist, they can be adhered to—e.g., normal zones in green, caution in yellow, violations of alarm conditions in red, etc.).  
      The data inputs for constructing the extended heart object are all available cardiac performance parameters including: filling pressures such as pulmonary capillary wedge pressure (“PCWP”)  48  and central venous pressure (“CVP”)  47 ; echo data dimensions of the of the RA, RV, LA and LV; valvular data, including aortic stenosis (“AS”), aortic insufficiency (“AI”), mitral stenosis (“MS”), mitral regurgitation (“MR”), tricuspid stenosis (“TS”), tricuspid regurgitation (“TR”), pulmonic regurgitation (“PR”), pulmonic stenosis (“PS); septal holes, wall motion abnormalities, cardiac conduction data conveying heart rhythm information, electrocardiogram (“EKG”) data related to ischemia and echocardiogram data showing decreased contractility of the RV and LV, hypertrophy, and/or diastolic dysfunction. Data can be obtained through an EKG that depicts conduction of electrical activity in the heart, and echocardiography to measure blood flow into and between the heart chambers, ventricle compliance and valve conditions, and a pulmonary artery catheter can be used for obtaining data relating to PCWP and CVP.  
      The four chamber shaped heart of the extended heart object  4 , as shown in  FIG. 2 , is a reference frame for the “normal” relative proportion and anatomy of the human heart. In other embodiments, the heart could be represented as two, two chambered hearts for the pulmonary versus systemic regulations.  
      In the extended heart object, the RA, RV, LA and LV of the heart can expand or contract to show the filling state of the individual chambers. For example, in  FIG. 2 , the RV  8  and the LV  12  are in a filled state. This is demonstrated by the outward bulging of the individual chambers. If the filling pressures were low, the CVP and PCWP meters would point inwards and the display would show the RV and LV chambers to be scalloped inwards. The shape of the chambers conveys the status of FULL vs EMPTY. Located in-between the RA  6  and the RV  8  on the far left is a CVP meter  47  which moves in conjunction with the filling state of the RV  8 . For example, if the RV is overfilled, the CVP meter  47  moves from the twelve o&#39;clock position toward the eleven o&#39;clock position or beyond. If the RV is under filled (not shown), the CVP meter moves from the twelve o&#39;clock position to the one o&#39;clock position or beyond. At the bottom of the LV chamber is the PCWP meter  48  which, like the CVP meter  47 , moves according to the filling state of the LV  12 .  
      Vertical lines ( 14  and  32 ), extending into and away from the heart chambers, illustrate the flow in and the flow out of blood from the various chambers. For example, global direction of flow is shown by the four arrows  14  from the RA  6  to the RV  8  through the tricuspid valve  16 . The four arrows from the RA  6  to the RV  8  represents normal flow from the RA  6  to the RV  8 . Mild regurgitation could be represented by three arrows in one direction and one arrow in the opposite direction. Arrows pointing in opposite direction as shown at  32  in  FIG. 2 , can have the following meanings: one arrow in the opposite direction to flow represents regurgitation (mild regurgitation); two arrows in the opposite direction represent (as shown at  32  in  FIG. 2  at the mitral valve) represents two plus regurgitation (moderate regurgitation) and three arrows in the opposite direction represents three plus (severe regurgitation) [standard terms used in quantifying valve function from echocardiogram studies].  
      Also shown in  FIG. 2  is sinus node  20  with conduction/rhythm information in the form of waves emanating outwardly in synchronization with an EKG trace.  
      Extending from the sinus node  20  is the arterial bundle  22 . Extending into the RA  6  is the venacava vein  24 , extending from the RV  8  is the pulmonary artery  26 , extending into the LA  10  is the pulmonary vein  28  and extending from the LV  12  is the aorta  44 .  
      In the middle of the extended heart object  4  is a bold vertical line representing the septum  34 . In the middle of the septum  34  is an oval shaped object  36  which represents the Atrio-ventricular node (AV-Node) and is intersected by the ventricular bundle (bundle of His  22 ). To the left of the septum  34  in the RV  8  is an elongated, rectangular shaded box  38  which represents the compliance state of the right ventricle. A reference box depicting the normal width is the same as the shaded box and therefore not visible. To the right of the septum  34  in the LV  12  are two vertically oriented rectangular, shaded boxes  40 A and  40 B, which illustrates non-compliant left ventricle because the shaded area extends beyond the reference box width that conveys the normal compliance state. Greater than normal compliance would be shown as a shaded area narrower than the reference box. Typically the reference box would be shown in a different color, such as purple. that would make it easy to see the patient state relative to the normal. As noted, to the left of the septum  34  is an another elongated, rectangular shaded box  38  and this represents a normal right ventricle. The RV and LV can be represented as being of normal, increased or decreased compliance.  
      Inside the two vertically oriented rectangular boxes  40 A and  40 B is a slightly offset triangle  42 , shaded in color wherein the size of triangle  42  changes based on ischemic changes in the EKG in relation to ST-changes which show various conditions such as angina or ischemia.  
      Below LV  12  and extending from the extended heart object  4  is an  10  example of stenosis of the aortic valve  44 . The one arrow extending from the aortic valve  44  shows obstructed blood flow. Separating the aortic valve  44  and the LV  12  are two, side-by-side, bolded, horizontally oriented rectangles  46 A and  46 B which represent a thickened aortic valve. Thickening of any valve would be shown in the same manner. The extended heart object  4  of the present invention mimics the human heart and displays information in an intuitive manner to physicians or other medical personnel allowing for the display of a large quantity of information in a simplified manner.  
      Referring now to  FIG. 3 , the process of updating the extended heart object begins when a start signal is transmitted by the user at start state  5 . The start signal can be a keystroke or a mouse command that initiates the software to begin collecting data. After receiving the start command at state  5 , the process moves to a state where the stroke volume (“SV”) is read. The stroke volume can be read from a table or buffer in the computer system. After the SV is read, the process moves to a state  9  where the heart rate (“HR”) is read.  
      Once data has been collected from a patient at any state, for example state  9 , a “data in range” decision can be made. That is, the software compares the data collected at a given state. e.g., state  9 , with known appropriate heart rates for a particular patient or previous heart rates read from previously collected data. If data at a given state, such as state  9 , is not within preprogrammed ranges or are completely anomalous (i.e., out of range of any possible human heart rate), an error/exception handling routine can be initiated and the process begins again. The error/exception handling routine loops the software back to process step  9  and begins again. In this manner, false or erroneous information is not fed into the rest of the program. If data collected at a given state in appropriate ranges, the software pointer moves to the next process state.  
      After the HR is read, the process then moves to a state  11  where central venous pressure (“CVP”) filling pressure is read. Like HR, CVP filling pressure may be collected from an EKG. A decision is then made at decision state  13  whether the CVP has changed since the last reading. If the CVP has changed, a determination is made at decision state  15  whether the CVP has increased or decreased. if the CVP has decreased, the process moves to a state  17  where the CVP meter is moved to the right and the outer boundary of the right ventricular metaphor moves inward to indicate a less filled right RV. In the alternative, if at decision state  15  the determination is made that the CV? has increased, the process moves to state  19  where the CV? meter is moved to the left and the outer boundary of the right ventricular metaphor moves outward to indicate a swollen or overfilled RV.  
      The process then moves to a state  21  where the pulmonary capillary wedge pressure (“PCWP”) is read. The process then moves to a state  23  to determine whether the PCWP has changed since the last reading. If the PCWP has changed, a determination is made at state  25  as to whether the PCWP has increased or decreased. if the PCWP has decreased, the process moves to state  27  where the PCWP meter is moved to the left and the outer boundary of the LV heart chamber moves inward, or to the left, to indicate an under filled LV. If the value of the PCWP has increased, the process moves to state  29  where the PCWP meter is moved outward, or to the right, and the outer boundary of the LV metaphor moves outward to indicate an overfilled or swollen LV.  
      The process then moves to decision state  31  where the valve function from RA to RY is read. The process then moves to a state  33  where a determination is made whether the valve function from the RA to the RV has changed since the last reading. If the valve function has changed, the process moves to state  35  where if the valve flow has decreased, the process moves to state  37  where the number of lines extending from the RA to the RV through the tricuspid valve is decreased and bars showing stenosis are extended. If the valve flow from the RA to the RV has increased, the process moves to state  39  where if the valve function has increased, the number of lines extending from RA to RV through the tricuspid valve is increased and the bars of stenosis are shortened.  
      The process then moves to state  41  where the valve function from the RV through the pulmonary artery (“PA”) is read. The process then moves to a state  43  where a determination is made whether the valve function from the RV through the pulmonary artery has changed since the last reading. If the valve function has changed, the process moves to state  45  to determine whether the valve flow has increased or decreased. If the valve flow has decreased, the process moves to state  47  where the number of lines extending from the RV through the pulmonary artery is decreased and bars showing stenosis are extended. If the valve flow has increased, the process moves to state  49  where the number of lines extending from the RV through the pulmonary artery is decreased and the bars of stenosis shortened.  
      The process then moves to state  51  where valve function from the LA to the LV through the mitral valve is read. The process then moves to a state  53  where a determination is made whether the blood flow from the LA to the LV has changed since the last reading. If the valve function has changed, the process moves to state  55  to determine whether the blood flow has increased or decreased. If the valve flow has decreased, the process moves to state  57  where the number of lines extending from the LA to the LV through the mitral valve is decreased and bars showing stenosis are extended. If the valve flow has increased, the process moves to state  59  where the number of lines extending from the LA to the LV through the mitral valve is decreased and the bars showing stenosis are shortened.  
      The process then moves to state  61  where valve function from the LV through the aortic valve  44  is read. The process then moves to a state  63  where a determination is made whether the valve function from the LV through the aortic valve has changed since the last reading. If the valve flow has changed, the process moves to state  65  to determine whether the valve flow has increased or decreased. If the valve flow has decreased, the process moves to state  67  where the number of lines extending from the LV through the aortic valve is decreased and the bars of stenosis are extended. If the valve flow has increased, the process moves to state  69  where the number of lines extending from the LV through the aortic valve is decreased and the bars of stenosis are shortened. If ST-changes are present on EKG, a triangle will be shown that represents a region of ischemia. The process then moves to state  89  where right and left ventricular compliance are read. The process then moves to state  91  where it is determined whether either the left ventricle or right ventricle has become less compliant (stiffened or thickened). If it is determined that either or both the RV or LV have become less compliant, the process then moves to state  93  to determine which or whether both ventricles have thickened. If either or both the RV or the LV have been identified as having thickened, rectangular boxes  38  and  40  are increased in width. This is shown in  FIG. 2  where two rectangular boxes,  40 A and  40 B are shown to illustrate a mildly noncompliant RV and a moderately noncompliant LV. The process then ends at an end state  97 .  
      B. Vascular Circuit Object  
       FIG. 4  shows a vascular circuit object  52  which visually illustrates the oxygenation circuit of blood as it is pumped from the RA  6  and RV  8  of the heart  4  to the alveolus  54  back through the LA  10  and LV  12  of the heart  4  for oxygenation of the cell/tissues  56 . Arrows depict the direction of the flow of blood from the RV  8  to the alveolus  54  and through the LV  12  to provide oxygen to the cell/tissues  56 . The vascular resistor objects ( 58  and  76 ) are used by medical personnel to optimize the hemodynamic physiology of patients during surgery.  
      Located between the heart object  4  and the alveolus object  54  is a pulmonary vascular resistor object  58  which measures blood flow as it leaves the RV  8 . Both vascular resistor objects  58  and  76  are used to display the blood flow equivalent of Ohm&#39;s law and represents the following equations: 
 
(Mean Arterial Pressure)−(Central Venous Pressure)=(Cardiac Output)×(Systemic Vascular Resistance); and 
 
(Mean Pulmonary Arterial Pressure)−(Pulmonary Capillary Wedge Pressure)=(Cardiac Output)×(Pulmonary Vascular Resistance). 
 
      This data is displayed into linear scales relating to the pressure gradient for blood flow in the form of a “pipe” shaped object which is the pulmonary vascular resistor object  58  wherein blood flow is from right to left. A set of two Y axes,  60  and  62 , produce the pipe shape of the vascular resistor object  58 . Right Y axis  60  includes a mean arterial pressure (MAP) indicator  64  and a central venous pressure (CVP) indicator  66  which are in the form of diamond shaped objects. The distance between the MAP indicator  64  and the CVP indicator  66  indicates the blood input area  68  and represents the flow of blood into the pipe. A left Y axis  62  includes a cardiac output (CO) indicator  70  which reflects the calculated or measured cardiac output of the patient. As the cardiac output of the patient increases, the distance between the horizontal line intersecting the CO indicator and parallel X-axis beneath the CO increases as CO increases and the distance decreases as CO decreases.  
      Upstream of pulmonary vascular resistor object  58  is red blood cell object  72 . Red blood cell object  72  reflects the level of oxygenation of the arterial blood prior to the blood reaching the alveolus  54 . Arterial Oxygenation Content=(Arterial Oxygen Saturation)×(Hemoglobin)×(1.34). As displayed in  FIG. 4 , the amount of shading of the blood cell object  72  shows the percentage of oxygenation of the blood. As shown at  72  in  FIG. 3 , less than half of the blood is oxygenated (when less than half shaded, the cell is only half filled with oxygen).  
      As the blood passes through the lungs the blood becomes oxygenated. This is illustrated in  FIG. 4  by the placement of the alveolus  54  between the left blood cell object  72  and the right blood cell object  74 . Right blood cell object  74  illustrates the level of oxygenation of venous blood oxygenated by the lung  54 . As with red blood cell object  72 , the level of oxygenation of the blood leaving the alveolus is indicated by the percentage of shading of red blood cell  74 . Both red blood cell objects mimic the in vivo state of oxygenation of the blood and are thus intuitive to physicians.  
      The blood then passes through the LA and the LV of the heart. As the blood leaves LV  12 , it passes through systemic vascular resistor object  76  which operates in the same manner as described with pulmonary vascular resistor object  58 . MAP indicator  78  and CVP indicator  80  represents the blood input area and represents the inflow of blood into the pipe. CO indicator  82  represents the calculated or measured cardiac output of the patient.  
      An alternative embodiment of the vascular circuit is shown in  FIG. 5 . In this embodiment, the extended heart object is omitted. In its place is an abbreviated heart object showing only the right ventricle (“RV”) object  86 . Blood flow is indicated by an arrow between the cell/tissue object  84  and RV object  86 . In this embodiment, the chambers of the heart are split with the LV  96  downstream. Blood flow leaves RV  86  and enters into a pulmonary vascular resistor object  88  which functions in the same manner as vascular resistor object  58  of  FIG. 4 . Vascular resistor object  88  is used to display the blood flow equivalent to Ohm&#39;s law and the data is visually displayed in the form of object  58  as a “pipe” shaped object wherein blood flow is from right to left. The area inside the pipe can be darkened to represent the represent the inflow of blood into the pipe and to aid visually. Both vascular resistance objects of  FIG. 5  can have a MAP, CVP and CO indicators in the same manner as vascular resistor objects  58  and  76  of  FIG. 4 .  
      Downstream of the RV is a red blood cell object  90  which indicates the level of oxygenation of the blood leaving the RV which, as previously described, is visually indicated by the amount of shading of the red blood cell object  90 . Further downstream from the red blood cell object  90 , beyond alveolus  94 , is a second red blood cell object  92 . Red blood cell object  92  shows that the blood, at this point in the vascular circuit, is almost completely oxygenated. This is of course due to the fact that the blood is oxygenated by alveolus  94  located between the red blood cell objects  90  and  92 .  
      Downstream from the red blood cell object  92  is LV  96  where blood passes through to the systemic vascular resistance object  98 . Vascular resistance object  98  operates in a similar manner as the vascular resistance object  76  shown in  FIG. 4 . Blood flow is from the left to right and the widened area of the “pipe” illustrates a large inflow of blood to the and the narrowed darkened portion of the pipe represents the flow of blood from the to the cells/tissue  84 . Blood then leaves the cell/tissue  84  area and enters the RV  86  and the cycle is repeated.  
      In an one embodiment, all of the information of extended heart object  2  is incorporated into the Vascular Circuit Object  52  in  FIG. 4  and can be displayed. This information could be accessed or suppressed at the desire of the user.  
      Referring to  FIG. 6 , a process of updating the Vascular Circuit Object is described. The process begins at start state  105  and then moves to a state  107  wherein the mean arterial pressure (MAP) is read. A determination is made at decision state  109  whether the MAP has changed since the last reading. If the MAP has changed, the process moves to state  111  to determine whether the MAP has increased or decreased. If MAP has decreased, the process moves to state  113  where MAP indicator  64  is moved downward along Y-axis  60 . If a determination was made at state  111  that MAP has increased, the process moves to state  115  where the MAP indicator moves upward along Y-axis  60 .  
      The process then moves to state  117  wherein the central venous pressure (“CVP”) of the patient is read. A determination is made at decision state  119  whether the CVP has changed since the last reading. If the CVP has changed, the process moves to state  121  to determine whether the CVP has increased or decreased. If the CVP has decreased, the process moves to state  123  wherein the CVP indicator  66  moves down Y-axis  60 . If the CVP has increased, the process moves to state  125  where the CVP indicator  66  moves up Y-axis  60 .  
      The process then moves to state  127  where the cardiac output (CO) is read. A determination is made at state  129  whether or not the CO has changed since the last reading. If the CO has changed, the process moves to state  131  to determine whether the CO has increased or decreased. If the CO has decreased, the process moves to state  133  wherein the cardiac output indicator  70  is moved downward along Y-axis  62 . If a determination is made at state  131  that the CO has increased, the process moves to state wherein the cardiac output indicator  70  moves up Y-axis  62 .  
      The process then moves to a state  137  where it reads the CaO 2  value of the blood prior to the blood being oxygenated by the lungs. This value could be read from a data table or from any type of memory storage in the computer system. Once the CaO 2  values are read, the process moves to state  139  to determine whether the CaO 2  value has changed from the last reading. If the CaO 2  value has changed, the process moves to state  141  to determine whether the CaO 2  value has increased or decreased since the last reading. If the CaO 2  value has decreased, the process moves to state  143  and the level of shading of red blood cell object  72  is decreased. However, if the process determined that the CaO 2  value has increased, the process moves to state  145  where the level of shading of red blood cell object  72  is increased.  
      The process then moves to state  147  where the CvO 2  value of the blood is read after the blood is oxygenated by the lungs. This value could be read from a data table or from any type of memory storage in the computer system. Once the CvO 2  value is read, the process moves to state  149  to determine whether the CvO 2  value has changed since the last sampling. If the CvO 2  value has changed, the process moves to state  151  to determine whether the CvO 2  has increased or decreased since the last reading. If the CvO 2  value has decreased, the process moves to state  153  and the level of shading of red blood cell object  74  is decreased. However, if the process determines that the CvO 2  value has increased, the process moves to state  155  where the level of shading of the red blood cell object  74  is increased.  
      Returning to  FIG. 4 , the blood then passes through LA  10  and LV  12  of Vascular Circuit  52  and then the process moves to systemic vascular resistor object  76 .  
      Systemic vascular resistor object  76  works in the same manner as pulmonary vascular resistor object  58  and the process steps will not be repeated again.  
      C. Cardiopulmonary Bypass Object  
      As shown in  FIG. 7  is a cardiopulmonary bypass object  102 . The cardiopulmonary bypass object  102  illustrates information on the oxygenation of blood diverted from the heart during a cardiopulmonary bypass procedure. The cardiopulmonary bypass object  102  is comprised generally of three components (reading right to left in  FIG. 7 ): 1) a venous reservoir object  104 ; 2) a roller pump object  106 ; and, 3) an oxygenator object  108 .  
      The venous reservoir object  104  graphically illustrates the quantity of blood in the venous reservoir. In the illustration of  FIG. 7 , a diamond shaped marker  110  shows the level of stored venous blood and moves up and down metered scale  104  as the volume of blood fluctuates. Blood flow moves from the venous reservoir  104  to the roller pump object  106 . Roller pump object  106  depicts the state of the pump as either being “off” or “on” by showing the roller  112  rotating clockwise or counter clockwise when “on” or static or unmoving when the pump is “off”. The roller  112  rotates clockwise or counter-clockwise depending on where the pump is located and the underlying global direction of blood flow. Total blood flow from the roller pump object is depicted by a diamond shaped marker  114  which, in the example of  FIG. 7 , has the number 5.1 located therein which depicts 5.1 L/min blood flow into the oxygenator object  108 . Horizontally extended lines  116  extending from roller pump to the oxygenation object  108  also depict blood flow. Five (5) arrows are shown which roughly corresponds to the 5.1 number in diamond shaped marker  114  representing 5.1 liters per minute of blood flow to oxygenator object  108 .  
      Intersecting diamond shaped marker  114  is a bold line  118  oriented above and parallel to the five (5) arrows  116 . Line  118  connects the roller pump object  106  to the blood oxygenator object  108  and also intersects and moves up and down a vertically oriented scale  120 . Scale  120  is metered (L/min) to show blood flow from the roller pump object  106  to the blood oxygenator object  108 . The shorter dashed lines  122  pointing to scale  120  show potential unused blood flow. As blood flow increases, horizontal bold line  118  moves vertically upward in a Y-axis direction (but remains horizontally oriented) and shorter dashed lines  122  lengthen and become solid lines and pass through under bold line  118  illustrating actual blood flow. As blood flow decreases, horizontal bold line  118  moves vertically downward and lines  116  shorten into shorter dashed lines  122 .  
      Blood flow is then shown moving from the roller pump object  106  to oxygenator object  108  as shown by the bold arrow  109  (which is a static line) moving through the top of oxygenator object  108 . Oxygenator object  108  graphically illustrates the relationship of blood flow and gas flow and concentration across a diffusion surface represented by the dashed line. Two sets of vertically oriented rectangles  124 A,  124 B and  126 A,  126 B, side-by-side, measure blood flow, gas flow and gas concentration. For example,  124 A is metered to measure arterial carbon dioxide concentration (PaCO 2 ) in the bloodstream while  124 B is metered to measure gas flow (oxygen) into the bloodstream.  126 A measures fraction of inspired oxygen in the blood stream (FiO 2 ) and  126 B measures mixed arterial oxygen tension (PaO 2 ). Two diamond shaped markers, one ( 128 A) measuring mixed arterial carbon dioxide tension PaCO 2  and the other gas flow ( 128 B) are shown and can be connected by a horizontal line which helps the user visualize the interrelationship of the PaCO 2  parameter of the blood and gas flow. Two other markers visually displaying FiO 2    130 A and the other marking displaying PaO 2  ( 130 B) are also displayed.  
      In an alternate embodiment, a meter could be displayed, adjacent or near the PaCO 2  meter, for measuring in real time the amounts of the anesthetic isoflourine both administered and respired. In the same manner as with the other meters for measuring various values, a marker could be used for measuring the amounts of administered isofluorine and another marker for measuring amounts of expired isoflourine. Both markers would move vertically up and down the meter (which would measure isolfluorine in ml/L). When the meters indicate two different values, this would indicate to the physician that the administered and measured isofluorine amounts are different telling the physician the amount of anesthetic in the patient.  
      Referring to  FIG. 8 , a process for updating Cardiopulmonary Bypass Object  102  is described. The process begins at start state  171  and then moves to state  173  wherein the level of stored venous blood in venous reservoir  104  is read. The process then moves to state  175  wherein the process determines whether the level of stored venous blood has changed since the last reading. If the level of stored venous blood has changed, the process moves to state  177  to determine whether the level of stored venous blood has increased or decreased. If the level has decreased, the process moves to state  179  where if the level of stored venous blood has decreased, diamond  110 , which acts as a marker along the venous reservoir object  104 , moves downward along venous reservoir object  104 . If it is determined that the level of stored venous blood has increased, the process moves to state  181  where the diamond  110  moves upward along object  104 .  
      The process then moves to state  183  where a determination is made whether the pump is activated. If the pump is not activated, the process moves to state  187  where object  112  is made stationary. However, if the pump is activated, that is “turned on”, the process moves to state  189  where the pump object rotates in the clockwise direction.  
      The process then moves to state  191  where the quantity of blood flow from roller pump object  106  to oxygenator object  108  is read. The process then moves to state  193  where it is determined whether the amount of blood flow from roller pump object  106  to oxygenator object  108  has changed. If it is determined that there has been a change, the process moves to state  195  where a determination is made whether the amount of blood flow from roller pump object  106  to oxygenator object  108  has increased or decreased. If it has decreased, the process moves to state  197  and line  118 , along with marker  114 , move down scale  120  in the Y direction and the number of horizontally extended arrows  116 , which correspond to the liters of blood flow from the roller pump object  106  to the blood oxygenator object  108 , are decreased accordingly. If the blood flow from roller pump object  106  to the blood pump object  108  has been determined to have increased at state  195 , the process moves to state  199  and the line  118 , along with marker  114 , are moved upward along meter  120  in the Y direction and the number of horizontally extended arrows  116  are increased accordingly.  
      The process then moves to state  201  where the PaCO 2  value of the blood is read. The process moves to state  203  where it is determined if the PaCO 2  value has changed. If the value has changed, the process moves to state  205  where it is determined whether the PaCO 2  value has increased or decreased. If the PaCO 2  value has decreased, the process moves to state  207  where diamond marker  128 A lowers along meter  124 A and reflects the appropriate PaCO 2  value. If it is determined that the PaCO 2  value has increased, the process moves to state  209  where diamond shaped marker  128 A raises along meter  124 A to reflect the updated PaCO 2  value.  
      The process then moves to state  211  where the gas flow, as shown in  FIG. 7 , is read. The process then moves to state  213  where it is determined whether the gas flow has changed since the last reading. If the gas flow has changed, the process moves to state  215  where it is determined whether the gas flow has increased or decreased. If the gas flow has decreased, the process moves to state  217  where marker  128 B, which marks the flow of gas as shown by meter  124 B, is lowered along meter  124 B to the sampled gas flow measurement. However, if it is determined that the gas flow has increased, the process moves to state  219  where marker  128 B is raised along meter  124 B to the corresponding value.  
      The process then moves to state  221  where the FiO 2  value of blood is read. The process then moves to state  223  where it is determined whether the FiO 2  value of the blood has changed since its last reading. If it has changed, the process moves to step  225  where it is determined whether the FiO 2  value has increased or decreased since the last sampling. If it has decreased, the process moves to state  227  where marker  130   a  is lowered along meter  126 A in the Y direction to the appropriate reading. If it is determined at state  225  that the FiO 2  value has increased, the process moves to state  229  and marker  130 A moves upward along meter  126 A to the corresponding FiO 2  value reading.  
      The process then moves to state  231  where the PaO 2  value is read. A determination is then made at decision state  235  whether the PaO 2  value of the blood has increased or decreased since the last sampling. If it is determined that the PaO 2  value has changed, the process moves to state  237  where it is determined whether the PaO 2  value has increased or decreased. If it is determined that the PaO 2  value has decreased, the process moves to state  239  where marker  130 B, which marks the PaO 2  value along meter  126 B, is lowered along meter  126 B to mark the last measured PaO 2  value. If it determined at state  237  that the PaO 2  value has increased, the process moves to state  241  and marker  130 B is raised to the appropriate PaO 2  value along meter  126 B.  
      D. Ventilator State Object  
      As shown in  FIG. 9  is Ventilator State Object  140 . Ventilator State Object  140  has two major components: a volume ventilator object  142  and a pressure ventilator object  144 . Many ventilators are either volume or pressure ventilators and some ventilators are mixed volume/pressure. The object display of  FIG. 9  allows physiological display information as to both types of ventilators or a mixed volume-pressure ventilator. However, when in a volume mode, the pressure ventilator settings are shaded gray or shaded in another color. Likewise, when in a pressure mode, the volume ventilator settings are shaded gray or shaded in another color.  
      The volume ventilator object  142 , which may be used in conjunction with a standard volume ventilator, is comprised of a rectangular box  146  which displays information related to respiratory rate (“RR”), breath cycle time (“BCT”), inspiration time (“I”), expiration time (“E”), I:E ratio and volume setting of the ventilator. Much of this data can be obtained from the RS232 serial ports on most ventilators.  
      A shaded rectangle  247  is divided between a darker shaded portion  148  which represents inspiratory time and another more lightly shaded portion of the rectangle  150  which represents expiratory time  150 . Both inspiratory and expiratory time added together equal breath cycle time “BCT” which is shown in lower BCT meter  152 .  
      As shown in  FIG. 9 , the I portion of the BCT is 1 second with the shading between the three and four second mark. The expiratory time portion (“E” portion) is 1.5 seconds (1/1.5 I:E ratio) which is the difference between 4 and 5.5 seconds of the BCT meter. Marker  154  shows the division between inspiratory time and expiratory time of the breath cycle. As the breath cycle shortens or lengthens based upon volume settings, rectangle  247  will also shorten or lengthen.  
      Above BCT meter  152  is respiratory rate (“RR”) meter  162 . Respiratory rate is defined as the number of breaths per minute and is set by the physician on the ventilator. In  FIG. 9 , the RR is set at 10 breaths/minute as is seen on the RR meter  162 . The lower the respiratory rate, the longer the BCT. Square marker  156  gives the user a clear indication between BCT and RR.  
      Above rectangular box  146  is a bellows object  158  which visually displays the volume of air being pushed into the lungs. In the case of  FIG. 9 , 700 cubic centimeters of air are shown as being pushed into the lungs by the ventilator. Marker  160  gives a clear indication of the setting of the ventilator.  
      Pressure ventilator object  144  is an alternate ventilator object useful with pressure ventilators. Located within the pressure ventilator object  144  is a propeller object  262  which rotates in the counter-clockwise direction to illustrate flow of air from the pressure ventilator to the patient. When the pressure ventilator is off or not functioning, the propeller object  262  is static and does not rotate. In an alternative embodiment, the rotational velocity of the propeller object  262  can indicate the level of air flow from the pressure ventilator to the patient.  
      Flow from the pressure ventilator to the patient is illustrated in the series of horizontal lines  164  extending from the pressure ventilator object  144  to the patient. The six horizontal lines indicate that 60 liters/min of air is flowing from the pressure ventilator to the patient. This is also illustrated by the diamond shaped object  166  which displays the number of liters of air per minute which is flowing to the patient. Horizontal bold line  168  intersects object  166  and the line  168  moves up and down depending on air flow to the patient.  
      The series of four horizontal lines  170  adjacent to propeller object  262  and above horizontal lines  164  illustrate potential unused air flow. Meter  172  also illustrates the quantity of liters of air per minute to the patient. The series of horizontal lines  164  are only displayed during inspiration of the patient&#39;s breath. During inspiration, the horizontal lines are turned off and are not shown.  
      To the right of object  166  is valve  174  which is closed while the patient is inspiring and open when the patient is expiring (when the pressure ventilator is activated). At the right hand side of the pressure ventilator object  144  is a meter  176  for displaying peak inspiratory pressure (“PIP”) and mean airway pressure (“MAP”). Meter  176  has a diamond shaped object  178  for displaying PIP levels and a diamond shaped object  180  for displaying MAP levels. Both objects move up and down meter  176  depending on the PIP and MAP levels. PIP and MAP levels are sometimes set by the physician depending on the ventilation mode.  
      Beneath the PIP and MAP indicators is positive end expiratory pressure (“PEEP”) indicator  182 . PEEP may be a triggered setting (patient initiated setting) which is indicated by the presence of box  184  which has a “T” inside of the box. PEEP can also be measured wherein the PEEP indicator  182  would be diamond shaped and box  184  would not be shown. When measured, diamond shaped PEEP indicator  182  moves vertically up and down meter  176 .  
      Beneath pressure ventilator object  144  is meter  186  which provides information on respiratory rate (“RR”) and breath cycle time (“BCT”) of the pressure ventilator in the same manner as with the volume ventilator. In an alternative embodiment, a similar configuration of the volume ventilator or pressure ventilator object can be positioned over the volume ventilator  142 .  
      Referring to  FIG. 10 , the process starts of modulating the ventilator state object starts at  261 . The process moves to state  263  where it is determined whether the ventilator is a volume ventilator, pressure ventilator or a mixed volume/pressure ventilator. If the process determines that it is a pressure ventilator, the process moves to state  283 . If the process determines that it is a volume ventilator, the process moves to state  265  where the process reads the volume of air being delivered to the patient&#39;s lungs. As stated previously, the volume of air pushed into the patient&#39;s lungs is a set parameter. After reading the volume, the process moves marker  160  to the corresponding reading on bellows object  158 . The process then moves to state  269  and reads the respiratory rate (“RR”) set by the physician. The process then moves to state  271  where marker  156  is moved to correspond to the RR along meter  162 . The process then moves to state  273  where inspiratory and expiratory times are read. The process then moves to state  275  where breath cycle time (the sum of inspiratory and expiratory time) is displayed on meter  152 . The process then moves to state  277  where the inspiratory/expiratory (“I:E”) time ratio is read. The process then moves to state  279  where the I:E ratio is displayed.  
      If the ventilator is only a volume ventilator, the process moves to end state  281 . If the ventilator is a pressure ventilator the process moves from state  263  to state  283 . Or, if the ventilator is a mixed pressure/volume ventilator, the process moves from state  279  to state  283 . At state  283 , the process determines if the pressure ventilator is on. If the pressure ventilator is off, the process moves to state  285  where propeller object  262  is made stationary. If the pressure ventilator is on, the process moves to state  287  where the propeller object  262  is rotated in the counter-clockwise direction. The process then moves to state  289  where air flow to the patient is read. The process then moves to state  291  where it is determined if the air flow has changed. If the air flow has changed, the process then moves to state  293  where it is determined whether the airflow has increased or decreased. If the airflow has decreased, horizontal line  168  along with air flow marker  166  is moved downward along meter  172 . If it is determined at state  293  that the air flow has increased, the process moves to state  297  and horizontal line  168  and marker  166  are moved up meter  172  to reflect the sampled air flow.  
      The process then moves to state  299  where the peak inspiratory pressure (“PIP”) is read. The process then moves to state  301  where it is determined whether the PIP has changed. If the PIP has changed, the process moves to state  303  where it is determined whether PIP has increased or decreased. If PIP has decreased, the process moves to state  305  where the PIP indicator  178 , moves downward along meter  176 . If it is determined at state  303  that PIP has increased, the process moves to state  307  where PIP indicator  178  moves up meter  176  to reflect the PIP reading.  
      The process then moves to state  309  where the mean airway pressure (“MAP”) is read. The process then moves to state  311  where it is determined whether the MAP has changed. If the MAP has changed, the process moves to state  313  where it is determined whether the MAP has increased or decreased. If the MAP has decreased, the process moves to state  315  where MAP indicator  180  is moved down meter  176 . If it is determined at state  313  that the MAP has increased, the process moves to state  317  and MAP indicator  180  is moved up meter  176  to reflect the higher MAP value.  
      The process then moves to state  319  where the system determines if the PEEP is patient triggered. If the PEEP is not patient triggered, the process moves to state  321  where box  184  is not displayed. If it is determined that PEEP is patient triggered, the process moves to state  323  where box  184 , with the letter “T” located therein indicating that PEEP is patient triggered, is displayed.  
      The process then moves to state  325  where PEEP is read. The process then moves to state  327  where it is determined whether PEEP has changed. If PEEP has changed, the process moves to state  329  where it is determined whether PEEP has increased or decreased. If PEEP has decreased, the process moves to state  331  and PEEP indicator  182  is lowered along meter  176 . If it is determined that PEEP has increased, the process moves to state  333  where PEEP indicator  182  moves upward along meter  176  to reflect the PEEP reading.  
      The process then moves to state  335  where respiratory rate (“RR”), which is set by the physician, is read. The process then moves to state  337  where RR is displayed at  186 . The process then moves to state  339  where breath cycle time (“BCT”) is read. The process then moves to state  341  where BCT is displayed at  186 . The process then moves to end state  343 .  
      E. Combined Lung and Ventilator Object  
      In  FIGS. 11-13  are objects displaying information concerning airway resistance and ventilator data. In  FIGS. 11-13 , combined lung and ventilator object  190  displays information such as tidal volume inspired (“TVI”), tidal volume expired (“TVE”), respiratory rate (“RR”), peak inspiratory pressure (“PIP”), positive end respiratory pressure (“PEEP”), lung compliance, information on CO 2  elimination, and information as to both pressure and volume ventilators.  
      Inside combined lung and ventilator object  190  is lung object  240 . Lung object  240  provides physicians with information concerning TVI and TVE (located behind the TVI diamond when TVI and TVE are the same) which are displayed by diamond shaped markers  192  (TVI) and  196  (TVE)(Not shown in  FIG. 11 ). Markers  192  and  196  move up and down meter  194  and displays to a physician the amount of air inhaled and exhaled by a patient. As shown at  198 , each breath for a total duration of a minute (longer intervals can be displayed) are displayed at  198  between meter  194  and  216 . Meter  216 , forming an X-axis, measures respiratory rate (“RR”) which is measured in breaths per minute. As shown in  FIG. 11, 10  breaths are displayed by vertically oriented columns  198  located above meter  216  which provides for an RR of 10 breaths/minute. Each breath is represented by a an elongated, vertically oriented column. There are a series of columns  198 , each of which conveys certain information to a physician. For example, the first column at  198  shows that the first breath had a TVI and a TVE of slightly above a volume of 500 ml. All other subsequent breaths had TVI and TVE of 1000 ml. The object can also display discrepancies between TVI and TVE. For example, in  FIG. 12 , the second breath shows a slightly lower TVE than TVI. This difference between TVI and TVE might indicate that air is being lost possibly through a leak in tubing or even a hole in the lung.  
      Lung object  240  is surrounded by a pair of curved outer boundaries  204  which represent the lungs. In  FIG. 11 , it is a thin boundary and represents a normal lung. However, in  FIG. 12 , outer boundaries  204  are thickened and represent diseased noncompliant lungs. Located adjacent the upper boundary  204  is meter  226  which measures compliance of the lungs. In  FIG. 1 , which illustrates compliant lungs, compliance is shown to be slightly above 120 ml/cm H 2 O. However, in  FIG. 12 , which shows a noncompliant lung, lung compliance is shown to be slightly above 60 ml/cm H 2 O.  
      Upstream from lung object  240  is an airway resistance object  208  which conveys information to a physician or user concerning resistance in the respiratory tract. Airway resistance object  208  uses a “pipe” shaped metaphor to convey information concerning resistance to air inspiration and expiration in the respiratory tract. Part of the pipe shaped metaphor, section  210 , contracts or levels off depending on whether blockage or resistance is encountered. For example, in  FIGS. 11 and 12 , section  210   b  is contracted or narrowed and could represent a bronchospasm, mucous plug or a tube with a kink. Located within airway resistance object  208  are PIP, mean airway pressure (“MAP”) (not shown) and PEEP indicators which, in the same manner as the ventilator state object of  FIG. 9 , display values for these parameters. Diamond marker  218  displays the PIP value on meter  224 . Diamond marker  220  displays Pplateau (behind the PIP diamond) on meter  224 . Rectangular marker  222  displays the PEEP value on meter  224 . PEEP marker  222  is rectangular shaped rather than diamond shaped to indicate that it is a physician set parameter rather than a measured patient parameter. When the PIP minus Pplateau are large, as is the case when obstruction to airflow is present, the resistor object will show narrowing as in  FIG. 13 .  
      Pressure ventilator object  212  (see  FIG. 11 ) is virtually the same as pressure ventilator object  144 . Located within pressure ventilator object  212  is propeller object  262  which as shown in pressure ventilator object  144 , rotates counter clockwise when there is flow of air from the pressure ventilator to the patient and is static and stationary where there is no air flow. Meter  172  and arrows  164  also display the amount to air flowing to the patient. The three horizontal lines indicate that there is 30 liters air/minute being directed to the patient. Below is meter  186 , which like meter  146  in  FIG. 9  as to the volume ventilator, displays information concerning RR and the ratio of inspiration to expiration time.  
      Above pressure object  212  is volume ventilator object  214 . As shown in  FIG. 1 , the volume ventilator is turned off and this can be understood in that volume ventilator object  214  is in gray and all of the parameters indicate that it is turned off.  
      However, in  FIG. 12 , pressure ventilator  212  is turned off and volume ventilator  214  is turned on. However, as mentioned before, there are mixed volume-pressure ventilators. In Ventilator and Lung Object  190 , were the patient receiving air from a mixed ventilator, both the volume ventilator object  214  and the pressure ventilator object  212  would be on and indicated as being operational.  
      In  FIG. 12 , volume ventilator object  214  is indicated as being on. Like the volume ventilator object of  FIG. 11 , volume ventilator object  214  has a bellows object  158  which indicates the volume of air the patient is receiving (the volume ventilator shows volume per breath on its scale and the pressure ventilator shows flow in L/min). Below volume ventilator  214  is box  146  which, like in  FIG. 9 , displays information concerning RR and inspiration and expiration time and I:E ratio.  
      Located above the lung object  210  is CO 2  elimination object  230 . For example, in  FIG. 13 , CO 2  elimination object displays information concerning CO 2  elimination in real time. Meter  242  displays information concerning minute ventilation total (“MVt”) as represented by marker  246  and minute ventilation ventilator (“MVv”) as represented by marker  248 . The left portion of meter  242  is shaded to represent how much CO 2  is eliminated by the ventilator (MVv) and the right portion of mater  242  demonstrates how much CO 2  is being eliminated by the patient. MVt marker gives the total CO 2  eliminated. The difference between MVt and MVv provides the amount of CO 2  eliminated by the patient.  
      Next to meter  242  is meter  244  which provides information concerning target CO 2  elimination value (as noted by marker  250 ), measured partial pressure CO 2  (“pCO 2 ”) and measured exhaled CO 2  values (“Et CO 2 ”). pCO 2  values are noted by marker  252  and EtCO 2  values are noted by marker  254 . Such values can be obtained from a spirometer. Differences between pCO 2  and EtCO 2  values can be an indicator of certain types of disease.  
      Meter  244  moves up and down in the Y direction depending on the pCO 2  and Et CO 2  values. The position of meter  244  along the Y axis and the position of markers  252  and  254  in relation to the MVt reading of  242  visually indicates excessive ventilation.  
      In  FIG. 14 , the process of updating the Combined Lung and Ventilator Object  190  is much the same as that of updating the Ventilator State Object  140  and therefore all of the steps will not be repeated here. When the process moves to updating lung object  210 , the process moves to state  361  to read PIP. The process then moves to state  363  to determined whether PIP has changed from the last reading. If it has not, the process moves to state  371 . However, if PIP has changed, the process moves to state  365  to determine whether PIP has increased or decreased. If PIP has decreased, the process moves to state  367  and lowers marker  218  to the appropriate PIP value on scale  224 . However, if PIP has increased, the process moves to state  369  where marker  218  is raised above marker  220  which also raises a portion  210   a  of pipe shaped metaphor  210  to raise level  210   a  above  210   b  and gives the “pipe” an expanded appearance.  
      The process then moves to state  371  where MAP is read. The process moves to state  373  where it is determined whether MAP has changed since its last reading. If MAP has changed, the process then moves to state  375  where it is determined whether MAP has increased or decreased. If MAP has decreased, the process moves to state  377  where MAP marker  220  is lowered along meter  224  to the appropriate setting.  
      However, if it is determined at state  375  that MAP has increased, the state moves to state  379  where MAP marker  220  is raised along meter  224  to the corresponding MAP value.  
      The process then moves to state  381  where PEEP is read. The process then moves to state  383  to determine whether PEEP has changed since its last reading. If it is determined that PEEP has changed, the process moves to state  385  to determine whether PEEP has increased or decreased. If it is determined that PEEP has decreased, the process moves to state  387  where PEEP marker  212  is lowered along meter  224  to the appropriate setting. If it is determined that PEEP has increased, the process moves to state  389  where PEEP marker  212  is raised to the appropriate setting along meter  224 .  
      The process then moves to state  401  where total volume inspired (“TVI”) is read. The process then moves to state  403  where it is determined whether TVI has changed since its last reading If it is determined that TVI has changed, the process moves to state  405  where it is determined whether TVI has increased or decreased. If it is determined that TVI has decreased, the process moves to state  407  where TVI marker  192  is lowered along meter  194 . If it is determined that TVI has increased, the process is moved to state  409  where marker  192  is raised along meter  194  and the corresponding TVI reading is indicated.  
      The process then moves to state  411  where respiratory rate (“RR”) is read. If process then moves to state  413  where it is determined whether RR has changed. If it is determined that RR has changed, the process moves to state  415  where it is determined whether RR has increased or decreased. If the RR has decreased, the process then moves to state  417  where the process moves RR marker  202  to the left. If the process determines that RR has increased, the process moves to state  419  where RR marker  202  is moved to the right to reflect the accurate RR reading.  
      The process then moves to state  421  where lung compliance is read. The process then moves to state  423  where it is determined whether lung compliance has changed. If lung compliance has changed, the process moves to state  425  to determine whether lung compliance has increased or decreased. If lung compliance has decreased, the process then moves to state  427  and scale  226  is updated and arrow  228  is moved to reflect the accurate lung compliance measurement. The process then moves the process to state  429  where the process enlarges i.e. thickens outer lung boundaries  204  to illustrate that the lungs have poor compliance. If the process determines that lung compliance has increased, the process moves to state  431  where scale  226  is updated to reflect the accurate lung compliance measurement.  
      The process then moves to state  431  where CO 2  elimination information is read. The process then moves to state  433  where it is determined whether CO 2  has changed. If it has changed, the process moves to state  435  where it is determined whether CO 2  elimination has increased or decreased. If it has decreased, the process moves to state  437  where markers  246  or  248  are moved down meter  242  to the appropriate reading. If the process determines that CO 2  elimination has increased, the process moves to state  439  and markers  246  and  248  are moved upward to the appropriate reading.  
      The process then moves to state  441  where PCO 2  is read. The process then moves to state  443  to determine whether pCO 2  has changed. If it has changed, the process then moves to state  445  where the process determines whether pCO 2  has increased or decreased. If pCO 2  has decreased, process moves to state  447  where marker  252  is moved down meter  244 . If pCO 2  has increased, the process moves to state  449  and marker  252  moves up meter  244 .  
      The process then moves to state  451  where EtCO 2  values are read. The process then moves to state  453  where it is determined whether EtCO 2  values have changed. If EtCO 2  values have changed, the process moves to state  455  where it is determined whether EtCO 2  values have increased or decreased. If the process determined that EtCO 2  values have decreased, the process moves to state  457  and marker  254  is moved down meter  244 . If the process determines that EtCO 2  values have increased, the process moves to state  459  and marker  254  moves up meter  244 . The process then moves to end state  461 .  
      F. Oxygenation Object  
       FIG. 15  illustrates an Oxygenation Object  600  which displays information relating to oxygenation of the blood and the state of lung tissue. Red blood cell object  602  is shown prior to being oxygenated by the lungs (flow, as indicated by the arrows, is from right to left). Boxes  604 ,  606  and  608  represent cross sections of blood vessels in the lung. Boxes  604 ,  606  and  608  can narrow or widen based on the difference between PaO 2  (marker  618 ) and PAO 2  (marker  620 ). Located within box  608  is red blood cell object  610  and soluble oxygenation object  612 . Soluble oxygenation object  612  shows the concentration of oxygen in the plasma which can be influenced by a liquid such as perflubron based OXYGENT, a soluble oxygen carrier of Alliance Pharmaceutical Corp. Soluble oxygenation object  612  can increase in size depending on the contribution of soluble oxygenation of the blood. Linking soluble oxygenation object  612  and red blood cell object  602  is soluble O 2  line  614 . The slope of line  614  can change based upon the level of soluble oxygenation of the blood. Where there is little or no oxygen solubility of the blood, the line levels out to a more horizontal slope.  
      Red blood cell object  610 , which is intersected by an oxy-hemoglobin curve  616 , visually indicates the level of hemoglobin and oxygenation of the arterial blood. CaO 2  total, represented by diamond  622  on the far left, represents the total arterial oxygenation of the blood. Marker  624  represents the amount of oxygenation of the blood by hemoglobin and marker  626  represents the amount of soluble oxygenation of the arterial blood. Both  624  and  626  move up and down in the Y direction as the respective values change. Marker  628  represents the arterial oxygen saturation (SaO 2 ) and 630 represents the hemoglobin (“Hb”) concentration in the blood. Thus as the Hb value increases marker  630  moves to the right and the red blood cell object  610  increases in size and can reach the ideal size that is shown as circle  632 .  
      Located above the red blood cell oxygenation portion of object  600  is the membrane portion of object  600  which illustrates physiological parameters as to oxygenation of the lung during ventilation and visual cues which indicate over ventilation of the lung. To the far left is lung object  640 . Above lung object  640  is a marker  642  for positive end expiratory pressure (“PEEP”) and a marker  644  for peak inspiratory pressure (“PIP”). Both PEEP marker  642  and PIP marker  644  move along X-oriented axis  646  to display the PIP and PEEP values. Adjacent PEEP and PIP markers are rectangular shaped objects  648  and  650  which are PEEP and PIP normal zones. When the PEEP or PIP marker  642  or  644  move beyond rectangular boxes  648  and  650  respectively, this indicates that the values are in a danger zone. For example, in  FIG. 15 , PIP marker  644  is beyond the PIP normal zone  650  and shows that it is in a danger zone. Below PIP and PEEP markers  642  and  644  is arrow  652  which shows the distance between PIP and PEEP values as further illustrated by vertically oriented lines  654  (extending downward from PIP marker  644 ) and line  656  descends from PEEP marker  642 . As lines  654  and  656  separate, as further indicated by arrow  652 , this visually cues the physician or other user that the patient might be in danger.  
      Adjacent lung object  640  is nonfunctional (collapsed or damaged) alveolus object  660 . As shown in  FIG. 15 , nonfunctional alveolus object  660  is in a collapsed state which may be due to various diseases such as atelectases, post-pneumonic states, etc. This further indicates that the current respirator settings need adjusting. Above lung object  640  and alveolar unit  660  is meter  658  which visually indicate the percentage of oxygen intake by the patient in real time. Below lung object  640  and dysfunctional alveolar unit  660  are PaO 2  and PAO 2  markers  618  and  620 . Together these illustrate the alveolar arterial oxygen gradient and anatomic shunt. Markers  618  and  620  can move both in the X direction and provide important information as to oxygen intake. The movement of PaO 2  from left to right affects many of the other parameters of object  600 . Above and linked to PAO 2  marker  620  is FiO 2  marker  662  which is linked to PAO 2  marker  620  by line  664  (the relationship between the FiO2 scale and the PO 2  scale is through Charles Law).  
      The process of updating object  600  is described in  FIG. 16 . The process reads the level of oxygenation of the blood at state  601  prior to oxygenation by the lungs. The process then moves to state  603  where it is determined whether the level of oxygenation of the blood has changed. If it is determined that the level of oxygenation has changed, the process then moves to state  605  where the process determines whether the level of oxygenation has increased or decreased. If it has decreased, the process then moves to state  607  the shading of object  602  is decreased. If it is determined at  605  that the level of oxygenation has increased, the process then moves to state  609  where the process determined whether there has been soluble oxygenation of the blood. If it is determined that there has been oxygenation of the blood by a soluble source, the size of box  612  is increased. If it is determined that there has been no contribution of a soluble oxygen carrier, the process then moves to state  613  where the hemoglobin concentration (i.e. oxygenation of the blood) is read. the size of circle  610  is changed to reflect the Hg concentration in the blood. Markers  622 ,  624 ,  626 ,  628 ,  630  and the oxy-hemoglobin curve are all moved accordingly based wholly or in part on the Hg concentrations and oxygenation levels of the blood at this stage.  
      The process then moves to state  617  where PAO 2  is read. The process moves to state  619  where it is determined whether PAO 2  has changed. If it is determined that PAO 2  has changed, the process then moves to state  621  where it is determined whether PAO 2  has increased. If PAO 2  has increased, the process moves to state  623  where marker  620  is moved to the left. If it is determined that PAO 2  has decreased, the process then moves to state  625  where  620  is moved to the right.  
      The process then moves to state  627  where PaO 2  is read. The process then moves to state  629  where it is determined whether PaO 2  has changed. If it is determined that PAO 2  has increased, the process then moves to state  633  where marker  618  is moved to the right. If the process determines that PaO 2  has decreased, marker  618  is moved to the left. Boxes  604 ,  606 ,  608  and alveolar object  660  can all change sizes based upon movement of PAO 2  and PaO 2.    
      The process then moves to state  637  where PEEP is read. The process then moves to state  639  where it is determined whether PEEP has changed since its last reading. If it has changed, the process then moves to state  641  where it is determined whether PEEP has increased or decreased. If PEEP has increased the process then moves to state  643  where marker  642  is moved to the right. If PEEP has decreased, the process then moves to state  645  where marker  642  is moved to the left.  
      The process then moves to state  647  where PIP is read. The process then moves to state  649  where it is determined whether PIP has changed. If PIP has changed, the process moves to state  651  where it is determined whether PIP has increased or decreased. If PIP has increased, the process moves to state  653  where marker  644  is moved to the right. If PIP has been determined to have decreased, PIP marker  644  is moved to the left. The process then moves to end state  657 .