Abstract:
The present invention provides apparatuses and methods to safely and economically deliver infusion fluid to a patient during a medical procedure. The infusion fluid may be a sedative, analgesic, amnestic or other pharmaceutical agent (drug) for alleviating a patient&#39;s pain and anxiety before, during and/or after a medical or surgical procedure. In general the apparatus comprises a microprocessor-based controller that receives inputs from a plurality of physiological monitors attached to a patient. The system controller processes the data from the physiological monitors and based upon a fluid infusion algorithm delivers infusion fluid to a patient. The physiological monitors monitor the patient throughout the course of the procedure and depending upon the health of the patient, drug delivery may be adjusted to optimize the procedure while ensuring the patient&#39;s health and pain level are maintained.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention is a divisional of U.S. patent application Ser. No. 11/530,576, filed on Sep. 11, 2006, now abandoned, which claims priority from U.S. provisional patent application No. 60/716,308 filed on Sep. 12, 2005. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an apparatus for controlling the administration and infusion of fluids to a patient and for automating activities related toward fluid infusion traditionally performed by a clinician. 
       BACKGROUND OF THE INVENTION 
       [0003]    In current practice, sedative drugs are delivered to patients undergoing certain medical procedures. Sedative drugs are stored in a reservoir and delivered to a patient by either a gravity feed mechanism or by way of a fluid pump. In some instances, multiple fluids are simultaneously supplied to a patient; in this case, the sedative may be mixed prior to entering the bloodstream or may enter the bloodstream apart from each other. 
         [0004]    After the patient has received the sedative drugs, either a clinician or an automated patient monitoring system monitors the patient for a physiological reaction to the infused fluid. Typically physiological parameters such as blood pressure, blood oxygen saturation, temperature, respiration rate, patient alertness and other parameters understood in the art are continuously evaluated to assess what effect the infused fluid is having upon the patient. In current practice, a clinician or patient monitoring device evaluates data provided by physiological monitors and a decision is made as to increase, maintain, decrease or cease the flow of infusion fluid to the patient. After a decision is made, the volume and rate of fluid infusion are then adjusted to achieve a desired patient condition. Care is given to avoid over infusion or under infusion of sedative drugs to a patient as this may endanger the patient. 
         [0005]    Others have attempted to address the automation and delivery of sedative drugs with varying degrees of success. As described in the examples below, previous attempts have been directed toward two approaches to automating infusion. The first approach being a very simple device for delivering a sedative drug to a patient with limited feedback and safety functions and the second approach involves a complex device with many feedback and safety functions. 
         [0006]    U.S. Pat. No. 6,165,151 to Weiner teaches a relatively simple sedation delivery system that uses a microprocessor controller that commands a flow restriction clamp to adjust the diameter of an intravenous line based upon an input signal of a pulse oximetry device. The patient&#39;s blood oxygen saturation is measured by a pulse oximetry device and then compared with known limits. If the patient&#39;s blood oxygen saturation level exceeds a first limit or falls below a second lower limit the flow restriction clamp will alter sedative drug flow accordingly by manipulating the cross section area of the infusion conduit. 
         [0007]    This device in its attempt to be simple has many shortcomings related to safety and efficacy. Particularly, this device lacks the ability to alert an attending physician of a change in sedation fluid flow rate and a change in the condition of the patient. Furthermore the above-mentioned device does not provide a means for a clinician to establish an initial drug delivery profile. This device fails to monitor many patient vital signs such as blood pressure, temperature, respiration rate, and capnography readings. A lone pulse oximetry device may not be able to accurately assess the true condition of the patient, leaving the patient vulnerable to improper controller adjustments of fluid flow rate. 
         [0008]    A more complex infusion automation and delivery apparatus is described in U.S. Pat. No. 6,745,764 to Hickle. This device adjust the flow of sedative drugs to a patient by monitoring a plurality of patient physiological parameters and comparing these parameters to preset values. A controller actively evaluates the input from the patient monitors and changes fluid flow accordingly. The device although safe and effective, is designed for specific applications and practice settings; consequently much of the functionality of this device is unneeded in other simpler practice settings. Accordingly a need clearly exists for a device that provides safety to a patient that can be relatively inexpensive and portable. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides apparatuses and methods to safely and economically deliver infusion fluid to a patient during a medical procedure. The infusion fluid may be a sedative, analgesic, amnestic or other pharmaceutical agent (drug) for alleviating a patient&#39;s pain and anxiety before, during and/or after a medical or surgical procedure. In general the apparatus comprises a microprocessor-based controller that receives inputs from physiological monitors attached to a patient. The system controller processes the data from the physiological monitors and based upon a fluid infusion algorithm delivers infusion fluid to a patient. The physiological monitors monitor the patient throughout the course of the procedure and depending upon the health of the patient, drug delivery may be adjusted to optimize the procedure while ensuring the patient&#39;s health is maintained. 
         [0010]    An additional aspect of this invention is directed toward monitoring the infusion delivery apparatus to ensure patient safety. Functionality detectors such as an occlusion sensor, air-in-line sensor and a fluid detection sensor alert a clinician to such hazards as a pressure build up in the infusion line, air-bubbles in the infusion line, and the absence of fluid in the infusion line. Upon detection of a hazard, system controller will adjust the flow of infusion fluid to mitigate the risk. 
         [0011]    An additional aspect of this invention is directed toward alerting an attending clinician of a change in the patient&#39;s condition. If the health of a patient changes beyond a user-specified amount, the clinician may be alerted to the situation by way of audio and/or visual alert device. Furthermore, the clinician may be alerted to a system hazard as detected by the functionality detectors. 
         [0012]    In accordance with the present invention, apparatus and methods are provided for improved automated delivery of sedative drugs to a patient. Safe and effective rates of infusion are provided by use of the system that monitors a plurality of patient parameters and adjusts the rate of infusion to an appropriate amount as decided by the clinician or system controller. Pre-established parameter ranges are provided before and/or during infusion of fluids into the patient. The infusion rate is continuously adjusted in response to increases or decreases in patient parameters compared to the pre-established parameter ranges. Attending clinicians are apprised of a patients condition at all times and are alerted to adverse patient responses to infused fluids and to actions taken by the system controller. Additional safety features include, line occlusion detection means, air-in-line detection means, and free flow prevention means. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an illustration of the apparatus of the present invention, including the controller and infusion delivery device. 
           [0014]      FIG. 2  is a block diagram detailing a measuring system for determining the concentration of infused fluid, particularly propofol, in respired gases. 
           [0015]      FIG. 3  is a block diagram illustrating a process for monitoring the pulse transit time of a patient being receiving infusion fluid. 
           [0016]      FIG. 4  is a schematic illustration of the apparatus of the present invention, including a blood pressure cuff and pulse oximetry probe. 
           [0017]      FIG. 5  is a schematic illustration of the apparatus of the present invention, including a blood pressure cuff and patient responsiveness device. 
           [0018]      FIG. 6  is a schematic illustration of the apparatus of the present invention including two infusion delivery devices. 
           [0019]      FIG. 7  is a block diagram depicting the flow rate logic utilized by the system controller. 
           [0020]      FIG. 8  is a schematic illustration depicting the system controller used in conjunction with a status indicator, user interface and patient sensors. 
           [0021]      FIG. 9-A  is a schematic illustration of a first infusion delivery device in a first closed flow position. 
           [0022]      FIG. 9-B  is a schematic illustration of a first infusion delivery device in a second intermediate position. 
           [0023]      FIG. 9-C  is a schematic illustration of a first infusion delivery device in a third free flow position. 
           [0024]      FIG. 10  is an illustration depicting the system controller used in conjunction with a wireless printer. 
           [0025]      FIG. 11  is a block diagram depicting multiple system controllers used together under a central server. 
           [0026]      FIG. 12  is a block diagram depicting the system controller used in conjunction with an external display. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0027]    Before explaining the present invention in detail, it should be noted that the invention is not limited in its application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative embodiments of the invention may be implemented or incorporated in other embodiments, variations and modifications, and may be practiced or carried out in various ways. Further, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative embodiments of the present invention for the convenience of the reader and are not for the purpose of limiting the invention. 
         [0028]    Further, it is understood that any one or more of the following-described embodiments, expressions of embodiments, examples, etc. can be combined with any one or more of the other following-described embodiments, expressions of embodiments, examples, etc. 
         [0029]    The system illustration of  FIG. 1  depicts a first expression of the system architecture of the invention. The diagram illustrates the relationship between system controller  1 , infusion delivery means  2  and a fluid source  50 , as well as other subsystems of note, each of which is described in more detail later. Infusion delivery means  2  delivers infusion fluid from fluid source  50  to patient  3  based upon control signals issued by system controller  1 . Infusion fluids administered to patient  3  may include but are not limited to chemical agents, analgesics, anesthetics, blood, plasma, antibiotics, crystalloids, saline, and colloids. System controller  1  receives information related to the patient&#39;s health by way patient sensors  4 . Patient sensors  4  may comprise one or a plurality of patient sensors including, but not limited to devices that monitor pulse oximetry, blood pressure, capnography, electrocardiogram (ECG), electroencephalogram (EEG), respiration rate, temperature, patient responsiveness, concentration of respired gases in the blood stream, and perceptive pain assessment. 
         [0030]    Pulse oximetry sensors (such as The Voyager manufactured by Dolphin Medical) are provided for trans-illumination of a blood-perfused portion of the body to measure light extinction during trans-illumination as is known in the art. The sensor is typically mounted on either a fingertip or earlobe and conforms to the contours of the patient&#39;s body. 
         [0031]    Blood pressure monitors and blood pressure cuffs (Advantage Mini from SunTech Medical Instruments) are comprised of an inflatable fabric cuff that when inflated constricts blood flow through a patient&#39;s arm. The cuff measures the periphery blood vessels pressure and the cuff then provides a patient&#39;s systolic, diastolic, and mean arterial blood pressure. An alternative embodiment involves a blood pressure cuff mounted on the patient&#39;s wrist. A LifeWise™ Wrist-Cuff Blood Pressure Monitor could easily be adapted to monitor a patient&#39;s blood pressure readings and send a corresponding signal to system controller  1 . 
         [0032]    Capnography modules such as the CO 2  WaveForm Analyzer from Cardiopulmonary Technologies used in conjunction with a standard oral-nasal cannula as are well known in the art, allow for collection of respired gases from a patient and an analysis of respiratory carbon dioxide concentration. An oral-nasal cannula is preferably positioned adjacent to the nose and mouth of a patient to receive the patient&#39;s respired breath. Excessive percentage of CO 2  found in a patient&#39;s respired breath might indicate an adverse reaction to infused fluids as is well understood by those skilled in the medical arts. The capnography module in combination with the oral-nasal cannula may also be used to monitor a patient&#39;s respiration rate by measuring the time between peak values as recorded by a pressure transducer or other means. 
         [0033]    Electrocardiogram (ECG) modules may consist of an M12A Front-End (FE) module; differential converter circuit and Receiver chip (1 1005-0,2-50 Rev Al from Mortara). Electrodes attached to the patient emit and receive electrical pulses to diagnose heart rate and vascular disorders. ECG modules are used to measure the rate and regularity of heartbeats, the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs. 
         [0034]    Electroencephalogram (EEG) modules are comprised of a plurality of electrodes fixed to a patient&#39;s head to detect electrical activity of the brain. This electrical activity can indicate information such as brain activity levels and neural disorders. Furthermore, an EEG device may be used to measure a patient&#39;s respiratory rate by a technique known as transthoracic impedance (TTI). In TTI, EEG electrodes are attached to a patient&#39;s trunk. Electrical signals are sent from the electrodes and the time required for the signals to return to the electrodes is measured. The difference in time can be indicative of the oxygen content of the patient&#39;s body, particularly the lungs. Consequently, respiration rate may be determined by taking a plurality of EEG measurements over a period of time. 
         [0035]    A patient responsiveness device, similar to the device disclosed in U.S. patent application Ser. No. 10/791,959 to Katz and Nesbitt, may be used in conjunction with the above-mentioned sensors. This device comprises a query initiate device and a query response device. The patient response system operates by obtaining a patient&#39;s attention with the query initiate device and commanding the patient to activate the query response device. The query initiate device may be any type of stimulus such as a speaker via an earpiece, which provides an auditory command to a patient to activate the query response device. The query response device may be a hand piece that can take the form of for example, a toggle or rocker switch or a depressible button or other movable member hand held or otherwise accessible to the patient so that the member can be moved or depressed by the patient upon the patient&#39;s receiving the auditory or other instruction to respond. Alternatively, a vibrating hand mechanism may be incorporated into the hand piece that cues the patient to activate the query response device. In one embodiment, the query initiate device is a cylindrical handheld device containing a small 12VDC bi-directional motor enabling the handheld device to vibrate the patient&#39;s hand to solicit a response ( FIG. 5 ) 
         [0036]    System controller  1  may serve to monitor the time delay between a signal generated by the query initiate device and a patient&#39;s response as recorded by query response device. An excessive time delay from the query to the response may indicate that a patient is experiencing an adverse reaction to the infused fluid, particularly if the infused fluid is a sedative and the patient is becoming over sedated. The time may be compared to a predetermined threshold value and if found to be outside an appropriate time range, system controller  1  will command infusion delivery means  2  to adjust the fluid flow rate through IV line  14  to a more acceptable range. 
         [0037]    In a second expression of the invention, a breath analyzer  33  is incorporated as part of the invention to detect the concentration of an infused fluid, for example, propofol, in a patient&#39;s blood stream as described in US20050022811 to Kiesele et al. As shown in  FIG. 2 , breathing gas sensor  33  is fluidly connected to a patient&#39;s airway and electrically connected to system controller  1 . Breathing gas sensor  33  may be a CO 2 , O 2  volume flow or temperature sensor to measure characteristics of a patient&#39;s respiratory gases. Propofol sensor  34  located downstream of breathing gas sensor  33  also receives exhaled patient gases. Propofol sensor  34  is further fluidly connected to a downstream pump  35 . Propofol sensor  34  may be an electrochemical gas sensor, SAW (Surface Acoustic Wave) sensor, ion mobility sensor, a gas chromatography, mass spectrometer, or a combination of a gas chromatograph and an ion mobility or mass spectrometer. System controller  1  is connected with propofol sensor  34  and pump  35 , so that system controller  1  actuates pump  35  for a sampling breathing gas depending on the signal of breathing gas sensor  33 . Propofol sensor  34  sends a measured signal for concentration of propofol to system controller  1 . 
         [0038]    In an alternate embodiment of the second expression, breathing gas sensor  33  receives respiration parameters from system controller  1  and actuates pump  35  such that propofol sensor  34  measures (for example) the end tidal propofol concentration in the respiratory flow breathed out. The mode of operation in the measuring system is such that depending on the measured signal of breathing gas sensor  33 , which is especially a CO2 sensor, pump  35  is actuated by system controller  1 , so that samples reproducible in respect to the propofol content, especially of alveolar air, are delivered for the propofol measurement from the respiratory flow. 
         [0039]    In still another alternate embodiment of the second expression, system controller  1  monitors a patient&#39;s respired gases in the event a patient sensor  4 , such as for example, a responsiveness monitor, indicates a patient is sedated or when a patient&#39;s blood oxygen saturation falls below a vital sign threshold value  5  ( FIG. 7 ). The concentration of propofol as measured by propofol sensor  34  will be used as a baseline value. Subsequent measurements that indicate the propofol concentration is greater than the baseline value will prompt system controller  1  to reduce the flow of infused fluids (in this example, propofol) to the patient  3 . 
         [0040]    A third expression of the invention includes means for assessing arousal, pain and stress during fluid infusion. As described in US2004/0015091 to Greenwald and Dahan, ECG electrodes and a photo-plethysmography (PPG) device may be used concurrently to generate a Pulse Transit Time (PTT) value that may be interpreted to evaluate the patient&#39;s consciousness as well as stress and pain levels. 
         [0041]    As shown in  FIG. 3 , system controller  1  continuously monitors ECG and PPG waveforms, both monitors are represented by item  4 . For each cardiac cycle, fiducial points are identified to indicate the pulse onset time (as measured by ECG) and pulse arrival time (as measured by PPG). The onset and arrival times for each cardiac cycle are paired, and the time difference or pulse transit time (PTT) is the interval estimate for that beat. System controller  1  monitors trends in PTT values for a rapid decrease or increase. A rapid decrease will result in system controller  1  prompting infusion delivery means  2  to provide supplemental infusion fluid to patient  3 , while a rapid increase in PTT will result in system controller  1  prompting infusion delivery means  2  to reduce the flow of infusion fluid to patient  3 . 
         [0042]    An alternate embodiment of the third expression incorporates an entropy module, such as for example, the S/5 Entropy Module developed by Datex-Ohmeda Division, Instrumentation Corp. As described in US20030055355, the entropy module monitors the change in entropy of an EEG signal. Interpretation of an entropy level can give a clinician an indication of the depth of anesthesia of a patient. A high level of signal entropy indicates a patient is fully awake and alert, conversely, as the entropy level approaches zero, a patient is entering a deep level of anesthesia. An entropy module may be incorporated into system controller  1  or may be electronically connected to system controller  1 . In either case, system controller  1  will evaluate the trend in entropy level and will prompt infusion delivery means  2  to alter the flow of infusion fluid to patient  3  accordingly. 
         [0043]    A combination of the above devices may be used to provide a more sound evaluation of the patient&#39;s condition. In one expression, patient sensors  4  comprise a pulse oximetry sensor that measures the percentage of oxygen found in a patient&#39;s bloodstream and a non-invasive blood pressure sensor for measuring a patient&#39;s systolic and diastolic blood pressure. It is understood in the art that measuring a patient&#39;s blood oxygen saturation and blood pressure provides an indication of the relative health of a patient. Blood pressure and blood oxygen saturation levels are of particular importance in assessing the effects of sedative drugs upon a patient. Various patient sensor  4  combinations are shown to illustrate the modularity of the current device. As an example,  FIG. 1  depicts the current invention with a lone pulse oximeter sensor, while  FIG. 4  depicts the current invention with a both a pulse oximeter sensor  4  and blood pressure device  4 . Other combinations of sensors can be used such as a blood pressure cuff  4  and a patient responsiveness monitor  4  as shown in  FIG. 5 . 
         [0044]    Now referring to  FIG. 1 , a fourth expression of the invention includes detectors in IV line  14  for detecting the presence or absence of infusion fluid in IV line  14 . A fluid detection sensor  31   a  continuously monitors IV line  14  for the presence of infusion fluid while infusion delivery means  2  is active. Upon sensing an absence of fluid in IV line  14 , a signal is sent to system controller  1  which in turn halts further delivery of infusion fluid and alerts the attending clinician by way of status indicator  6 . The fluid detection sensor  31   a  may be any of a number of different types of sensors including but not limited to optical sensors, ultrasonic sensors, proximity sensors, or electromagnetic sensors. 
         [0045]    An air-in-line sensor  31   b  monitors IV line  14  for the presence of air bubbles, which may present a danger if air bubbles reach the patient&#39;s bloodstream. The air-in-line sensor  31   b  may be any number of different sensor types including optical and ultrasonic sensors. The sensor periodically sends a signal to system controller  1  describing the air content of IV line  14 . This command indicates the amount of air detected in the line over a particular time period. Alternatively, the air-in-line sensor  31   b  may register an air bubble greater that a predetermined maximum volume. Upon receiving a signal from the air-in-line sensor  31   b , system controller  1  will compare the signal with a predetermined threshold value. System controller  1  may maintain, increase, decrease, or halt the flow of fluid similar in a manner similar to that described above relating to sensors  4 . 
         [0046]    The current invention may also include means to detect an occlusion or blockage in IV line  14 . Occlusions pose a risk to the patient in that if the blockage is removed, a sudden bolus of infusion fluid may reach the patient. If the blockage is not removed and pressure continues to increase, IV line  14  or a blood vessel may rupture. To circumvent this situation, an occlusion sensor  31   c , which may be a strain gauge, piezoelectric, or other type of pressure transducer continuously monitors the pressure of IV line  14 . The occlusion sensor  31   c  sends an output signal to system controller  1  regarding the pressure of IV tube  14 . System controller  1  will compare the value of the occlusion sensor  31   c  with a predetermined pressure threshold. System controller  1  will in turn send an appropriate command to infusion delivery means  2  to reduce or cease the fluid flow. 
         [0047]    The occlusion sensor  31   c , air-in-line sensor  31   b , and fluid detection sensor  31   a  all serve to monitor the functionality of infusion delivery means  2 . These three sensors will collectively be referred to herein as functionality detectors  31 , and are schematically depicted in  FIG. 1 . 
         [0048]    Now referring to  FIG. 6 , a fifth expression of the invention includes the capability to deliver two or more infusion fluids  50  and  52  to a patient simultaneously. In a first embodiment, the alternative infusion fluid(s) will be supplied to patient  3  by way of alternate infusion delivery means  10 . Infusion delivery means  2  delivers a first infusion fluid from fluid source  50  to patient  3  while alternate infusion delivery means  10  supplies a second infusion fluid from fluid source  52 . Alternate infusion delivery means  10  like infusion delivery means  2  may be a gravity feed device or a fluid pump as described later. All functionality associated with infusion delivery means  2  may be duplicated with such devices as an alternate occlusion detector, alternate free-flow detector, and alternate air-in-line detectors, referred to collectively as alternate functionality detectors  30 . All outputs of alternate functionality detectors  30  are transmitted to system controller  1  which evaluates sensors  4 , functionality detectors  31 , and alternate functionality detectors  30  to regulate the rate of fluid infusion. 
         [0049]    As shown in  FIG. 3 , a clinician may establish an initial infusion profile by programming system controller  1  by way of user interface  7  ( FIG. 1 ). An infusion profile may include the type of fluid to be infused, initial bolus of fluid, maintenance rate, total amount of fluid to be infused, average rate of infusion, and total infusion time. In a second embodiment, a clinician may choose an infusion profile from a stored group of infusion profiles. In addition to setting an infusion profile, a clinician may enter information about the patient by way of user interface  7  and a suggested infusion profile will be calculated based upon patient information and a pre-programmed pharmacological model. After calculation of the suggested infusion profile, the clinician will have the opportunity to reject or allow the infusion profile by indicating so on user interface  7 . The technique of infusing fluids into a patient to achieve a desired effect-site concentration is known as target controlled infusion (TCI) and is well understood in the sedation and anesthesia arts. An alternative infusion delivery algorithm that may be employed in the current invention is found in U.S. application Ser. No. 10/886,255 filed Jul. 7, 2004, which discloses a drug delivery algorithm for use in an automated infusion delivery device. 
         [0050]    An alternative to a pre-programmed infusion profile is a patient controlled fluid delivery device. Patient controlled analgesia, and patient controlled sedation are well known in the infusion delivery arts and are easily incorporated into the current invention. 
         [0051]    After entering an infusion profile, a clinician may enter patient threshold values into system controller  1 . Patient threshold values  5  ( FIG. 7 ) are numeric values representing patient vital signs and are electronically stored in system controller  1 . A lower and upper patient threshold value  5  may be set for each physiological parameter measured by patient sensors  4 . For instance, an upper threshold value of 135/90 mm HG may be set for a blood pressure sensor while the lower threshold value may be 90/50 mm HG. Furthermore, functionality threshold values  8  may be entered into system controller  1 . Functionality threshold values  8 , similar to patient threshold values  5 , provide an upper and lower limit for functionality detectors  31  and alternate functionality detectors  30 . In an alternate embodiment, system controller  1  may automatically generate threshold values  5 , 8 . These values are based upon pre-programmed algorithms contained in system controller  1 . A clinician may prompt system controller  1  to generate threshold values  5  and  8 , then the clinician may approve, reject, or modify the generated threshold values  5 , 8 . 
         [0052]    Upon establishing the initial flow profile and threshold values  5  and  8 , system controller  1  will prompt infusion delivery means  2  and alternate infusion delivery means  10  to begin delivering infusion fluid to patient  3 . As infusion fluid is being delivered, patient sensors  4 , functionality sensors  31 , and alternate functionality sensors  30  monitor their respective fields. Data from sensors  4 ,  30 , and  31  are transmitted to system controller  1  for further analysis. Data received from sensors  4  are compared against vital sign threshold values  5 . Similarly, data received from functionality sensors  30  and  31 , are compared against functionality threshold values  8 . 
         [0053]    System controller  1  will issue commands to infusion delivery means  2  and  10  to maintain or alter the infusion fluid delivery profile based upon comparisons between sensors  4 , 30  and  31  with threshold values  5  and  8 . These command are an attempt to affect the vital signs of patient  3  and the operating parameters of the infusion delivery means  2  and  10 . Infusion delivery means  2  and  10  are devices that physically induce or prohibit the flow of infusion fluid through IV line  14  into patient  3 . The commands issued by system controller  1  to infusion delivery means  2  and  10  may be to increase, maintain, decrease, or cease the current flow of infusion fluid into patient  3 . 
         [0054]    System controller  1  is a typical electronic controller that is well understood in the art. System controller  1  has the capability to receive multiple input signals from an external source such as sensors  4  and to analyze these signals with a microprocessor. Output signals are issued based upon a predetermined software response to particular input signals. The software included in system controller  1  has predefined threshold limits of patient parameters. An input signal above an upper threshold limit will induce system controller  1  to produce an output signal commanding infusion delivery means  2  and  10  to increase the flow of infusion fluid to patient  3 . Likewise, an input signal below a lower threshold limit will induce system controller  1  to produce an output signal commanding infusion delivery means  2  and  10  to decrease or cease the flow of infusion to patient. An input signal that is neither below the lower threshold limit nor above the upper threshold limit will induce system controller  1  to maintain the current flow of infusion fluid into patient  3 . Examples of medical controllers that are sold today, which could easily be adapted for use in the current invention include; the Cancion CRS Therapy from ORQIS Medical, The Avant® 2120 sold by Nonin Medical, and the Vital Signs Monitor 300 Series from Welch Allyn. 
         [0055]    System controller  1  allows a clinician to establish a threshold hierarchy  9  whereby the actions of system controller  1  in response to sensors  4 ,  30 , and  31  are governed in a particular manner. For example, if more than one sensor is in use, a clinician may program system controller  1  to alter infusion delivery means  2  only if all the sensors  4  report patient parameters outside a threshold value. Alternatively, particular patient or system parameters may be given a higher priority than others, where only a subset of sensors  4 ,  30 , and  31  report a patient or system parameter outside of a threshold value is sufficient alter infusion delivery means  2 . Furthermore, system controller  1  may be programmed in a multitude of other ways depending upon clinician preference, which will be obvious to those skilled in the art. 
         [0056]    Now referring to  FIG. 8 , system controller  1  may further include a user interface  7  ( FIG. 1 ) to allow a clinician to adjust settings and parameters associated with system controller  1 . User interface  7  ( FIG. 1 ) also includes means to display operating parameters to the clinician indicating the status of system controller  1 , patient  3  and infusion delivery means  2 . In a preferred embodiment, user interface  7  is an LCD touchscreen  26 . LCD touchscreen  26  has both the ability to display patient and system operating parameters and at the same time allow a clinician to provide input into system controller  1 . 
         [0057]    Status indicator  6  is a module electrically connected to system controller  1  that alerts an attending physician of a change in a multitude of operating parameters measured by the current invention. In the event the patient&#39;s physiological parameters reach a dangerous level, status indicator  6  will alert an attending clinician to the patient&#39;s condition and any corrective action already taken by system controller  1 . In certain circumstances, status indicator  6  will alert a clinician to a patient condition requiring clinician intervention. 
         [0058]    In a first embodiment, status indicator  6  is a light bar  32  comprised of a plurality of LED lights as shown in  FIG. 8 . Light bar  32  may produce a first color to indicate a change in patient condition; a second color to indicate an action by system controller  1 , and a third color to indicate that clinician intervention is required. Additional colors may be used to indicate further changes and operating conditions. A second embodiment comprises an audio output device  25 , such as a speaker or earphone, which produces a unique sound for situations such as a change in patient condition, an action taken by system controller  1 , a request for clinician intervention and other system actions. The unique sound may be a pre-recorded voice apprising the clinician of the patient&#39;s status, and suggesting a course of action. In a third embodiment, text messages are displayed to the user by way of LCD touchscreen  26 , providing detailed information regarding patient&#39;s  3  condition and the current actions of system controller  1  by way of LCD touchscreen  26 . It should be noted that two or more of the embodiments mentioned above might be combined to provide multiple indicia of patient and system conditions. As an example, status indicator may flash a light, emit a sound and display a text message to alert a clinician to a change in patient status. Furthermore, the severity of a change may dictate what means status indicator  7  uses to alert a clinician. A loud audio alert, and several flashing lights may signify life-threatening events, while a soft chirp from audio output device  25  may represent a minor change in patient condition. 
         [0059]    In a first embodiment, infusion delivery means  2  is a gravity feed mechanism which utilizes a variable pressure clamp  20  to contact IV line  14  and physically reduce the cross sectional area of IV line  14  as shown in  FIGS. 9  A-C. Variable pressure clamp  20  consists of two opposably mounted rigid bodies whereby variable body  21  is capable of lateral motion with respect to fixed body  22  as shown in  FIG. 9 . Movement of variable body  21  is made possible by bi-directional motor  24 . Bi-directional motor  24  receives operating commands from system controller  1  in the form of voltage signals.  FIG. 9-A  depicts variable pressure clamp  20  in a first closed flow position where IV line  14  has an original cross sectional area of approximately zero.  FIG. 9-B  depicts variable pressure clamp  20  in a second intermediate position. Bi-directional motor  24  has increased the distance between variable body  21  and fixed body  22  whereby the cross sectional area of IV line  14  is increased by a predictable amount. Finally  FIG. 9-C  depicts variable pressure clamp  20  in a third free flow position. In this position, bi-directional motor  24  has moved variable body  21  even farther away from fixed body  22 , whereby IV line  14  is completely unobstructed allowing unimpeded flow through IV line  14 . 
         [0060]    Although only three fluid flow positions are shown, bi-directional motor is capable of finely tuning the distance between variable body  21  and fixed body  22  to produce many different fluid flow rates. Furthermore, bi-directional motor may move variable body  21  closer to fixed body  22  to decrease the flow rate of infusion fluid as directed by the clinician and system controller  1 . In an alternate embodiment, bi-directional motor  24  may be replaced by a manual engagement knob, which would allow a clinician to manually adjust the amount of engagement between variable body  21  and IV line  14 . 
         [0061]    In a first embodiment, variable pressure clamp  20  contains biasing springs  23  which have a spring constant sufficiently high to ensure variable body  21  is biased toward a default closed flow position as shown in  FIG. 9-A . Biasing springs  23  are included to serve two purposes, the first being a means to prevent inadvertent fluid flow through IV line  14 , the second being a means to compensate for the variances in manufacturing tolerances. Infusion fluid allowed to flow freely to the patient  3 , may present a health hazard. Biasing variable pressure clamp  20  to the default fluid flow rate to zero mitigates the possibility of experiencing a free flow condition. Defaulting the initial fluid flow to zero will calibrate the fluid flow rate as the bi-directional motor  24  retracts variable body  21  by a known distance. 
         [0062]    Similarly, biasing springs  23  will compensate for small variances in tolerances that may lead to a fluid flow rate out of calibration. In a first embodiment system controller  1  issues commands to bi-directional motor  24  to adjust the position of variable body  21  but does not rely on a sensor to detect the rate of fluid flow through IV line  14 . Without biasing springs  23 , there is no insurance that variable body  21  is positioned close enough to fixed body  22  to ensure that fluid flow through IV line  14  is zero in the default position. This may lead to fluid being supplied to the patient inadvertently and unexpectedly, which may put the patient at risk. Furthermore, the fluid flow rate through IV line  14  will not be known as the variable body  21  retracts from fixed body  22 . 
         [0063]    In a second embodiment, fluid flow meter  27  ( FIG. 9-A ) may be introduced into the IV line  14  downstream of variable pressure clamp  20  to monitor the volumetric flow rate, mass flow rate, flow velocity or other flow characteristics through the line and allow system controller  1  to adjust the distance between variable body  21  and fixed body  22  accordingly. Either an inline flow meter or an insertion flow meter may be used as is well known in the art. The output of fluid flow meter  27  is sent to system controller  1  which will adjust infusion delivery means  2  to ensure the preferred fluid flow rate is being supplied to the patient  3 . 
         [0064]    In a third embodiment, infusion delivery means  2  is a peristaltic type pump. A peristaltic pump utilizes a row of peristaltic fingers that sequentially compress and uncompress IV line  14  to create a wavelike motion to induce fluid flow through IV line  14 . The speed of peristaltic motion is governed by voltage signals delivered to infusion delivery means  2  by system controller  1 . In the current invention line  14  is removably attached to fluid reservoir at one end and removably attached to patient  3  at the opposite end. Ideally, IV tubing  14  is a segment of tubing specifically adapted for use with a peristaltic pump that may endure a series of deforming impacts and still maintain the original fluid flow properties and flexibility of a line that has not been subject to deforming impacts. Alternatively many alternative pumps may be used in place of a peristaltic pump, including but not limited to, bellows, diaphragm, piston, syringe, roller, lobe, and oscillating pumps. 
         [0065]    Now referring to  FIG. 10 , the current invention may be adapted to interface with wireless printer  38 . In a first embodiment, system controller  1  transmits relevant data to wireless printer  38  by way of an integrated wireless transmitter  39 . Wireless transmitter  39  may incorporate either an IEEE 802.11 or Bluetooth type technology. Similarly, wireless printer  38  receives data transmitted from system controller  1  with a wireless receiver  40 . Wireless receiver  40  may be either electrically connected or fully integrated with wireless printer  38 . In the event where multiple wireless printers are found in a single location, a clinician may select which printer system controller  1  communicates with. Options include, printing to the printer with the strongest wireless signal strength or printing to a designated printer. 
         [0066]    Another implementation of the current invention includes system controller  1  wirelessly communicating with central server system  100  as seen in  FIG. 11 . Central server system  100  is a typical computer server such as an IBM Cluster 1350 xSeries 346 or a HP Integrity RX8620-32 server, which receives information regarding a patient&#39;s condition and operating parameters of system controller  1 . Central server system  100  resides is a second room location and is capable of receiving and processing data from multiple system controllers located throughout a health care facility. Server user interface  101  allows a clinician or operator to monitor the various system controllers reporting to central server system  100  and to operate the system controllers remotely. This allows a single clinician to monitor multiple system controllers reducing the number of skilled personnel needed to effectively monitor a patient care center. 
         [0067]    Now referring to  FIG. 12 , an external display  105  may be used in conjunction with system controller  1 . External display  105  may be a LCD or cathode ray display device, such as for example, the MFGD 5621HD Display form Barco. In a first embodiment, external display  105  communicates with system controller  1  by way of wireless or infrared technology. System controller  1  utilizes wireless transmitter  39  to transmit data to external display  105 . Data to be transmitted may include, information pertaining to the health of patient  3 , information pertaining to the operation of the device as described by functionality detectors  30  and  31 . Furthermore, the output of status indicator  6  may be duplicated by external display  105 . 
         [0068]    The interface between external display  105  and system controller  1  allows for a periodic verification of connection. In a first embodiment, external display sends a signal to system controller  1  indicating either an error is present in external display  105  or that no error is present in external display  105 . An error may include conditions where external display  105  is not functioning properly. Upon receiving an error signal, system controller  1  will take appropriate action, which may include reducing the flow of infusion fluid to patient  3  and/or alerting a clinician of the change in status. A clinician may specify what action is to be taken by entering threshold values  5  ( FIG. 7 ) into system controller  1  by way of user interface  7 . Additional signals to be sent from external display  105  including an identifier unique to external display  105  whereby system controller  1  will recognize the identifier and associate all data from a particular identifier with a particular external monitor  105 . 
         [0069]    While aspects, embodiments and examples, etc. thereof, it is not the intention of the applicants to restrict or limit the spirit and scope of the appended claims to such detail. Numerous other variations, changes, and substitutions will occur to those skilled in the art without departing from the scope of the invention. For instance, system controller and components thereof of the invention have application in robotic assisted surgery taking into account the obvious modifications of such systems and components to be compatible with such a robotic system. It will be understood that the foregoing description is provided by way of example, and that other modifications may occur to those skilled in the art without departing from the scope and spirit of the appended claims.