Abstract:
Ventilator enables operator to enter into the microprocessor estimate of a patient&#39;s individual characteristic, such as weight, which the microprocessor uses to control delivered tidal volume and other parameters to match the patient. The operator can select one of several ventilator operational modes (intube, mask, CPR). Sensors input data to the microprocessor to maintain parameter optimizations and accuracy. Visual/audible alarms and tools activate when one or more parameters exceed or fail to exceed predetermined values for patient&#39;s weight. Manual over-ride is available. The ventilator has a quick start capability in which the operator turns on power, selects the automatic operating mode, enters patient&#39;s characteristic, selects control option starting automatic ventilation of proper volumes inhalation/exhalation periods, pressure, and oxy-air mixture.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. application Ser. No. 10/893,156, filed Jul. 16, 2004, which claims priority to U.S. Provisional Application No. 60/488,013, filed Jul. 17, 2003, both of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to patient breathing assist systems and, more particularly, to such systems that are microprocessor-controlled patient ventilator systems and methods of control and operation therefor. 
         [0003]    Designers have improved human patient ventilators in the last ten years by including microprocessors to control various functions of the ventilator equipment. See, for example, U.S. Pat. Nos. 5,692,497 and 6,512,938. Standard microprocessor controlled ventilators operate in two or three different modes, depending upon the nature of the injury or illness giving rise for patient&#39;s need for assisted breathing, and the operators selection of one or more specific mode settings. In addition, the microprocessor can respond to various sensors to modify air-oxygen mixture, flow rates, and other parameters pursuant to protocols stored in the microprocessor unit. 
         [0004]    But these conventional ventilators are not free of technical problems. For example, conventional microprocessor controlled ventilators can force delivery of the wrong tidal volumes, flow rates, gas mixtures, inspiratory pressure, inspiratory/expiratory ratio, or other operating parameters. In addition, if the conventional system delivers the wrong quantity or at the wrong rate, the operator must use visual patient reaction to sense and determine the sufficiency of or incorrect setting of the system. These shortcomings of conventional microprocessor controlled ventilators may cause delay in establishing normal patient breathing which can lead to patient injury or death. 
         [0005]    In addition, manual ventilation is currently the standard of care in pre-hospital setting. This form of ventilation requires that a rescue operator, usually having low level skill and training, squeeze a self-inflating bag connected to an indwelling tube or simultaneously holds a mask in place to deliver breathing gas to the patient. Studies have shown that, in order to minimize breathing gas leakage, this process often requires two rescuers, one to hold the mask firmly in place and the other to squeeze the bag. This technique obliges the rescuer to guess: how often to squeeze the bag, how quickly to squeeze the bag, and for how long to squeeze the bag. This process is repeated each time a manual breath is delivered. 
         [0006]    In the pre-hospital care setting, patients receive ventilations rendered by emergency medical technicians (EMTs), paramedics, police officers, and firemen. Each of these personnel categories has limited mechanical ventilation skills and is not clinically qualified to make most operator control settings, which are normally dependent upon multiple cycles of in-hospital tests to ascertain. The self-inflating bag, described above, and the automatic transport ventilator (ATV) are the two most popular devices available for breathing gas delivery in the pre-hospital care environment. At the present time, ATV&#39;s are automatic only in the sense that they can automatically and repeatedly cycle from off to on. The operator is responsible for making control settings based on his/her perception of what he/she thinks the patient needs and within the gas delivery/functionality limitations of the ATV. Depending upon the clinical expertise of the caregiver, which is generally minimal, these control settings are little more than a “best guess”. Furthermore, the ATV has no mechanism for self-correction or ability to provide assurance that the mechanical ventilations delivered to the patient actually represents the ATV settings. Although the literature reports ATV&#39;s as being robust devices and superior to the self-inflating bag, most hospital medical directors require their field personnel to manually ventilate patients, because this mode will pose the least threat from pressure-related injury due to incorrect ATV settings. 
         [0007]    Mechanical ventilation is used in pre-hospital or clinic. In the hospital or clinic, mechanical ventilation is used therapeutically to wean a patient to that point where mechanical breathing support is no longer required. In all clinical environments, there exists a need to have mechanical ventilation capability without the need for significant input and attention from the operator. 
         [0008]    In the hospital/clinic environment, patients receive ventilations rendered by nurses, physicians, respiratory therapists, and anesthesiologists. Each of these personnel categories has some degree of manual and/or mechanical ventilation skills, ranging from minimal to considerable, and traditionally subordinates to that member of the clinical team that is most proficient in ventilating the patient. The self-inflating bag, described earlier, and battery-powered critical care ventilators are the two most popular adjuncts available for breathing gas delivery in the hospital/clinic setting. The self-inflating bag is subject to the same limitations described earlier and is typically used during emergency procedures or short intra-hospital transports. The less-rugged critical care ventilator can be used during emergency procedures but is used more typically where longer periods of continuous use in specialized therapeutic care are required. More importantly, the critical care ventilator is dependent upon the availability of a highly skilled operator to assure that its control settings continuously represent the patient&#39;s immediate needs, safety, and comfort level. Incorrect settings place the patient at risk from hypo or hyperventilation and pressure-related injury to sensitive tissue. 
         [0009]    A common need has always existed, in both the pre-hospital care and hospital/clinic environments for a mechanical ventilator that can be quickly and easily deployed and is simple-to-use by low skill level personnel. Thus, it should provide emergency ventilatory care intervention to facilitate its use rather than present a therapeutic ventilatory care interface that is impractical for the application and is likely to intimidate the operator or permit patient injury. 
         [0010]    In the pre-hospital care setting, such a device would be routinely used by personnel, regardless of their level of training, and allow them to automatically provide safe, consistent and repeatable ventilations. In field settings, it would prove invaluable, as it is commonly known that injuries from mass destruction (fires, explosions, chemical clouds, etc.) specifically involve patients&#39; respiratory systems leading to incapacitation and death if emergency ventilatory care is not provided within a short period of time. 
         [0011]    In the hospital/clinic setting, a similar need exists to provide immediate care to many patients who&#39;ve become the victims of mass destruction affecting the respiratory system. The problem is the same as that encountered in pre-hospital settings. The location of use is different but the solution remains the same, whereas the use of conventional microprocessor controlled ventilators or manual adjuncts will limit the amount of patients/victims served, cause critical delays in providing needed ventilatory intervention, and lend itself to further patient injury or death. 
       SUMMARY OF THE INVENTION 
       [0012]    It is an object to provide a microprocessor controlled ventilator that solves the foregoing technical problems, provides other and further benefits and advantages, and provides a faster start, more automatic and more reliable ventilation assistance to patients in need of such assistance than conventional or known mechanical units of this type, and enable these benefits with lesser skilled or trained operators. In addition, a preferred embodiment lends itself to implementation in a small lightweight package with AC or, alternately, battery power for convenient portability, storage and in-field, ambulance and hospital usage. 
         [0013]    One exemplary embodiment of a ventilator system, according to the principles of the present invention, includes a subassembly for delivering to the patient air or oxygen or a mixture thereof. Unlike conventional systems and methods, the present system enables the operator to enter into the microprocessor storage register the operator&#39;s estimate of a patient&#39;s individual characteristic or factor, such as weight. This approximate weight factor is then used automatically by the microprocessor in the protocol, algorithm, or stored table look-up for the particular mode of ventilator operation selected by the operator. For example, the microprocessor will control the delivered tidal volume and control other parameters to match the specific patient&#39;s individual characteristic, such as the patient&#39;s weight, during the specific ventilator operational mode. 
         [0014]    Another object of the invention is to provide such ventilators that use the entered individual characteristic in combination with one or more sensor inputs to the microprocessor to control one or more of the various system parameters for the specific mode of system operation. 
         [0015]    A further object of the present invention is to provide such ventilators in which the microprocessor chip (MC) controls one or more visual and/or audible alarms when one or more parameters exceed or fail to exceed predetermined values for the individual characteristic and specific mode operation of the system. 
         [0016]    Yet a further object of the invention is to provide a ventilator with quick start capability in which the operation turns on power, selects the automatic operating mode (intubate/non-intubate, 100% oxygen/oxy-air mixture), enters the individual characteristic, and selects a control option to start automatic ventilation of proper volumes inhalation/exhalation periods, and oxy-air mixture. 
         [0017]    Advantageously, a low-skill level operator can more effectively operate the present ventilator because of the few data and mode selection inputs to the present ventilator. 
         [0018]    Yet another object of the present invention is to provide an automatic ventilator that can be used during and to assist an operator during CPR. The inventive ventilator here includes a metronome and audio and/or visual indicator to indicate the patient&#39;s heart beat. It also sequences the patient ventilation during operator pauses in chest pressure. 
         [0019]    Further objects and aspects of the present invention include new and better methods of providing breathing assistance to patients applicable in a wide variety of injury, illness, or aged conditions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Other and further features, objects, and benefits provided by the present invention shall become apparent with the following description of an exemplary embodiment when taken in view of the appended drawings in which: 
           [0021]      FIG. 1  is a schematic and block diagram of part of an exemplary embodiment according to the present invention. 
           [0022]      FIG. 2  is similar to  FIG. 1  showing a different part of the exemplary embodiment. 
           [0023]    It will be understood that  FIGS. 1 and 2  should be read together to form a complete diagram. Letters A-G, respectively, identify common lines on each  FIGS. 1 and 2 . 
           [0024]      FIG. 3  is a schematic diagram of an exemplary embodiment of the pneumatic circuit of the embodiment of  FIGS. 1 and 2 . 
           [0025]      FIG. 4  is a perspective view of one exemplary housing and controls for the embodiment of  FIGS. 1 and 2 . 
           [0026]      FIG. 5  is a table showing exemplary default ventilator settings based on Radford values and patient weight settings. 
           [0027]      FIG. 6  is similar to  FIG. 5  for child weight settings. 
           [0028]      FIG. 7  is a flow diagram of an exemplary start-up method of the embodiment of  FIGS. 1 and 2 . 
           [0029]      FIG. 8  is a flow diagram of an exemplary ventilation mode selection method of the embodiment of  FIGS. 1 and 2 . 
           [0030]      FIG. 9  is a flow diagram of an exemplary quick-start mask mode method of the embodiment of  FIGS. 1 and 2 . 
           [0031]      FIG. 10  is a flow diagram of an exemplary quick-start tube mode method of the embodiment of  FIGS. 1 and 2 . 
           [0032]      FIG. 11  is a flow diagram of an exemplary CPR tube mode method of the embodiment of  FIGS. 1 and 2 . 
           [0033]      FIG. 12  is a flow diagram of an exemplary CPR mask mode method of the embodiment of  FIGS. 1 and 2 . 
           [0034]      FIG. 13  is a flow diagram of an exemplary change settings for quick start mode method of the embodiment of  FIGS. 1 and 2 . 
           [0035]      FIG. 14  is a flow diagram of an exemplary change settings in CPR modes method of the embodiment of  FIGS. 1 and 2 . 
           [0036]      FIG. 15  is a flow diagram of an exemplary change settings/return to mode method of the embodiment of  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]      FIGS. 1 and 2  show one exemplary ventilation embodiment  10  according to the principles of the present invention. Elements and subassemblies of ventilator  10  shall now be described. 
       Sensors 
       [0038]    Gaseous medical-grade air, e.g., from cylinder  11 , is regulated to nominal  50 -PSI through a pressure regulator or provided via an oil-less compressor with appropriate filter and regulator (not shown). Interconnection is made between the air source and ventilator&#39;s External Air Input Connector  13  by color-coded pressure hose and size-indexed fittings. Pressure is sensed continuously by pressure sensor transducer  100  and triggers the External Air Low/Fail Alarm audible/LED/message when pressure falls below the ventilator&#39;s external air alarm set point value, details of which are further described below. 
         [0039]    Gaseous medical-grade oxygen, e.g., from cylinder  12 , is regulated to nominal  50 -PSI through a pressure regulator. Interconnection is made between the oxygen source and ventilator&#39;s External Oxygen Input Connector  14  by color-coded pressure hose and size-indexed fittings. Pressure is sensed continuously by a pressure sensor transducer  110  and triggers the Oxygen Low/Fail Alarm audible/LED/message when pressure falls below the ventilator&#39;s oxygen alarm set point value, as further described below. 
         [0040]    External Air Flow Sensor  120  is part of a closed loop measurement and medical-grade air delivery sub-system that includes the External Air Flow Sensor  120 , Variable Orifice Valve  300 , Air/Oxygen Mixer  520 , CPU  200 , Differential Pressure Transducer  150 , and Disposable Ventilator Circuit  400 . 
         [0041]    The External Air Flow Sensor  120  can be a pneumotach that consists of a differential pressure transducer; a fine mesh screen located between the transducer inputs and associated electronic circuitry. The sensor outputs the pressure drop signal across the mesh screen. The output signal is processed and quantified at the microprocessor  200  then compared to data contained within the ventilator&#39;s memory (“look-up table”). The look-up table data contains a gas flow value (calibrated for air) equivalent to each measured pressure drop over the ventilator&#39;s usable range. In use, the ventilator is preset to deliver a volume (set tidal volume) within an established time (inspiratory time) for a particular patient, as further described below. Based on the sensor&#39;s real-time measurements and flow equivalents, the microprocessor  200  makes on-the-fly aperture adjustments to the Variable Orifice Valve  300  to control flow and insure “delivered” volume equals “set” volume. 
         [0042]    An External Oxygen Flow Sensor  130  is part of a closed loop measurement and oxygen delivery sub-system that includes the External Oxygen Flow Sensor  130 , Variable Orifice Valve  310 , Air/Oxygen Mixer  520 , CPU  200 , Differential Pressure Transducer  150  and Disposable Ventilator Circuit  400 . The External Oxygen Flow Sensor  130  can be a pneumotach that consists of a differential pressure transducer; a fine mesh screen located between the transducer inputs and associated electronic circuitry. The sensor outputs the pressure drop signal across the mesh screen. The signal is processed and quantified at the microprocessor  200  then compared to data contained within the ventilator&#39;s memory (“look-up table). The look-up table data contains a gas flow value (calibrated for oxygen) equivalent to each measured pressure drop over the ventilator&#39;s usable range. In use, the ventilator is preset to deliver a volume (set tidal volume) within an established time (inspiratory time) for a particular patient. Based on the sensor&#39;s real-time measurements and flow equivalents, the microprocessor  200  makes on-the-fly aperture adjustments to the Variable Orifice Valve  310  to control flow and insure “delivered” volume equals “set” volume. 
         [0043]    A Proximal Pressure Sensor  140  is a differential transducer. One input  15  is open to atmosphere and the other input is connected to Autocal Valve  320 . The output of sensor  140  is to directed CPU  200 . 
         [0044]    At startup (power is set to “ON”), the microprocessor  200  performs a Self-Check. Self-Check is a series of diagnostic checks that the ventilator must successfully pass before regular operation is allowed to begin. One of these checks includes setting the pressure signal baseline to “zero” (the equivalent of local atmospheric pressure). Additionally, during operation, the ventilator performs automatic recalibrations at regular intervals to compensate for baseline drift or dramatic changes in altitude that would effect, or have affected, the zero baseline. The signal output of the Proximal Pressure Sensor  140  represents any offset that may exist between the input open to atmospheric pressure and pressure line input from the Ventilator Circuit  400  through the Autocal Valve  320 . 
         [0045]    The Differential Pressure Transducer  150  is part of a closed loop measurement and external air and oxygen delivery sub-system that includes the External Air Flow Sensor  120 , Variable Orifice Valve  300 , the External Oxygen Flow Sensor  130 , Variable Orifice Valve  310 , Air/Oxygen Mixer  520 , CPU  200 , Differential Pressure Transducer  150 , and Disposable Ventilator Circuit  400 . The Differential Pressure Transducer  150  is part of a pneumotach sensor that is created when a Disposable Ventilator Circuit&#39;s  400  Pressure Line  410  and Delivered Flow/Exhaled Flow Line  420  tubing are connected to their respective ventilator tube connectors. The opposite ends of the Pressure Line  410  and Delivered Flow/Exhaled Flow Line  420  tubing are attached to tube fittings located on either side of a fine mesh screen  460 . The Differential Pressure Transducer  150  outputs the pressure drop signal across the mesh screen  460 . The signal is processed and quantified at the microprocessor  200  then compared to data contained within the ventilator&#39;s memory (“look-up table”). The look-up table data contains a gas flow value (calibrated for air, air and oxygen mixtures, and oxygen) equivalent to each measured pressure drop over the ventilator&#39;s usable range. In use, the ventilator is preset to deliver a volume (set tidal volume) within an established time (inspiratory time) for a particular patient. The Differential Pressure Transducer&#39;s  150  real-time measurements allow the microprocessor  200  to “see” delivered flow during the inspiratory cycle, which, in turn, makes on-the-fly aperture adjustments to the respective Variable Orifice Valve  300  and  310  to insure “delivered” volume equals “set” volume. 
         [0046]    A Baro Sensor  160  provides barometric pressure information to the CPU  200 . Gas density changes with altitude and affects the accuracy of readings measured by each of the ventilator&#39;s pneumotachs. To automatically compensate when necessary, the Baro Sensor  160  continuously monitors barometric pressure so that correction factors can be added to pneumotach measurements to maintain accuracy. 
       Electronic and Electrical Components 
       [0047]    CPU  200  processes signal information sent from its switches, control, power and sensor inputs. It also sends control signals to the Variable Orifice Valve  300  and  310 , Autocal Valve  320 , Exhalation Valve Manifold  330  and  340  and Motor Speed Control and Tachometer  250 . Sends settings, alarm, and measurement information to an LCD  230  for display purposes and alarm signals to an Alarm Piezo  220  for annunciation. One example of a suitable CPU is 800552-P80C552-IBA, manufactured by Philips Semiconductors. 
         [0048]    A Trigger Circuit  210  allows a “measured” breath to be delivered each time a Manual Breath Pushbutton  620  is pressed. A Manual Breath is equal in volume and duration to current ventilator settings for “set” tidal volume and inspiratory time for a particular patient. The Alarm Piezo  220  is activated each time an alarm is triggered and muted for a predetermined period, or cancelled, when an Alarm Mute/Cancel Pushbutton  610  is pressed. The Alarm Piezo  220  is also used to emit a “chirp” acknowledging each time pushbutton switches  610  and  620  are pressed and each time the CPR Metronome indicates chest compression is required. 
         [0049]    The LCD Display and LED&#39;s  230  present visual, text and graphical information to the operator. LCD information includes: ventilator settings, alarm by name and associated message, power status, charging status, pressure measurement and metronome Off/On. LED information includes: Chest Compression, Alarm and System Failure. 
         [0050]    Power Supply  240  circuitry provides ventilator operating and/or battery charging power. In addition, the Power Supply  240  circuitry provides internal battery and external power status signals to the microprocessor  200  displayed in the LCD  230 . The Battery  240  provides operating power independent from an external power source. 
         [0051]    The Motor Speed Control and Tachometer  250  circuit controls an Internal Compressor&#39;s  510  motor speed. This insures a reliable airflow source to meet “set” volume requirements. A separate input allows the Motor Speed Control and Tachometer  250  to become activated for one breath each time the Manual Breath Pushbutton  620  is pressed. 
       Pneumatics 
       [0052]    Ventilator  10  pneumatic apparatus will now be described. The External Air Variable Orifice Valve  300  is part of a closed loop measurement and medical-grade air delivery sub-system that includes the External Air Flow Sensor  120 , Variable Orifice Valve  300 , Air/Oxygen Mixer  520 , CPU  200 , Differential Pressure Transducer  150  and Disposable Ventilator Circuit  400 . Based on real-time measurements and flow equivalents made by the External Air Flow Sensor  120  and Differential Pressure Transducer  150 , both described earlier, the microprocessor  200  can make on-the-fly aperture adjustments to the Variable Orifice Valve  300  to control flow and insure “delivered” volume equals “set” volume. 
         [0053]    The External Oxygen Variable Orifice Valve  310  is part of a closed loop measurement and medical-grade air delivery system that includes the External Oxygen Flow Sensor  130 , Variable Orifice Valve  310 , Air/Oxygen Mixer  520 , CPU  200 , Differential Pressure Transducer  150  and Disposable Ventilator Circuit  400 . Based on real-time measurements and flow equivalents made by the External Oxygen Flow Sensor  130  and Differential Pressure Transducer  150 , both described earlier, the microprocessor  200  can make on-the-fly aperture adjustments to the Variable Orifice Valve  310  to control flow and insure “delivered” volume equals “set” volume. 
         [0054]    The Autocal Valve  320  is used to set the zero pressure baseline during the startup Self-Check and at regular intervals during operation. The Autocal Valve  320  works in conjunction with the Disposable Ventilator Circuit&#39;s  400  Pressure Line  410 , the Proximal Pressure Transducer  140  and the CPU  200 . The signal output of the Proximal Pressure Sensor  140  represents any offset that may exist between the input open to atmospheric pressure and pressure line input from the Ventilator Circuit  400  through the Autocal Valve  320 . Solenoid #1 of the Exhalation Valve Manifold  330  is used to control a Disposable Ventilator Circuit&#39;s  400  Exhalation Valve Control Line  430 . When de-energized, Solenoid #1 keeps the Exhalation Valve Control Line  430  open to atmosphere. When energized, it causes an Exhalation Valve  451  diaphragm to close, forcing delivered gas into the patient inspiration or the partial retention of delivered volume during exhalation (PEEP). 
         [0055]    Solenoid #2 of the Exhalation Valve Manifold  340  is used as a safety backup for Solenoid #1. Solenoid #2 is normally closed in its de-energized state, which allows Solenoid #1 to have complete control over the Exhalation Valve Diaphragm  451 . Solenoid #2 is energized when a failure of Solenoid #1 is detected and results in the Exhalation Valve Control Line  430  being opened to atmosphere. 
       Ventilator Circuit 
       [0056]    The Disposable Ventilator Circuit  400  interfaces between the patient and the ventilator via connecting tubing. The ventilator controls its Exhalation Valve  450 ,  451  and  452  to allow breathing gas to pass to and from the patient during inspiration and exhalation. The Pressure Line  410  connects the Disposable Ventilator Circuit&#39;s  400  most distal connector to the Differential Pressure Transducer  150 . The Pressure Line  410  signal (valve) is used to measure and display airway pressure and is part of the delivered/exhaled volume pneumotach. The Pressure Line  410  together with the Delivered Flow/Exhaled Flow Line  420  provide the pressure signals used to measure the pressure drop across the pneumotachs fine mesh screen  460 , The Delivered Flow/Exhaled Flow Line  420  connects the ventilator-side of the delivered/exhaled volume pneumotach to the Differential Pressure Transducer  150 . The Delivered Flow/Exhaled Flow Line  420  along with the Pressure Line  410  provide the pressure signals used to measure the pressure drop across the pneumotachs fine mesh screen  460 . The Exhalation Valve Control Line  430  connects the ventilator&#39;s Exhalation Valve Manifold  330  and  340  pneumatic control signal to the Exhalation Valve Diaphragm  451  via the Exhalation Valve Cap  450 . 
         [0057]    The Inspiratory Line  440  connects the ventilator&#39;s “Gas To Patient” connector with the Disposable Ventilator Circuit&#39;s  400  exhalation valve input. During inspiratory periods, gas is allowed to flow through the Inspiratory Line  440 , Exhalation Valve  450 - 453 , Delivered Flow/Exhaled Flow Mesh Screen  460 , HME  470  and Patient Connection  480  to the patient. The Inspiratory Line  440  isolated from with expiratory gas flow. 
         [0058]    The Exhalation Valve Cap  450  secures the Exhalation Valve Diaphragm  451  to the Exhalation Valve Body  452  and includes a hose fitting that attaches to one end of the Exhalation Valve Control Line  430 . The Exhalation Valve Diaphragm  451  is normally de-energized when gas is not flowing, which allows gas to pass unrestricted from the patient into the atmosphere. The Exhalation Valve Diaphragm  451  is energized closed during inspiratory cycles thereby forcing delivered gas into the patient and when retention of a part of the delivered volume is saved during exhalation (PEEP). Pneumatic control signals are applied through the Exhalation Valve Control Line  430  and Exhalation Valve Cap  450  to the Exhalation Valve Diaphragm  451 . The Exhalation Valve Body  452  houses the Exhalation Valve Diaphragm  451  and connects with the Exhalation Valve Cap  450 , the Condensate Diverter Elbow  453  and a Ventilator Circuit Tee  461 . The Exhalation Valve Body  452  also contains a hose fitting that attaches to one end of the Delivered Flow/Exhaled Flow Line  420 . 
         [0059]    A Condensate Diverter Elbow  453  attaches to the Exhalation Valve Body  452 . This component functions as a small trap for exhaled condensate when the exhalation valve assembly is oriented vertically. The Delivered Flow/Exhaled Flow Mesh Screen  460  is located between the Exhalation Valve Body  452  hose fitting that attaches to one end of the Delivered Flow/Exhaled Flow Line  420  and the Ventilator Circuit Tee  461  hose fitting connected to one end of the Pressure Line  410 . The mesh screen  460  provides a slight resistance to the flow of gas during inspirations and exhalations. This resistance is sensed as a small pressure drop and is quantified (measured) by the Differential Pressure Transducer  150 . The pressure drop is then compared to data contained within the ventilator&#39;s memory (“look-up table”). The look-up table data contains a gas flow value (calibrated for oxygen) equivalent to each measured pressure drop over the ventilator&#39;s usable range. The Ventilator Circuit Tee  461  connects to the patient-side of the Exhalation Valve and the HME  470 . It contains a hose fitting connected to one end of the Pressure Line  410 . The HME  470  (i) provides self-humidification by recycling moisture from the patient&#39;s previous exhalation back to the patient and (ii) protects the Delivered Flow/Exhaled Flow Mesh Screen  460  from collecting condensate. Such condensate would distort pressure drop readings by causing a higher reading than actual. The Patient Connection  480  is a standard 22 mm/15 mm OD/ID fitting that interfaces with masks, endotracheal tubes, or tracheostomy tubes. 
       Mechanicals 
       [0060]    Further mechanical elements include Air Filter  500  that traps particulate which would otherwise enter the Internal Compressor  510  and be passed along to the patient and Delivered Flow/Exhaled Flow Mesh Screen  460 . As with condensate, particulate could collect in the screen and distort pressure drop readings, i.e., higher than actual. The Internal Compressor  510  allows the ventilator to function independent of an external gas source. When cycled “On”, the Internal Compressor  510  provides filtered air to the patient, or filtered air that can be mixed with external oxygen, for delivery to the patient, through the Air/Oxygen Mixer  520  and Disposable Ventilator Circuit  400 . The Air/Oxygen Mixer  520  is a manifold for passing gas or mixing gases intended for delivery to the patient. Ventilator  10  can be manufactured to deliver 100% Oxygen only (Model A) or operate in a variety of selectable delivery modes (Model B), preferably such as: 
       Model A—100% Oxygen 
     Model B— 
       [0061]    External Air 
         [0062]    External Air+External Oxygen (adjustable, 21 to 100%) 
         [0063]    Internal Air 
         [0064]    Internal Air+External Oxygen (adjustable, 21 to 100%) 
         [0065]    The following components are mechanically attached to, or physically contained within, the Air/Oxygen Mixer  520 . The function of each component is described above: 
       External Air Input Pressure Sensor  100   
     External Oxygen Input Pressure Sensor  110   
     External Air Flow Sensor  120   
     External Oxygen Flow Sensor  130   
     Proximal Pressure Sensor  140   
     External Air Variable Orifice Valve  300   
     External Oxygen Variable Orifice Valve  310   
     Autocal Valve  320   
     Solenoid #1 of the Exhalation Valve Manifold  330   
     Solenoid #2 of the Exhalation Valve Manifold  340   
     Internal Compressor  510   
       [0066]    In exemplary Model A, oxygen passes through the Air/Oxygen Mixer  520  to the Disposable Ventilator Circuit&#39;s  400  Inspiratory Line  440  and Solenoid #1 of the Exhalation Valve Manifold  330 . Model A has no gas mixing capability. 
         [0067]    In exemplary Model B, oxygen, external air or air from the Internal Compressor  510  passes through the Air/Oxygen Mixer  520  to the Disposable Ventilator Circuit&#39;s  400  Inspiratory Line  440  and Solenoid #1 of the Exhalation Valve Manifold  330 . 
         [0068]    If the Air/Oxygen mixture set point is 21% or 100%, no gas mixing takes place and the air or oxygen simply passes through the mixer. 
         [0069]    If the Air/Oxygen mixture set point is set between 22% and 99%, the microprocessor  200  apportions how much air and how much oxygen is required to meet the “set” oxygen mixture (percentage) and “set” volume requirements. 
       Operator Controls 
       [0070]    Exemplary operator interface switches and controls will now be described. Pressing a Power Pushbutton Switch  600  applies or removes operating power. The Rotary Encoder Pushbutton Switch  610  allows the operator to make and enter operating mode and function settings described below. The Alarm Mute/Cancel function is part of the Rotary Encoder Pushbutton Switch  610 . This function allows the operator to mute or cancel specific alarms. The Manual Breath Pushbutton Switch  620  permits delivery of one ventilator-generated breath. The manual breath is equal in duration and volume to the current inspiratory time and “set” volume settings. 
       Estimated Patient Weight Settings 
       [0071]    According to the principles of the present invention, ventilator  10  enables the operator to enter and store data representing a patient&#39;s individual weight. CPU applies such data to stored algorithm to generate control signals to vary the durations, phases, and volumes of tidal air delivery and exhalation. 
         [0072]    The operator enters the patient&#39;s estimated weight by using rotary switch  610  to bring the weight menu to the display, turning knob  610  to the estimated weight and pressing knob  610  to enter the weight data into storage. 
         [0073]    Default weight related values of Rate, I, VT, MVV, and Pressure Relief/Alarm Setpoint are also separately stored for use in various procedures such as those described below. Preferably, Radford Default Values, such as those shown in  FIGS. 5 and 6 , are stored for adult and child patient ventilation. 
       Exemplary Ventilator Package Design 
       [0074]    With reference to Figure X, one preferred embodiment of portable ventilator  10  can have an internal frame that supports one or more printer circuit boards to which electrical and device elements are mounted (all not shown). Ventilator  10  also includes a universal AC power supply/docking module (not shown). Housing  20  includes two opposite and removable side panels  22  that fasten to the internal frame, an input-output (JO) panel  24  and a control panel  26 . Alpha-numeric display  28  and indicator lights  30  mount on panel  26  along with controls “store/save-set value” push button switch/rotary encoder knob  610 , “manual [breath] push button switch”  620 , and IO power switch  600 . 
         [0075]    Ventilator  10  includes gas outlet hose connector  38  mounted to but connected through panel  24 . A conventional anti-asphyxia leave valve (not shown) internally mounts in communication with connector  38 . Oxygen inlet fitting  40  also mounts to panel  24 . Flow transducer hose barbs  42 ,  44  and exhalation valve hose barb  46  are also provided. Elements  38 ,  40 ,  42 ,  44  and  46  can connect to a disposable ventilator pneumatic circuit better seen in  FIG. 2  at  400 . One example of the controls for circuit  400  elements is shown in Figure Y. 
         [0076]    The rotary encoder pushbutton switch knob  610  enables the operator to perform various functions hereafter, all references to “SET VALUE” and “SELECT” shall pertain to the rotary encoder, and all references to “STORE”, “SAVE” and “ENTER” shall pertain to its integral pushbutton switch. 
         [0077]    The Rotary Encoder with Integral Pushbutton Switch is used to: Make selections—Turning its rotary component clockwise or counterclockwise moves the highlight cursor (“reverse video”) from one selection to another. 
         [0000]    Set values—Turning knob  610  rotary component clockwise or counterclockwise changes the value of a selection up or down (increase or decrease).
 
Store (ENTER) the selection or value by pressing knob  610  momentary pushbutton switch.
 
Save (ENTER) the selection or value by pressing knob  610  momentary pushbutton switch.
 
         [0078]    Using the Rotary Encoder with Integral Pushbutton Switch  610  the operator can: SELECT, STORE and SAVE the patient&#39;s approximate individual characteristic such as estimated weight. 
         [0079]    Change the existing weight setting. 
         [0080]    Change the default high-pressure alarm/peak inspiratory pressure relief setting. 
         [0081]    Enable PEEP “ON” or set PEEP back to its “OFF” (default) setting. 
         [0082]    Mute an Operating Alarm or Cancel an Advisory Alarm. 
         [0083]    Pressing the manual breath switch  620  during operation initiates delivery of one MANUAL BREATH. Each MANUAL BREATH is equal to one complete ventilatory cycle, in the selected Operating Mode (except as noted below). Such cycle includes the current INSPIRATORY TIME/TIDAL VOLUME “settings” and expiratory time period. 
         [0084]    If selected Operating Mode is CPR MASK with adult values (a weight setting 25 Kg or greater), pressing the MANUAL BREATH Pushbutton  620  will generate, e.g., a 2-second inspiration and 4-second exhalation (1:2 I:E Ratio). If desired, ventilator  10  can be made to support a manual “second breath” with, e.g., 1:4 I:E Ratio. 
         [0085]    A MANUAL BREATH should not be delivered until airway pressure sensor indicates the pressure has reached the expiratory baseline (zero or PEEP). Each time a MANUAL BREATH is triggered by pressing switch  610 , an audible “beep” is generated to advise the operator. The MANUAL BREATH Pushbutton should be protected against accidental contact by a cylindrical guard, generally as shown. 
         [0086]    For a patient with no spontaneous breath in whom the patient or operator wants to maintain a constant I:E of 1:3 with no stacked breaths, the microprocessor can be programmed to store the following exemplary algorithm to set the Inspiratory flow (liters/min): VI SPON =3(V T /V ESPON ). 
         [0087]    Ventilator  10  operation and methods will now be described. 
         [0088]    OPERATION (Note: # paragraphs are not continuous and references to letters are to the letters circled in the respective drawing Figures herein. “?” means an operator choice or change of manual settings (e.g., parameter) or choice of mode selection. 
         [0089]    2. Set Power to “On”: the POWER pushbutton switch allows the operator to power the ventilator from “OFF” to “ON”. To power “ON”, depress the switch for 1 second. 
         [0090]    4. Set Operating Mode: the operator selects 1 of 4 operating modes: CRP Mask Mode, CPR Tube Mode, Quick-Start Mask Mode, or Quick-Start Tube Mode (described below). 
         [0091]    6. Set Patient Weight: the operator is required to enter an estimate of the patient&#39;s ideal: body weight. To enter the weight, the operator turns the rotary encoder which increments the weight values up or down. Weights are displayed simultaneously in both pounds (lbs) and kilograms (kg). 
         [0092]    8. Confirm Setting: after each operator-initiated action, the operator is asked to confirm the resultant change. The user is given the option of accepting (“YES”), returning to modify the action (“NO”) or exiting the Change Settings Menu (“EXIT”). 
         [0093]    9. Begin Operation: once the user has confirmed the selected settings the ventilator immediately begins operation. 
       Ventilation Mode Selection 
       [0094]    10. Set Quick-Start Mask Mode: in the QUICK-START MASK Operating Mode, the V T  Alarm (Tidal Volume), comparing exhaled volume to delivered volume and delivered volume to set volume, is an Advisory Alarm. It triggers when exhaled volume is more than 25% less than delivered volume or delivered volume is more than 20% less than set volume. When initiated, the V T  alarm is accompanied by a message in the LCD&#39;s AMC that includes the actual percentage offset. This alarm can be easily influenced by mask leakage. Once the Alarm Mute/Cancel Pushbutton Switch is pressed, the audible component of this alarm is disabled until power is recycled to “OFF” and then “ON” again. The accompanying Alarm LED illuminates as applies, as does its AMC message. This alarm along with the accompanying message guide the operator to assure a secure seal while ventilating patients with a mask. 
         [0095]    12. Set Weight: the operator is required to enter an estimate of the patient&#39;s ideal body weight. To enter the weight, the operator turns the rotary encoder which increments the weight values up or down. Weights are displayed simultaneously in both pounds (lbs) and kilograms (kg). 
         [0096]    14. Tube?: in selecting the operating mode the user is required to determine wither the patient has a protected or unprotected airway. An unprotected airway requires that the operator ventilate the patient using a securely fitting oral/nasal mask. Protected airways include a device that is used to assure a patient airway suitable for positive pressure ventilation. A number of methods are available to secure the airway: endotracheal tube, Combitube, intubating laryngeal mask airway, tracheostomy, cricothyrotomy, etc. 1 2    
         [0097]    16. Set Quick-Start Tube Mode: in the QUICK-START TUBE Operating Mode, the V T  Alarm (Tidal Volume), comparing exhaled volume to delivered volume and delivered volume to set volume, is an Operating Alarm. It triggers when exhaled volume is more than 20% less than delivered volume or delivered volume is more than 20% less than set volume. When initiated, the V T  alarm is accompanied by a message in the LCD&#39;s AMC that includes the actual percentage offset. This alarm is less likely to be influenced by leakage. Once the Alarm Mute/Cancel Pushbutton Switch is pressed, the audible component of this alarm is muted for 30 seconds. The accompanying Alarm LED illuminates as applies, as does its AMC message. 
         [0098]    18. CPR?: CPR Operating Modes are designed in accordance with published International ECC and CPR Guidelines 2000. Each Mode simplifies and insures qualitative CPR delivery by carefully maintaining precise performance in conjunction with safety features to protect the patient and operator against harm during use. 
         [0099]    20. Tube?: see #14. 
         [0100]    22. Set CPR Tube Mode: in the CPR TUBE Operating Mode, controlled ventilations are delivered to the patient&#39;s protected airway. Controlled ventilations are mandatory ventilations delivered at fixed intervals. They are triggered irrespective of the presence of spontaneous breathing. Ventilator-generated breaths are delivered in accordance with published International ECC and CPR Guidelines 2000 for Rate, Inspiration Time, Inspiratory/Expiratory Ratio (I:E) and Gas Flow/Kilogram. Volume is determined by patient weight (operator-selected). 
         [0101]    In accordance with published International ECC and CPR Guidelines 2000, the following defaults apply: 
       Rate: 
       [0102]    Adults: 10 ventilations per minute
 
Children: 20 ventilations per minute
 
       Inspiration Time: 
       [0103]    Adults: 2.0-seconds
 
Children: 1.0-seconds
 
       I:E Ratio: 
     Adults: 1:2 
     Children: 1:2 
     Gas Flow: 
     Adults: 30 Liters Per Minute 
     Children: 15 Liters Per Minute 
     Delivered Volume: 
       [0104]    Adults: 1000 ml (unless pressure limit setpoint is exceeded)
 
Children: 500 ml (unless pressure limit setpoint is exceeded)
 
         [0105]    Pressure Limiting: 60 cmH 2 0 (default value), adjustable range is 20 to 80 cmH 2 0 
         [0106]    The ventilator determines whether the patient is an adult or child when the operator enters the patient&#39;s approximate weight. Accordingly, the International ECC and CPR Guidelines 2000 default values for adult or child are invoked. The operator may change the patient&#39;s approximate weight setting at any time before or during operation. To reduce “dead space” and “compressible volume”, the Model, ventilator&#39;s pediatric ventilator circuit should always be used whenever pediatric operation is selected. 
         [0107]    The ventilator LCD screen continuously displays settings, directions, airway-pressure information and battery status during operation. 
         [0108]    In the CPR TUBE Operating Mode, the V T  Alarm (Tidal Volume), comparing exhaled volume to delivered volume and delivered volume to set volume, is an Operating Alarm. It triggers when exhaled volume is more than 10% less than delivered volume or delivered volume is more than 10% less than set volume. When initiated, the V T  alarm is accompanied by a message in the LCD&#39;s AMC that includes the actual percentage offset. This alarm is less likely to be influenced by leakage. Once the Alarm Mute/Cancel Pushbutton Switch is pressed, the audible component of this alarm is muted for 30 seconds. The accompanying Alarm LED illuminates as applies, as does its AMC message. 
         [0109]    The CPR TUBE Operating Mode includes a metronome to guide rescuers in their performance of CPR. The metronome produces an audible “chirp” accompanied by an illuminating LED whenever chest compression is required. Because this device is intended for use by emergency personnel, it assumes that 2 rescuers are performing CPR (but applies equally if there is only 1 rescuer), and its metronome is timed in accordance with published International ECC and CPR Guidelines 2000 for use on intubated patients. 
         [0110]    The following metronome defaults apply: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 CPR WITHOUT MASK 
                 ADULT 
                 CHILD 
               
               
                   
                   
               
             
             
               
                   
                 Compression/Ventilation Ratio 
                 5:1 
                 5:1 
               
               
                   
                 Inspiration Time 
                 2 seconds 
                 1 second 
               
               
                   
                 Time sequence per cycle 
                 2, 4 
                 1, 2 
               
               
                   
                 (seconds) 
               
               
                   
                 Number of cycles per minute 
                 10 
                 20 
               
               
                   
                   
               
             
          
         
       
     
         [0111]    24. Set CPR Mask Mode: in the CPR MASK Operating Mode, controlled ventilations are delivered via the operator-held mask to the patient&#39;s unprotected airway. Controlled ventilations are mandatory ventilations delivered at fixed intervals. They are triggered irrespective of the presence of spontaneous breathing. Ventilator-generated breaths are delivered in accordance with published, for example, International ECC and CPR Guidelines 2000 for Rate, Inspiration Time, Inspiratory/Expiratory Ratio (LE) and Gas Flow/Kilogram. Volume is determined by patient weight (operator-selected). 
         [0112]    In accordance with published International ECC and CPR Guidelines 2000, the following defaults apply: 
       Rate: 
       [0113]    Adults: 8 ventilations per minute
 
Children: 20 ventilations per minute
 
       Inspiration Time: 
       [0114]    Adults: 2.0-seconds
 
Children: 1.0-seconds
 
       I:E Ratio: 
       [0115]    Adults: Cyclic—1:1, 1:4.5 then repeats 
       Children: 1:2 
     Gas Volume: 
       [0116]    Adults: 7 ml/Kg
 
Children: 7 ml/Kg
 
Pressure Limiting: 30 cmH 2 0 (default value), adjustable range is 20 to 80 cmH 2 0
 
         [0117]    The Model Ventilator™ determines whether the patient is an adult or child when the operator enters the patient&#39;s approximate weight. Accordingly, the International ECC and CPR Guidelines 2000 default values for adult or child are invoked. The operator may change the patient&#39;s approximate weight setting at any time before or during operation. To reduce “dead space” and “compressible volume”, the Model ventilator&#39;s pediatric ventilator circuit should always be used whenever pediatric operation is selected. 
         [0118]    The ventilator LCD screen continuously displays current and updated settings, directions, airway-pressure information and battery status during operation. 
         [0119]    In the CPR MASK Operating Mode, the V T  Alarm (Tidal Volume), comparing exhaled volume to delivered volume and delivered volume to set volume, is an Advisory Alarm. It triggers when exhaled volume is more than 25% less than delivered volume or delivered volume is more than 25% less than set volume. When initiated, the V T  alarm is accompanied by a message in the LCD&#39;s AMC that includes the actual percentage offset. This alarm can be easily influenced by mask leakage. Once the Alarm Mute/Cancel Pushbutton Switch is pressed, the audible component of this alarm is disabled until power is recycled to “OFF” and then “ON” again. The accompanying Alarm LED illuminates as applies, as does its AMC message. 
       Quick-Start Mask Mode 
       [0120]    26. SET DEFAULT SETTINGS FROM TABLE: See #24 
         [0121]    27.  FIGS. 8 ,  9  REFERENCE B: reference from the VENTILATION MODE SELECTION flow diagram. 
         [0122]    28. HIGH PEAK PRESSURE?: during first 4 breaths the High Peak Pressure auditory alarm is disabled. During this time, the Model Ventilator™ assess the peak inspiratory pressure. If the peak inspiratory pressure of the first delivered breath is greater than the Pressure Relief Alarm Setpoint (see Appendix 1), then the respiratory rate is increased by 10% and the tidal volume is decreased by 10%. Using this approach, the default minute volume is maintained will the ventilator attempts to decrease the peak inspiratory pressure. If the peak inspiratory pressure second breath is greater than the Pressure Relief Alarm Setpoint, then the respiratory rate is increased by 10% (20% total) and the tidal volume is decreased by 10% (20% total). If the peak inspiratory pressure remains greater than the Pressure Relief Alarm Setpoint, then the auditory High Pressure Alarm is enabled and High Pressure Alarm message is displayed on the LCD screen. The user is also prompted that the patient&#39;s weight may be too high, the patient&#39;s airway may be occluded or that the ventilator tubing may be kinked. 
         [0123]    The patient is protected from high airway pressure during all ventilations by a pressure relief mechanism based on the patient&#39;s weight (see Appendix 1). The High Pressure Relief has a range from 20 to 80 cm H 2 0 that the operator may change independent of the patient&#39;s weight setting, at any time during operation. 
         [0124]    30. INCREASE RR MAINTAIN VMIN: if the Peak Inspiratory Pressure is greater than the Default Pressure Relief Setpoint, the Model Ventilator™ increases the respiratory rate by 10% and decreases the tidal volume by 10% maintaining minute volume and reducing the peak inspiratory pressure, see #28 for a complete description. 
         [0125]    32. HIGH PEAK PRESSURE?: the patient is protected from high airway pressure during all breaths by a pressure relief mechanism based on the patient&#39;s weight (see Appendix 1). The High Pressure Relief has a range from 20 to 80 cm H 2 0 that the operator may change independent of the patient&#39;s weight setting, at any time during operation. 
         [0126]    34. INCREASE RR MAINTAIN VMIN: if the Peak Inspiratory Pressure is greater than the Default Pressure Relief Setpoint, the Model Ventilator™ increases the respiratory rate by 10% and decreases the tidal volume by 10% maintaining minute volume and reducing the peak inspiratory pressure, see #28 for a complete description. 
         [0127]    36. HIGH PEAK PRESSURE?: see #32 for description. 
         [0128]    38. CHANGE SETTINGS?: during operation, if it becomes necessary to change a setting (ventilation mode, new patient weight, pressure limit Setpoint, or positive end-expiratory pressure), the user pushes the encoder 2 times to open the CHANGE SETTINGS Menu Screen. (See CHANGE SETTING, QS MODES, #138-174, and CHANGE SETTING, CPR MODES #180-218 for detailed description.) 
         [0129]    40.  FIG. 9  REFERENCE I: this is the reentry point following a change in the Pressure Relief/Alarm Setpoint on the CHANGE SETTINGS, QS MODE flow diagram. 
         [0130]    41.  FIG. 9  REFERENCE F: references to the CHANGE SETTINGS, QS MODE flow diagram. 
         [0131]    42. POWER OFF?: at any time during operation the user can select to turn the unit off. To do this, the user presses and holds the Power Switch for 3 seconds. A screen prompt then asks the user to confirm power off. The default selection is yes and the user is only required to press the encoder once to turn the unit off. If the user selects no, the screen reverts back to the operating screen. 
         [0132]    When the Model Ventilator™ is connected to external power during power off, the unit does not turn completely off A Power Management screen is displayed indicating the charging status of the internal battery. 
         [0133]    44. END OPERATION: indicates the ventilator is no longer in operation. See #42 for additional information. 
       Quick-Start Tube Mode 
       [0134]    46. Set Default Settings From Table: see #24. 
         [0135]    47.  FIG. 10  REFERENCE C: reference from the VENTILATION MODE SELECTION flow diagram. 
         [0136]    48. HIGH PEAK PRESSURE?: see #28 for description. 
         [0137]    50. INCREASE RR MAINTAIN VMIN: see #30 for description. 
         [0138]    52. HIGH PEAK PRESSURE?: see #32 for description. 
         [0139]    54. INCREASE RR MAINTAIN VMIN: see #34 for description. 
         [0140]    56. HIGH PEAK PRESSURE?: see #36 for description. 
         [0141]    58.  FIG. 10  REFERENCE J: this is the reentry point after a new Pressure Relief/Setpoint value has been entered in the CHANGE SETTING, QS MODE flow diagram. 
         [0142]    60. CHANGE SETTINGS?: see #38 for description. 
         [0143]    61.  FIG. 10  REFERENCE F: reference to the CHANGE SETTINGS, QS MODE flow diagram. 
         [0144]    62. POWER OFF?: see #42 for description. 
       CPR Tube Mode 
       [0145]    See #22 for a complete description of CPR TUBE mode. 
         [0146]    64. WEIGHT&gt;24KG?: patients greater than 24 kg are treated using the adult default settings following the International ECC and AHA CPR Guidelines 2000 CPR procedures. NOTE: To reduce breathing dead space and compressible volume, the Model ventilator&#39;s pediatric ventilator circuit should always be used whenever pediatric operation is selected. 3    
         [0147]    65.  FIGS. 8 ,  11  REFERENCE D: reference from the VENTILATION MODE SELECTION flow diagram. 
         [0148]    66. SET I-TIME=2.0 SEC: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 2.0 second inspiratory time when ventilating an adult with a protected airway. 3    
         [0149]    68. SET I:E=1:2: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1:2 I:E ratio when ventilating an adult with a protected airway. 3    
         [0150]    70. SET VT=1000 ML: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1000 ml tidal volume when ventilating an adult with a protected airway. 3    
         [0151]    72. CONFIRM SETTINGS: see #8 for description. 
         [0152]    74.  FIG. 11  REFERENCE L: this is the reentry point after a new High Pressure Limit has been entered on the CHANGE SETTING, CPR MODES flow diagram. 
         [0153]    76. BEGIN OPERATION: see #9 for description. 
         [0154]    78. 5 COMPRESSIONS @ 100/MIN: International ECC and AHA CPR Guidelines 2000 CPR procedures call for a chest compression rate of 100 compressions/minute when performing CPR. 3    
         [0155]    80. 1 BREATH: International ECC and AHA CPR Guidelines 2000 CPR procedures call for 1 breath for every 5 chest compression when performing CPR on an adult with a protected airway. 3    
         [0156]    82. CHANGE SETTINGS: see #28 for description. 
         [0157]    84. SET I-TIME=1.0 SEC: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1.0 second inspiratory time when ventilating a child with a protected airway. 3    
         [0158]    86. SET I:E=1:2: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1:2 I:E ratio when ventilating a child with a protected airway. 3    
         [0159]    88. SET VT=500 ML: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 500 ml tidal volume when ventilating a child with a protected airway. 3    
         [0160]    90. CONFIRM SETTINGS: see #8 for description. 
         [0161]    92.  FIG. 11  REFERENCE M: this is the reentry point after a new High Pressure Limit has been entered on the CHANGE SETTING, CPR MODES flow diagram. 
         [0162]    94. 5 COMPRESSIONS @ 100/MIN: International ECC and AHA CPR Guidelines 2000 CPR procedures call for a chest compression rate of 100 compressions/minute when performing CPR. 3    
         [0163]    96. 1 BREATH: International ECC and AHA CPR Guidelines 2000 CPR procedures call for 1 breath for every 5 chest compression when performing adult CPR on a patient with a protected airway. 3    
         [0164]    98. CHANGE SETTINGS?: see #38 for description. 
       CPR Mask Mode 
       [0165]    See #22 for a complete description of CPR MASK mode. 
         [0166]    100. WEIGHT&gt;24?: patients greater than 24 kg are treated using the adult default settings following the International ECC and AHA CPR Guidelines 2000 CPR procedures. NOTE: To reduce breathing dead space and compressible volume, the Model ventilator&#39;s pediatric ventilator circuit should always be used whenever pediatric operation is selected. 3    
         [0167]    101.  FIG. 12  REFERENCE E: reference from the VENTILATION MODE SELECTION flow diagram. 
         [0168]    102. SET I-TIME=2.0 SEC: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 2.0 second inspiratory time when ventilating an adult using a facemask. 3    
         [0169]    104. SET I:E=1:2: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1:2 I:E ratio when ventilating an adult with a facemask. 3    
         [0170]    106. SET TIDAL VOLUME=7 ML/KG: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 6-7 ml/kg tidal volume when ventilating a patient without a protected airway. 3    
         [0171]    108. CONFIRM SETTINGS: see #8 for description. 
         [0172]    110.  FIG. 12  REFERENCE N: this is the reentry point after a new High Pressure Limit has been entered on the CHANGE SETTING, CPR MODES flow diagram. 
         [0173]    112. BEGIN OPERATION: see #9 for description. 
         [0174]    114. 15 COMPRESSIONS @ 100/MIN: International ECC and AHA CPR Guidelines 2000 CPR procedures call for a 5:1 chest compression to breath ratio when performing CPR on an adult without a protected airway. 3    
         [0175]    116. 2 BREATHS: International ECC and AHA CPR Guidelines 2000 CPR procedures call for 2 breaths for every 15 chest compression when performing CPR on an adult without a protected airway. 3    
         [0176]    118. CHANGE SETTINGS: see #28 for description. 
         [0177]    120. SET I-TIME=1.0 SEC: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1.0 second inspiratory time when ventilating a child without a protected airway. 3    
         [0178]    122. SET I:E=1:2: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 1:2 I:E ratio when ventilating a child without a protected airway. 3    
         [0179]    124. SET TIDAL VOLUME=7 ML/KG: 7 ML/KG: International ECC and AHA CPR Guidelines 2000 procedures call for the use of a 6-7 ml/kg tidal volume when ventilating a patient without a protected airway. 3    
         [0180]    126. CONFIRM SETTINGS: see #8 for description. 
         [0181]    128.  FIG. 12  REFERENCE 0: this is the reentry point after a new High Pressure Limit has been entered on the CHANGE SETTING, CPR MODES flow diagram. 
         [0182]    130. BEGIN OPERATION: see #9 for details. 
         [0183]    132. 5 COMPRESSIONS @ 100/MIN: International ECC and AHA CPR Guidelines 2000 CPR procedures call for a 5:1 chest compression to breath ratio when performing CPR on a child without a protected airway. 3    
         [0184]    134. 1 BREATH: International ECC and AHA CPR Guidelines 2000 CPR procedures call for 1 breath for every 5 chest compression when performing CPR on a child without a protected airway. 3    
         [0185]    136. CHANGE SETTINGS: see #38 for description. 
       Change Settings, QS Mode 
       [0186]    During operation if it becomes necessary to change a setting, this can be accomplished by pressing the encoder 2 times. This opens the CHANGE SETTINGS MENU SCREEN, which allows the user to select a new mode of operation, set a new patient weight, set a new high-pressure limit, or add or remove PEEP. If the CHANGE SETTINGS MENU SCREEN was opened inadvertently, the user may also return to the previous operating screen by selecting CONTINUE CURRENT SETTINGS. 
         [0187]    138. SET NEW MODE?: SET NEW MODE is the default selection. By pushing the rotary encoder, the MODE selection menu is opened and the current operating mode is highlighted. Using the encoder, the user can select any of the operating modes by turning the encoder to highlight the desired mode and pressing the encoder. Note: the user may select the current operating mode. Doing this, allows the user to enter a new patient weight and resets the high-pressure limit to the default value. 
         [0188]    140.  FIG. 13  REFERENCE G: reference to CHANGE SETTINGS/RETURN TO MODE flow diagram. 
         [0189]    142. SET NEW WEIGHT?: by highlighting SET NEW WEIGHT and pressing the encoder, the user is able to enter a new patient weight. See #6 for additional details. 
         [0190]    144.  FIG. 8  REFERENCES B: reference to QUICK-START MASK MODE flow diagram. 
         [0191]    146. TUBE?: see #14 for description. 
         [0192]    148. ON-PAGE REFERENCE C: reference to QUICK-START TUBE MODE flow reference. 
         [0193]    150. SET HIGH PRESSURE LIMIT?: by highlighting the SET HIGH PRESSURE LIMIT and pressing the encoder, the current high-pressure alarm/limit is displayed. Turning the encoder increases or decreases the value. Pressing the encoder stores the value. NOTE: the range of the HIGH PRESSURE alarm/limit is 10-80 cm H 2 0. 
         [0194]    152. ENTER NEW VALUE: the user is prompted to enter a new value. 
         [0195]    158 CONFIRM SETTINGS: see #8 for description. 
         [0196]    160. ON-PAGE REFERENCE H: reference to insert figure #158 on the CHANGE SETTINGS, QS MODE flow diagram. 
         [0197]    162. SET PEEP?: by highlighting the SET PEEP and pressing the encoder, the user can add 5 cm H 2 0 of positive end-expiratory pressure (PEEP). The Model ventilator only allows zero baseline pressure or 5 cm 1120. NOTE: the default start-up PEEP is zero cm H 2 0. 
         [0198]    164. CONTINUE CURRENT SETTINGS: allows the user to exit the CHANGE SETTINGS window without effecting the current mode or settings. 
         [0199]    168. CONFIRM SETTINGS: see #8 for description. 
         [0200]    170.  FIG. 13  REFERENCE H: see #160 for details. 
         [0201]    176.  FIG. 13  REFERENCE I: the reentry point in the QUICK-START MASK MODE flow diagram. 
         [0202]    177. 
         [0203]    178.  FIG. 13  REFERENCE J: the reentry point in the QUICK-START TUBE MODE flow diagram. 
       Change Settings, CPR Modes 
       [0204]    During operation, if it becomes necessary to change a setting, this can be accomplished by pressing the encoder 2 times. This opens the CHANGE SETTINGS MENU SCREEN, which allows the user to select a new mode of operation, set a new patient weight, or a new high-pressure limit. If the CHANGE SETTINGS MENU SCREEN was opened inadvertently, the user may also return to the previous operating screen by selecting CONTINUE CURRENT SETTINGS. 
         [0205]    180. SET NEW MODE?: see #138 for description. 
         [0206]    182.  FIG. 13  REFERENCE G: reference to the CHANGE SETTINGS/RETURN TO MODE flow diagram. 
         [0207]    184. SET NEW WEIGHT?: see #142 for description. 
         [0208]    186. ENTER NEW VALUE: see #152 for description. 
         [0209]    187. CONFIRM SETTINGS: see #8 for description. 
         [0210]    188. TUBE?: see #14 for description. 
         [0211]    190.  FIG. 12  REFERENCE E: reference to CPR MASK MODE flow diagram. 
         [0212]    192.  FIG. 11  REFERENCE D: reference to CPR TUBE MODE flow diagram. 
         [0213]    194. SET HIGH PRESSURE LIMIT?: see #150 for description. 
         [0214]    196. CONTINUE CURRENT SETTINGS: see #164 for description. 
         [0215]    198. ENTER NEW VALUE: see #152 for description. 
         [0216]    204. CONFIRM SETTINGS: see #8 for description. 
         [0217]    206. TUBE?: see #14 for description. 
         [0218]    208. WEIGHT&gt;24 KG: see #64 for description. 
         [0219]    210.  FIG. 14  REFERENCE O: reference to reentry point on CPR MASK MODE flow diagram. 
         [0220]    212.  FIG. 14  REFERENCE N: reference to reentry point in CPR MASK MODE flow diagram. 
         [0221]    214. WEIGHT&gt;24 KG: see #64 for description. 
         [0222]    216.  FIG. 14  REFERENCE L: reference to reentry point on CPR TUBE MODE flow diagram. 
         [0223]    218.  FIG. 8  REFERENCE M: reference to reentry point on CPR TUBE MODE flow diagram. 
       Change Settings/Return to Mode 
       [0224]    220. CPR?: see #18 for description. 
         [0225]    222. TUBE?: see #14 for description. 
         [0226]    224.  FIG. 9  REFERENCE E: reference to CPR MASK MODE flow diagram. 
         [0227]    226.  FIG. 14  REFERENCE D: reference to CPR TUBE MODE flow diagram. 
         [0228]    228. TUBE?: see #14 for description. 
         [0229]    230.  FIGS. 8 ,  10  REFERENCE C: reference to QUICK-START TUBE MODE flow diagram. 
         [0230]    232.  FIGS. 8 ,  9  REFERENCE B: reference to QUICK-START MASK MODE flow diagram. 
         [0231]    Other improvements and changes can be made to the herein disclosed exemplary embodiment without departing from the spirit and scope of the present invention. 
       REFERENCE LIST 
       [0000]    
       
         1. Foley L J, Ochroch E A. Bridges to establish an emergency airway and alternate intubating techniques. Crit Car Clin 2000; 16:429-44, vi. 
         2. Anonymous. Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 6: advanced cardiovascular life support: section 3: adjuncts for oxygenation, ventilation and airway control. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Circulation 2000; 102:195-104. 
         3. Pepe P E, Gay M, Cobb L A, Handley A J, Zaritsky A, Hallstrom A, et al. Action sequence for layperson cardiopulmonary resuscitation. Ann Emerg Med 2001; 37:S17-25.