The following materials represent the Vortran Training Program available on the Access CE website

Transcription

1 The following materials represent the Vortran Training Program available on the Access CE website Presented here as a courtesy for MCDH staff utilizing the Vortran Automatic Resuscitator Questions: David.Gibson@hcahealthcare.com

2 Gas Powered VORTRAN Automatic Resuscitator (VAR) for Short Term, Emergency Ventilation by James I.C. Lee Clinical Advisors Gordon A. Wong, M.D., FACP, FCCP Mario Romano, RCP Barry Hickerson, EMT-P, CFP Continuing Education 1.0 Contact Hours CME through East Valley Medical Center, Glendora, California Check with your state licensing organizations about recognition of these providers for your continuing education. This module is supported by an Unrestricted Educational Grant. Table of Contents I. Objective II. Introduction III. Description of Available Devices IV. Using an Automatic Resuscitator V. Setting up Patient for Short Term Emergency Ventilation or Transport VI. Clinical Applications of Automatic Resuscitator VII. Reference

3 Objectives At the completion of this in-service, the practitioners will be able to: Use the equipment needed to provide short term, emergency ventilation for the mechanically ventilated patients. Describe the different resuscitation methods. Describe the rationale for using an automatic resuscitator. Complete exam components at 85% competency. II. Introduction In this section you will learn: Oxygenation and ventilation Tidal volume Minute volume IE ratios Typical ventilation pressures Common terms [A] Oxygenation and ventilation Caring for mechanically ventilated patents is a logistically difficult and potentially dangerous process. The importance of this method of ventilation has been shown when comparing manual versus portable mechanical ventilation in a short term emergency situation and during patient transportation. 1-2 Using a transport ventilator, Hurst et al. 3 found no appreciable changes in ph or PaCO 2 compared to a marked respiratory alkalosis when manual ventilation was used during patient transportation. Utilizing a swine pediatric transport model, an automated transport ventilator provided more effective ventilation than did bag-valve or demand valve devices. 4 Using the patient s ICU ventilator is often limited by lack of mobility in the size and weight of the ventilator and the need for continuous power supplies. 5 Similar and related limitations exist in emergency medical care. Serious complications, such as pneumothorax, have been reported during transportation with self-inflating bag-valve devices. 6 In the emergency setting EMS providers commonly treat respiratory emergencies in one of two ways, increase oxygen concentration of inspired gases and /or support respirations. Any patient that has insufficient oxygenation or respiratory effort needs

4 immediate intervention. This may be in the form of providing more oxygen by using an oxygen cannula or mask. It also may include an increase in tidal volume, respiratory rate or complete ventilatory support in the case of a respiratory or cardiac arrest. Do not confuse the need to provide supplemental oxygen to a patient that is in need of ventilatory support. A patient with a low respiratory rate or decreased volume needs ventilatory support in the form of a BVM or resuscitator. Patients with low oxygen levels need oxygen therapy with an oxygen cannula or oxygen mask. Some patients may require ventilation and oxygenation simultaneously. [B] Tidal Volume and Minute Volume When providing ventilatory support to a patient, it is important to understand some basic numbers. The total volume of air in each breath is known as the tidal volume. This is roughly 10 ml per kg. The average 70 kg patient would, therefore, have a tidal volume of 10 ml x 70 kg = 700 ml. Multiply this volume times the respiratory rate, and you have the minute volume. As in the 70 kg example, if the respiratory rate is 12 breaths per minute, the minute volume is 700 ml x 12 = 8400 ml minute volume or 8.4 liters per minute. [C] IE ratios During the inspiratory and expiratory phases of respirations, pressures change within the lungs. At the beginning of the inspiratory cycle, pressures are at a minimum. Pressure is required to inflate the lungs to the point were either a specific volume has been reached or a specific pressure. When this volume or pressure has been reached, the expiratory cycle starts. The inspiratory plus the expiratory time equals the complete respiratory cycle. The inspiratory time and the expiratory time are typically not the same. The relationship between the two is referred to as the inspiratory / expiratory ratio or IE ratio. This ratio is typically 1:2 ~ 1:3. The longer expiratory time is due to the fact this is a passive process. In the case of a patient that is breathing 12 times per minute, the total respiratory cycle is 5 seconds (60 seconds divided by 12 breaths). The inspiratory portion of this may only be 1.0 to 1.5 seconds, with the remaining 3.5 to 4.0 seconds being the

5 expiratory phase. Pressure and flow rates control the I time while exhalation flow resistance controls the E time. During the respiratory cycle pressures are increased and decreased within the lungs. If you think of the lung as two large rubber bags, as you inflate them, the pressure continues to increase until it becomes difficult to inflate any further. The lungs are very much the same. Factors that affect the amount of pressure it takes to inflate the lungs are the presence of lung disease, obstructions, and external pressures, such as the presence of a pneumothorax. Without disease or mechanical factors, lungs will become fully inflated within the same pressure range regardless of size. This is an important concept because the same pressure range will be appropriate for most patients regardless of their size. [D] Typical ventilation pressures The typical pressures within the lungs start out at 2 cm-h 2 O and reach a peak of cm-h 2 O. This peak pressure of should provide adequate inflation in the majority of patients. You may have to increase this for diseased lungs, patients with asthma, or in cases of chest trauma. The peak pressure is known as Peak Inspiratory Pressure or PIP and occurs at the end of the inspiratory cycle. This will be a setting on pressure-cycled ventilators, such as the VAR. At the end of expiration, the body naturally retains a slight pressure in the lungs known as Positive End-Expiratory Pressure or PEEP. This keeps the lungs from totally collapsing at the end of the respiratory cycle and makes it easier for the next breath. When using a ventilator, the operator will set an artificial PEEP to replace the natural PEEP. III. DESCRIPTION OF available DEVICES In this section you will learn: Methods of transport ventilation Effects of CPR Understanding gas-powered automatic resuscitators [A] Manual Resuscitation

6 Since the late 1950's, the Bag-Valve-Mask (BVM) resuscitator, (see Figure 1), originally developed by Ambu in Denmark, has been the mainstay of the healthcare provider for emergency ventilation of the patient in respiratory and/or cardiac arrest. Certainly, in the early days of CPR, these devices were the only available adjuncts for the rescuer which did not require the use of exhaled breath to ventilate the patient. As such, they were a significant advance in emergency respiratory care. However, considering the major advances in medicine that have taken place over the last 35 years, we are still, in the most part, relying on old technology to perform the key task of oxygenating the respiratory/cardiac arrest patient. Figure 1 - Photo of Bag-Valve-Mask resuscitator That technology has not only been superseded by superior equipment during this time but has also been proven to be ineffective in the way in which it provides ventilation and is potentially dangerous (especially in some non-protected airway situations). The American Heart Association "Guidelines for CPR" published in the Journal of the American Medical Association, October 28, 1992, 7 quite clearly noted that these devices were generally ineffective in providing adequate ventilation to the patient. A wealth of clinical evidence to support these claims has been accumulated over the past 30 years and this evidence has, for the most part, been ignored as die-hard "baggers" continue to utilize these devices. This continued use is not based on sound clinical evidence that they provide good ventilation, but because - " it has always been done this way." Some claim that the "feel" they get from the BVM allows them to make

7 clinical judgments on the patient's lung condition. In reality what they are probably feeling is the back pressure created by the high flowrates generated when squeezing the bag too hard or for too short an inspiratory time. The majority of all prehospital ventilation is accomplished using the BVM device. This device has improved with the addition of colorimetric CO 2 monitoring and injection ports. The BVM is an inexpensive, easy-to-use, dependable device for providing ventilatory support for non-breathing patients or for supporting breathing patients. When connected to an oxygen source and used in conjunction with a reservoir, the BVM can obtain oxygen concentrations of greater than 90%. In the event of electrical failure and/or loss of an oxygen source, the BVM allows continuation of ventilations on room air. It is the mainstay of prehospital and emergency ventilatory support. In the real world of emergency medicine, the BVM has some real limitations. First of all, the BVM requires a dedicated set of trained hands. The operator must be exactly synchronized with any and all patient movements. If the patient is receiving ventilations via mask, it is almost impossible to maintain an adequate seal during patient movements. If the patient is intubated, any deviation of the BVM operator may result in an accidental extubation or right main stem intubation. During certain types of patient movement, such as loading or unloading, the patient may not be ventilated at all! These are all serious risks to the patient. During ventilation of a patient by the BVM, it is impossible to accurately control rate and volume. Even the best-trained hands cannot precisely control the rate and volume delivered. The rate and volume directly affect the level of CO 2 in the blood and blood chemistry. If ventilations are too slow or are inadequate, an elevation in CO 2 results. This in turn causes a drop in PH creating a respiratory acidosis. If ventilations are too rapid or have too much volume, this lowers the PH and results in a respiratory alkalosis. While hyperventilation and a decreased CO 2 is thought to be beneficial to a patient, primarily in head injuries and cardiac arrests, the effect is just the opposite. A respiratory alkalosis will cause a left shift in the oxyhemoglobin disassociation curve and impair the uptake and release of oxygen by the hemoglobin molecule. Moderate to severe hyperventilation is dangerous to your patient, and it is, therefore, important to control ventilations.

8 In an ill or injured patient, variations in the CO 2 level and blood chemistry can affect mortality and morbidity. It is vital that patients receiving ventilatory support have their rate and controlled. With a manual device, this is not possible. The BVM is an acceptable alternative for very short periods of time or when no other device is available. It is inexpensive, easy to use and the set up time is immediate. In the prehospital care setting, there is no time inside a crushed car or on a shopping mall floor to set-up a ventilator that has 10 buttons, alarms, knobs and 10 feet of tubing. It is not practical and will probably never happen. There are only a few practical ventilators for prehospital care and attempts to simplify their use has nit been accomplished. IV. Using an Automatic Resuscitator In this section you will learn: Use of the VAR Benefits of controlling rate and volume [A] Automatic Resuscitator In the 1960's, the first of the manually triggered, oxygen powered resuscitators came onto the market and enabled healthcare providers to provide 100% oxygen under positive pressure to their patients. In the American Heart Association "Guidelines for CPR" published in the Journal of the American Medical Association 1986, 8 these flowrates were lowered to 40 liters per minute as a way of reducing the inspiratory pressures, gastric distension, and risk of barotrauma. To further reduce the risks to the patient, the maximum delivery pressure these devices can produce was limited to 60 cm-h 2 O. Cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC) are important life-saving procedures. 8 Adjunctive equipment for oxygenation, ventilation, and airway control includes manually-operated self-inflating bag-valve units and pressure cycled automatic mechanical ventilators and resuscitators. 8 During these procedures, closed-chest compression may interrupt or interfere with pulmonary ventilation. Intrathoracic pressures may vary depending upon the pulmonary

9 ventilation procedures and the use of adjunctive ventilatory equipment. The flow from gas-powered resuscitators is pressure sensitive and may cease prematurely because of high airway resistance "without alerting the rescuer." 7 Because of these factors and the published guidelines, 7 the American Society for Testing and Materials (Philadelphia, PA) has provided a "Standard Specification for Minimum Performance and Safety Requirements for Resuscitators Intended for Use with Humans" (ASTM Designation ). 9 Specifically, paragraph A3.1.31(11.1.1) provides, "Manufacturer's Warning - These resuscitators are unacceptable for use during closed chest cardiopulmonary resuscitation because the increase in intrathoracic pressure caused during chest compression causes the resuscitator to cycle from the inspiratory mode to the expiratory mode prior to adequate ventilation of the lungs." 10 ASTM provides a prudent general warning for the typical pressure-cycled, time-controlled mechanical ventilators, which could malfunction during chest compression. A properly designed pressure-cycled, pressure-controlled automatic mechanical ventilator should be able to adequate ventilation without the risk of barotrauma during closed chest resuscitation. On the other hand, the manual bag resuscitator requires trained synchronization during chest compression and may reduce pulmonary ventilation and markedly increase intrapulmonary pressures during inhalation. [B] VORTRAN Automatic Resuscitator (VAR) The VAR provides constant-flow, pressure-cycled ventilatory support (See Figure 2), is a disposable gas-powered automatic resuscitator intended to provide short term, emergency, non-continuous ventilatory support to patients while being monitored by a clinician. During inhalation, exhalation will not start until peak pressure is reached. During exhalation, inhalation will not begin until pressure drops to the positive end-exhalation pressure (PEEP). This unique feature among ventilators allows it to operate effectively during CPR.

10 Figure 2 - Photo of VORTRAN Automatic Resuscitator (VAR ) The VAR runs on a continuous fixed flow rate of gas (inspiratory flow) of up to 40 L/min (maximum flow at typical 50 PSIG supply pressure). When connected to a 50 PSIG high flow source, the VAR will automatically deliver 40 L/min (667 ml/second). Peak pressure may be adjusted from between 20 and 50 cm-h 2 O and PEEP is approximately 10% to 20% of the set peak inspiratory pressure (PIP). This device meets ASTM requirements and includes an inspiratory pressure relief valve that opens automatically at approximately 60 cm-h 2 O and has a distinctive and easily recognized sound. An optional pressure gauge (manometer) allows visualization of airway pressure during use. Also, the audible signal of the inhalation-exhalation breathing cycle allows the rescuer to qualitatively monitor the breathing rate and associated inspiratory tidal volume as an indication of high airway resistance or poor lung compliance. The flow rate from your regulator will determine the I or inspiratory time. Oxygen flows through the VAR and inflates the patient s lungs. The rate at which this happens is dependent on the oxygen flow rate and the size of your patient. Although a flow rate of 15 lpm may work when you are trying to conserve oxygen, the I time will be extended. Increasing the flow rate to 25 lpm will shorten the I time due to the increased flow and decreased time needed to inflate the lungs. The RATE control knob determines the rate at which gas escapes from the breathing circuit by making an opening smaller or larger. This will determine the E expiratory time. Changes in I or E times will affect the overall respiratory rate. Flow rate determines I time; the RATE knob determines E time; together they control both the I

11 and E time. Turn the round RATE dial clockwise (inward) for a slower rate, or counter clockwise (outward) for a faster rate. Remove the VAR from the package and connect one end of the oxygen tubing to the VAR DISS fitting and the other to your oxygen source. Turn on the oxygen source and set the flow rate to 25 lpm (15 lpm if outside ambulance and you need to conserve oxygen) or greater. Confirm you have gas flow through the resuscitator. Make sure all connections are tight. Set PRESSURE setting to the ranges. Connect flex tubing from VAR to the endotracheal tube adapter (patient) and adjust PRESSURE control knob for chest rise. Verify chest rise, bilateral breath sounds and overall patient appearance. Confirm with pulse oximeter readings and other vital signs. You should observe the inline manometer rise and fall, indicating that the airway circuit is patent. Adjust the RATE control knob to 12 ~ 20 breaths per minute or based on end tidal carbon dioxide levels of 35 ~ 40. Always follow your local hospital or EMS policies and procedures when you use the VAR or any medical device. Once you have the PRESSURE and RATE set, secure the VAR to the side of the patient s head so as to act as a strain relief for the ET tube. When moving the patient, consider placing a portable oxygen cylinder on the stretcher to minimize the chance of pulling the ET tube. During patient use, continue to monitor your patient observing chest rise and fall, overall appearance and vital signs. Continue to make adjustments as needed to correct PRESSURE or RATE. Never leave the patient unattended while on the VAR. A kinked or plugged ET tube will cause the VAR to flutter rapidly, as PIP is reached very quickly. Identify the cause of this problem immediately and correct it. A loose fitting or hose will cause a leak and PIP may never be reached. If a leak prevents the VAR from reaching PIP, the VAR will never cycle. You must immediately identify the problem and correct it. If you are unsure what is wrong, immediately substitute the VAR with a BVM and attempt manual ventilation.

12 V. setting up Patient for Short Term Emergency Ventilation or Transport In this section you will learn: Method of transport ventilation Setting PIP and RATE FiO 2 Settings 100% or 50% [A] Setting Short Term, Emergency, Non-Continuous Ventilator The VAR provides short term, pressure cycled, and constant flow ventilatory support for either breathing or non-breathing patients. This allows the patient to receive consistent reliable ventilatory support. The VAR is pressure cycled on inhalation and exhalation (PIP and PEEP), which minimizes the possibility of gas trapping. During inhalation, exhalation will not start until PIP is reached. During exhalation, inhalation will not begin until pressure drops to PEEP. For the spontaneous breathing patient, the rate dial of the VAR is set so that the baseline pressure is above the set PEEP, allowing the patient to initiate inhalation by drawing the baseline pressure down to the set PEEP. Because the VAR is a constant flow pressure cycled device, changes in patient compliance will result in changes in the respiratory rate (stiffer or smaller compliance produces faster rates). The advantage of this is that the danger of barotraumas is minimized. However, it should be emphasized that the VAR is to be used only by trained personnel who continuously monitor the patient. The VAR is not an ICU stand-alone ventilator with multiple monitoring features. [B] Setting up and use of the VAR is simple: Set desired flow rate (Q) Adjust pressure dial to obtain desired PIP Adjust rate dial to obtain desired breathing rate 1. Set desired flow rate - The VAR runs on a continuous flow of gas (inspiratory flow) of 15 to 40 L/min, depending on the patients inspiratory flow demand. When connected to a 50 PSIG gas source, the VAR will automatically deliver 40 L/min (667 ml per second) per ASTM guidelines. Delivered tidal volume may be

13 determined by multiplying the flow in ml per second and the inspiratory time in seconds, or using the tidal volume table (Table 1). Table 1 - Tidal Volume Table at Various Flow Rates Flow Inspiratory Time (Seconds) (LPM) NOTE: The gas flow, patient s lung compliance and PIP settings control the inspiratory time and tidal volume. Calculate inspiratory time (ti) by desired flow (Q) to attain tidal volume (TV = Q X ti). 2. Adjust pressure dial to obtain desired PIP. It may be adjusted from 10 and 50 cm H 2 O. PEEP is typically 10 to 20% of PIP (depending on the model of the VAR). Inspiratory time and rate are adjustable over a wide range. Changes in the pressure dial setting or flow will normally also affect the respiratory rate. It is important to check all settings when making a change to any of the three variables (flow, pressure, rate). For example: reducing the pressure dial setting may cause the VAR to go into spontaneous breathing mode. If so, turn the rate dial counter-clockwise to restart automatic cycling. 3. The rate dial controls exhalation time (time-e), and when dialed down enough will cause the VAR to stop cycling automatically (infinite exhalation time). Under these circumstances the VAR is delivering pressure supported ventilatory support, and the patient must trigger the VAR to begin subsequent full inhalations. If the patient is apneic or pressure control ventilation is desired, restart automatic cycling of the VAR by adjusting the rate dial counter clockwise until cycling begins again. Whenever the VAR stops cycling, the first step, in the absence of obvious clinical factors, is to check if it is in pressure support mode by rotating the rate dial counter clockwise (out). If rotating the rate dial counter clockwise substantially (3 or 4 turns) does not start automatic cycling, the patient s airway may be occluded or there may be a very large leak.

14 Figure 3 Airway Pressure

15 4. The air entrainment valve is included with VAR which allows the patient to entrain additional air and respond to the demands of the patient. Patient entrainment of outside air is normally audibly detectable and the percent oxygen delivered to the patient will be reduced. Specific concentrations of oxygen may be delivered to the patient with the use of an oxygen blender. 5. Pressure pop-off valve - Although the design of the modulator is similar to that of a pop-off valve and is inherently safe, the VAR is also equipped with a redundant pop-off valve that relieves pressure at 60 cm H 2 O. When the pop-off valve is activated, the pop-off valve piston will move slightly. 6. Manometer - Although peak pressures are listed on the side of the pressure dial, those are only approximate. Clinicians using the VAR are still required to use good clinical judgment and monitor the patient appropriately. A manometer may be connected between the modulator and the patient connector tee. Because the VAR is pressure cycled on PEEP as well as PIP, in the pressure control mode there is no prolonged stage where the flow of exhalation gas stops for a significant duration of time. In the pressure support mode, exhalation time is determined by the patient. This occurs because the exhalation time is set with the rate dial by varying the exhalation resistance so that the patient just finishes exhalation with the beginning of the subsequent inhalation. The volume of gas with which the patient s lungs are inflated when reaching PEEP is the same as with any other means of obtaining PEEP. As with all ventilatory support modes, short exhalation times on patients with high airway resistance may lead to gas trapping, which is not detectable in the patient s external airways. Upon occlusion of the patient s airways, the VAR will stop cycling and may sometimes cycle rapidly. 7. Using a Mask - The VAR will work with any mask that provides a good seal on the patient (Figure 4). All clinicians should receive adequate training with a mask prior to using the VAR. In the presence of a small leak, the VAR will still cycle between PIP and PEEP. Noticeable changes in the presence of a leak are

16 increased inspiratory times and decreased expiratory times. The VAR works very well with an endotracheal tube. An inhalation may be immediately initiated by briefly removing the mask from the patient or briefly disconnecting the modulator from the patient adapter tee. In either event, inhalation begins because pressure drops down to PEEP and the VAR is pressure cycled. Figure 4- Photo of VAR with mask 8. Upon contamination of the VAR with vomitus, the VAR may be cleared by disconnecting the modulator from the patient connector tee (see enclosed instructions) and tapping out vomitus on a hard surface. Additionally, if needed, the rate dial may also be removed to facilitate removal of vomitus from the modulator. This operation should take less then 20 seconds, and in a lab setting has consistently been shown to take approximately 11 seconds. Alternatively, upon contamination with vomitus, the clinician may choose to discard the device and use a new one. Inhalation and exhalation are audibly detectable and easily recognizable during operation of the VAR.

17 9. Optional gas entrainment feature for VAR If 100% of supply gas is to be delivered to the patient, connect the tubing to the green colored gas connector marked "100%" with the DISS thread connection on the patient tee. If 50% FiO 2 delivery is desired, remove the green adapter and connect the oxygen tubing to the gray colored entrainment adaptor marked "50%" with the Diss thread connection on the patient tee. The VAR will deliver FiO2 of 50% (10%) when connected to the gray colored 50% entrainment connector and is supplied with an oxygen flow from 6 to 15 L/min with resulting output flow of 20 to 40 L/min respectively (see "Entrained Flow Table 2").

18 10. The duration of an E cylinder when using a VAR will depend on the flow. An E cylinder contains 625 L of gas. At 40 L/min, 625 L will last up to 15 minutes; at 20 L/min, 625 L will last up to 30 minutes. 15 L/min orifice type flowmeters used on many E cylinders will not be able to deliver more than 15 L/min. When clinicians decide that 15 L/min is not sufficient flow, the VAR can be attached to a regulator that has a high flow port (50 PSIG) to deliver 40 L/min. One of the disadvantages of continuous flow of gas is that E cylinders will not last as long as other ventilators. The length of use for various sizes of compressed oxygen tanks (D, E, M & H) is a function of the supplied oxygen flow from 6 to 40 L/min to VAR (see TABLE 3).

19 VI. Clinical Applications of Automatic Resuscitator In this section you will learn: Inter- and Intra Hospital of transport Use in MRI or CT Scan Using in Mass Casualty Incidents (MCI) [A] Inter- and Intra Hospital transport Ventilatory support is an important aspect of transporting a mechanically ventilated patient out of the ICU. It is equally important under emergency care conditions. Various techniques have been established for this purpose including the use of manual self-inflating bag-valve ventilation, portable mechanical ventilation and manual bag-valve ventilation during actual patient movement followed by returning to standard mechanical ventilator at the destination. Significant expense and respiratory therapy effort is required when portable and standard ventilators are used in transporting ventilator dependent patients. Direct expenses include the purchase of transport ventilators and the need for portable battery systems for standard ventilators. Indirect costs include the set up and cleaning time for these ventilators. The direct costs, indirect expenses and time requirements limit the number of transport ventilators available in a given hospital. The VAR with a portable continuous oxygen source is a useful, disposable, pressure-cycled mechanical ventilator for transporting patients out of the ICU. The automatic nature of the PEEP setting results in a small decrease (mean 1.4 cm-h 2 O) in PEEP during transportation. The VAR is easy to use, extremely portable and is not associated with any complications (e.g. no barotrauma). Similar results are suggested for use of the VAR as an automatic resuscitator in emergency care medicine. The VAR automatic, pressure-cycled, disposable mechanical ventilator has been demonstrated to be well tolerated during transportation of mechanically ventilator dependent patients outside of an ICU. [B] Use in MRI or CT Scan

20 Many medical facilities do not have MRI compatible ventilators. As a result MRI studies on intubated patients are frequently delayed until the patient is extubated. Although there are mechanical ventilators that are MRI compatible, the cost for purchasing them for MRI use only is impractical, especially in light of the limited number of intubated patients needing an MRI. The VAR can be a safe and cost effective ventilator for use in the MRI unit without the need to purchase capital equipment. The VAR was tested and functioned properly in a Pickering 1.0 MRI unit and General Electric 1.5 MRI unit. There was a slight image artifact, which according to the MRI technician, was no more significant than what would be caused by a spinal pin or dental fillings. By positioning the device away from the target, a complete image was obtained. A Quality Control test was completed on the MRI unit during the test procedure. QC was within normal limits. The device functioned without incident. There was no attraction to the magnet or any movement of the VAR. The patient was able to trigger the device during spontaneous breathing without incident. Figure 5 - VAR with Extension Tubing [C] Use during Mass Casualty Incidents (MCI) The March 1995 Tokyo, Japan incident sounded a wake-up call to health care workers. The intentional release in the subway system, Sarin a chemical neurotoxin, resulted in 11 deaths and five thousand casualties exhibiting a variety of toxic symptoms requiring medical evaluation. This number rapidly overwhelmed the health care system.

21 (Brackett D.W., Holy Terror, Armageddon in Tokyo, New York: Weatherhill, Inc. 1996). It had long been recognized that it was not a matter of if but when a terrorist initiated mass casualty incident would happen. Recognizing this potential scenario for the National Capital Region, the Ottawa Hospital embarked on a series of planning and preparation exercises. The Respiratory Therapist representative on the Chemical, Biological, Radiation, Nuclear Committee noted that it became rapidly apparent that there was a serious discrepancy between the number of ventilators that would be required and the actual ventilator resources that would be available. Although most large hospitals have ventilators available at each site, these numbers would be woefully inadequate in the context of a mass casualty incident. An additional complicating factor was that, on average, 60% of the ventilators are in use with the remaining 40% either in for maintenance or in readiness for the next patients. In any mass casualty incident (accidental, industrial or terrorism), the finite limit of ventilators determines the number of patients that can be managed. This limit was determined to be both unacceptable and avoidable. The Respiratory Therapy department wanted to prevent compromised patient care and was cognizant of the two major factors facing the health care institution - that of limited health care dollars/funding and the potential number of patients that would present in a mass casualty incident. So, the department undertook a study to determine the most cost effective way of providing basic mechanical ventilation to a large number of patients. The VAR offered the capabilities of managing the largest number of patients at the most financially responsible cost. In addition, the unit had the advantage of ease of use. The other very important variable was that the equipment offered a simple solution to the handling of contaminated units from a biological or terrorism incident because it was disposable. The cost of the other units prohibited one time use and would result, therefore, in a lengthy and expensive decontamination process, which might also pose a hazard to hospital staff charged with decontaminating the units.

22 VII. References. 1. Gervais HW, Eberle B, Konietzke D, Hennes HJ, Dick W. Comparison of blood gases of ventilated patients during transport. Crit Care Med 1987;15: Braman SS, Dunn SM, Amico CA, Millman RP. Complications of intrahospital transport in critically ill patients. Ann Intern Med 1987;107: Hurst JM, Davis K, Jr., Branson RD, Johannigman JA. Comparison of blood gases during transport using two methods of ventilatory support. J Trauma 1989;29: Auble TE, Menegazzi JJ, Nicklas KA. Comparison of automated and manual ventilation in a prehospital pediatric model. Prehosp Emerg Care 1998;2: Barton ACH, Tuttle-Newhall JE, Szalados JE. Portable power supply for continuous mechanical ventilation during intrahospital transport of critically ill patients with ARDS. Chest 1997;112: Silbergleit R, Lee DC, Blankreid C, McNamara RM. Sudden severe barotrauma from self-inflating bag valve devices. J Trauma 1996;40: A.H.A Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care - J.A.M.A Oct.28, 1992: Raabe, OG, Romano M. Comparison of RespirTech PRO and Ambu SPUR Resuscitators During Simulated CPR Chest Compression, Submitted to Respir Care National Conference on Cardiopulmonary Resuscitation and Emergency Cardiac Care. Standards and guidelines for cardiopulmonary resuscitation (CPR) and Emergency Cardia Care (ECC). JAMA 1986;255: American Society for Testing and Materials Committee F-29. Standard Specification for Minimum Performance and Safety Requirements for Resuscitators Intended for Use with Humans, ASTM Designation , American Society for Testing an Materials, Philadelphia, PA; Gervais HW, Eberle B, Konietzke D, Hennes HJ, Dick W. Comparison of blood gas of ventilated patients during transport, Crit Care Med 1987;15: Braman SS, Dunn SM, Amico CA, Millman RP. Providence, Rhode Island: Complication of intrahospital transport in critically ill patients, Ann Int Med 1987;107: Hurst JM, Davis K, Jr, Branson RD, Johannigman JA. Comparison of blood gases during transport using two methods of ventilatory support. J. Trauma 1989;29: Hoekstra OS, van Lambalgen AA, Groeneveld AB, van den Bos GC, Thijs LG. Abdominal compressions increase vital organ perfusion during CPR in dogs: relation with efficacy of thoracic compressions, Ann Emerg Med 1995;25:

23 15. Christenson JM, Hamilton DR, Scott-Douglas NW, Tyberg JV, Powell DG. Abdominal compressions during CPR: hemodynamic effects of altering timing and force, J Emerg Med 1992;10: Sack JB, Kesselbrenner MB, Bregman D. Survival from in-hospital cardiac arrest with interposed abdominal counterpulsation during cardiopulmonary resuscitation, JAMA 1992;267: