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The Journal of Emergency Medicine, Vol. 41, No. 6, pp. 607–612, 2011Copyright © 2011 Elsevier Inc.

Printed in the USA. All rights reserved0736-4679/$–see front matter

doi:10.1016/j.jemermed.2009.04.038

OriginalContributions

PEDIATRIC SELF-INFLATING RESUSCITATORS: THE DANGERS OFIMPROPER SETUP

James O’Neill, MD,*† Charry Scott, RRT,‡ Niranjan Kissoon, MD,§ Peter Wludyka, PHD,�Robert Wears, MD,* and Robert Luten, MD*

*Department of Emergency Medicine, University of Florida at Jacksonville, Jacksonville, Florida, †Department of Emergency Medicine,Wake Forest University Health Sciences, Winston-Salem, North Carolina, ‡Department of Respiratory Therapy, Wolfson Children’s

Hospital, Jacksonville, Florida, §Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada, and�Department of Mathematics and Statistics, University of North Florida, Jacksonville, Florida

Reprint Address: James O’Neill, MD, Department of Emergency Medicine, Wake Forest University Health Sciences, Medical Center

Boulevard, Winston-Salem, NC 27157-1089

e Abstract—Background: Self-inflating resuscitators (SIRs)are often used in pediatric resuscitation. Improper setup of theSIR can lead to inadequate ventilation and oxygenation. Ob-jectives: To present clinical scenarios in which SIRs deliveredinadequate tidal volumes due to improper use. Second, toevaluate tidal volumes delivered using SIRs at varying lungcompliances with the manometer and pop-off valve port openand closed. Third, to suggest methods to overcome improperuse. Methods: Five pediatric resuscitators were tested underconditions simulating normal lungs, lungs with moderatelydecreased compliance, and lungs with poor compliance (0.015,0.010, and 0.005 L/cm H2O, respectively) to determine vol-umes delivered with proper SIR setup (manometer and pop-off valve closed) and improper SIR setup (manometer orpop-off valve open). Results: With each SIR, an open manom-eter port or an open pop-off valve (improper setup) led tosignificant decreases in volume delivered. In normal lung com-pliance, the proper setup delivered 149 � 10 cc, vs. 112 � 12cc, 106 � 25 cc, and 90 � 14 cc (pop-off open, manometeropen, and both open, respectively). In poor lung compliance,the proper setup delivered 122 � 13 cc, vs. 56 � 10 cc, 70 �17 cc, and 44 � 7 cc (pop-off open, manometer open, and bothopen, respectively). All differences above are significant (p <0.0001). Conclusions: In a normal lung, the volumes deliveredby SIRs are significantly decreased with the pop-off valveand manometer port open. Proper set-up of the SIRbecomes even more important when lung compliance ispoor. © 2011 Elsevier Inc.

RECEIVED: 31 October 2008; FINAL SUBMISSION RECEIVED:

CCEPTED: 10 April 2009

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e Keywords—self-inflating resuscitator (SIR); resuscita-tion; emergency; manual ventilation; bag valve mask ven-tilator; malfunctions

INTRODUCTION

Bag valve mask ventilation is effective in non-intubatedchildren requiring airway support, and also delivers ef-fective tidal volume in the setting of endotracheal intu-bation (1). Bag valve mask ventilation is a skill that iswidely taught and is an indispensable first-line adjunct toadvanced airway management. However, the techniqueis not without complications. Barotrauma is a commoncomplication of pediatric positive-pressure ventilation(2). When inexperienced users administer excessive vol-umes of gas, the elevated pressures produce tissue injury,air leaks, and gas accumulation in various body cavities.These air collections—pneumothorax, pneumomediasti-num, or pneumoperitoneum—are among the leadingcauses of morbidity and mortality associated with bagvalve ventilation (3). In an effort to prevent the abovecomplications, a safety leak valve was implemented andis now a permanent fixture of pediatric self-inflatingresuscitators (SIR).

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608 J. O’Neill et al.

The safety leak or “pop-off” valve, as it is commonlyreferred to, limits the buildup of pressure by allowing gasto leak out of the system once pressure exceeds a pre-setvalue (most SIRs have the pop-off mechanism set at35–40 cm of water pressure, which is approximately twoto three times the pressure needed for lung expansion inthe setting of normal compliance). Although designed tolimit excessive pressures, when more than 35–40 cm ofwater is needed to deliver adequate tidal volumes, as inpoor lung compliance, the valve must be closed. Casereports and our own experience demonstrate that notclosing the valve in cases of poor lung compliance mayactually lead to inadequate ventilation (4).

Inadequate ventilation can have a variety of causes. Ifthe manometer port is not closed, gas will escape fromthe system. Such pressure leakage from an open manom-eter pressure port occurs immediately, upon compressionof the bag. The actual volume lost varies from SIR toSIR, depending on the size of the port. The volumelost will vary from bag to bag as well as from breathto breath (5,6).

This article has three purposes. First, we present twoclinical scenarios that depict the consequences associatedwith an inability to generate necessary pressures andtherefore adequate tidal volumes—due to either poorlung compliance or SIRs malfunction. Second, we sim-ulate clinical situations of varying lung compliance andSIR malfunction in a bench model to demonstrate howthese two factors affect adequate bag valve ventilation.Third, we suggest preventative strategies to avoid com-mon SIR complications leading to inadequate bag valveventilation.

CASE PRESENTATIONS

Case 1

A 16-day-old newborn was being intubated electively forrecurrent apneic episodes. Initial attempt at intubationwas unsuccessful, and bag valve mask ventilation wasbegun with a SIR. Chest rise was minimal and oxygensaturations continued to decline despite optimal airwayposition and continued bagging. Gas was eventuallynoted to be escaping through an open pop-off valve.After the valve was closed, immediate chest rise andimproved oxygenation was noted.

Case 2

A 6-month-old infant presented to the Emergency De-partment in cardiorespiratory arrest. While preparing for

intubation, the patient was aggressively bagged with a

SIR. Oxygen saturations failed to improve; this wasinitially attributed to poor peripheral perfusion. The pa-tient was intubated, tube position was confirmed, andbagging was resumed. Still, no improvement in oxygensaturation was seen, and chest rise remained poor. Onreassessment of the SIR apparatus, gas was found to beescaping from an open pop-off valve. After closing thevalve, both chest rise and the patient’s color improveddramatically.

These two cases demonstrate the clinical consequencesof improperly engaged pop-off valve or manometer portsand prompted the experiments outlined below.

MATERIALS AND METHODS

The experiment was a complete factorial design with fivefactors: manometer at two levels (on [open] and off[closed]), pop-off at two levels (on and off), complianceat three levels (normal, medium, and poor), five differentbag valve masks (listed below), and set rates at threelevels (20, 40, and 60 breaths/min). The compliancevalues were as follows; normal (0.015 L/cm H2O), mod-rately decreased (0.010 L/cm H2O), and poor (0.005/cm H2O).

Bag valve masks used included Vital Signs® Pedilue II® Resuscitator (Totowa, NJ), Ambu® Brand

SPUR® II Disposable Resuscitators (Linthicum, MD),Cardinal Health Airlife® Pediatric Manual Resuscitator(McGaw Park, IL), Mercury Medical® Pediatric CPR

ag Disposable Manual Resuscitator (Clearwater, FL),nd Capno-Flo® Single-Patient-Use Pediatric Resuscita-

tion Bag (Pleasanton, CA).The experiment was performed in two phases. Phase

1 was designed to simulate the clinical situation in whichinadequate ventilation is not noticed (absence of chestrise) and the force of gas delivery (squeezing the SIR) iskept constant. Phase 2 is designed to simulate the situa-tion in which inadequate ventilation is noticed and theforce of ventilation with the SIR is maximized to com-pensate. All simulations were done utilizing a test lungthat is commonly used and available on the market (DualTTL Test Lung, Grand Rapids, MI). The ideal lungcapacity of this test lung is 150 cc, based on a 15-kginfant. Lung compliance was also varied for each phaseof the experiment.

In phase 1, the operator of the SIR was blinded tovolumes delivered as if they were not paying attention tochest rise in a patient. A respiratory therapist with 25years experience used the SIR and was also blinded tothe volumes delivered to the test lung. One hundredeighty runs were performed in a randomized order, using

all bags under all conditions.

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Pediatric Self-inflating Resuscitators 609

In phase 2, the operator of the SIR attempted tocompensate for poor chest rise (defined as chest rise of50 cc or less) by increasing the force used to ventilate.Again, 180 runs were performed in a randomized order,using all bags under all conditions.

Phase 2 was performed by a Pediatric EmergencyMedicine Fellow, board certified in Emergency Medi-cine, with 180 runs in a different randomized order,using all bags under all conditions. The operator was notblinded in this phase. Two-hand ventilation of the SIRwas employed to deliver the maximum volumes. Therespiratory rate used in both phases was set and keptconstant with a metronome. The rates used were 20, 40,and 60 breaths/min for each setup of compliance, bag,and manometer and pop-off combinations.

RESULTS

Because primary interest was not in the bags, an analysisof variance (using PROC GLM) utilizing the three vari-ables (pop-off, manometer, and compliance) as predic-tors of total volume was undertaken. For compliance,Tukey-Kramer confidence intervals were used to exam-ine the three pairwise comparisons. This maintained 95%simultaneous confidence.

Phase 1 Controlled ventilation:Volume Change for Manometer/PopOff Setting

by Compliance Level

0

20

40

60

80

100

120

140

160

Man ON Man OFF

Popoff & Manometer

Aver

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Tota

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ume

A

21

Pop Open Pop Open Pop Closed Pop Closed

Man Closed Man Open

Figure 1. Effect of open valves on delivered tidal volumes durventilation. (A) Under controlled ventilation, closing an open(1 and 2); if the manometer port is also open, there is virtuawhen attempting to compensate for poor chest rise), closinvolume. Note: Different-colored points represent normal, m

Table 1. Specifications of Self-inflating Resuscitators (SIRs

Bag Pop-off Pressure Limit

Vital Signs Pedi Blue II 35–45 mm HgAmbu® Brand SPUR® II

Disposable Resuscitator40 mm Hg Inf

Cardinal Health AirlifePediatric Resuscitator

40 mm Hg

Mercury Medical PediatricCPR Bag

42 � 5 mm Hg

Capno-Flo® Pediatric Adjustable 15–50 mm H2O

Resuscitation

Figure 1 graphically demonstrates the results of phase1 and phase 2. Actual values for phase 2, the mostclinically pertinent demonstration, are presented here andare also organized in Table 1. In normal lung complianceconditions, the proper setup delivered 149 � 10 cc, vs.112 � 12 cc, 106 � 25 cc, and 90 � 14 cc (pop-off open,

anometer open, and both open, respectively). Withoderately decreased lung compliance, the proper setup

elivered 137 � 8 cc, vs. 92 � 13 cc, 88 � 15 cc, and2 � 9 cc (pop-off open, manometer open, and bothpen, respectively). In poor lung compliance conditions,he proper setup delivered 122 � 13 cc, vs. 56 � 10 cc,0 � 17 cc, and 44 � 7 cc (pop-off open, manometerpen, and both open, respectively). All differencesbove are significant (p � 0.0001). The results areummarized in Table 1. The variables of pop-off,anometer, and compliance were significant as main

ffects (all p � 0.0001).

DISCUSSION

he two case presentations illustrate potential problemsncountered when SIRs are used without meticulousttention to details. These types of errors are more likelyo occur under stress, especially in situations where crit-

Phase 2 Maximum Forced Ventilation:olume Change for Manometer/PopOff Setting

by Compliance Level

Pop ON Pop OFF Pop ON Pop OFF

Popoff & Manon

NormalMiddleHigh

4

3

Pop Open Pop Open Pop Closed Pop Closed

Man Closed Man Open

Low

ntilation at various resistances with controlled vs. maximumff valve has only a modest effect on delivered tidal volumeeffect. (B) Using maximum forced ventilation (for example,pen pop-off valve (3 and 4) dramatically improves deliverednd low compliance states.

Intended Use Total Volume Stroke Volume

7–30 kg 900 cc 480 ccnd children up to 30 kg 635 cc 450 cc

10–30 kg 1000 cc 500 cc (one hand)

7–30 kg 500 cc 360 cc

10–40 kg 700 cc Not available

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100120140160

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610 J. O’Neill et al.

ically ill children are treated infrequently and staff maybe less familiar with pediatric equipment. An apprecia-tion of the role of the pop-off valve and manometer portand the consequences of their malfunctioning may serveto avoid some of these iatrogenic mishaps.

The pop-off valve is unique to pediatric SIRS and isnot present on larger adult SIRS. The situation caused byinadequate ventilation in the presence of adequate com-pression of the bag is more obvious in adults, as it is mostcommonly caused by a poor seal of the mask on thepatient’s face resulting in visible and audible leaks. Inchildren, inadequate ventilation due to open valves onthe pediatric bag produces no visible or routinely recog-nizable sound.

The problem of an open pop-off valve has been re-ported and remains a potential danger (4). An informalsurvey of 200 emergency physicians attending an airwaycourse (a motivated group) revealed that � 50% had noknowledge of the pop-off valve or its function. Fewerthan 25% could identify the manometer port.

No study has reported the hazards of an open manom-eter port during bag valve mask ventilation. Our studydemonstrates that in situations of high airway resis-tance, a malfunction in either can lead to hypoventi-lation (Figure 1).

From a clinical perspective, if the malfunction goesunnoticed, and mask ventilation is done with normalinflation pressures (Figure 1A), no appreciable leak isnoted with the pop-off valve open until the resistance iselevated to the point of producing a pressure � 40 cm ofwater. With an open manometer port seal, the rise willbegin immediately, even with normal ventilatory pres-sures. In situations of increased airway resistance, in theface of poor chest excursion, adequate chest rise may beobtained by squeezing the bag with more force, thusincreasing ventilatory pressure with the delivery of ade-quate volumes (Figure 1B). However, with either thepop-off valve or manometer port seal open, varyingdegrees of hypoventilation will occur, as demonstrated.

The average delivered tidal volume with the pop-offvalve only open in the low compliance group was 56 cc,with a range of 46–66 cc. The average tidal volumedelivered with manometer port only open in the lowcompliance group was 70 cc, with a range of 53–87 cc.The larger variance with the open manometer port re-flects differences in manometer port design, that is, somehave higher resistances than others, whereas all pop-offvalves are designed to allow gas to escape at a pre-setlevel regardless of design. This probably represents anarea for further study to determine which brands of SIRsare more risk-averse for complications from manometerport dislodgement. It should be noted also that pop-offpressure escape valves that have been noted to be unre-

liable may also be activated at varying pressures, de-

pending on the force of ventilation in the same SIR (5,6).The average maximum delivered volume with bothvalves disengaged under conditions of poor complianceand maximal ventilation was 44 cc. This represents only28% of starting volumes under conditions of normalcompliance (149 cc) and 36% of starting volumes underconditions of poor compliance (122 cc).

The three compliances set on the test lung representarbitrary values, not representative of any specific clini-cal condition. Although 28% of normal starting volumesand 36% of poor compliance volumes could be obtainedat the pre-set poor compliance settings on the test lung, itis logical to assume that in situations of high-gradeobstruction, a bag with all valves open would be evenless effective than demonstrated here, indeed a point ofworsening compliance would be reached in which life-sustaining tidal volumes can be obtained only with allvalves closed.

A

B

Figure 2. (A) Negative leak test. With the face mask removedand one hand over the patient port, the bag is squeezed. Thebag remains tight with minimal give as it is squeezed. Theblack arrows point to the closed pop-off valve and the closedmanometer port. (B) Positive leak test. With the face maskremoved and one hand over the patient port, the bag issqueezed. The bag collapses as it is squeezed. Arrow points toan open pop-off valve (white arrow), which allows escape of

gas, and a closed manometer port (black arrow).

Pediatric Self-inflating Resuscitators 611

Cognizant of these issues, we suggest two measuresthat may be useful in decreasing or eliminating theseiatrogenic problems: a remote preparation equipmentstorage protocol, and an immediate pre-use protocol uti-lizing the leak test. The remote preparation equipmentstorage protocol involves checking all the equipment andstoring them in a specially configured manner.

Remote Preparation: Equipment Storage Protocol

Because the pop-off valve is a safety device designed toprevent barotrauma with use, the SIR tends be packagedfrom the manufacturer with the valve open, ready tofunction by limiting barotrauma with initial ventilations.This can usually be manually closed through the pack-aging before stocking without breaking the sterility. Themanometer port may also be checked at this time, how-ever, it tends to come closed from the manufacturer.

Immediate Pre-use Protocol: The Leak Test

The leak test involves a quick check of the integrity ofthe device. Instead of inspecting all the possible valvesand tubes for secure fit, a simple procedure can quicklydetermine whether a clinically significant leak is present.The leak test is performed by removing the mask fromthe SIR, occluding the mask port with the palm of onehand, and squeezing the bag with the other hand. If thebag remains tight, no escape of gas or “leak” has oc-curred. If the bag does not remain tight, gas is escapingfrom the system, and the pop-off valve or manometerport should be checked, although another cause for theleak may be present. After a negative test, that is, the bagremains tight with squeezing, the port-occluding palmhand should be released, and the bag squeezed to confirm

that gas escapes properly from the outlet valve (Figure 2).

Limitations

Our study suffers from a few limitations. The test lung isan imperfect model that can only simulate normal lungmechanics. The three chosen resistances are not repre-sentative of any specific disease states. No effort wasmade either to define inadequate ventilation or to deter-mine what lung resistance would produce that number;rather, the study was designed to demonstrate the prin-ciples involved when the valves are used improperly.

CONCLUSIONS

In summary, the pop-off valve and manometer port po-sitions are important determinants of delivered tidal vol-umes, especially in situations of decreased lung compli-ance. Attention to details during storage and a leak testbefore use will circumvent delivery of low tidal vol-umes attributable to manometer port and pop-off valvepositions.

REFERENCES

1. Gausche M, Lewis RJ, Stratton SJ, et al. Effect of out-of-hospitalpediatric endotracheal intubation on survival and neurological out-come: a controlled clinical trial. JAMA 2000;283:783–90.

2. Miller RD, Hamilton WK. Pneumothorax during infant resuscita-tion. JAMA 1969;210:1090–1.

3. Klick JM, Bushnell LS, Bancroft ML. Barotrauma, a potentialhazard of manual resuscitators. Anesthesiology 1978;49:363–5.

4. Hirschman AM, Kravath RE. Venting vs ventilating. A danger ofmanual resuscitation bags. Chest 1982;82:369–70.

5. Connors R, Kissoon N, Tiffin N, Frewen TC. An evaluation of thephysical and functional characteristics of infant resuscitators. Pedi-atr Emerg Care 1993;9:104–7.

6. Kissoon N, Connors R, Tiffin N, Frewen TC. An evaluation of the

physical and functional characteristics of resuscitators for use inpediatrics. Crit Care Med 1992;20:292–6.

612 J. O’Neill et al.

ARTICLE SUMMARY1. Why is this topic important?

Pediatric self-inflating resuscitators are different thanadult self-inflating resuscitators. Improper setup can limitoxygenation and ventilation.2. What does this study attempt to show?

This study shows the differences tidal volumes deliv-ered to a test lung from both properly and improperlysetup pediatric self-inflating resuscitators in normal andlow compliance conditions.3. What are the key findings?

An improperly set up pediatric self-inflating resuscita-tor (manometer port open and pop-off valve unlocked)delivers dangerously low volumes to a low complianceinfant test lung.4. How is patient care impacted?

Two simple techniques are discussed that can be usedduring pediatric resuscitations to prevent improper func-tion of pediatric self-inflating resuscitators.