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Resuscitation 81 (2010) 1161–1165

Contents lists available at ScienceDirect

Resuscitation

journa l homepage: www.e lsev ier .com/ locate / resusc i ta t ion

imulation and education

n evaluation of bag-valve-mask ventilation using an ergonomically designedacemask among novice users: A simulation-based pilot study�

ric B. Baumana,∗, Aaron M. Joffeb, Lynn Lenzc, Stephen A. DeVriesd, Scott Hetzele, Samuel P. Seider f

Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United StatesDepartment of Anesthesiology and Pain Medicine, University of Washington-Harborview Medical Center, Seattle, WA, United StatesDirector of Clinical Education, Respiratory Care, Western Technical College, La Crosse, WI, United StatesTri-State Ambulance, La Crosse, WI, United StatesDepartment of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, United StatesCollege of Letters and Science, University of Wisconsin-Madison, Madison, WI, United States

r t i c l e i n f o

rticle history:eceived 31 January 2010eceived in revised form 4 May 2010ccepted 7 May 2010

eywords:esuscitationirway managementacemaskentilation

a b s t r a c t

Purpose: We sought to compare the ability of novice operators to provide artificial ventilation using astandard facemask and a new ergonomically designed facemask. Whether or not proper technique wasused was also assessed.Methods: Thirty-two allied-health students used both masks in random crossover fashion to ventilate anairway trainer. Breaths were delivered by a mechanical ventilator and exhaled tidal volume was recordedfor each of 12 breaths for each participant for each mask. The effect of each mask during ventilation overtime was assessed using repeated-measures ANOVA. Assessment of mask technique among participantsand association between mask type and hand repositioning were analyzed using the Wilcoxon-Rank SumTest and McNemar’s paired proportions test, respectively.Results: The tidal volume achieved when participants used the ergonomic mask was higher than whenparticipants used the standard mask by the fourth breath (361 ± 104 mL vs. 264 ± 163 mL; Bonferroni

adjusted p-value = 0.040) and increased over time. The repeated-measures ANOVA showed that theergonomic mask consistently resulted in higher tidal volumes than the standard mask regardless of res-cuer’s gender. Over time the standard mask resulted in a linear decrease in tidal volume of −10 mL/breath(estimated difference in decay of 10 mL/breath versus the ergonomic mask; p < 0.001).Conclusion: Novice airway operators were better able to provide facemask ventilation using an ergonom-ically designed mask than with a traditional facemask. We conclude that better hand position facilitating

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improved mask seal and

. Introduction

Providing adequate oxygenation and ventilation for an apnoeicatient is the primary goal of rescuer-provided artificial ventilation.raditionally, this has been performed using a self-inflating resus-itation circuit interfaced with a facemask, generically referred tos bag-valve-mask (BVM). Generation of an effective seal betweenhe mask and the patient’s face in order to establish and maintain

pper airway patency is needed for effective BVM ventilation.

Efficacy of BVM ventilation is dependent on the interactionetween operator-dependent variables such as experience,1–3

and size,4 gender,5 and patient-dependent variables including

� A Spanish translated version of the summary of this article appears as Appendixn the final online version at doi:10.1016/j.resuscitation.2010.05.005.∗ Corresponding author. Tel.: +1 608 263 5911.

E-mail address: ebauman@wisc.edu (E.B. Bauman).

300-9572/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.oi:10.1016/j.resuscitation.2010.05.005

perator fatigue account for our findings.© 2010 Elsevier Ireland Ltd. All rights reserved.

obesity, facial hair, lack of teeth, age, limited cervical spine motion,and facial anatomic features impeding a mask seal.6–8 In addition,situation-dependent variables including mask ergonomics, envi-ronmental familiarity, and the presence or absence of distractionswill also influence the effectiveness of artificial ventilation witha BVM.9 Given the number of variables at play in stressful andunfamiliar environments surrounded by distractions, it is not sur-prising that rescuers with limited airway management experienceare unable to provide adequate BVM ventilation.10

The ErgoMaskTM (EM, King Systems, Noblesville, IN) is a newfacemask designed to ergonomically fit the clinician’s hand. Itis available as a left-handed device only (Fig. 1). This designmay enable better contact between the operator’s hand and the

mask, avoid hand fatigue, and allow for better control of the face-mask resulting in a better mask seal. In addition, an ergonomichand position may be more effective in maintaining patient posi-tioning maneuvers such as the head-tilt/chin-lift that facilitateupper airway patency.11 We hypothesized that an ergonomic face-

1162 E.B. Bauman et al. / Resuscitation 81 (2010) 1161–1165

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simulating artificial or rescue breathing using a BVM and two dif-ferent types of facemasks. This study did not attempt to addresseffectiveness of ventilation during cardio-pulmonary resuscitation(CPR) or any component related to circulation.

Fig. 1. Side-by-side comparison of the

ask would promote better technique among novice operatorsith limited or little experience providing BVM ventilation. We

lso hypothesized that using an ergonomically designed facemaskould promote more effective ventilation. The purpose of this

tudy was two-fold. First, we sought to compare the ability of noviceperators to provide artificial ventilation using both a standardacemask (SM) and the EM and second, to compare the operator’sbility to use adequate technique for each mask.

. Methods

Participants were 32 allied-health students with minimal air-ay management training. The convenience sample included 6

mergency medical technician students (EMT), 9 paramedic stu-ents, and 17 respiratory therapy students enrolled at a Midwestechnical college. Twelve (37.5%) of the subjects were men and 2063.5%) were women. The mean age for all participants was 28ears old. All participants had taken the American Heart Associ-tion Basic Life Support course at least once as a prerequisite toheir current training program. This curriculum provides specificraining on rescue breathing with a BVM. Additional basic train-ng in rescue breathing and BVM ventilation technique is includeds part of the EMT, paramedic and respiratory therapy curricula athe technical college. Instructional staff from the college’s Respira-ory Therapy and Paramedic programs collected all data. Primarynvestigators were not involved in data collection. The ethics com-

ittee of Western Technical College (La Crosse, Wisconsin) andhe Health Sciences Institutional Review Board at the Universityf Wisconsin-Madison approved the study.

Prior to data collection, a brief tutorial was provided to eacharticipant about the proper use of the SM and the EM. For theM, participants were instructed to use the “E-C” technique asrescribed by the American Heart Association guidelines for emer-ency cardiac care in which the thumb and forefinger form aC” shape over the mask and exert downward pressure on theask while the third, fourth, and fifth fingers (forming an E) are

ositioned along the jaw to maintain the jaw thrust.12 For theM, participants were instructed in its use per manufacturer rec-mmendations (Fig. 2). The SM used for all procedures was a

ingle-use medium size adult mask (Clear Comfort® Air-CushionaceMask, Teleflex Medical, Research Triangle Park, NC) with the-ring removed. One SM and EM were reused for all study proce-ures. Each participant performed all study procedures using bothM and EM in a random, crossover fashion.

askTM (left) and standard mask (right).

A single left-handed technique was used with both masks. Par-ticipants were asked to perform basic airway maneuvers, includingopening the airway and properly placing the facemask on aLaerdal®Airway Management Trainer (Laerdal Medical Corpora-tion, Wappingers Falls, NY). After obtaining a mask seal, breathswere delivered using a Pulmonetics LTV®1200 volume-cycled ven-tilator (CareFusion, San Diego, CA) set to deliver a tidal volume of500 mL, 12 times per minute, at an inspiratory-to-expiratory ratioof 1:4 (cycle-length 5 s). In order to simulate actual BVM ventila-tion, participants squeezed a breathing bag with their free handin time with each ventilator-delivered breath. The experimentalsetup is shown in (Fig. 3). The exhaled tidal volume was recordedfor each of 12 breaths by the ventilator for each participant usingboth the SM and the EM. During performance of each study proce-dure, two non-blinded expert observers evaluated participants onairway positioning, hand technique, quality of mask seal, and main-tenance of mask seal over time using a one through six Likert-stylescale with one representing the poorest possible technique and sixthe best possible technique. Repositioning of the airway and/or themask during the data collection period was also recorded. The studyprotocol only sought to evaluate the effectiveness of ventilation by

Fig. 2. Top view of th ErgoMaskTM in use on the Laerdal® Airway ManagementTrainer. The recommended asymmetric left-handed grip is demonstrated.

E.B. Bauman et al. / Resuscitation 81 (2010) 1161–1165 1163

Fig. 3. The experimental setup: A participant is using the ErgoMaskTM on themgta

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Fig. 4. Summary of repeated measures ANOVA with fitted regression lines: Y = tidalTM

annikin while squeezing the breathing bag in time with the ventilator (fore-round). Notice the breathing bag is being held just above the mask to simulatehe ergonomics of actual bag-valve-mask ventilation. The mechanical ventilator islso pictured (background).

The effect of each mask during ventilation over time wasssessed using repeated-measures ANOVA (RM-ANOVA) with thexhaled tidal volume set as the response variable. Mask type,umber of breaths, gender, age, and the presence of two-way

nteractions with mask type were examined as possible depen-ent variables. Normal distribution was assumed and parametricesting was used when assumptions of the RM-ANOVA were met.onferroni’s post-test was performed to adjust p-values when theM-ANOVA model stated that tidal volume was statistically dif-

erent based on breath time and mask type with p-values < 0.05.ssessment of proper technique with each mask among par-

icipants was analyzed using the Wilcoxon-Rank Sum Test andcNemar’s paired proportions test, respectively. Expert scoresere averaged as the final score in each category for the operator.ata is presented as mean ± SD or median [IQR] unless otherwiseoted. Statistical significance was defined as a p-value < 0.05.

. Results

Differences in exhaled tidal volume were examined at eachf the 12 breaths and compared by mask type. Results are sum-arized in (Table 1). By the fourth breath, the tidal volume

chieved when participants used the EM was higher than thatith the SM (361 ± 104 mL vs. 264 ± 163 mL; Bonferroni adjusted

-value = 0.040). This difference increased over time such that byhe end of the study period, participants using the EM achieved,n average, a tidal volume of 154 mL greater per breath than with

able 1ean (sd) tidal volume (mL) by breath and mask type.

Breatha Standard Mask ErgoMask Difference p-Valueb

1 330 (125) 377 (99) 47 (133) 0.6822 317 (136) 369 (104) 52 (145) 0.5943 304 (142) 364 (106) 60 (150) 0.3694 264 (163) 361 (124) 97 (172) 0.0405 261 (155) 372 (114) 111 (171) 0.0116 260 (161) 370 (106) 110 (183) 0.0237 257 (152) 363 (122) 106 (194) 0.0498 244 (166) 370 (118) 126 (181) 0.0059 234 (170) 368 (108) 134 (193) 0.00510 218 (164) 365 (114) 147 (197) 0.00311 223 (168) 370 (114) 147 (173) <0.00112 216 (170) 370 (119) 154 (195) 0.001Total 261 (159) 368 (111) 107 (176) <0.001

a Breaths were taken successively every 5 s.b Paired t-tests and are Bonferroni adjusted for 12 comparisons.

volume; X = number of breaths; Dots represent ErgoMask ; Triangles representstandard mask; Red represents Males; Black represents Females. (For interpretationof the references to color in this figure legend, the reader is referred to the webversion of the article.)

the SM. The RM-ANOVA showed a significant interaction betweenmask type and number of breaths (i.e. over time). Additionally,mask type, time, gender, the interaction of mask type and time,and the interaction of mask type and gender were all associatedwith tidal volume. The final model showed that use of the EM bystudy participants consistently yielded higher tidal volume than theSM regardless of gender and that over time, tidal volume remainedconstant (decay = −0.13 mL/breath, p = 0.921). However, use of theSM resulted in a linear decrease in tidal volume of −10 mL/breath(estimated difference in decay of 10 mL/breath; p < 0.001). This wasindependent of the participant’s gender. Lastly, the model showeda difference between the first breath tidal volume by mask typeamong females (277 mL for the Standard and 351 mL for the EM,p < 0.001), but no difference between males (409 mL for the Stan-dard and 399 mL for the EM, p = 0.568). The fitted RM-ANOVA modelwith estimated regression lines for mask type and gender is pre-sented in (Fig. 4).

There was reasonable agreement between the two expertsgrading operator technique in all areas (interclass correlationcoefficient > 0.5). No differences were found between masks infacilitating airway positioning prior to ventilation (EM: 6 [6–6],Standard: 6 [5.5–6], p = 0.175). Participants were more likely touse proper hand technique when they were using the SM (5.8[4.9–6]) and appeared to have difficulty using the demonstratedtechnique for the EM (5.0 [4.0–5.5], p = 0.002). However, genera-tion and maintenance of an effective mask seal were judged asbetter when participants used the EM (6 [5.5–6] and 6 [5.5–6])compared to the SM (4.5 [3.5–5.6] and 4.5 [3.5–6], p < 0.001 andp = 0.001, respectively).

4. Discussion

Failure to provide effective ventilation can be associated withnegative patient outcomes including hypoventilation, hypercarbia,hypoxia and acidosis.13 Historically, effective use of the BVM hasbeen challenging even among skilled clinicians.10,14 Teaching effec-tive BVM skills to clinicians who will act as first responders in and

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ut of the hospital remains an important and relevant aspect foruccessful resuscitation. It is not feasible to provide all first respon-ers, whether they are EMT’s, nurses, physicians or others withdvanced airway management skills.3 It is widely accepted thatffective BVM ventilation is more likely to occur when two rescuersre using the BVM, one rescuer using both hands to maintain maskeal and the other rescuer squeezing the bag. However, this is notlways possible or even feasible during initial emergency responsend as such; the one rescuer/single hand EC technique contin-es to be taught as part of the American Heart Association Basicife Support for Healthcare Providers course. In the United States,he American Heart Association Basic Life Support for Healthcareroviders curriculum is the practice standard for first responderraining for those practicing in both the hospital and out of hospi-al settings.12 Thus, devices that improve clinical performance inhis group of practitioners are of particular relevance.

In our simulation-based pilot study, novice airway managersere more able to provide effective facemask ventilation using an

rgonomically designed device, the EM, than with a SM as indicatedy higher average tidal volume per breath over time. Additionally,entilation provided using the EM was constant over the studyeriod, whereas effectiveness of ventilation decayed over timehen subjects provided facemask ventilation via the SM. A prior

tudy using a Resusci-Annie mannequin reported that >50% of themergency medical technicians tested were not capable of venti-ating to the minimum emergency cardiac care standard using aingle left-handed technique with a tear-drop shaped, clear plas-ic, soft air-cushion mask.14 Our study supports these findings andxtends observations attributing difficult or ineffective BVM ven-ilation and adequate mask seal to a single-handed mask sealingechnique and provides a potential effective alternative to the “fourand/two person skill.”14

Matioc hypothesized that the design of the traditional facemasktself has been a contributing factor associated with ineffective BVMentilation among novice clinicians. The single handed “E-C” tech-ique traditionally used with a standard facemask often tilts the

acemask to the left allowing air to leak under the right side ofhe mask.11 Our findings suggest that creation and maintenancef an adequate mask seal are improved by using an ergonomi-ally designed facemask. Despite demonstrations of proper maskechnique for each mask tested, participants were more likely tose proper technique when using the SM. Because all of the par-icipants had some exposure to the SM and the E-C techniquehrough their current program of study, this finding is likely relatedo prior experience and familiarity with the SM. Still, mask sealnd its maintenance over time were better with the EM than withhe SM.

Our study has limitations. It is simulation-based and may haveimited generalizability to actual clinical scenarios. Our method-logy, however, is consistent with previous studies that havettempted to evaluate novice airway managers.10,14 Although ourtudy design employed a mechanical ventilator to deliver thereaths provided during ventilation, we believe the process androcedure of providing traditional BVM ventilation was accuratelyimulated. We used an inspiratory-to-expiratory ratio set on theentilator (1:4) to simulate the type of flow rate that might be seenn practice when a breathing bag is squeezed by a person perform-ng actual BVM, but acknowledge that higher gas flow rates mayave highlighted any leaks in the system. This could have biased theesults in favor of the EM. However, given that the mean effect sizen tidal volumes with the EM was 36–71%, it is doubtful that our

esults were substantially altered by inspiratory flow rate alone.

e believe that our method of evaluation adequately controlledor the subjects’ ability to squeeze the self-inflating breathing bagnd reduced variability between subjects in delivered tidal vol-mes. Our intent was to study the participant’s ability to generate

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and maintain a mask seal, not to assess tidal volume generated bysqueezing the self-inflating breathing bag. Further, the random-ized crossover design of our study controlled for any variables thatmay have been related to hand size that could have confounded theability of subjects to generate and maintain a mask seal using eithermask. While improved performance using the EM was independentof gender, men were able to provide higher baseline tidal volumesthan women with both masks. Because we did not include handsize, digital spread, flexibility, and hand dominance as recordedvariables, the observed differences between genders may be relatedto these unmeasured variables.

In a previous study Koga and Kawamoto found that it was moredifficult for female anesthesia residents to provide an effectivemask seal early in their training as compared to their male counter-parts and that gender was shown to be an independent risk factorfor difficult mask ventilation.5 Our data is consistent with the gen-der findings shown by Koga and Kawamoto, but we also found thatfemales were able to maintain consistent tidal volumes when usingthe EM and hypothesize that the use of the EM might be particu-larly beneficial to female rescuers in their attempts to provide BVMventilation in actual patients.

We acknowledge the use of novices in all evaluations is a lim-itation. Novices were chosen, as they resemble in skill level manyfirst responders. However, use of novices in our study likely exag-gerated differences in performance between SM and EM. Thus, ourfindings may not be valid in and should not be extrapolated to moreexperienced operators.

5. Conclusions

Novice airway managers were able to more effectively venti-late with a facemask during this simulation-based investigation byusing an ergonomically designed device than they were with a tra-ditional SM. Future studies using the ErgoMaskTM should involveanaesthetized patients undergoing actual BVM ventilation by bothnovice and more experienced operators. Our finding related to con-stant performance over time when participants used the EM maybe of particular interest and warrants study for durations greaterthan the 1 min period included in our simulation.

Conflict of interest statement

None.

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