Article, Emergency Medicine

Effect of a backboard on compression depth during cardiac arrest in the ED: a simulation study

a b s t r a c t

Research Purpose: We evaluated the impact of a backboard on chest compression depth during cardiac arrest practice sessions conducted using a high-fidelity mannequin on a standard emergency department stretcher. Methods: Forty-three health care trainees completed Cardiac resuscitation simulations requiring 2 minutes of uninterrupted chest compressions. Twenty-one were randomly allocated to the intervention group in which a backboard was concealed by placement between the Stretcher mattress and a top sheet and, 22 were allocated to the control group in which no backboard was placed. The mannequin software automatically recorded mean chest compression depth in 10-second intervals for the 2 minutes of compressions.

Results: The backboard group achieved a mean compression depth of 41.2 mm (95% confidence interval, 37.8-44.6). The no-backboard group’s mean compression depth was 41.4 mm (95% confidence interval, 38.7-44.2). Most subjects in both groups did not achieve the 50-mm compression depth threshold recommended by the American Heart Association.

Conclusions: Use of a backboard as an adjunct during cardiopulmonary resuscitation of a simulated patient lying on a standard emergency department stretcher did not improve the mean chest compression depth achieved by advanced life support rescuers. Most rescuers did not achieve the minimum compression depth of 50 mm recommended by the American Heart Association.

(C) 2015

Introduction

The initial guidelines for cardiopulmonary resuscitation published in the Journal of the American Medical Association in 1974 as the “Standards for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiac Care (ECC)” [1] provided the foundation for CPR and Advanced cardiac life support training. In the 2005 update of these standards, greater emphasis was placed on high-quality chest compressions during CPR [2] including definitions for appropriate compression rate, depth of com- pression, recoil, and maximum acceptable time limits for interruption of continuous compressions. In 2010, the American Heart Association (AHA) again emphasized “prompt high-quality CPR with minimal inter- ruptions” as “The foundation of successful ACLS” [3]. Time is a critical factor in CPR and interruptions in chest compressions have been shown to decrease the successful defibrillation rate [4]. A delay of as little as 15 seconds has been shown to compromise the rate of successful resuscitation and increase adverse outcomes if return of spontaneous circulation is achieved [5]. Actions, such as placing a backboard, which lead to delays in initiating chest compressions or interruptions after compressions have started, can only be accepted if the action serves to improve chest compression performance.

The AHA currently recommends the placement of a backboard be- fore starting chest compressions in a hospital setting, but acknowledges

* Corresponding author. Cox Institute, 3525 Southern Blvd, Kettering, OH 45429-1221.

a weak basis for this recommendation stating, “we have traditionally recommended the use of a backboard despite insufficient evidence for or against the use of backboards during CPR” [6]. Previous studies have addressed CPR performance on a variety of support surfaces [7] in- cluding air mattresses before and after deflation [8]. Although some studies conclude that backboards can improve chest compressions [9-11], others suggest that backboards do not improve chest compres- sion quality and can cause adverse outcomes by delaying compressions unnecessarily [12]. We did not find any studies that specifically evaluated the impact of backboard use for patients on a standard 10-cm foam mattress used on emergency department stretchers.

We performed a randomized, controlled, single-blinded study using a high-fidelity simulation mannequin to compare the mean compres- sion depth achieved by subjects during 2 minutes of CPR in an experi- mental group (backboard placed under the simulation mannequin) and a control group (no backboard in place). We hypothesized that the use of a backboard underneath the simulation mannequin in this setting would not increase the mean compression depth.

Methods

This study was reviewed and approved by our university institutional review board as an exempt protocol. After approval, we measured and re- corded chest compression data from 43 health care trainees completing high-fidelity simulation practice in Cardiac arrest scenarios. Each scenario

http://dx.doi.org/10.1016/j.ajem.2015.10.035

0735-6757/(C) 2015

E.J. Fischer et al. / American Journal of Emergency Medicine 34 (2016) 274277 275

Fig. 1. SimMan Essential on emergency department stretcher during backboard placement.

included a SimMan Essential (Laerdal, Norway) mannequin on an emer- gency department stretcher (Stryker Medical, Portage, MI) with a standard 10-cm foam mattress (Fig. 1) and required at least one 2-minute sequence of chest compressions in accordance with the AHA guidelines. Subjects were recruited from trainees including physi- cian assistant students, fourth-year medical students, and first-year emergency medicine residents participating in resuscitation practice in our simulation laboratory. All subjects had completed CPR and ACLS training prior to participation in the simulation sessions. Subjects were informed that automatically recorded data from the mannequin would be evaluated as part of a research project, but the specific nature of the data being assessed was not revealed to the subjects.

Subjects were allocated, using a random number generator, to either the intervention group in which a backboard was placed under the mannequin prior to the simulation or to a control group in which no backboard was used. The backboard was placed between the stretcher mattress and a top sheet prior to the subjects entering the room, so as not to be readily apparent to subjects in the intervention group. Neither group was informed that backboards were being used in any of the scenarios.

Prior to each simulation day, we reviewed the institutional review board-approved cover letter with all subjects and gave them a written copy. Before each simulation scenario, the trainees were oriented to the room and equipment. We instructed them to complete all resuscita- tions in accordance with AHA standards and to do everything they would do in an actual cardiac arrest. During the 2-minute episodes of chest compressions, the mannequin software automatically recorded mean compression depth in 10-second segments.

Statistics

Each individual’s chest compression depths were averaged over the course of the first 100 seconds of the 120-second compression se- quence. These results were subsequently transferred to an Excel spread sheet (Microsoft, Redmond, WA) for analysis. The mean chest compres- sion depth with 95% confidence intervals (CIs) was determined for the intervention group and the control group. A t test assuming equal variance (homoscedastic) was used to compare the means, and a P value less than .05 was considered statistically significant. We calcu- lated that a sample size of 19 subjects per group was required to detect

a 5-mm difference in compression depth between groups with an ?

of .05 and a power of 0.80.

Results

All of the 43 eligible trainees consented to participate in the study. Twenty-one were allocated to the backboard group and 22 were allo- cated to the group without a backboard (Fig. 2). There was no signifi- cant difference in mean depth of chest compressions between the 2 groups. The mean compression depth of the backboard group was

41.2 mm (95% CI, 37.8-44.6). The mean compression depth of the no- backboard group was 41.4 mm (95% CI, 38.7-44.2; Fig. 3).

Fig. 2. CONSORT flowchart.

276 E.J. Fischer et al. / American Journal of Emergency Medicine 34 (2016) 274277

Fig. 3. Chest compression comparisons.

In both the intervention and control groups, the mean depth of chest compression did not reach the AHA-recommended guidelines for ade- quate depth (50 mm). Among the 43 subjects, only 4 individuals, 2 from each group, achieved a mean compression depth equal to or greater than the AHA-recommended minimum depth of 50 mm.

Discussion

Studies have shown that rescuers performing chest compressions frequently do not attain adequate depth [13,14]. Over the last decade, the AHA has placed an increased focus on achieving high-quality chest compressions during cardiac resuscitation. There are a number of ways to potentially improve the likelihood of achieving adequate chest compressions. Ultimately, any intervention that delays or inter- rupts chest compressions should be justified by a demonstrated benefit in the overall quality of compressions. Our results do not support the need for a backboard when performing CPR on an emergency depart- ment stretcher with the typical 10-cm foam mattress, as this action did not improve compression depth. Although we did not assess the delay in initiating CPR, any amount of time spent inserting a backboard between the patient and the mattress on a typical emergency depart- ment stretcher does not provide an adequate benefit in the form of improved chest compression depth.

It may be better for resuscitation teams to direct their attention to other readily available options that can be used to enhance the rescuer’s ability to perform better chest compressions. Although not an end point of this study, we noted that most subjects providing chest compressions did not use a readily available stepstool, or lower the bed to gain a height advantage and improve compression mechanics. All subjects were extensively briefed on the set up of the laboratory and its equip- ment including the location of the step stool and the mechanism for raising and lowering the bed. In the arrest scenarios, we also noticed that verbal feedback regarding chest Compression quality was rarely given. There are many activities occurring simultaneously in simulated and real arrests. During our simulated arrests, the resuscitation teams frequently failed to address chest compression quality and appeared task saturated with rhythm interpretation, medication doses, and resus- citation algorithms. This may be due to the fact that our sample

population was relatively inexperienced in running arrest scenarios and did not focus on the Quality of chest compressions or were not able to assess whether team members were achieving the AHA- recommended compression depth standards of 50 mm or greater.

Limitations

There are a number of limitations to our study. First, we only investi- gated one of many variables affecting depth of chest compression during a cardiac arrest scenario and we did not anticipate that most subjects would fail to achieve the recommended AHA minimum depth of 50 mm. Second, we only assessed depth of compression which is just one of the components of quality chest compression. Rate of compres- sions and recoil were not assessed because depth of compression is the variable most likely to be impacted by a backboard. Third, although the simulation scenarios were identical to situations that one would encounter in the hospital setting, they were still simulations. We were not able to assess if the subjects who failed to achieve adequate chest compressions would be more likely to increase their compression depth when faced with real life and death situations. Fourth, our sample size was small, but it exceeded the sample size of 19 per group needed to detect a 5-mm difference in compression depth between groups. Finally, our results only represent findings from a single institution.

Conclusions

Use of a backboard as an adjunct during cardiopulmonary resuscita- tion performed on a simulated patient lying on a standard emergency department stretcher did not improve the mean chest compression depth achieved by advanced life support rescuers. Most rescuers did not achieve the minimum compression depth of 50 mm recommended by the AHA.

References

  1. Standards for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1974;227:852-60 [Suppl.].

    E.J. Fischer et al. / American Journal of Emergency Medicine 34 (2016) 274277 277

    Hazinski MF, Nadkarni VM, Hickey RW, O’Connor R, Becker LB, Zaritsky A. Major changes in the 2005 AHA guidelines for CPR and ECC: reaching the tipping point for change. Circulation 2005;112(24 Suppl.):IV206-11.

  2. Field JM, Hazinski MF, Sayre MR, Chameides L, Schexnayder SM, Hemphill R, et al. Part 1: executive summary: 2010 American Heart Association Guidelines for Cardio- pulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010; 122(18 Suppl. 3):S640-56.
  3. Edelson DP, Abella BS, Kramer-Johansen J, Wik L, Myklebust H, Barry AM, et al. Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest. Resuscitation 2006;71(2):137-45.
  4. Yu T, Weil MH, Tang W, Sun S, Klouche K, Povoas H, et al. Adverse outcomes of interrupted precordial compression during automated defibrillation. Circulation 2002;106(3):368-72.
  5. Berg RA, Hemphill R, Abella BS, Aufderheide TP, Cave DM, Hazinski MF, et al. Part 5: Adult basic life support: 2010 American Heart Association guidelines for cardiopulmonary re- suscitation and emergency cardiovascular care. Circulation 2010;122(18 Suppl 3): S685-705.
  6. Noordergraaf GJ, Paulussen IW, Venema A, van Berkom PF, Woerlee PH, Scheffer GJ, et al. The impact of compliant surfaces on in-hospital chest compressions: effects of common mattresses and a backboard. Resuscitation 2009;80(5):546-52.
  7. Perkins GD, Benny R, Giles S, Gao F, Tweed MJ. Do different mattresses affect the Quality of cardiopulmonary resuscitation? Intensive Care Med 2003;29(12): 2330-5.
  8. Sato H, Komasawa N, Ueki R, Yamamoto N, Fujii A, Nishi S, et al. Backboard insertion in the operating table increases chest compression depth: a manikin study. J Anesth 2011;25(5):770-2.
  9. Nishisaki A, Maltese MR, Niles DE, Sutton RM, Urbano J, Berg RA, et al. Backboards are important when chest compressions are provided on a soft mattress. Resuscitation 2012;83(8):1013-20.
  10. Andersen LO, Isbye DL, Rasmussen LS. Increasing compression depth during manikin CPR using a simple backboard. Acta Anaesthesiol Scand 2007;51(6):747-50.
  11. Perkins GD, Smith CM, Augre C, Allan M, Rogers H, Stephenson B, et al. Effects of a backboard, bed height, and operator position on compression depth during simulated resuscitation. Intensive Care Med 2006;32(10):1632-5.
  12. Abella BS, Alvarado JP, Myklebust H, Edelson DP, Barry A, O’Hearn N, et al. Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest. JAMA 2005;293(3): 305-10.
  13. Wik L, Kramer-Johansen J, Myklebust H, Sorebo H, Svensson L, Fellows B, et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005; 293:299-304.

Leave a Reply

Your email address will not be published. Required fields are marked *