a b s t r a c t

Objective: The goal of this study was to compare chest compression interruption times required to apply, adjust, and remove 2 different automated chest compression (ACC) devices using the same evaluation protocol.

Methods: Twenty-nine registered nurses and Respiratory therapists used 2 ACC devices in separate resuscitation scenarios involving a patient manikin simulating a 45-year-old man in cardiac arrest in his intensive care unit room. Device presentation was randomized, with half of the participants using LUCAS 2 in the first scenario and the other half using AutoPulse in the first scenario.

Results: The mean chest compression interruption time to apply the ACC device to the patient was significantly shorter for AutoPulse (mean [M] = 31.6 +- 8.44) than for LUCAS 2 (M = 39.1 +- 11.20; t(28) = 3.65, P =

.001). The mean chest compression interruption time to remove the ACC device from the patient and resume Manual compressions was also significantly shorter for AutoPulse (M = 6.5 +- 3.65) than for LUCAS 2 (M =

10.1 +- 3.97; t(26) = 3.36, P = .002). There was no difference in the mean chest compression interruption

time to adjust the position of the ACC device on the patient between AutoPulse (M = 14.3 +- 5.24) and LUCAS 2 (M = 12.5 +- 3.89; t(23) = -1.45, P = .162).

Conclusions: The results of this study trended in favor of AutoPulse. However, the interruption in chest compres- sion to apply either device to the patient was notably longer than the maximum interruption time recommended by the American Heart Association.

Introduction

Automated chest compression (ACC) devices, sometimes referred to as mechanical Chest compression devices or cardiac resuscitators, were developed as an alternative way to maintain continuous high-quality chest compressions during the resuscitation process [1]. Specifically, ACC devices were developed to eliminate the decline in quality of circula- tion resulting from rescuer fatigue during prolonged manual compres- sions and to decrease the number of injuries rescuers sustain while delivering manual compressions. The 2 most commonly investigated

? Source of Funding: The execution of this work was supported by a Medical Education and Patient Safety grant through the Veterans Research Foundation at VA Pittsburgh Healthcare System, Pittsburgh, PA. The sponsor of this research had no involvement in

the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit this article for publication.

?? Disclaimer: The material is the result of work supported with resources and the use of

facilities at VAPHS. The views expressed in this article are those of the authors and do not represent the official views of the Department of Veterans Affairs or the United States Government.

? Conflicts of interest: The authors have no conflicts of interest relevant to this work.

* Corresponding author. VA Pittsburgh Healthcare System, University Drive C Research Building #30, G-39, Pittsburgh, PA 15240. Tel.: +1 412 360 2249; fax: +1 412 360 2492.

E-mail address: [email protected] (J.L. Estock).

ACC devices are LUCAS Chest Compression System (Physio-Control/Jolife AB, Lund, Sweden) and AutoPulse Resuscitation System (ZOLL Circulation, Sunnyvale, CA). Several studies have compared the clinical outcomes of patients treated with one of these ACC devices vs patients treated with manual compressions, such as the return of spontaneous circulation, Survival to hospital admission, and survival to hospital discharge [2-14]. Most of these studies focused on evaluating the effectiveness of ACC devices during out-of-hospital resuscitation [2-13]. One study compared the effectiveness of ACC devices vs manual compressions during in- hospital resuscitation [14]. This study only compared the 2 treatment methods after 10 minutes of failed advanced life support interventions, making it difficult to determine the Clinical effectiveness of ACC devices for the immediate treatment of in-hospital cardiac arrest. Furthermore, none of these clinical outcome studies measured the primary use- related hazard associated with ACC devices.

A use-related hazard is a potential source of Patient harm caused specifically by how a medical device is used [15]. With ACC devices, the most common use-related hazards are the interruptions in chest compressions that occur during the application, position adjustment, and intentional removal of these devices for resumption of manual com- pressions. These interruptions are sometimes referred to as “No-flow time” or “hands-off time.” Longer interruptions in chest compressions

http://dx.doi.org/10.1016/j.ajem.2015.09.011 0735-6757/

during the resuscitation process are associated with reduced survival rate postcardiac event as well as an increase in potential brain damage should the patient survive [16-18]. Prior studies have measured the interruptions in chest compression that occurred when using a single ACC device, but the differences in evaluation protocols and metrics used in these single-device studies make it difficult to compare inter- ruption times across different ACC devices [18-24]. Furthermore, these studies are limited in that they only measured the aggregate chest compression interruption time over the entire resuscitation event or the interruption time to apply the ACC device to the patient. Interruptions in chest compression can also occur when a rescuer readjusts the position of the device on the patient. Position adjust- ments may be required to assure adequate compressions when the ACC device migrates out of position during operation. In addition, in- terruption in chest compression can occur when the device is re- moved from the patient to resume manual compressions. Such removal may be required due to device malfunction or inadvertent ap- plication to a patient who exceeds the size limits of the device. To our knowledge, there are no published data on the length of chest compres- sion interruptions that occur when a rescuer needs to adjusts the posi- tion of an ACC device on a patient or remove an ACC device from a patient’s body to resume manual compressions.

The goal of our study was to compare chest compression interrup- tion times required to apply, adjust, and remove 2 different ACC devices using the same evaluation protocol. We also sought to identify Potential causes of any extended interruption times by collecting user feedback. With this information, we hoped to inform a decision about the purchase of an ACC device to assist medical emergency response teams in the immediate treatment for patients who experience in-hospital cardiac arrest.

Methods

Design

This study used a randomized, Crossover design where each partici- pant used both ACC devices.

Setting

The study took place at Veterans Affairs Pittsburgh Healthcare System (VAPHS), a large academic medical center affiliated with the US Department of Veterans Affairs. Our evaluation took place in the VAPHS Clinical Simulation Center’s mock intensive care unit (ICU) suite. The suite is embedded into an operational ICU at VAPHS and contains all of the same equipment and supplies found in an operational

ICU room. We used the Advanced Life Support Simulator (Laerdal, Gatesville, TX) to mimic a patient in cardiac arrest. This study was deter- mined to be “Exempt” by the institutional review board at VAPHS.

Participants

Eligible participants included the 165 doctors, nurses, and respiratory therapists on the multidisciplinary VAPHS medical emergency response team. This team is available 24/7 to evaluate, stabilize, and triage critically ill patients throughout the VAPHS campus. No members of the VAPHS medical emergency response team were excluded from participating in the study. Twenty-nine participants were recruited by 3 of the investiga- tors in person and by e-mail during the month of August 2014, with evaluation sessions occurring in September 2014. Of the 29 study par- ticipants, 23 were registered nurses and 6 were respiratory therapists. None of the participants had previous experience using either ACC device.

Devices

AutoPulse

AutoPulse is an automated, portable, battery-powered ACC de- vice (Fig. 1). AutoPulse was designed to deliver the compression force over a broader surface area of the thoracic cavity than manual compressions [25]. The device consists of 3 primary components-a platform backboard, a single-use chest compression band (LifeBand), and a rechargeable battery.

LUCAS 2

LUCAS 2 is an electric-powered ACC device (Fig. 2). LUCAS 2 was de- signed to deliver uninterrupted compressions at a consistent rate and depth [26]. The device consists of 3 primary components-a backboard, a top portion that contains an electrically driven piston rod that acts on the patient’s chest via a pressure pad that is surrounded by a single-use suction cup, and a rechargeable battery. LUCAS 2 can be powered either by battery alone or using a wall or car electrical outlet.

Measures

The primary outcomes measured in this evaluation were the chest compression interruption times to apply, adjust, and remove the ACC de- vices. The interruption time to apply the ACC device was measured from the last manual compression to the first automated compression after application of the device. If a participant resumed manual compres- sions at any point during application of the ACC device, we excluded that manual compression time from their interruption time to apply measure- ment. The interruption time to adjust the ACC device was measured from

Fig. 1. Zoll’s AutoPulse noninvasive cardiac support pump.

Fig. 2. Physio-Control’s LUCAS 2 chest compression system.

the last automated compression to the first automated compression sur- rounding the adjustment of the device. The interruption time to remove the ACC device was measured from the last automated compression to the first manual compression after successfully removing the device. To identify the potential causes of extended chest compression interruption times, we collected user feedback through postsimulation interviews.

Procedures

Study activities for each participant took approximately 2 hours, with an hour for each ACC device. Device presentation was randomized, with half of the participants using LUCAS 2 first and the other half using AutoPulse first. Study procedures were the same for both devices.

Device training

Participants started with a 30-minute ACC device training session that mimicked the typical procedure used for training VAPHS clinical staff on how to use a new device. It consisted of a 15- to 20-minute computer-based training provided by the device manufacturer and a 15-minute instructor-led skills practice session applying and using the ACC device on a mannequin. The computer-based training instructed participants how to apply and use the ACC device to manage a patient in cardiac arrest. A nurse educator led participants through the skills practice session using a standard checklist of skills to cover and a gradual release of responsibility teaching model. Participants were allowed to practice using the ACC device at their own pace and ask the instructor questions about how to use the device properly.

Simulation

Participants were first provided a presimulation briefing where they were told about the patient in cardiac arrest. They were asked to manage the situation and apply the same sense of urgency as they would with a real patient in the clinical environment. Participants then experienced a team resuscitation scenario involving a patient manikin simulating a 45- year-old man found unconscious and in cardiac arrest in his ICU room. Two “standardized colleague” actors from the University of Pittsburgh served as additional rescuers in the scenario with the participant to con- trol for possible confounding variables that could be caused by unreliable execution of the scenario. The standardized colleagues executed a semistructured script to guide the participant through the scenario. The script was designed to have enough structure to capture data on the 3 primary outcome metrics, while being flexible enough to capture any er- rors that may naturally occur in the use of ACC devices. The structured portion of the script guided the rescuers to serve in 3 primary roles (de- livering ventilation, monitoring the defibrillator, and providing compres- sions) and mandated that the participant complete the 3 tasks required

for the primary outcome metrics (applying the ACC device, adjusting the position of the ACC device on the patient, and removing the ACC de- vice to resume manual compressions). Participants were blinded to the outcome measures to avoid any potential effects this knowledge might have on their time to apply, adjust, or remove the ACC devices. All chest compression interruption times were measured in seconds and captured in real time during the simulation by 2 trained investigator- observers using stopwatches. The average time from the 2 stopwatches was used in the analyses.

Interview

Participants were interviewed after completing the simulation sce- nario. During the 15-minute interview, participants were asked to de- scribe the strengths and weaknesses of the ACC device for use during medical emergency response. The participants were also asked to report any prior experience with the ACC device during the interview. Partici- pant feedback was transcribed in real time by the principal investigator.

Analysis

Data were analyzed using the SPSS software version 21 (IBM Corpo- ration, Armonk, NY). For LUCAS 2, the manufacturer (i.e., Physio-Control) recommends a 2-step application procedure where the rescuer resumes manual compressions after placing the backboard under the patient and before attaching the top portion of the device [26]. Most participants used this 2-step application procedure in our evaluation. To make a fair comparison across ACC devices, we used the total interruption time to apply LUCAS 2 in our analysis (i.e., we combined the chest compression interruption time to place the backboard and interruption time to attach the top portion of LUCAS 2). Paired-samples t tests were used to compare the mean chest compression interruption times measured with the 2 ACC devices. Given the slightly skewed distribution of our dependent variables, related-samples Wilcoxon signed-rank tests were also con- ducted to compare the median chest compression interruption times measured with the 2 ACC devices and verify the t test results.

The affinity diagram method was used to identify common themes from the participants’ feedback about the strengths and weaknesses of the ACC devices. Affinity diagraming is a method of qualitative analysis wherein common themes are identified from large quantities of data, such as statements from a free response interview [27]. Individual comments gathered from the participants were grouped by investiga- tors according to natural relationships and then reviewed to establish common themes. Common themes were defined when at least 25% of participants made similar statement about the strengths or weaknesses of the ACC devices for use during medical emergency response.

Results

Table 2

Participant feedback about LUCAS 2 for in-hospital medical emergency response

Chest compression interruption times in seconds

Application

Strength/Weakness % of participants

identifying the strength/weakness

Sample participant comments

The mean (M) chest compression interruption time to apply the ACC device to the patient was significantly shorter for AutoPulse (M = 31.6 +- 8.44) than for LUCAS 2 (M = 39.1 +- 11.20; t(28) = 3.65, P = .001). A

significant difference in the median interruption time to apply the ACC de- vice was also found between Autopulse (30.7 seconds; interquartile range [IQR], 26-35 seconds) and LUCAS 2 (37.5 seconds; IQR, 30-47 seconds; z = -3.28, P = .001).

Adjustment

There was no difference in the mean chest compression interruption time to adjust the position of the ACC device on the patient between AutoPulse (M = 14.3 +- 5.24) and LUCAS 2 (M = 12.5 +- 3.89; t(23) =

-1.45, P = .162). In addition, there was no difference in the median interruption time to adjust the position of the ACC device between Autopulse (13.0 seconds; IQR, 11-17 seconds) and LUCAS 2 (11.5 seconds; IQR, 10-14 seconds; z = -1.16, P = .248).

Removal

The mean chest compression interruption time to remove the ACC device from the patient and resume manual compressions was signifi- cantly shorter for AutoPulse (M = 6.5 +- 3.65) than for LUCAS 2 (M =

10.1 +- 3.97; t(26) = 3.36, P = .002). A significant difference in the median interruption time to remove the ACC device was also found between Autopulse (5.5 seconds; IQR, 4-8 seconds) and LUCAS 2 (9.1 seconds; IQR, 7-12 seconds; z = -3.06, P = .002).

User feedback

AutoPulse

From the qualitative coding, more than 25% of participants iden- tified one strength and one weakness of using AutoPulse for medical emergency response (Table 1). Participants reported finding it easy to switch between automated and manual compressions with AutoPulse. Although transporting the ACC device was not part of our evaluation scenario, participants anticipated that it might be difficult to transport AutoPulse to all of the possible locations of an in-hospital

Weakness: Difficult to find proper placement on the patient

Weakness: Required too many steps to operate

Weakness: Difficult to attach to the top portion to the backboard

Weakness: Changes position as it operates

Weakness: Intrusiveness during a medical emergency

45 “I do not think that I ever achieved the proper positioning of LUCAS 2 on the patient, even when I tried again.”

“LUCAS 2 takes more time to get it in the correct position on the patient. If you do not get the correct placement, the patient might not get any compressions to the heart at all.”

31 “People may fumble with LUCAS 2 in a stressful situation and struggle with all of the steps involved in operating the system.”

“You have to hit three buttons every time you do something with LUCAS 2.”

28 “I had trouble getting the latch on the top portion to clip on to the backboard. The height and weight of LUCAS 2 make it difficult to put it on the patient.”

“I found it difficult to latch the top portion to the backboard, especially in the faster paced simulation.”

38 “LUCAS 2 did not seem to be stable on the patient. I could see it sliding as it compressed.”

“I am worried about the need to readjust LUCAS 2 constantly. They even readjusted it three times in the training video.”

38 “It seems like LUCAS 2 would be more in the way during medical emergency response because people are doing a lot of things around the chest, such as inserting lines and pushing medications.” “It can be crowded during medical emergency response and it would be difficult to maneuver around LUCAS 2.”

medical emergency. 3.2.2. LUCAS 2

Five weaknesses and no strengths were identified by more than 25% of participants with regard to using LUCAS 2 for medical emergency

Table 1

Participant feedback about AutoPulse for in-hospital medical emergency response

response (Table 2). Participants reported finding it difficult to attach the top portion of LUCAS 2 to the backboard and difficult to find proper

Strength/Weakness % of participants identifying the strength/weakness

Sample participant comments

placement of the device on the patient’s body. They also thought that LUCAS 2 required too many steps to operate and expressed concern about it changing position on the patient’s body as it operated. Although

Strength: Easy to switch between automated and manual compressions

Weakness: Might be difficult to transport to the location of a medical emergency

28 “Something can always go wrong with electronics, but with AutoPulse it is easy to stop and resume manual compressions.” “AutoPulse was faster to put on and take off of the patient. Faster application and removal is better with devices that will be used in a stressful situation.”

28 “AutoPulse would take longer to get to the patient because it is on the wheeled cart as opposed to in a backpack.”

“One challenge might be getting AutoPulse close enough to the patient to put it on because of the large number of people who respond to Medical emergencies here.”

our evaluation scenario did not include the same number of rescuers who respond to an actual medical emergency at VAPHS, participants anticipated that LUCAS 2 might be intrusive given the limited space around the patient during an actual medical emergency.

Discussion

Interruptions in chest compression are the primary use-related hazard associated with ACC devices. These interruptions can result in reduced survival rate postcardiac event as well as an increase in poten- tial brain damage should the patient survive. Previous studies measured the chest compression interruption times to apply ACC devices, but interruptions in chest compression also occur during the position adjustment and intentional removal of ACC devices for resumption of manual compressions. Our study measured the chest compression interruption times required to apply, adjust, and remove ACC devices.

Previous studies compared the interruptions in chest compression that occur when using one ACC device with those occurring during the use of manual chest compressions, but this research design makes it difficult to compare interruption times across different ACC devices. Our study compared interruptions in chest compression that occur across 2 different ACC devices using the same evaluation protocol.

Our study found that the mean chest compression interruption time to apply the ACC device to the patient was significantly shorter for AutoPulse than for LUCAS 2. Themes identified from the participants’ feedback helped to explain this difference. For LUCAS 2, participants reported that it was difficult to attach the top portion to the backboard and difficult to find proper placement on the patient and required too many steps to operate. Interestingly, the mean chest compression inter- ruption times to apply either ACC device were notably longer than the 10-second maximum interruption in chest compression recommended by the American Heart Association (AHA) [28].

Our study found that the mean chest compression interruption times to adjust the position of AutoPulse and LUCAS 2 on the patient were statistically equivalent, but the mean interruption times to adjust either ACC device were slightly longer than the 10-second maximum interruption in chest compression recommended by the AHA.

Finally, our study found that the mean chest compression interrup- tion time to remove the ACC device from the patient to resume manual compressions was significantly shorter for AutoPulse than for LUCAS 2. Themes identified from the participants’ feedback also helped to explain this difference. For AutoPulse, participants reported that it was easy to switch between automated and manual compressions. The mean chest compression interruption times to remove either ACC device were less than or equal to the 10-second maximum interruption in chest compression recommended by the AHA.

Conclusion

Previous studies on the clinical outcomes and use-related hazards associated with ACC devices have limitations that constrain their utility in advising ACC device purchasing decisions. As a result, the goal of our study was to compare the use-related hazards of 2 different ACC devices using the same evaluation protocol and metrics to support a purchasing decision. Overall, the results of our evaluation trended in favor of AutoPulse. However, the 31.6-second interruption in chest compression to apply AutoPulse to the patient was notably longer than the maximum interruption time recommended by the AHA. One method for reducing the chest compression interruption time to apply an ACC device is to adopt a 2-step application procedure. Physio-Control recommends a 2-step application procedure for LUCAS 2 to reduce the length of any single interruption in chest compression. Although Zoll does not currently recommend a 2-step application procedure for AutoPulse in their instructional material, this procedure could be adopted to reduce the chest compression interruption times that occur when applying AutoPulse to a patient. Future research should compare the chest compression interruption times to apply these 2 ACC devices when a 2-step application approach is adopted.

Acknowledgments

We thank Dr Ali Sonel and Dr Ira Richmond for supporting our Medical Education and Patient Safety grant proposal to incorporate human factors evaluations into the acquisition process at VAPHS. We thank the registered nurses and respiratory therapists who volunteered to participate in the evaluation and the managers in the Critical Care Service Line, Emergency Department, and Respiratory Therapy for allowing us to recruit participants from their staff. We also thank the CPR Committee, the Clinical Products Review Committee, the American Federation of Government Employees, and the Pitt Standard- ized Patient Program for supporting the execution of this evaluation. We thank Dr Ashley Hedges for contributing to our recruitment materials

and data collection efforts, Mr Jeston Robinson for coordinating with the manufacturers to provide their ACC devices for this evaluation, and the Education Department for supporting this evaluation with simulation resources and use of facilities. Finally, we thank Dr Monique Kelly and Dr Keri Rodriquez for providing guidance on our data analysis, and Dr David Eibling, Dr Lauren Broyles, and Dr Kelly H. Burkitt for serving as the outside reviewers of our manuscript.

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