Elsevier

Resuscitation

Volume 84, Issue 4, April 2013, Pages 508-514
Resuscitation

Simulation and education
Improving the quality of cardiopulmonary resuscitation by training dedicated cardiac arrest teams incorporating a mechanical load-distributing device at the emergency department

https://doi.org/10.1016/j.resuscitation.2012.07.033Get rights and content

Abstract

Objective

Determine if implementing cardiac arrest teams trained with a ‘pit-crew’ protocol incorporating a load-distributing band mechanical CPR device (Autopulse™ ZOLL) improves the quality of CPR, as determined by no-flow ratio (NFR) in the first 10 min of resuscitation.

Methods

A phased, prospective, non-randomized, before–after cohort evaluation. Data collection was from April 2008 to February 2011. There were 100 before and 148 after cases. Continuous video and chest compression data of all study subjects were analyzed. All non-traumatic, collapsed patients aged 18 years and above presenting to the emergency department were eligible. Primary outcome was NFR. Secondary outcomes were return of spontaneous circulation (ROSC), survival to hospital admission and neurological outcome at discharge.

Main results

After implementation, mean total NFR for the first 5 min decreased from 0.42 to 0.27 (decrease = 0.15, 95% CI 0.10–0.19, p < 0.005), and from 0.24 to 0.18 (decrease = 0.06, 95% CI 0.01–0.11, p = 0.02) for the next 5 min. The mean time taken to apply Autopulse™ decreased from 208.8 s to 141.6 s (decrease = 67.2, 95% CI, 22.3–112.1, p < 0.005). The mean CPR ratio increased from 46.4% to 88.4% (increase = 41.9%, 95% CI 36.9–46.9, p < 0.005) and the mean total NFR for the first 10 min decreased from 0.33 to 0.23 (decrease = 0.10, 95% CI 0.07–0.14, p < 0.005).

Conclusion

Implementation of cardiac arrest teams was associated with a reduction in NFR in the first 10 min of resuscitation. Training cardiac arrest teams in a ‘pit-crew’ protocol may improve the quality of CPR at the ED.

Introduction

Sudden cardiac arrest is a global concern. The incidence of out-of-hospital cardiac arrest (OHCA) in USA has been estimated at 1.89/1000 person-years and at 5.98/1000 person-years in subjects with any clinically recognized heart disease.1 Published survival rates for OHCA ranged from 3.0% to 16.3% in North America.2

The problem with standard cardiopulmonary resuscitation (STD-CPR) is that it provides only one third of normal blood supply to the brain and 10–20% of normal blood flow to the heart.3 Thus there have been efforts to develop mechanical CPR as an alternative. It is also increasingly recognized that although defibrillation is the definitive treatment for ventricular fibrillation, its success is also dependent on adequate circulation.4, 5, 6 Thus effective CPR is often a prerequisite for effective defibrillation.

The Autopulse™ (Revivant Corporation, Sunnyvale, CA) is a non-invasive load-distributing band (LDB), mechanical CPR device that generates artificial circulation mechanically. LDB–CPR is based on the concept that distributing force over the entire chest improves the effectiveness of chest compressions by delivering more total energy to the torso. The device adjusts automatically to the size and shape of each patient and is constructed around a backboard that contains a motorized rotating shaft under microprocessor control. It utilizes a load-distributing band, which is connected to the rotating shaft to compress the chest. The band is tightened or relaxed around the chest rhythmically to provide a “squeezing” effect. The microprocessor is programmed to provide a consistent 20% reduction in the anterior–posterior dimension of the subject's chest during the compression phase. This would be equivalent to a compression depth of maximum 5 cm.

Other theoretical advantages of the mechanical CPR include elimination of rescuer fatigue factor and the need to stop CPR during rescuer changes and patient transfers, as well as more consistent and reliable chest compression. Additionally, distributing compressive force over the anterior chest may help to mitigate chest wall trauma, abdominal injury and thoracic visceral injury that occur frequently during STD-CPR.

However, survival outcomes from clinical trials with the LDB device have been conflicting. In a single center, phased, before–after clinical trial with 783 patients, the addition of the autopulse device to an EMS system was found to improve survival to discharge for out-of-hospital cardiac arrest patients.7 However a simultaneously reported clinical trial failed to find any significance difference between manual and LDB–CPR in their primary outcome of survival to 4 h or survival to discharge.8 Possible explanations for these unexpected results advanced by the authors included a Hawthorne effect for manual CPR, prolonged deployment time for the devices resulting in delayed defibrillation and enrollment bias.8 This study highlights the importance of incorporating the LDB device into overall treatment protocols in cardiac arrest resuscitations, to improve the quality of mechanical CPR by reducing interruptions to CPR and decreasing human-dependent variables such as deployment time.

Quality of CPR can be determined by various variables.9 The no-flow ratio (NFR) is a function of pauses to compressions in the CPR cycle, and thus a direct measure of device deployment efficiency as well. In this study, the objective is to determine if implementing cardiac arrest teams trained in a ‘pit-crew’ protocol incorporating a LDB device, improves the quality of CPR as determined by the NFR in the first 10 min of resuscitation in the ED.

Section snippets

Methods

We conducted a phased, prospective cohort evaluation with intention-to-treat analysis of adults with non-traumatic cardiac arrest. The intervention was implementation of cardiac arrest teams trained in a sequenced protocol (see Fig. 1) in deploying and using Autopulse™ in one urban ED. The study was approved by the hospital's ethics committee.

The ED in the study has been using LDB–CPR as standard of care since August 2007. This design was chosen because the ED implemented cardiac arrest teams

Results

A total of 248 patients were included in the study 100 in Phase 1 and 148 in Phase 2. Table 1 shows the characteristics of patients in the two phases. Patients in both phases were comparable for age and gender. There were significant differences in ethnicity, prevalence of respiratory disease and cause of collapse.

Table 2 shows the difference in quality of CPR between Phases 1 and 2. The mean NFR for the first 10 min decreased from 0.33 in Phase 1 to 0.23 (decrease = 0.10, 95% CI 0.07–0.14) in

Discussion

In our study, we found that a team resuscitation protocol significantly decreases the NFT and NFR in the first 5 min as well as the next 5 min of resuscitation. In the first 5 min, the reduction is attributed to decreased time taken to apply the LDB device and ensuring that hands-off time is kept within a reasonable range. In the next 5 min, the reduction in NFT and NFR can be attributed to being trained to check pulse, intubate, analyze cardiac rhythm and defibrillate even as the LDB device is

Conclusion

Implementation of cardiac arrest teams specially trained with a ‘pit-crew’ protocol in using a LDB device was associated with lower NFT and NFR in the first 5 min, next 5 min as well as overall first 10 min of resuscitation. This was probably due to shorter time taken to apply the LDB device in the first 5 min and reducing interruptions to compressions for procedures in the next 5 min. This translates into a better quality of mechanical CPR for the patient.

Conflict of interest statement

Dr. Marcus Ong has a patent filing and a licensing agreement with ZOLL Medical Corporation unrelated to the technology described in the study (Method of predicting acute cardiopulmonary events and survivability of a patient, application number: 13/047,348). All the other authors have neither commercial nor personal associations or any sources of support that might pose a conflict of interest in the subject matter or materials discussed in this manuscript.

Funding source

The study was funded by ZOLL Medical Corp. The funding sources had no involvement in the study design, collection, analysis, and interpretation of data, writing of manuscript, and in the decision to submit the manuscript for publication.

Acknowledgements

We would like to thank and acknowledge the contributions from all the doctors and nurses from Department of Emergency Medicine, Singapore General Hospital.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.07.033

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