Elsevier

Resuscitation

Volume 73, Issue 2, May 2007, Pages 212-220
Resuscitation

Clinical paper
Pauses in chest compression and inappropriate shocks: A comparison of manual and semi-automatic defibrillation attempts

https://doi.org/10.1016/j.resuscitation.2006.09.006Get rights and content

Summary

Background

Semi-automatic defibrillation requires pauses in chest compressions during ECG analysis and charging, and prolonged pre-shock compression pauses reduce the chance of a return of spontaneous circulation (ROSC). We hypothesised that pauses are shorter for manual defibrillation by trained rescuers, but with an increased number of inappropriate shocks given for a non-VF/VT rhythm.

Methods

From a prospective study of CPR quality during in- and out-of-hospital cardiac arrest, the duration of pre-shock, inter-shock, and post-shock pauses were compared with Mann–Whitney U-test during manual and AED mode with the same defibrillator, and proportions of inappropriate shocks were compared with Chi-squared tests.

Results

A 635 manual and 530 semi-automatic shocks were studied. Number of shocks per episode was similar for the two groups. All pauses measured in seconds (s) were shorter for manual use (P < 0.0001); median (25, 75 percentiles); 15 (11, 21) versus 22 (18, 28) pre-shock, 13 (9, 20) versus 23 (22, 26) inter-shock, and 9 (6, 18) versus 20 (11, 31) post-shock, but 163 (26%) manual shocks were inappropriate compared with 30 (6%) AED shocks, odds ratio (OR) 5.7 (95% CI; 3.8–8.7). A 150 (78%) of the inappropriate shocks were delivered for organised rhythms. The proportion of inappropriate manual shocks was higher for resident physicians in-hospital than paramedics out-of-hospital; 77/228 (34%) versus 86/407 (21%), OR 1.9 (1.3–2.7).

Conclusion

Manual defibrillation resulted in shorter pauses in chest compressions, but a higher frequency of inappropriate shocks. A higher formal level of education did not prevent inappropriate shocks.

Trial registrationhttp://www.clinicaltrials.gov/ (NCT00138996 and NCT00228293).

Introduction

The development of automated external defibrillators (AEDs) has made defibrillation more readily available for patients in cardiac arrest. A number of studies have confirmed the safety and effectiveness of AEDs, and the importance of early defibrillation,1 but population-based investigations from Seattle and Sweden have shown at best a moderate increase in survival over the years despite a decreased time to defibrillation.2, 3

Studies have shown that the probability of successful defibrillation and subsequent return of spontaneous circulation (ROSC) deteriorates rapidly with even short pauses in chest compressions.4, 5 The use of AEDs requires time without chest compressions during rhythm analysis and charging, in addition to any further human delays.6 In many systems, medical personnel trained in advanced life support (ALS) are therefore encouraged to use defibrillators in manual mode to shorten time used for analysis, but the ability to recognise different ECG-patterns may be more difficult during a stressful clinical situation than during manikin simulation.

We have recently reported on CPR quality in three ambulance services (London, Stockholm, and Akershus)7, 8 and one university hospital (Chicago)9 using defibrillators modified to enable continuous monitoring of ventilation and chest compression depth and rate. The defibrillators were used in manual mode (Akershus and Chicago), or in AED mode (London and Stockholm). In this pre-planned analysis we hypothesised that manual use of the defibrillator would result in shorter pauses between chest compression and subsequent shock (pre-shock pause), between shocks (inter-shock pause), and from last shock in a series to the resumption of chest compressions (post-shock pause), but more frequent shocks for non-VF/VT rhythms (i.e., inappropriate shocks).

Section snippets

Materials and methods

Methods, especially regarding CPR-sensing technology and subject enrolment, have been presented in detail previously.7, 8, 9 The present description of study methods highlights concepts particular to this analysis of defibrillation and compression pauses.

Discussion

In this prospective study peri-shock intervals without chest compressions were shorter with defibrillators in manual mode than in AED mode, but more inappropriate shocks were given in manual mode.

Such intervals without chest compressions have only been studied previously during the use of AEDs,16, 17, 18, 19 and the present findings in the AED group are similar to previous findings. Sunde et al found median 20 s pre-shock pauses for ambulance personnel using Heartstart 3000 defibrillators

Conclusion

Manual defibrillation attempts resulted in less time without chest compressions than AED use of identical defibrillators, but a higher proportion of inappropriate shocks. A higher formal level of education did not prevent inappropriate shocks.

Conflict of interest statements

All authors have received funding and technical support for research projects regarding quality of CPR from Laerdal Medical and Philips Medical Systems. Drs. Abella, Becker, and Edelson have received honoraria from Laerdal Medical and/or Philips Medical Systems. Dr. Wik is on a medical advisory board for Medtronic Medical. Dr. Steen is a board member of Laerdal Medical and The Norwegian Air Ambulance Foundation.

Acknowledgements

The authors wish to thank all participating EMTs, paramedics, nurses, and physicians for their invaluable effort in obtaining and collecting the data. The helpfulness and technical skills of Ståle Freyer, MSc (Unversity of Stavanger, Norway), Salem Kim, Helge Myklebust and all the staff at Laerdal Medical, Research and Development, Stavanger, Norway are most appreciated.

Funding. Funding for this project was received from The Norwegian Air Ambulance Foundation (Kramer-Johansen, full time PhD

References (32)

  • J. Herlitz et al.

    Experiences from treatment of out-of-hospital cardiac arrest during 17 years in Göteborg

    Eur Heart J

    (2000)
  • L.A. Cobb et al.

    Changing incidence of out-of-hospital ventricular fibrillation, 1980–2000

    JAMA

    (2002)
  • T. Yu et al.

    Adverse outcomes of interrupted precordial compression during automated defibrillation

    Circulation

    (2002)
  • T. Eftestøl et al.

    Effects of interrupting precordial compressions on the calculated probability of defibrillation success during out-of-hospital cardiac arrest

    Circulation

    (2002)
  • D. Snyder et al.

    Wide variation in cardiopulmonary resuscitation interruption intervals among commercially available automated external defibrillators may affect survival despite high defibrillation efficacy

    Crit Care Med

    (2004)
  • L. Wik et al.

    Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest

    JAMA

    (2005)
  • Cited by (79)

    • Minimizing pre- and post-shock pauses during the use of an automatic external defibrillator by two different voice prompt protocols. A randomized controlled trial of a bundle of measures

      2016, Resuscitation
      Citation Excerpt :

      According to the Guidelines 2000 for emergency cardiac care, automated external defibrillators (AEDs) should prompt for pauses in cardiopulmonary resuscitation (CPR) for rhythm analysis, shock delivery and pulse checks similar to procedures for manual defibrillators.1,2 These pauses however limit the delivery of chest compressions to less than 50% of the time spent in the resuscitation attempt.3–6 To decrease hands-off time, Guidelines 20057,8 eliminated post-shock pauses for rhythm analysis and pulse checks.

    • Rhythm analysis and charging during chest compressions reduces compression pause time

      2015, Resuscitation
      Citation Excerpt :

      ALS providers often operate the defibrillator in manual mode when treating cardiac arrest patients. Manual rhythm analyses can generally be conducted more quickly than automated analyses, however, manual analyses are less accurate.18,19 Specifically, in one investigation, pre-shock pause was 7 s shorter with manual vs. AED analyses; however 26% of shocks were inappropriate following manual analyses compared with 6% following AED analyses.18

    View all citing articles on Scopus

    A Spanish translated version of the summary of this article appears as Appendix in the final online version at 10.1016/j.resuscitation.2006.09.006.

    View full text