Elsevier

Resuscitation

Volume 82, Issue 6, June 2011, Pages 685-689
Resuscitation

Clinical paper
Performance of a rectilinear biphasic waveform in defibrillation of presenting and recurrent ventricular fibrillation: A prospective multicenter study

https://doi.org/10.1016/j.resuscitation.2011.02.008Get rights and content

Abstract

Objectives

We tested the hypothesis that shock success differs with initial and recurrent episodes of ventricular fibrillation (VF).

Methods

From September 2008 to March 2010 out-of-hospital cardiac arrest patients with VF as the initial rhythm at 9 study sites were defibrillated by paramedics using a rectilinear biphasic waveform. Shock success was defined as termination of VF within 5 s post-shock. We used generalized estimating equation (GEE) analysis to assess the association between shock type (initial versus refibrillation) and shock success.

Results

Ninety-four patients presented in VF. Mean age was 65.4 years, 78.7% were male, and 80.9% were bystander-witnessed. VF recurred in 75 (79.8%). There were 338 shocks delivered for initial (n = 90) or recurrent (n = 248) VF available for analysis. Initial shocks terminated VF in 79/90 (87.8%) and subsequent shocks in 209/248 (84.3%). GEE odds ratio (OR) for shock type was 1.37 (95% CI 0.68–2.74). After adjusting for potential confounders, the OR for shock type remained insignificant (1.33, 95% CI 0.60–2.53). We observed no significant difference in ROSC (54.7% versus 52.6%, absolute difference 2.1%, p = 0.87) or neurologically intact survival to hospital discharge (21.9% versus 33.3%, absolute difference 11.4%, p = 0.31) between those with and without VF recurrence.

Conclusions

Presenting VF was terminated with one shock in 87.8% of cases. We observed no significant difference in the frequency of shock success between initial versus recurrent VF. VF recurred in the majority of patients and did not adversely affect shock success, ROSC, or survival.

Introduction

Defibrillation is conventionally defined as termination of ventricular fibrillation (VF) for at least 5 s after shock delivery [1]. Although biphasic truncated exponential (BTE) defibrillators terminate VF with the initial shock in 86–98% of cases 2, 3, 4, 5, 6, first shock efficacy of the rectilinear biphasic waveform (RLB) using the definition of shock success as termination of presenting VF at 5 s post-shock has not been reported. The 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care [1] state “There is no new evidence regarding the first shock success rate with the rectilinear biphasic waveform since publication of the 2005 guidelines,” and the 2010 European Resuscitation Council guidelines indicate that first-shock success of the RLB waveform using 120 J is up to 85% but that the data were supplied by personal communication [7].

To our knowledge there have been only two published studies assessing the performance of the RLB waveform in out-of-hospital cardiac arrest (OHCA) 8, 9. These studies reported success using an escalating energy (120 J–150 J–200 J) protocol and did not report first shock success for termination of presenting VF using the conventional definition stated above. The objective of the study we report here was to assess the performance of the RLB waveform using a non-escalating low-energy protocol for the first 3 shocks and to assess performance for subsequent shocks.

Section snippets

Study setting and population

We conducted the study in 9 EMS sites in Minnesota and Wisconsin in which prehospital care is provided by Mayo Clinic Medical Transport (MCMT, Gold Cross Ambulance Service). We have described our experience with OHCA in Rochester, MN in several previous publications 10, 11, 12, 13, 14, 15. In September 2008 we expanded our data collection from the Rochester, MN site to all of the 9 EMS locations. The same protocols are employed at all sites. We included adults (≥18 years of age) with

Results

Of the 408 cardiac arrests of documented or presumed cardiac cause, 94 (23.0%) had VF as the presenting rhythm (Table 1). There were 59 (62.8%) patients who were shocked by first responder AEDs prior to paramedic arrival. Of these, 25 (42.4%) were in VF on arrival of paramedics. In these 25 patients previously shocked by first responder AEDs the initial paramedic shock terminated VF in 24 (96.0%). Hospital discharge survival data were available for 92 of 94 cases (97.9%). Mean (S.D.) call-to-on

Summary of major findings

In this prospective multicenter study we observed a high frequency of shock success using a RLB defibrillator with a fixed 120 J selected energy protocol for the first three shocks. Termination of VF occurred in 87.8% with the first shock and 97.8% within three shocks. This is the first study to report the first-shock success rate for presenting VF using a RLB defibrillator at a selected energy of 120 J using the conventional definition of shock success 1, 7. There was no significant difference

Conclusions

We report the performance of the RLB waveform with a non-escalating energy (120 J–120 J–120 J) protocol for the first three shocks. A high rate of conversion of presenting VF was observed with this protocol. To our knowledge, this is the first report of the performance of this waveform using this energy protocol. We observed a high rate of shock success for initial and recurrent episodes of VF. VF recurred in the majority of patients and did not adversely affect shock success, ROSC, or survival.

Funding

Dr. Hess is supported in part by a grant from the American Heart Association, the Society for Academic Emergency Medicine, and the Emergency Medicine Foundation (Award ID # 0775030N).

Conflicts of interest statement

The authors have no conflicts of interest to declare.

References (20)

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Cited by (17)

  • European Resuscitation Council Guidelines 2021: Adult advanced life support

    2021, Resuscitation
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    Refibrillation is common and occurs in >50% of patients following initial first-shock termination of VF.212 Two studies showed termination rates of subsequent refibrillation were unchanged when using fixed 120 J or 150 J shock protocols respectively,214,221 but a larger study showed termination rates of refibrillation declined when using repeated 200 J shocks, unless an increased energy level (360 J) was selected.212 In a retrospective analysis, conversion of VF to an organised rhythm was higher if the VF had first appeared after a perfusing rhythm, than after PEA or asystole.222

  • European Resuscitation Council Guidelines for Resuscitation 2015. Section 3. Adult advanced life support.

    2015, Resuscitation
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    Distinct from refractory VF, defined as ‘fibrillation that persists after one or more shocks’, recurrence of fibrillation is usually defined as ‘recurrence of VF during a documented cardiac arrest episode, occurring after initial termination of VF while the patient remains under the care of the same providers (usually out-of-hospital).’ Two studies showed termination rates of subsequent refibrillation were unchanged when using fixed 120 J or 150 J shock protocols respectively,490,502 but a larger study showed termination rates of refibrillation declined when using repeated 200 J shocks, unless an increased energy level (360 J) was selected.326 In a retrospective analysis, termination rate of VF into a pulse generating rhythm was higher if the VF appeared after a pulse generating rhythm, than after PEA or asystole.503

  • Part 4: Advanced life support. 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations

    2015, Resuscitation
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    In 2010, it was concluded that it was reasonable to start at a selected energy level of 150–200 J for a BTE waveform, and no lower than 120 J for an RLB waveform for defibrillation of VF/pVT cardiac arrest, acknowledging that the evidence was limited.12,13 For the important outcome of termination of VF/pVT, low-quality evidence (downgraded for imprecision and risk of bias, respectively) from a post hoc report from an RCT and a cohort study showed a first-shock success rate of 73 of 86 (85%) and 79 of 90 (87.8%), respectively, when using a 120 J initial shock with an RLB waveform.15,16 We recommend an initial biphasic shock energy of 150 J or greater for BTE waveforms, and 120 J or greater for RLB waveforms (strong recommendation, very-low-quality evidence).

  • Recurrent ventricular fibrillation: Experience with first responders prior to advanced life support interventions

    2015, Resuscitation
    Citation Excerpt :

    However, the recurrence of VF has received relatively less attention. During OHCA recurrence of VF is common and has been reported in 52–80% of cases.1–5 Not only is recurrent VF frequent, but the duration of recurrent VF has also increased since the 2005 AHA/ILCOR Guidelines for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC).6

  • A low tilt waveform in the transthoracic defibrillation of ventricular arrhythmias during cardiac arrest

    2012, Resuscitation
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    Shock success rates following three shocks were higher at 97.8% vs. 93%. Differences in inclusion criteria between the two studies may have influenced these findings.24 A limitation of the study lies in the re-entry of patients into the study.

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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.02.008.

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