Elsevier

Resuscitation

Volume 85, Issue 1, January 2014, Pages 75-81
Resuscitation

Clinical paper
Optimal loop duration during the provision of in-hospital advanced life support (ALS) to patients with an initial non-shockable rhythm

https://doi.org/10.1016/j.resuscitation.2013.08.261Get rights and content

Abstract

Background

In advanced life support (ALS), time-cycled “loops” of chest compressions form the basis of action. However, the provider must compromise between interrupting compressions and detecting a change in cardiac rhythm. An “optimal” loop duration would best balance these choices. The current international CPR guidelines recommend 2-min loop durations. The aim of this study was to investigate the “optimal” loop duration in patients with initial asystole or pulseless electrical activity (PEA).

Materials and methods

Detailed defibrillator recordings from 249 in-hospital cardiac arrests at the University of Chicago Medicine (Chicago, IL) and St. Olav University Hospital (Trondheim, Norway) were analysed. The clinical states of asystole, PEA, ventricular fibrillation/-tachycardia (VF/VT) and return of spontaneous circulation (ROSC) were annotated along the time axis. PEA and asystole were combined as a single state for the analysis of state development. The probability of staying in PEA/asystole over time was estimated non-parametrically. In addition, to distinguish between initial and secondary PEA/asystole, the latter was defined by the transition from VF/VT or ROSC.

Results

Among patients with initial PEA (n = 179), 25% and 50% of patients had left PEA/asystole after 4 and 9 min of ALS efforts, respectively. The corresponding time points for patients with initial asystole (n = 70) were 7.3 and 13.3 min, respectively. The probability of transition from secondary PEA/asystole to ROSC or VF/VT varied between 10% and 20% in each 2–4 min interval.

Conclusion

The “optimal” first loop duration may be 4 min in initial PEA and 6–8 min in initial asystole. If secondary PEA/asystole is encountered, 2-min loop duration seems appropriate.

Introduction

When providing advanced life support (ALS) to patients in cardiac arrest, regular assessments are necessary because the clinical status may improve or deteriorate during resuscitation. Accurate assessments of the electrocardiographic (ECG) rhythm and circulatory status are difficult during chest compressions and require regular pauses to assess the rhythm and/or check for a pulse. The first standards for cardiopulmonary resuscitations (CPR) published in 1966 by the American Heart Association (AHA) addressed this issue with the recommendation that “periodic palpation of carotid or femoral pulses should be employed”.1 Subsequent recommendations emphasised sequences of actions to be performed prior to assessment and/or defibrillation, e.g., the recommended pattern of “drug-shock, drug-shock” reported in the 1992 ALS algorithms.2 However, the 1992 guidelines for ALS provided by the European Resuscitation Council (ERC) differed by introducing the concept of time-cycling, with 2-min “loops” of chest compressions between patient assessments and/or defibrillations.3 The 1997 ALS guidelines provided by the International Liaison Committee on Resuscitation (ILCOR) conditioned the loop duration on the patient's ECG rhythm and clinical states during ALS by recommending 1 min for patients in ventricular fibrillation or-tachycardia (VF/VT) and 3 min for patients in asystole or those with pulseless electrical activity (PEA).4, 5 This guideline was replaced by the recommendation for a 2-min loop duration regardless of cardiac rhythm in the ERC 2005 ALS guidelines.6 However, the Norwegian Resuscitation Council challenged this report by recommending 3-min loop durations, arguing that one human study showed that 3 min of chest compressions were superior to shorter intervals when predicting ROSC after defibrillation of patients in VF/VT.7, 8 Despite differing recommendations, the scientific basis for the choice of loop duration in ALS is sparse. For patients with an initial non-shockable rhythm, an “optimal” loop duration would best balance the compromise between interrupting chest compressions and detecting a meaningful change in the clinical state, e.g., from PEA to ventricular fibrillation/tachycardia (VF/VT). Moreover, this latter state may lead to increased consumption of oxygen and a depletion of adenosine triphosphate (ATP) stores in the myocardium, necessitating defibrillation.9, 10, 11 The decision to stop chest compression to assess the clinical state should ideally be made when there is a reasonable probability that a change in clinical state has occurred. The aim of this study was to investigate the “optimal” loop duration for patients with initial PEA and asystole receiving in-hospital ALS by estimating the transition probabilities between clinical states.

Section snippets

Materials and methods

The University of Chicago Medicine (Illinois, USA) is an academic tertiary care facility. Patients with cardiac arrest between December 2002 and April 2004, and between December 2004 and December 2005, were included in the current study registered at ‘clinicaltrials.gov’ (NCT00228293). St. Olav University Hospital (Trondheim, Norway) is a tertiary care university hospital. Patients with confirmed cardiac arrest between January 2009 and January 2012 were included in the current study (NCT00920244

Results

A total of 304 episodes of cardiac arrest occurring in 277 patients presented with an initial rhythm of PEA or asystole (sites combined). Defibrillator recordings were available for further analysis in 249 episodes (86%). Baseline patient demographic data are presented in Table 1.

For patients with initial PEA (n = 179), the probability of staying in PEA/asystole during the first 20 min of ALS is shown in Fig. 1 (black curve). Twenty-five and fifty percent of the patients receiving ALS had left

Discussion

This is the first study to investigate transition probabilities between clinical states in patients with initial PEA and asystole during in-hospital ALS. The main goal was to give empirical estimates of how often rhythm assessments should be made during ALS, in an effort to determine “optimal” loop durations. One main finding is that more than seventy percent of patients in initial asystole remained in PEA or asystole during the first 8 min of ALS, suggesting little benefit of frequent rhythm

Conclusions

In this report, we have provided an empirical description and a probability model to describe the expected development of clinical states during in-hospital ALS for patients with initial PEA and asystole. We conclude that the “optimal” loop duration for patients with initial PEA may be 4 min for the first loop of chest compressions. For patients with initial asystole, the first loop may be in the range of 6–8 min. Because patients in secondary PEA/asystole demonstrated a more dynamic clinical

Conflict of interest statement

The authors T. Nordseth, D. Bergum, T.M. Olasveengen, T. Eftestøl, J.T. Kvaløy, R. Wiseth and E. Skogvoll have no conflicts of interests to report. D.P. Edelson is supported by a career development award from the National Heart, Lung, and Blood Institute (K23 HL097157-01) and has received research support from Philips Healthcare (Andover, MA) and Laerdal Medical (Wappingers Falls, NY). B.S. Abella: Research grants: Philips Healthcare, NIH, National Heart, Lung, and Blood Institute (NHLBI),

Role of the funding source

The authors T. Nordseth, D. Bergum and E. Skogvoll have received research funding from the Norwegian Air Ambulance Foundation (Drøbak, Norway) to conduct this study. This funding source had no influence on the study design or the collection, analysis and interpretation of data.

Acknowledgements

We wish to thank Trevor Yuen for his help in handling the dataset from the University of Chicago Medicine. We wish to thank the doctors and nurses involved in the ALS efforts for their help in the registration of the clinical data.

References (32)

  • J.B. Allen et al.

    The effect of the level of the ligature on mortality following ligation of the circumflex coronary artery in the dog

    Am Heart J

    (1950)
  • T. Endo et al.

    Relationship between the extent of the hypoperfused zone of the myocardium and the occurrence of ventricular fibrillation

    Am Heart J

    (1983)
  • Z. Kalenda

    The capnogram as a guide to the efficacy of cardiac massage

    Resuscitation

    (1978)
  • R.W. Koster et al.

    Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest

    Resuscitation

    (2008)
  • Cardiopulmonary resuscitation

    JAMA

    (1966)
  • Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Part III. Adult advanced cardiac life support

    JAMA

    (1992)
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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.2013.08.261.

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