Clinical paperOptimal loop duration during the provision of in-hospital advanced life support (ALS) to patients with an initial non-shockable rhythm☆
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.
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2015, ResuscitationCitation Excerpt :Continuing high-quality CPR however may improve the amplitude and frequency of the VF and improve the chance of successful defibrillation to a perfusing rhythm.344–346 The optimal CPR time between rhythm checks may vary according to the cardiac arrest rhythm and whether it is the first or subsequent loop.371 Based on expert consensus, for the treatment of asystole or PEA, following a 2-min cycle of CPR, if the rhythm has changed to VF, follow the algorithm for shockable rhythms.
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2015, ResuscitationCitation Excerpt :Continuing high-quality CPR however may improve the amplitude and frequency of the VF and improve the chance of successful defibrillation to a perfusing rhythm.203–205 The optimal CPR time between rhythm checks may vary according to the cardiac arrest rhythm and whether it is the first or subsequent loop.214 Based on expert consensus, for the treatment of asystole or PEA, following a 2-min cycle of CPR, if the rhythm has changed to VF, follow the algorithm for shockable rhythms.
When should chest compressions be paused to analyze the cardiac rhythm? A systematic review and meta-analysis
2015, ResuscitationCitation Excerpt :However, any more frequent cardiac rhythm analyses are constrained by minimizing chest compression interruptions. The authors next modeled the time-dependent probabilities of transitioning from an initial non-shockable rhythm to either a shockable rhythm or ROSC.43 For initial rhythms of asystole, 70% of patients remained in a non-shockable rhythm during the first 8 min of resuscitation, suggesting little benefit of frequent rhythm assessments during this time interval.
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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.