Clinical paperEffects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest☆
Introduction
Although rapid defibrillation remains the cornerstone of treatment for ventricular fibrillation (VF), a number of studies have supported the notion that cardiopulmonary resuscitation (CPR), especially in the time preceding defibrillation, may also play a key therapeutic role.1, 2 However, the effect of CPR quality on clinical outcomes remains poorly understood.
Recent work, relying on new technology capable of sensing compression rate and depth, has shown that CPR quality is inconsistent in actual clinical practice, with frequent pauses and shallow compression depth.3, 4 Using this technology, the effects of these CPR variables on clinical outcomes can now be evaluated. Of particular interest are the duration of time from the end of chest compressions until the defibrillation shock is given (i.e., the pre-shock pause) and the measured depth of chest compressions preceding defibrillation. Both have been shown to have significant impact on outcomes in animal studies,5, 6, 7, 8 yet neither has been rigorously investigated in the clinical setting.
Understanding the effects of these variables has significant public health and policy implications. Pre-shock pauses are particularly important as automated external defibrillators (AEDs), that generally require long pre-shock pauses for rhythm analysis,8, 9, 10 have gained widespread acceptance and have been implemented in a variety of settings.11, 12, 13, 14 Additionally, understanding the relative importance of these variables of CPR quality on outcomes will have implications for resuscitation guidelines and training. We therefore examined whether pre-shock pause and compression depth, two likely determinants of blood flow preceding defibrillation, affect the ability of a shock to terminate VF.
Section snippets
Study design
An international, multi-center, observational study of in-hospital and out-of-hospital cardiac arrests occurring between March 2002 and December 2005 was conducted. Approval was granted by the Institutional Review Board of the University of Chicago Hospitals and the regional ethics committee in Akershus, with mechanisms to satisfy waiver of consent provisions at both sites. Additionally, an oral consent process was used for rescuers in Chicago.
Details of the study design and methods have been
Results
A total of 60 patients received a first electrical shock for VF during the study period. Table 1 summarizes the baseline characteristics of the entire cohort. Characteristics of successful and unsuccessful shocks are compared in Table 2, Table 3. There were no statistically significant differences in age, sex, arrest location or time to shock by first shock success. However, successful shocks were associated with a shorter median pre-shock pause duration (11.9 s versus 22.7 s; p = 0.002) and higher
Discussion
Using technology that measures multiple variables of CPR quality accurately, our international study group has gathered data that demonstrate a significant association between termination of VF and two variables that have received little formal evaluation during human cardiac arrest, pre-shock pause duration and compression depth. Specifically, we have shown that each 5 mm increase in compression depth and each 5 s decrease in pre-shock pause portend an approximate two-fold increase in the
Conclusions
Using objective measurements of CPR quality during actual cardiac arrest, we have found that longer pre-shock pauses and shallower chest compressions are correlated significantly with decreased shock success. The opportunity to improve the quality of CPR in clinical practice is now practically available and may significantly improve resuscitation success. Approaches to minimize (or eliminate) pre-shock pauses and optimize compression depth should be made and consideration should be given to the
Conflict of interest
The sponsor had no role in data collection, interpretation of results or drafting of the manuscript. One author at the study sponsor (Mr. Myklebust) was involved in study conception and design. Drs. Abella and Becker have received honoraria and research support from Philips Medical Systems (Andover, MA) and Laerdal Medical Corporation (Stavanger, Norway) while Drs. Steen, Wik and Kramer-Johansen have received research support from Laerdal Medical Corporation (Stavanger, Norway).
Acknowledgements
We thank Jason Alvarado, Nicholas O’Hearn, Kuang-Ning Huang, Salem Kim, Nate Teisman and David Snyder, PhD for assistance during data collection and manuscript preparation; Ronald Thisted, MD for advice and statistical expertise; and Lynne Harnish for administrative assistance. We also thank the paramedics and instructors in the Akershus Ambulance Service and the members of the cardiac arrest resuscitation team at the University of Chicago. This work was supported by a grant from the Laerdal
References (35)
- et al.
Relationship of blood pressure and flow during CPR to chest compression amplitude: evidence for an effective compression threshold
Ann Emerg Med
(1983) - et al.
The critical importance of minimal delay between chest compressions and subsequent defibrillation: a haemodynamic explanation
Resuscitation
(2003) - et al.
The Department of Health National Defibrillator Programme: analysis of downloads from 250 deployments of public access defibrillators
Resuscitation
(2005) - et al.
Estimated cost effectiveness of a police automated external defibrillator program in a suburban community: 7 years experience
Resuscitation
(2002) - et al.
Improving CPR performance using an audible feedback system suitable for incorporation into an automated external defibrillator
Resuscitation
(2003) - et al.
An automated voice advisory manikin system for training in basic life support without an instructor. A novel approach to CPR training
Resuscitation
(2001) - et al.
Electrocardiographic evaluation of defibrillation shocks delivered to out-of-hospital sudden cardiac arrest patients
Resuscitation
(1999) - et al.
When minutes count—the fallacy of accurate time documentation during in-hospital resuscitation
Resuscitation
(2005) - et al.
Automated external defibrillators: to what extent does the algorithm delay CPR?
Ann Emerg Med
(2005) - et al.
Quality assessment of defribrillation and advanced life support using data from the medical control module of the defibrillator
Resuscitation
(1999)
Improved hemodynamic performance with a novel chest compression device during treatment of in-hospital cardiac arrest
Resuscitation
Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation
Resuscitation
Feasibility of shock advice analysis during CPR through removal of CPR artefacts from the human ECG
Resuscitation
Better adherence to the guidelines during cardiopulmonary resuscitation through the provision of audio-prompts
Resuscitation
Improvement in timing and effectiveness of external cardiac compressions with a new non-invasive device: the CPR-Ezy
Resuscitation
Influence of cardiopulmonary resuscitation prior to defibrillation in patients with out-of-hospital ventricular fibrillation
JAMA
Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial
JAMA
Cited by (542)
Cardiopulmonary Resuscitation: The Importance of the Basics
2023, Emergency Medicine Clinics of North AmericaDefibrillation in the Cardiac Arrest Patient
2023, Emergency Medicine Clinics of North AmericaEffectiveness of Lay Bystander Hands-Only Cardiopulmonary Resuscitation on a Mattress versus the Floor: A Randomized Cross-Over Trial
2023, Annals of Emergency Medicine
- ☆
A Spanish translated version of the summary of this article appears as Appendix in the online version at 10.1016/j.resuscitation.2006.04.008.