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JAMA: The Journal of the American Medical Association
Manual Chest Compression vs Use of an Automated Chest Compression Device During
Resuscitation Following Out-of-Hospital Cardiac Arrest: A Randomized Trial
ISSN: 0098-7484Accession: 00005407-200606140-00027Full Text (PDF) 144 K
Author(s):
Hallstrom, Al PhD; Rea, Thomas D. MD, MPH; Sayre, Michael R. MD; Christenson,
James MD; Anton, Andy R. MD; Mosesso, Vince N. Jr MD; Van Ottingham, Lois BSN;
Olsufka, Michele RN; Pennington, Sarah RN; White, Lynn J. MS; Yahn, Stephen
EMT-P; Husar, James EMT-P; Morris, Mary F.; Cobb, Leonard A. MD
Issue:Volume 295(22), 14 June 2006, p 2620-2628
Abstract
Context: High-quality cardiopulmonary resuscitation (CPR) may improve both
cardiac and brain resuscitation following cardiac arrest. Compared with manual
chest compression, an automated load-distributing band (LDB) chest compression
device produces greater blood flow to vital organs and may improve resuscitation
outcomes.
Objective: To compare resuscitation outcomes following out-of-hospital cardiac
arrest when an automated LDB-CPR device was added to standard emergency medical
services (EMS) care with manual CPR.
Design, Setting, and Patients: Multicenter, randomized trial of patients
experiencing out-of-hospital cardiac arrest in the United States and Canada. The
a priori primary population was patients with cardiac arrest that was presumed
to be of cardiac origin and that had occurred prior to the arrival of EMS
personnel. Initial study enrollment varied by site, ranging from late July to
mid November 2004; all sites halted study enrollment on March 31, 2005.
: Standard EMS care for cardiac arrest with an LDB-CPR device (n = 554) or
manual CPR (n = 517).
Main Outcome Measures: The primary end point was survival to 4 hours after the
911 call. Secondary end points were survival to hospital discharge and
neurological status among survivors.
: Following the first planned interim monitoring conducted by an independent
data and safety monitoring board, study enrollment was terminated. No difference
existed in the primary end point of survival to 4 hours between the manual CPR
group and the LDB-CPR group overall (N = 1071; 29.5% vs 28.5%; P = .74) or among
the primary study population (n = 767; 24.7% vs 26.4%, respectively; P = .62).
However, among the primary population, survival to hospital discharge was 9.9%
in the manual CPR group and 5.8% in the LDB-CPR group (P = .06, adjusted for
covariates and clustering). A cerebral performance category of 1 or 2 at
hospital discharge was recorded in 7.5% of patients in the manual CPR group and
in 3.1% of the LDB-CPR group (P = .006).
Conclusions: Use of an automated LDB-CPR device as implemented in this study was
associated with worse neurological outcomes and a trend toward worse survival
than manual CPR. Device design or implementation strategies require further
evaluation.
Trial Registration: clinicaltrials.gov Identifier: NCT00120965
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METHODS
Study Design
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Population
Adults with out-of-hospital cardiac arrest who received attempted resuscitation
by a participating EMS agency were enrolled unless an exclusion criterion was
present (Figure). Patients treated by EMS subsequently determined to meet
exclusion criteria were excluded from the analysis.
A primary comparison population, patients who were in cardiac arrest at the time
of EMS arrival and whose cardiac arrest was considered to be of cardiac origin,
was chosen a priori as the population most likely to benefit from chest
compressions. Cardiac etiology was determined by the site study coordinator or
investigator based on the EMS report forms and hospital records. Early in the
enrollment, study adherence (application of the LDB-CPR device based on
out-of-hospital report) was very low at site D when the advanced life support
unit arrived before the study unit. Arrival of an advanced life support unit 90
seconds or longer before the study unit was added as a site-specific exclusion
from the primary comparison population.
Study Protocol and Intervention
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During a run-in period ranging from 0.7 to 2.8 months, EMS personnel integrated
the automated device into out-of-hospital care. Initial training of EMS
personnel included hands-on skill practice using the device with a mannequin and
a video presentation with rationale for the LDB-CPR device. Refresher training
was not specified by design to best replicate real-world conditions and was
highly variable during the study.
The protocol allowed 3 options for the resuscitation intervention. Initially all
sites chose option 1, a "quick look
Option 2 was immediate CPR with manual compressions regardless of randomization
until the first shock assessment. Site C, the only EMS with a comprehensive
quality-improvement effort to reduce pauses in chest compressions, changed its
resuscitation intervention to option two 110 days after starting the study. The
change was implemented after quality-improvement review identified prolonged
time without compressions while deploying the LDB-CPR device.
Option 3 allowed analysis, and shock if appropriate, before beginning CPR. In
all cases, after rhythm assessment and shock if indicated, additional necessary
compressions were to be performed manually or with the LDB-CPR device according
to randomization. In all other aspects, sites followed their standard resuscitation
protocol until the patient was declared dead or regained stable spontaneous
circulation and was transported to and arrived at the emergency department.
End Points
The primary end point was defined as survival with spontaneous circulation 4
hours after the 911 call. This measure avoids inherent inconsistencies in
site-to-site variations in the definition of "admittance to the hospital."
Secondary end points included discharge from the hospital and cerebral
performance category score at discharge from the hospital that was obtained from
the hospital records. 21
Data Collection
Data were collected from EMS reports, defibrillator recordings, a study
questionnaire, and hospital records.[removed further description]
Sample Size
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Statistical Analysis
Comparisons were made by intention-to-treat assignment. Logistic regression was
applied using generalized linear mixed models with the robust sandwich estimator
of the variance to compare the outcome of individual episodes between the 2
study groups. 27-30 Models were adjusted for covariates previously demonstrated
to predict survival 31,32 as well as cluster (a source of nonindependence).
A single a priori subgroup analysis of the primary population was specified
based on initial rhythm (asystole, ventricular fibrillation/ventricular
tachycardia, pulseless electrical activity). In 6.1% (47/767) of participants,
electrocardiographic rhythm was not available and the automated external
defibrillator did not advise to shock. These were assumed to be asystole or
pulseless electrical activity. Three of the 47 cases were assigned the rhythm
observed at the next electrocardiographic analysis. In the remaining 44 cases,
the initial rhythm was imputed based on factors that discriminated significantly
between patients with initial rhythm of pulseless electrical activity and
asystole.
Post hoc subgroup analyses evaluated whether the intervention effect differed by
site or by the time since the site began enrolling patients. Interactions were
tested using an interaction term between treatment group and the covariate of
interest.
Analyses were conducted using SPSS version 12.0 (SPSS, Chicago, Ill) and R
version 2.3 (R Foundation for Statistical Computing) statistical software.
Unless explicitly stated, P values are unadjusted for covariates or clustering.
For the primary and secondary end points, P values were generally adjusted; by
protocol, the [alpha] level for the primary end point was set at .05.
RESULTS [parts selectivly removed]
The data and safety monitoring board met on March 11, 2005, and again on March
28, 2005, to review the results for 757 patients enrolled through January 31,
2005, and recommended suspension of enrollment until data for the 314 patients
enrolled during February and March could be evaluated. Results prompted
additional data collection, including estimates of chest compression duration in
the first 5 minutes of the resuscitation effort, drugs administered prior to the
patient arriving at the hospital, mode of in-hospital death, and other details
indicating lung, heart, or cerebral damage. On June 27, 2005, the steering
committee reviewed these expanded data and recommended that the trial be halted.