Different CPR Durations Found Equally Successful; CPR Device Does Not Add
Benefit
Enrollment has ended early in a large, multicenter clinical trial comparing
two distinct resuscitation strategies delivered by emergency medical service
(EMS) providers to increase blood flow during cardiac arrest. The study's
independent monitoring board and the National Heart, Lung, and Blood
Institute (NHLBI), the lead sponsor of the study, stopped enrollment based
on preliminary data suggesting that neither strategy significantly improved
survival. One strategy compared different durations of manual
cardiopulmonary resuscitation (CPR) by EMS providers before they assessed
whether defibrillation was needed, and the other strategy tested the
potential benefits and risks of an investigational device to maintain
pressure in the chest during CPR.
After reviewing data on approximately 11,500 study participants, the study's
Data and Safety Monitoring Board (DSMB) recommended on Oct. 23 that the
NHLBI stop enrollment because sufficient data had been gathered, and
continuing recruitment was unlikely to change the overall outcomes of the
study. The board had no concerns about the safety of any of the
interventions tested, and NHLBI accepted the DSMB recommendations on the
same day. Researchers will continue to monitor study participants who agree
to follow-up visits for up to six months. They will analyze and publish the
final data in the coming months. The NHLBI is part of the National
Institutes of Health.
"Survival rates for patients who suffer cardiac arrest before reaching a
medical facility are tragically low," said Susan Shurin, M.D., deputy
director of the NHLBI, who oversees clinical trials supported by NHLBI and
accepted the DSMB recommendation." This study provides important evidence to
help inform first responders and other health care providers on safe and
effective life-saving treatment options. We will continue to search for new
ways to save lives in the precious few moments after cardiac arrest - and
evaluate the benefits and risks of commonly used practices."
The Resuscitation Outcomes Consortium (ROC), the largest clinical research
network to study prehospital treatments for cardiac arrest in the United
States and Canada, tested both resuscitation strategies as part of the
Prehospital Resuscitation using an IMpedance valve and Early versus Delayed
(ROC PRIMED) clinical trial. An impedance valve, also called an impedance
threshold device (ITD), is a small, hard plastic device about the size of a
fist that is attached to the face mask or breathing tube during CPR
administered by EMS providers. The device is designed to improve circulation
by enhancing changes in pressures within the chest during CPR. Researchers
found that ITD use did not significantly improve or worsen survival rates
for cardiac arrest patients.
The early versus delayed strategy compared two currently used timing
strategies of assessing the heart's rhythm in relation to when CPR is
started by EMS providers. The heart rhythm assessment is done to determine
whether defibrillation to restore the heart to its normal rhythm is needed.
The study compared patient survival rates after EMS providers performed at
least 30 seconds of CPR before assessing the need for defibrillation with
delivering three minutes of CPR before the assessment. Based on current
study data, both timing strategies were equally effective.
EMS providers assess approximately 350,000 people with cardiac arrest in the
United States each year. Only 5 to 10 percent of people who have sudden
cardiac arrest survive. When administered as soon as possible, CPR and, in
some cases, rapid treatment with a defibrillator - a device that sends an
electric shock to the heart to try to restore its normal rhythm - can be
lifesaving. When delivered by EMS professionals, CPR is a combination of
chest compressions, to keep oxygen-rich blood circulating until an effective
heartbeat is restored, and rescue breathing. Lay bystanders are encouraged
to immediately begin CPR using only chest compressions until professional
help arrives, according to the American Heart Association.
ROC PRIMED was designed to test the two promising strategies to increase the
chance of survival without functional impairments of patients who suffer
cardiac arrest outside of a hospital setting. To test the ITD strategy,
patients were randomly assigned to receive standard CPR from participating
EMS providers either with an ITD or with a non-working replica (sham) of an
ITD.
In animal studies and in small studies in humans, the ITD has been shown to
markedly increase blood flow to the heart and to raise blood pressure. Human
studies have also showed a tendency toward improved short-term outcomes
without adverse effects. A modified version of the ITD is approved by the
Food and Drug Administration (FDA) for use in conditions other than cardiac
arrest.
However, a large human clinical trial was needed to show whether the device
significantly improves survival with preserved neurologic function. Patients
with preserved neurologic function are able to carry out activities of daily
living. In contrast, patients who suffer neurological damage following
cardiac arrest may no longer be able to care for themselves due to injury to
parts of the brain.
The study's preliminary results indicate similar survival rates of patients
with preserved neurologic function between both groups of patients,
suggesting that standard CPR without an ITD is as effective as using an ITD.
"While the ITD is based on a sound physiologic principle, in this study it
did not appear to improve survival rates for adults in cardiac arrest
outside of the hospital," said Tom Aufderheide, M.D., a professor of
emergency medicine at the Medical College of Wisconsin in Milwaukee and a
ROC principal investigator. "We will continue to seek out and thoroughly
test new devices as well as alternative applications that hold promise for
saving the lives of cardiac arrest patients."
The other principal strategy studied in ROC PRIMED was the timing of
assessing the heart's rhythm to determine whether defibrillation is needed
in relation to when CPR is started. For patients randomly assigned to the
Analyze Early group, EMS providers were instructed to perform CPR until they
were able to analyze the patient's heart rhythm (approximately 30 to 90
seconds). Patients in the Analyze Later group received CPR for at least
three minutes before their heart rhythm was analyzed. When indicated,
defibrillation was provided.
Some smaller studies have suggested that longer periods of CPR before
defibrillation might increase survival, while other studies have suggested
that more immediate defibrillation - when the patient is treated within two
minutes after the start of cardiac arrest - might be better.
"The ROC PRIMED study answers a long-standing question in the EMS community
over whether it is better to defibrillate earlier or later when trying to
resuscitate a patient," said Ian Stiell, M.D., professor and chair of the
Department of Emergency Medicine at the University of Ottawa, senior
scientist at the Ottawa Hospital Research Institute, and a principal
investigator for the ROC PRIMED Analyze Early vs. Later protocol. "Both
techniques appear to be equally beneficial."
Myron Weisfeldt, M.D., ROC Steering Committee chair and director of the
Department of Medicine at the Johns Hopkins University School of Medicine in
Baltimore, added, "Questions like this one - which address the relative
benefits of current medical practices - are an important example of
comparative effectiveness research and, in this case, can help advance
emergency medical care."
ROC PRIMED and other ROC clinical trials are conducted under strict U.S. FDA
and Canadian guidelines that allow for patients in life-threatening
situations to participate in research under an exception to explicit
informed consent, according to U.S. and Canadian laws. This is necessary
because, among other reasons, participants in cardiac arrest are unconscious
and therefore cannot give consent. Before any patients were enrolled,
communities were consulted about participation and made aware that informed
consent will not be obtained for most study participants, as required by
law.
To ensure patient safety during the study, the DSMB that monitors ROC
studies reviews the accrued data approximately every six months or more
frequently if needed. The ROC DSMB includes experts in trauma, cardiac
arrest, statistics, ethics, and the conduct of clinical trials. During its
interim data review on Oct. 23, the DSMB recommended stopping enrollment in
both ROC PRIMED assessments based on results that suggest that both types of
strategies were equally beneficial and that continued enrollment was
unlikely to yield different results. The NHLBI accepted the recommendation,
and ROC clinical sites stopped enrollment.
The ROC is a large clinical research network of 10 centers in the United
States and Canada. Approximately 150 EMS and fire services organizations,
involving more than 20,000 EMS providers who serve a combined population of
nearly 15 million people from diverse urban, suburban, and rural regions
participated in ROC PRIMED. ROC research focuses on treatments for patients
with life-threatening traumatic injury or cardiac arrest in real-world
settings, typically where patients collapse or are critically injured,
before they reach the hospital. Participating EMS providers receive
intensive training, and give standard emergency care to all patients, with
some patients randomly selected to receive the intervention to be tested in
addition to usual care.
"The ROC is the largest research network to study real-world, pre-hospital
interventions for cardiac arrest," noted George Sopko, M.D., ROC project
officer in the NHLBI Division of Cardiovascular Sciences. "Conducting these
studies through this robust and experienced network allows us to implement
and compare clinical interventions in meaningful ways and to disseminate the
results as quickly as possible so they can be applied to improve public
health."
Earlier this year, the NHLBI stopped enrollment early for two ROC clinical
trials that examined whether concentrated (hypertonic) saline improved
survival over standard saline for trauma patients. Patients in the study
were either suffering from shock due to significant blood loss or had
experienced a traumatic brain injury. In both types of patients, hypertonic
saline solution did not improve outcomes over the use of a standard saline
solution.
The NHLBI is the lead federal sponsor of the ROC studies. Additional funding
is provided by the NIH's National Institute of Neurological Disorders and
Stroke, the Institute of Circulatory and Respiratory Health of the Canadian
Institutes of Health Research, US Army Medical Research & Materiel Command,
American Heart Association, Defence Research and Development Canada, and the
Heart and Stroke Foundation of Canada.
Further information about this trial (NCT00394706) can be found at
http://www.clinicaltrials.gov/.
To interview an NHLBI spokesperson, contact the NHLBI Communications Office
at 301-496-4236 or at mailto:. To interview Dr.
Aufderheide, contact Toranj Marphetia at 414-456-4744 or . To
interview Dr. Stiell, contact Jennifer Paterson at 613-798-5555 x 73325 or
. To interview Myron Weisfeldt, M.D., ROC Steering
Committee chair, contact David March at 410-955-1534 or
mailto:%.
More information:
Resuscitation Outcomes Consortium:
https://roc.uwctc.org/tiki/tiki-index.php
Q&A on ROC PRIMED:
http://public.nhlbi.nih.gov/newsroom/home/qanda.htm
Sudden Cardiac Arrest:
http://www.nhlbi.nih.gov/health/dci/Diseases/scda/scda_whatis.html
Part of the National Institutes of Health, the National Heart, Lung, and
Blood Institute (NHLBI) plans, conducts, and supports research related to
the causes, prevention, diagnosis, and treatment of heart, blood vessel,
lung, and blood diseases; and sleep disorders. The Institute also
administers national health education campaigns on women and heart disease,
healthy weight for children, and other topics. NHLBI press releases and
other materials are available online at:
http://www.nhlbi.nih.gov/.
The National Institutes of Health (NIH) - The Nation's Medical Research
Agency - includes 27 Institutes and Centers and is a component of the U.S.
Department of Health and Human Services. It is the primary federal agency
for conducting and supporting basic, clinical and translational medical
research, and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and its programs,
visit
http://www.nih.gov/.
Reference:
http://www.defrance.org/artman/publish/article_2458.shtml