New cardiopulmonary resuscitation guidelines issued by the American Heart Association got high marks from some in the neurology community for their emphasis on chest compression and low marks for soft pedaling therapeutic hypothermia.
“We brain specialists like anything that keeps the blood flowing, and keeps people pumping on the chest,” neurologist William M. Coplin said in an interview. “Once you start the heart you can keep the brain perfused and that's what's important,” said Dr. Coplin, chief of neurology and medical director of neurotrauma and critical care at Detroit Receiving Hospital, Detroit.
“We used to worry so much more about getting the lungs working, but we've certainly known for long enough that you can have lower oxygen in your system and as long as the blood is flowing the brain will survive,” he said.
The resuscitation guidelines are aimed at both the lay public and health care professionals. The guidelines emphasize how best to achieve optimal chest compression. “Push hard, push fast, allow full chest recoil after each compression, and minimize interruptions to chest compressions,” said the authors of the 2005 AHA Guidelines for CPR and ECC (emergency cardiovascular care) published in a supplement to Circulation (www.circulationaha.org).
The guidelines are aimed at improving the survival rate for out-of-hospital cardiac arrest, which “remains low worldwide, averaging 6% or less,” Mary Fran Hazinski, R.N., of Vanderbilt Children's Hospital, Nashville, Tenn., and her colleagues noted in an accompanying summary of the key changes from the previous guidelines, issued in 2000 (Circulation 2005; 112:IV206-IV211).
And while the research behind the new guidelines included debate about all aspects of detection and treatment of cardiac arrest, “the last summation returned to the beginning question: How do we get more bystanders and health care providers to perform CPR and to perform it well?” they said.
“Our greatest challenge and highest priority is the training of lay rescuers and health care providers in simple, high-quality CPR skills that can be easily taught, remembered, and implemented to save lives,” according to Ms. Hazinski and her associates. Evidence shows that “few victims of cardiac arrest receive CPR, and even fewer receive high-quality CPR.”
To address this issue, the authors recommend a simplification of previous instructions on CPR, with a stronger emphasis on continuous chest compression with minimal interruptions for ventilation and rhythm checks.
“The combination of inadequate and interrupted chest compressions and excessive ventilation rates reduces cardiac output and coronary and cerebral blood flow and diminishes the likelihood of a successful resuscitation attempt,” they said.
Thus, a universal compression-ventilation ratio of 30:2 for all lone rescuers (lay or trained) of victims of any age (excluding newborns) is recommended. Children can be treated using a 15:2 ratio if there are two rescuers present, since asphyxial arrest is more likely in this population. And a priority for ventilation was reaffirmed in the case of newborn resuscitation.
Dr. Coplin and cardiologist Dr. James J. Ferguson III, of Baylor College of Medicine, Houston, and the Texas Heart Institute of St. Luke's Episcopal Hospital there, agreed that the new guidelines promise to be useful in overcoming hesitance from bystanders who are worried about disease-exposure with mouth-to-mouth resuscitation. “By stressing the importance of chest compressions this may sidestep some of those issues, but it raises the concern that later on in the resuscitation efforts, when ventilation becomes more important, that it may be ignored to some extent,” Dr. Ferguson said in an interview. However, he said that “the working philosophy of ‘keep it simple and maximize your early benefit’ would seem to provide the most benefit to the most people. Many more people who are saved are saved early, rather than late.”
Dr. Coplin also agreed with the effort to simplify procedures. “This isn't supposed to be rocket science. The idea is to keep things under control until the rocket scientist is available.”
Dr. Coplin said that he was disappointed with the guidelines' failure to fully endorse therapeutic hypothermia to improve neurologic outcome in comatose survivors of cardiac arrest.
“I wish they hadn't been so soft about it. It is a very soft endorsement, and I don't understand why,” said Dr. Coplin, who also works in the department of neurology and neurologic surgery at Wayne State University. Citing three studies showing improvement in patients treated with hypothermia, the guidelines state that both permissive hypothermia and active induction of hypothermia play a role in postresuscitation care. However, although mild spontaneous hypothermia (defined as more than 33° C) “may be beneficial to neurologic outcome and is likely to be well tolerated,” active induction of hypothermia may only be beneficial to a subset of unconscious, hemodynamically stable adults with a return of spontaneous circulation after an out-of-hospital ventricular fibrillation cardiac arrest, according to the guidelines.
Although the guidelines' recommendation for therapeutic hypothermia is a class IIa rather than a class I recommendation, this should still be interpreted as a strong endorsement—especially because the issue was not even addressed in the previous 2000 guidelines, said Dr. Robert O'Connor, one of the authors of the guidelines.
“We actually issued interim recommendations in 2002 encouraging the use of therapeutic hypothermia because we felt it was so important to endorse it that we couldn't wait until the 2005 scheduled revision,” said Dr. O'Connor, director of the emergency medicine program at Christiana Care Health System in Newark, Del., and professor of emergency medicine at Jefferson Medical College, Philadelphia.
But there have been practical problems with implementing a hypothermia protocol, Dr. O'Connor added, including issues such as temperature overshoot (in which the patient became too cool) and inadvertent rewarming. It's also not clear from current evidence whether this protocol applies to arrest conditions other than ventricular fibrillation,” he explained. “So we still recommend it, but with a word of caution.”
The main change in the guidelines concerning defibrillation is the recommendation for only one shock rather than three, and the emphasis on immediate postshock chest compressions and CPR, rather than rhythm checks.
“This change is based on the high first-shock success rate of new defibrillators and the knowledge that if the first shock fails, intervening chest compressions may improve oxygen and substrate delivery to the myocardium, making the subsequent shock more likely to result in defibrillation,” said Ms. Hazinski and her associates. Although lay rescuers are encouraged to use automated external defibrillators as soon as possible, emergency medical service providers “may consider about five cycles (or 2 minutes) of CPR before defibrillation for unwitnessed arrest,” they suggested.
The first rhythm check should be done about 2 minutes after defibrillation and every subsequent 2 minutes. Vasopressors and antiarrhythmics should be administered as soon as possible after a rhythm check.
For acute ischemic stroke, there was reaffirmation of the previous recommendation to using tissue plasminogen activator (TPA) therapy “when administered by physicians in hospitals with stroke protocols that rigorously adhere to the eligibility criteria and therapeutic regimen of the National Institute of Neurological Disorders and Stroke (NINDS) protocol,” Ms. Hazinski and her associates said.
FULL TEXT
