Image: A new study asserts that injecting adrenaline following a heart attack can cause brain damage (Photo courtesy of Getty Images).
A new study shows that using adrenaline in cardiac arrests nearly doubles the survivors’ risk of severe brain damage.
Researchers at the University of Warwick (Coventry, United Kingdom), Royal United Hospital Bath (RUH; United Kingdom), the London Ambulance Service (United Kingdom), and other institutions conducted a study in five National Health Service (NHS) ambulance trusts in the United Kingdom. The study included 8,007 patients in cardiac arrest who were allocated randomly to be given either adrenaline or a salt-water placebo. All those involved in the trial, including ambulance crews and paramedics, were unaware which of the two treatments the patient received.
The results revealed that of 4,012 patients given adrenaline, 3.2% were alive at 30 days, compared with 2.4% of the 3,995 patients who were given placebo. Of the patients given adrenaline who survived to hospital discharge, 30.1% suffered severe brain damage, compared with 18.7% of survivors who had been given a placebo. Severe brain damage was defined as someone in a vegetative state requiring constant nursing care and attention, or unable to walk and look after their own bodily needs without assistance. The study was published on July 19, 2018, in the New England Journal of Medicine (NEJM).
“We found that the benefits of adrenaline are small, one extra survivor for every 125 patients treated, but the use of adrenaline almost doubles the risk of a severe brain damage amongst survivors,” said lead author Professor Gavin Perkins, MD, of the University of Warwick. “Patients may be less willing to accept burdensome treatments if the chances of recovery are small or the risk of survival with severe brain damage is high. Our own work with patients and the public before starting the trial identified survival without brain damage is more important to patients than survival alone.”
“This trial has answered one of the longest standing questions in resuscitation medicine. Taking the results in context of other studies, it highlights the critical importance of the community response to cardiac arrest,” said study co-author Professor Jerry Nolan, MD, consultant in anesthesia and intensive care medicine at RUH Bath. “Unlike adrenaline, members of the public can make a much bigger difference to survival through learning how to recognize cardiac arrest, perform CPR, and deliver an electric shock with a defibrillator.”
Once cardiac arrest is recognized, cardiopulmonary resuscitation (CPR) and defibrillation are applied without delay. The application of adrenaline is one of the last things attempted to treat cardiac arrest, in an effort to increase blood flow to the heart. At the same time, however, it also reduces blood flow in the brain, which may worsen brain damage. Observational studies involving over 500,000 patients have reported worse long-term survival and more brain damage among survivors who were treated with adrenaline.
University of Warwick
Royal United Hospital Bath
London Ambulance Service