When a patient's heart stops beating, a shot of adrenaline is a last-resort treatment that doctors use to wake the vital organ back up. It's a routine procedure in emergency rooms across the country, but new research is now questioning the safety and effectiveness of this common intervention.
Adrenaline increases blood flow to the heart and increases the chance of restoring a heartbeat. However, it also reduces blood flow in the tiny small blood vessels in the brain, which may cause brain damage. In a study published on Wednesday in the New England Journal of Medicine, researchers in the U.K found that a third of cardiac arrest survivors who received adrenaline ended up in a vegetative state or were unable to walk and care for themselves, compared with 18 percent of survivors who were given a placebo.
The trial found that the use of adrenaline almost doubles the risk of severe neurological damage in those who survive, and does not greatly improve the rate of survival, lead author of the study, Gavin Perkins, told Newsweek.
"We have 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 Perkins, professor of Critical Care Medicine in Warwick Medical School in the U.K.
Most people who suffer from a sudden cardiac arrest—when the heart stops beating due to an electrical malfunction in the heart—die from the condition, according to the National Institutes of Health (NIH). The American Heart Association reports that as many as 475,000 people die in the United States every year from cardiac arrest.
Typically, doctors first try chest compressions. If that fails to work on its own, then a shot of epinephrine is administered, Dr. Clifton Callaway, a professor of emergency medicine at the University of Pittsburgh, told Newsweek.
The administration of adrenaline shots became a common practice 55 years ago. The intent has always been to make chest compressions more effective.
"It's thought that if you give a drug like epinephrine that you can increase the blood pressure during chest compressions," said Callaway, who was not involved in the study.
To put this idea to the test, paramedics throughout the U.K. were given packets of syringes pre-filled with either adrenaline or a placebo to use if they encountered people in cardiac arrest. The paramedics were instructed to only use the shots if initial attempts at resuscitation by CPR or defibrillation failed to work.
People living in the areas where the trial was conducted were told about the study and given the option to wear "no study" bracelets if they did not want to participate.
During the trail, of the 4,012 people who were treated with adrenaline, 130 survived after a month, compared with 94 of the 3,995 patients who were given the placebo. However, a significant number of people who survived long enough to be discharged from the hospital had brain damage.
Of the 128 patients who had adrenaline, 40 had brain damage, compared with 17 out of 91 survivors who had the placebo.
"The increase in survival is tempered by the fact that the survivors seem to not being doing as well," said Calloway. "I think we will have to ponder this new data to see if this is the right dose and the right way to use that drug."
