TUCSON, July 1 (UPI) -- New research suggests doctors may be jumping the gun when judging that cardiac arrest patients will not recover if they do not come out of induced comas within two days of having a heart attack, the long-time standard for such recovery.
Researchers at the University of Arizona found cardiac arrest patients may wake up as long as a week after being treated with therapeutic hypothermia to prevent brain injury with no future neurological effects, according to a study published in the Annals of Emergency Medicine.
About half of patients who experience a cardiac arrest outside the hospital are revived after attempted resuscitation, but just 10 percent of those survive to leave the hospital and half of those patients have some type of brain impairment because of a lack of oxygen to the brain.
It has been generally assumed that if a patient does not come out of the induced coma within 48 hours, their chance of waking up is low, but researchers found in the new study that many patients wake up hours to days later than this and leave the hospital with little or no impairment.
"We may be able to save thousands of lives each year across the country by simply giving cardiac arrest victims more time to awaken in the hospital," Dr. Samuel Keim, a professor and chair of the University of Arizona Department of Emergency Medicine, said in a press release.
For the study, researchers analyzed medical records for 573 patients who had cardiac arrest outside a hospital and were treated with targeted temperature management between January 2008 and March 2014.
Of these, 316 became responsive, with 60 of the patients, or 19 percent, waking up at least 48 hours after being warmed back up -- and eight patients became responsive more than 7 days after rewarming, with 6 of them discharged from the hospital with good performances on cognitive tests.
"Most patients are comatose after resuscitation and accurately predicting those who will wake up can be extremely challenging," said Dr. Bentley Bobrow, a professor at the University of Arizona and co-director of the Arizona Emergency Medicine Research Center. "There are many factors involved, but we know that it is common for doctors to try to decide who will and who won't wake up after 24 to 48 hours of hospitalization. However, our study found that a substantial number of cardiac arrest victims wake up longer than many people would expect. Sometimes they awaken from coma five, six or seven days after being admitted to the hospital and many of these have a good neurological outcome."