OCTOBER 6, 2009
How Ice Can Save Your Life
'Therapeutic Hypothermia' Can Protect the Brain in the Aftermath of Cardiac Arrest
By RON WINSLOW
WSJ
For decades, conventional wisdom in treating patients with cardiac arrest was that if the heart stopped beating for longer than six to 10 minutes, the brain would be dead. Now a new treatment being embraced by a growing number of U.S. hospitals suggests that patients can be brought back to a healthy life even if their heart is stopped for 20 minutes, perhaps longer. The difference is profound. In recent months around the U.S., doctors and nurses say, cardiac-arrest patients who would previously have been given up for dead have been revived and discharged to return to their families and jobs with all or nearly all of their cognitive abilities intact.
The treatment is called therapeutic hypothermia and at its core is the simplest of technologies: ice. Once a patient's heartbeat is restored, emergency-room doctors, cardiologists and rescue squads are quickly applying ice and other coolants to moderately lower a patient's body temperature by about six degrees. Then the patient is put in a drug-induced coma in intensive care for 24 hours before gradually being warmed back up to normal temperature.
(snip)
Experience with the treatment is injecting optimism in a field long plagued by frustration. Despite faster emergency squads, deployment of automated defibrillators at airports and other public places, and improvements in cardiopulmonary resuscitation techniques, fewer than 10% of the 300,000 Americans who suffer cardiac arrest each year survive long enough to leave the hospital—a rate that hasn't budged much over the years. The rationale behind the new treatment is that the brain is more resilient than previously believed during the early period after the heart goes down. Of course, the brain can't live long without the oxygen provided by normal blood flow. But an initial rush of blood to the brain, when resuscitation gets the heart beating again, also kills tissue and is "a more important insult," Dr. Mooney says.
At normal temperatures, the restoration of blood flow triggers a cascade of inflammatory and other responses over the following minutes and hours, which can injure tissue in the brain and exact a lethal toll. Scientists say icing the body slows metabolism and protects the brain from at least some of the damage caused by the restored blood flow. The benefits of cooling in cardiac arrest were demonstrated in two landmark studies, one done in Australia, the other in Europe, and both published in 2002 the New England Journal of Medicine. The findings prompted the American Heart Association to include therapeutic hypothermia in 2005 guidelines for treating cardiac-arrest patients outside of a hospital.
(snip)
Doctors caution that not all cardiac-arrest patients are candidates for therapeutic hypothermia, and even some patients who receive it still don't benefit. But it doesn't seem to matter whether the cardiac arrest is the result of a heart attack, a heart defect or another cause. Cooling remains just one part of the process. Quick use of CPR or defibrillators to restore heart rhythm remains critical, as does monitoring of cooled patients by nurses in the ICU. "It's not a one-trick pony," says Bentley J. Bobrow, an emergency-medicine doctor at Maricopa Medical Center, in Phoenix. More research is needed to document results and get a better grasp of issues such as optimal duration for cooling; doctors say they need to understand possible side effects, including infection and bed sores.
Physicians typically are slow to adopt clinical recommendations, and this one — involving costly ICU care and intense collaboration among rescue squads, doctors and nurses — is no exception. In the past couple of years, as researchers such as Drs. Bobrow, Mooney and Abella and their respective colleagues have reported promising results with therapeutic hypothermia, more hospitals have adopted the approach. Companies that market cooling technology, such as closely held Medivance Inc., of Louisville, Colo.; Zoll Medical Corp., of Chelmsford, Mass.; and Royal Philips Electronics NV, are fueling interest.
(snip)
http://online.wsj.com/article/SB10001424052748703298004574455011023363866.html (subscription)
Printer-friendly format
Email this thread to a friend
Bookmark this thread
(1000+ posts)
Send PM |
Profile |
Ignore
