August 19, 2009

BIRMINGHAM, Ala. - University of Alabama at Birmingham (UAB) emergency medicine physicians are now inducing hypothermia in patients with cardiac arrest in an effort to prevent brain damage caused by loss of oxygen. Cardiac arrest patients whose hearts stop and then are restarted following CPR or defibrillation are candidates for the hypothermia therapy, which cools the patient to 32 degrees Celsius (89.6 Fahrenheit).

When a person's heart stops, oxygen-rich blood is no longer pumped to the brain, causing damage or death of brain cells. While the reasons are unclear, medicine has long known that the rapid return of blood to the brain following successful resuscitation carries with it the potential for additional damage to brain cells.

"We know that the return of blood to the brain, called reperfusion, causes injury to brain cells," said Henry Wang, M.D., an associate professor in the Department of Emergency Medicine. "We also know that cooling the body for a period of time has a neuroprotective effect. While the reason for that protection is still poorly understood, studies have definitely shown that cooling leads to much better outcomes for cardiac arrest patients."

Wang says patients are kept in a hypothermic state for 24 hours after resuscitation using cooling blankets, cold IV fluids and icebags. Patients are then slowly warmed to normal temperatures over two or three days.

"The damage caused by rapid reperfusion may be the result of overexcitement of neurons when oxygen is restored to the brain," said Jason Begue, M.D., assistant professor of emergency medicine. "Induced hypothermia slows the body's metabolism and may help neurons better prepare for the return of oxygen by reducing that excitability."

Begue and Wang say induced hypothermia for cardiac arrest is now the standard of care at UAB Hospital, the first Birmingham-area hospital to establish a comprehensive hypothermia program for cardiac arrest. The multidisciplinary approach involves critical care medicine, cardiology, neurology and rehabilitation medicine, along with emergency medicine practitioners.

"This truly demands a team effort," said Wang. "Patients will spend multiple days in intensive care, under the care of critical care specialists and neurologists. Cardiologists will be needed for the underlying heart issues and, invariably, patients will need rehab in order to achieve the best outcomes. We have the expertise of all those specialties here at UAB."

Only 3 percent of all cardiac arrest patients in Alabama are successfully resuscitated. The amount of brain damage suffered by those survivors depends on many factors, including their age, health and length of time that oxygen was deprived from the brain. Wang and Begue believe that innovations such as induced hypothermia may be able to double the number of survivors while reducing brain damage.

About the UAB Health System

The UAB Health System includes all of the University of Alabama at Birmingham's patient care activities, including UAB Hospital, the Callahan Eye Foundation Hospital and The Kirklin Clinic. UAB is the state of Alabama's largest employer and an internationally renowned research university and academic health center whose professional schools and specialty patient care programs are consistently ranked as among the nation's top 50; find more information at www.uab.edu and www.uabhealth.org.