Hypertension Drug Helps Burn Patients Recover
Stops adrenaline, aids rebuilding of muscle mass
WEDNESDAY, Oct. 24, 2001 (HealthDayNews) -- A drug that dulls the body's fright hormone helps burn patients and other trauma victims preserve much-needed muscle mass during the early days and weeks of recovery, new research says.
Doctors say propranolol, a blood pressure drug that slows the heart, can stop the destruction of muscle and fat caused by the flood of the hormone adrenaline (also called epinephrine) after major burns that cover large swaths of a person's skin.
"When you're burnt or have a big injury, your epinephrine level is massively elevated," says Dr. David Herndon, chief of staff at the Shriners Hospitals for Children and lead author of the study. "This drug serves to take the edge off that elevation." A report on the findings appears in the Oct. 25 issue of the New England Journal of Medicine.
In response to trauma, such as burn wounds or multiple bone breaks, the brain releases adrenaline, which causes the heart to beat faster. To keep up with this pace, the body burns muscle for fuel in a process called catabolism, which saps patients of strength and causes them to lose significant amounts of weight.
Advances in surgery, more potent antibiotics, and better nutritional therapy have all lessened the impact of muscle breakdown for burn victims and patients with other traumatic conditions. But doctors still struggle with ways to prevent these patients from cannibalizing themselves after the injury.
Various steroids and muscle-building hormones have been tried to stop the wasting, with mixed success. But although those compounds attempt to bulk up the body, the latest approach takes a different tack, using a beta-blocker to reduce muscle's appetite for itself.
Beta-blockers are blood pressure drugs that are also used to prevent heart attacks in patients with cardiovascular disease who come to the hospital for major surgery. These compounds, which disrupt beta-adrenergic stimulation that makes the heart contract during stress, can safely calm the pump and trim energy expenditure.
Herndon, a professor of surgery at the University of Texas Medical Branch in Galveston, and his colleagues gave propranolol to 13 of 25 children who'd suffered burns over at least 40 percent of their body. Patients with burns this severe typically lose 20 to 30 percent of their muscle mass, and more if they develop infections, Herndon says.
The researchers tried to give the patients enough of the oral drug to suppress their heart rate by 20 percent -- down from a blistering 160 or so beats per minute.
After at least two weeks, the children taking propranolol had lower heart rates and spent less energy than a dozen patients taking inactive pills. Their muscle-protein balance -- a measure of muscle building -- rose by 82 percent, on average, while that of the placebo group fell by 27 percent during the period. The drug also helped burn patients preserve muscle mass, which dropped markedly in the untreated children.
"This drug makes the muscle make more muscle by protein synthesis," Herndon says. In other words, patients who take it are "significantly stronger. That should let them get off of ventilators, get off to school, be stronger."
In addition to burn patients, beta-blockers should also help protect other trauma victims from muscle loss, Herndon says. The drugs might even prove beneficial for patients with AIDS and other wasting diseases, though they haven't been tested in these cases, he adds.
Beta-blockers do carry some side effects, and three of the 13 patients who took propranolol had to stop the treatment briefly because blood pressure in their arteries dropped dangerously. The drugs are also harmful for people with asthma and other respiratory conditions and should not be given to them, Herndon says.
Dr. Robert Sheridan, a Harvard University burn specialist and author of an editorial accompanying the journal article, says it's too soon to be sure beta-blockers are helpful for trauma victims.
"The trouble with all of these therapies is that the whole biological mechanism [of muscle breakdown] is something we don't know much about," says Sheridan, clinical director of the acute burn service at Shriners Burns Hospital in Boston.
Because every animal experiences a similar reaction to massive injury, the response probably holds evolutionary importance and is "unlikely to be completely harmful," he says. By shutting it down, "you don't know if you're robbing Peter to pay Paul, improving one aspect but harming another unknown aspect" of recovery.
What To Do
The American Burn Association says more than 1 million people in this country suffer burn injuries each year, and 4,500 die from burns or in fires. While the number of admissions to burn centers has doubled since 1971, the death rate hovers around 6 percent of burn patients, according to the group.