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Study on Recovery from Smoke Inhalation Injury Produces Unexpected Results

A study by researchers at Loyola University Chicago Stritch School of Medicine generated some surprising findings about the response of the immune system in victims of severe burns and smoke inhalation.

Contrary to expectations, patients who died from their injuries had lower inflammatory responses in their lungs than the patients who survived. “Perhaps a better understanding of this early immune dysfunction will allow for therapies that further improve outcomes in burn care,” researchers reported.

The study was published in the January/February issue of the Journal of Burn Care & Research. First author of the study was Christopher S. Davis, MD, MPH, a research resident in the Loyola Burn & Shock Trauma Institute. Assisting him was Elizabeth J. Kovacs, PhD, director of research of the Burn & Shock Trauma Institute.

Researchers followed 60 burn patients in the Loyola Burn Center. As expected, patients with the worst combined severe burn and smoke inhalation injuries required more time on a ventilator, in the intensive care unit, and in the hospital. They also were more likely to die. Also in line with expectations was this finding: Patients who died were older and had larger injuries on the whole than patients who survived.

But the immune system findings were not expected. Researchers measured concentrations of 28 immune system modulators in fluid collected from the lungs of patients within 14 hours of burn and smoke inhalation injuries. These modulators are proteins produced by white blood cells and other cells such as those that line a person’s airway. Some of these modulators recruit white blood cells (leukocytes) to areas of tissue damage, or activate them to begin the repair process within damaged tissue.

Based on studies conducted at Loyola and other centers, researchers had expected to find higher concentrations of modulators in the fluid of patients who died, because sicker patients tend to have greater inflammatory responses. However, researchers found the opposite: Most patients who died had lower concentrations of these modulators in their lungs.

The question is this: Why do some patients mount robust immune responses in the lungs after smoke inhalation and burn injuries, while others do not? The reason may be due to a few things working together: age, genetics, differences in patients’ pre-existing health conditions, or anything that might disrupt the balance between too much and too little inflammation.

Survival of severe burn patients has significantly improved since the 1950s, due to advancements such as better wound care and treatment and prevention of infections. But progress has somewhat stalled in the last 10 years.

The immune response to lung injury from smoke or burns “remains not completely understood, and additional effort is required to improve survival of burn-injured patients,” researchers wrote.

The study was presented at the 2011 meeting of the American Burn Association, where it won the 2011 Carl A. Moyer Resident Award for the best study submitted by a resident physician. The study was funded by grants from the National Institutes of Health, Department of Defense, International Association of Fire Fighters and the Dr. Ralph and Marian C. Falk Medical Research Trust.

Loyola’s Burn Center is one of the busiest in the Midwest, treating more than 600 patients annually in the hospital, and another 3,500 patients each year in its clinic. It is one of only two centers in Illinois that have received verification by the American Burn Association.

The study is among the results of research over the last several years conducted in Loyola’s Burn Center and its Burn & Shock Trauma Institute, the latter of which is investigating the lung’s response to burn and inhalation injuries.