Tech. Sgt. Derek Matway, 10th Expeditionary Aeromedical Evacuation Squadron technician, sets up medical equipment inside a C-17 Globemaster III, at Ramstein Air Base, Germany. Matway and a crew of medical Airmen flew to a deployed location in Southwest Asia in November to retrieve servicemembers in need of medical attention. Air Force photo by Staff Sgt. Armando A. Schwier-Morales

BALTIMORE — U.S. warfighters injured in combat in Iraq and Afghanistan had a 90% or more rate of survival, with a substantial part of that success attributed to medical evacuation teams that swiftly flew wounded servicemembers to locations such as Landstuhl Regional Medical Center in Germany or to Brooke Army Medical Center in Texas.

A new study funded by the Air Force noted, however, that one-fourth of all wounded warriors evacuated to receive more-extensive treatment outside of battle zones had head injuries and questioned whether air evacuation was the best course of action for them.

The University of Maryland researchers said they have uncovered evidence that those air evacuations might have caused more damage to already injured brains by exposing them to reduced barometric pressure, as well as vibration, acceleration and temperature variations.

“This research shows that exposure to reduced barometric pressure, as occurs on military planes used for evacuation, substantially worsens neurological function and increases brain-cell loss after experimental TBI — even when oxygen levels are kept in the normal range,” explained lead researcher Alan Faden, MD. “It suggests that we need to carefully re-evaluate the cost-benefit of air transport in the first days after injury.”

Background information in the article, published recently in the Journal of Neurotrauma, pointed out that more than 330,000 military personnel suffered a traumatic brain injury (TBI) during the last 15 years.

Faden, director of the University of Maryland’s Shock, Trauma and Anesthesiology Research Center (STAR) as well as the National Study Center for Trauma and Emergency Medical Services, and colleagues performed an animal study using a model that simulates key aspects of human brain injury.

For the research, rats were exposed to six hours of lowered air pressure, hypobaria, at levels that simulated conditions during transport. They then were compared to a control group exposed to normal pressure. All of the animals received extra oxygen to restore normal oxygen concentrations in the blood.

In a companion study, animals received oxygen, either as in the first study or at much higher 100% concentration, which is often used during military air evacuations, according to the researchers. >>Long-Term Cognitive Function