Predicting diver vulnerability

SILVER SPRING, Md. - Naval Submarine Medical Research Laboratory (NSMRL) scientists presented their findings during the annual Undersea Hyperbaric Medicine Annual Scientific meeting June 27 in Puerto Rico, and how expired nitric oxide (NOexp) can be used as a non-invasive physical indicator of hyperbaric (high-pressure) oxidative stress to divers. Navy Special Operation Divers use closed circuit underwater breathing devices that operate at high oxygen levels. These levels limit mission length and may cause lung problems. NSMRL has led a series of human oxygen exposure testing, and developed an experimental model of the temporary changes that occur in expired nitric oxide following diving stress, for more than 12 years. Exhaled expired nitric oxide was studied as an indicator of airway inflammation and oxidative stress in a variety of lung diseases, according to Dr. David Fothergill, science director of the Naval Submarine Medical Research Laboratory. Initially, the importance of expired nitric oxide was not clear, he says. “To be useful to our war-fighter, we needed to establish a well-defined relationship between oxygen exposure and the changes in expired nitric oxide.” Fothergill and his colleagues – including Dr. John Florian, a senior research physiologist and the head of Warfighter Human Performance at the Navy Experimental Diving Unit in Panama City, Fla. - explained how they can accurately predict the relative change in expired nitric oxide after prolonged dry and immersed dives. “For the first time we now have a non-invasive biomarker, which will allow us to predict a diver’s vulnerability to respiratory oxygen toxicity,” said Ross. (Source: NSMRL 07/03/19)