A Reason Not to Practice Free Ascents

A new study of free-ascents (CESAs) involving experienced military divers at the French Military Diving School and reported online in the July Journal of Applied Physiology, suggests that factors beyond exhalation technique might contribute to pulmonary stress.

Groups of seven divers performed two open-water dives to 30 feet. One was a control dive, breathing normally through a regulator, and the other a CESA dive involving continuous exhalation without a mouthpiece on the ascent. Their lungs were examined by ultrasound.

A second phase involved four divers performing CESAs from 15 feet and 30 feet to record the speed and efficiency with which the body adjusts its breathing rate and depth to meet the changing oxygen demands.

They found that after the CESA dives, the divers, although symptom-free, had increased extravascular lung water, as occurs in cases of pulmonary edema or interstitial lung disease.

While the results are not conclusive, the researchers say their findings challenge the assumption that the absence of symptoms equates to the absence of injury. They believe CESA training may expose healthy individuals to silent alveolar stress, highlighting the need for improved monitoring tools and individualized ventilatory assessment during ascent training. https://tinyurl.com/y5spmrbh