Submarine escape from depths of 30 and 60 feet: 41,183 training ascents without serious injury.

Introduction: In the case of a submerged, disabled submarine, survivors may be forced to escape by entering the water and ascending rapidly to the surface. The large pressure changes involved may produce pulmonary barotrauma, arterial gas embolism, or barotrauma. To assess the likelihood of such injuries, we retrospectively evaluated medical problems due to submarine escape training among military personnel.

Methods: We evaluated 41,183 controlled ascents performed over the past 21 yr in the escape training tank at Gölcük-Kocaeli, Turkey. Each trainee performed two free ascents from 30 ft and two hooded ascents from 60 ft. Before participating, candidates were screened by physical examination, spirometry, and chest X-rays; ear examinations for barotrauma were made after ascents. If a trainee failed to exhale properly during ascent, an instructor aborted the ascent and took him to a bell or side recess of the tank.

Results: No record of pulmonary barotrauma or other major complications were found. Middle-ear barotrauma was observed following 1,643 of the ascents (4.1%), with rupture of the tympanic membrane in 35 cases.

Discussion: Submarine escape ascents can be safely performed provided that subjects are medically screened and well trained.