Natural history of severe decompression sickness after rapid ascent from air saturation in a porcine model

We developed a swine model to describe the untreated natural history of sev ere decompression sickness (DCS) after direct ascent from saturation condit ions. In a recompression chamber, neutered male Yorkshire swine were pressu rized to a predetermined depth from 50-150 feet of seawater [fsw; 2.52-5.55 atmospheres absolute (ATA)I. After 22 h, they returned to the surface (1 A TA) at 30 fsw/min (0.91 ATA/min) without decompression stops and were obser ved. Depth was the primary predictor of DCS incidence (R = 0.52, P < 0.0001 ) and death (R = 0.54, P ( 0.0001). Severe DCS, defined as neurological or cardiopulmonary impairment, occurred in 78 of 128 animals, and 42 of 51 ani mals with cardiopulmonary DCS died within 1 h after surfacing. Within 24 h, 29 of 30 survivors with neurological DCS completely resolved their deficit s without intervention. Pretrial Monte Carlo analysis decreased subject req uirement without sacrificing power. This model provides a useful platform f or investigating the pathophysiology of severe DCS and testing therapeutic interventions. The results raise important questions about present models o f human responses to similar decompressive insults.