Predicting risk of decompression sickness in humans from outcomes in sheep

In animals, the response to decompression scales as a power of species body mass. Consequently, decompression sickness (DCS) risk in humans should be well predicted from an animal model with a body mass comparable to humans. No-stop decompression outcomes in compressed air and nitrogen-oxygen dives with sheep (n = 394 dives, 14.5% DCS) and humans (n = 463 dives, 4.5% DCS) were used with linear-exponential, probabilistic modeling to test this hypo thesis. Scaling the response parameters of this model between species (with out accounting for body mass), while estimating tissue-compartment kinetic parameters from combined human and sheep data, predicts combined risk bette r, based on log likelihood, than do separate sheep and human models, a comb ined model without scaling, and a kinetic-scaled model. These findings prov ide a practical tool for estimating DCS risk in humans from outcomes in she ep, especially in decompression profiles too risky to test with humans. Thi s model supports the hypothesis that species of similar body mass have simi lar DCS risk.