Interspecies Scaling in Blast Pulmonary Trauma

Abstract

The increased frequency of blast exposure from improvised explosive devices in military settings and terrorist bombings in civilian settings has led to extensive investigation of blast trauma. Thousands of tests have been conducted in animal models of blast trauma across a large range of body size. Experimental results are often compared without consideration of interspecies scaling. A dataset of published fatality data from 4193 tests using 5 different large and small blast trauma model species was compiled to assess interspecies scaling and pulmonary fatality risk. Simultaneously, an overpressure duration interspecies scaling based on allometric principles was optimized to create a common fatality risk model scaled for species. A two-variable nonlinear logistic regression model was used to describe fatality risk. Minimization of the loglikelihood was used to optimize the fit. A large portion of existing blast trauma data was excluded due to incomplete reporting of methodology or blast dosage. The most common species used was mice with 1828 tests followed by sheep with 1309. A nonlinear regression model with an optimized duration interspecies scaling model was used to fit the experimental data from all species. Long duration peak pressure tolerance for small and large animals was found to be approximately 90 and 145 kPa, respectively. Using a body mass ratio scaling model for overpressure duration, the duration interspecies scaling exponent was found to be α = 0.351. This study shows the importance and strong effect of interspecies scaling for blast research, especially when extrapolating the human equivalent dose from the small species commonly used.