but if a significant of the muscle dies from I-R injury then fibrosis will occur and function will be compromised. A study in progress by Zamboni et al. (40) employs a rabbit hindlimb model of physiologic amputation that simulates the clinical situation. Following 8 hours of global ischemia, the indlimb is reperfused and muscle significant improvement in muscle function from animals treated with HBO during ischemia, compared to untreated controls. Since blood flow is blocked to the extremity during ischemia, the animal sees the HBO, but the hindlimb does not. This suggests that HBO is affecting a systemic circulating element(i.e. the neutrophil) rather than acting on the ischemic endothelium. A trend toward improvement has also been noted in several HBO groups treated during reperfusion, but numbers are too small at this point to permit statistical comparison to controls.