Nicolas Andry Award. Increased tissue pressure and its effects on muscle oxygenation in level and elevated human limbs.

Increased tissue pressure is an important cause of local circulatory compromise. In both rabbit and human model systems known external pressures were applied to otherwise normal limbs. Side-by-side comparison of the wick and the infusion techniques revealed that both methods of pressure measurement yielded essentially identical results when tissue pressure was elevated. Measured tissue pressure significantly exceeded the external pressure applied to the limb. Using a mass spectrometer-Teflon membrane catheter system, we monitored muscle PO2 and PCO2 at different applied pressures. Muscle PO2 decreased progressively with increasing tissue pressure but did not approach zero until tissue pressure exceeded local arterial pressure. Comparison of results with level and elevated limbs indicated that elevation of an extremity dramatically lowered its tolerance for increased tissue pressure. Although they may be clinically useful modalities, these are conditions in which compression and elevation have a significant potential for compromising local circulation.