Critical tissue oxygen tension defines tissue oxygen debt in the isolated hindlimb of the pig during progressive ischemia

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Abstract
Objective To determine a critical skeletal muscle oxygen tension (PO2) value below which a tissue oxygen debt develops. Design Descriptive study of oxygen transport values in relation to skeletal muscle PO2 throughout progressive ischemia by means of arterial blood flow reductions in an isolated hindlimb model in the pig. Setting Surgical Research department of the University of Amsterdam. Subjects Six female Yorkshire pigs weighing 26 to 35 kg (average 33). Interventions Controlled blood flow to the isolated hindlimb was achieved by means of extracorporeal circulation. The hindlimb was studied during progressive flow reduction. Measurements and Main Results Oxygen delivery (DO2) and oxygen consumption were calculated as the product of extracorporeal blood flow and, respectively, arterial oxygen content and arterial-venous oxygen content difference. In this fashion, an oxygen supply dependency could be determined in all animals. A critical DO2 value was determined below which a tissue oxygen debt developed. Skeletal muscle PO2 was measured continuously, using a Clark-type polarographic oxygen sensor. Combining the critical DO2 value with the corresponding skeletal muscle PO2 value resulted in a critical skeletal muscle PO2 value of 15.2 +/- 0.4 torr (2.0 +/- 0.1 kPa). Conclusion In this pig model, a critical skeletal muscle PO2 value could be determined below which a tissue oxygen debt presumably developed. (Crit Care Med 1995; 23:931-938)