Determination of a critical level of tissue oxygenation in acute intestinal ischaemia.

Tissue oxygen tension (PtO2) was measured using a miniaturised polarographic oxygen electrode in 134 segments of rat small intestine of varying degrees of ischaemia. Without knowledge of the PtO2 levels, the viability of each segment was scored using clinical parameters and tissue damage scored by independent histological examination. Histologically non-viable bowel had significantly impaired tissue oxygenation when compared with viable bowel (t test, p less than 0.001). Marked degrees of tissue hypoxia were frequently tolerated before major histological damage became apparent, a critical PtO2 level of 1.9 mmHg being identified. The overall accuracy rate of PtO2 measurement in the operative prediction of intestinal viability was 92.5%, which contrasts with a rate of only 57.7% for clinical criteria alone.