Subcutaneous and gut tissue perfusion and oxygenation changes as related to oxygen transport in experimental peritonitis.

Abstract

Peritonitis and septic shock may lead to tissue hypoxia, but this risk is not identical in all organ systems. This study was undertaken to measure changes in tissue oxygenation and perfusion in the gut wall and subcutaneous tissue, respectively, and to examine their relation to oxygen delivery and consumption. Twelve pigs were anesthesized and mechanically ventilated. An ultrasonic flow probe was placed around the superior mesenteric artery for registration of blood flow. A mesenteric vein was cannulated for blood sampling. For calculation of gut intramural pH (pHi), a Silastic balloon (Tonomitor) was placed in the lumen of the midileum. pHi was calculated from tonometrically measured PCO2 and arterial bicarbonate concentration. The subcutaneous PO2 was measured by means of an oxygen-permeable Silastic tube implanted in the subcutis of the abdominal wall. Oxygen delivery (DO2) and consumption (VO2) were determined for the gut as well as for the whole body. In six randomly allocated animals, peritonitis was induced after a stabilization period of at least 1 hr, by instillation of autologous faeces into the abdominal cavity, while the other six animals served as controls. The animals were then followed for 5 hr. pHi remained stable in the control group, whereas a drop from 7.37 to 7.02 took place in the peritonitis group. In the test group, subcutaneous oxygen tension (PscO2) already began to fall 1 hr after the induction of peritonitis, and gained the minimum at the end of the study. In peritonitis, a moderate correlation was seen between pHi and DO2 (r = 0.51 +/- 0.16); no statistical difference was noted if pHi was correlated to gut DO2 (r = 0.56 +/- 0.18).(ABSTRACT TRUNCATED AT 250 WORDS)