SUBCUTANEOUS AND GUT TISSUE PERFUSION AND OXYGENATION CHANGES AS RELATED TO OXYGEN-TRANSPORT IN EXPERIMENTAL PERITONITIS

Peritonitis and septic shock may lead to tissue hypoxia, but this risk is not identical in all organ systems. This study was undertaken to m easure changes in tissue oxygenation and perfusion in the gut wall and subcutaneous tissue, respectively, and to examine their relation to o xygen delivery and consumption. Twelve pigs were anesthesized and mech anically ventilated. An ultrasonic flow probe was placed around the su perior mesenteric artery for registration of blood flow. A mesenteric vein was cannulated for blood sampling. For calculation of gut intramu ral pH (pH(i)), a Silastic balloon (Tonomitor) was placed in the lumen of the midileum. pH(i) was calculated from tonometrically measured PC O2 and arterial bicarbonate concentration. The subcutaneous PO2 was me asured 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 si x randomly allocated animals, peritonitis was induced after a stabiliz ation period of at least 1 hr, by instillation of autologous faeces in to the abdominal cavity, while the other six animals served as control s. The animals were then followed for 5 hr. pH(i) remained stable in t he control group, whereas a drop from 7.37 to 7.02 took place in the p eritonitis group. In the test group, subcutaneous oxygen tension (PscO 2) 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 pH(i) and DO2 (r = 0.51 +/- 0.16); no st atistical difference was noted if pH(i) was correlated to gut DO2 (r = 0.56 +/- 0.18). There was a significantly better (P < 0.05) correlati on between PscO2 and DO2 (r = 0.67 +/- 0.08). (C) 1993 Wiley-Liss, Inc .