HEMODYNAMIC-CHANGES ASSOCIATED WITH STRANGULATION OBSTRUCTION IN CATS

While changes in blood flow associated with simple intestinal obstruct ion have been studied extensively, little is known about blood flow ch anges associated with strangulation obstruction. Closed loop strangula tion was produced in anesthetized cats by means of a baby pressure gas ket. Intestinal blood flow was measured by transit time flowmetry. Blo od pressure was measured in a carotid artery and in veins of a closed loop of small intestine. The gasket pressure was increased stepwise in 10 mm Hg increments after which the intestinal venous pressure was ke pt constant at 50 mm Hg for 5 h. Increasing gasket pressure was follow ed by a corresponding increase in venous pressure in the closed bowel loop. Blood flow in the closed loop decreased with increasing venous p ressure and was closely related to the arteriovenous perfusion pressur e under stepwise increase of the gasket pressure and during prolonged periods with increased venous pressure. At constant elevated venous pr essure the intestinal blood flow was determined by the arterial pressu re. The vascular resistance in the closed loop increased exponentially with increasing venous pressure and especially at very low blood flow . In conclusion, we have found that strangulation obstruction is assoc iated with increased venous pressure in the closed loop which contribu tes to maintaining intestinal blood flow during the obstruction.