The Supply of Oxygen to the Human Small Intestine in Mechanical Ileus

Abstract

Mechanical ileus results in an intraluminar increase in pressure proximal to the obstruction, with stretching of the intestinal wall. Aside from the role played by the intestinal contents and swallowed air, which are carried further from the proximal sections of the intestine, reasons for the intraluminar increase could be continuing secretion and the formation of gas from the fermentation of the congested intestinal contents [3]. The subsequent damage to the intestinal wall, which can lead to necrosis, and edema formation have been interpreted as the result of disturbed microcirculation and the hypoxia or anoxia caused by this disturbance. With the aid of the PO₂ surface electrode developed by Kessler and Lübbers [6], it is now possible to measure the local tissue PO₂ in the microvessels without causing any damage to the tissue. The surface of the organ must be smooth, the membrane must be < 20 µm thick, and the capillary blood supply must reach below the membrane. These conditions exist on the serous membrane side of the wall of the small intestine, since the visceral serous membrane has a thickness of approximately 10 µm and the musculature beneath it is supplied with capillaries (1). An animal experiments, we were able to prove that an increase in intraluminar pressure results in a pressure dependent reduction in the tissue PO₂ of the intestinal wall [5]. The objektive of our clinical investigation was to measure, in a prospective study, the tissue oxygen pressure in the obstructed human intestine in order to obtain information on the oxygen supply.