Radioxenon washout for evaluation of vasodilator therapy in mesenteric ischemia

Mesenteric ischemia follows a critical reduction in blood flow to the intestine. Absence of a practical diagnostic test results in delayed diagnosis and inability to evaluate changes in blood flow due to vasodilator therapy. We recorded the disappearance of radioxenon (133Xe) from ischemic bowel to quantitate the decreased perfusion and to assess changes in submucosal blood flow after intra-arterial papaverine. The ischemic colon, its only blood supply from collaterals, was formed into a Thirty-Vella loop. An infusion catheter placed at the origin of the superior mesenteric artery (SMA) was used to deliver saline or papaverine (0.1 mg./kg./min). Eleven control dogs received N.S. only. In nine dogs papaverine infusion was started immediately and in another 12 dogs two hours after the production of ischemia. Submucosal blood flow was determined by the per cent washout at two minutes of an 0.05 ml. injection of 133Xe dissolved in N.S., made into the submucosal space of the colostomy.