Mesenteric Reperfusion Syndrome During Recovery from Severe Hypoxia with Extracorporeal Membrane Oxygenation (ECMO) Therapy. † 1011

Abstract

Patients being placed on ECMO have sustained a prolonged period of severe hypoxia. The effect of this pre-ECMO event on mesenteric blood flow has not been studied, thus making the question of enteral feedings while on ECMO controversial. The following study was undertaken to address these concerns. Newborn lambs, 1-7 days of age (n=4) were used for the study. After intubation and ventilation catheters were placed in the left ventricle (microsphere injection), right femoral artery (arterial blood gas sampling & microsphere withdrawal), femoral vein (IV fluid administration), and mesenteric vein (venous blood gas sampling). Blood flow was determined using the radiolabled microsphere (RLM) technique. In 3 animals, Doppler flow of the superior mesenteric artery was measured & resistive indices (RI) were calculated to determine the correlation between RI & RLM blood flow. Mesenteric oxygen delivery, consumption, and extraction were calculated. Studies were obtained at the following intervals: Baseline (1 hr stabilization); 1 hr of hypoxia (SaO2 ≤0.40); 30 & 60 minutes after recovery with ECMO to a normoxic state; 30 & 60 minutes after removal from ECMO to a normoxic ventilation state. Results: A significant negative correlation was noted between RI & RLM blood flow(p JI>LT. Mesenteric oxygen consumption was maintained constant throughout the study period. Of significance, was the marked increase in oxygen delivery after 30 & 60 minutes of ECMO, average 155% and 102% respectively, associated with a marked reduction in oxygen extraction at both 30 & 60 minutes of ECMO, -73% & -55%, respectively. This pattern persisted after removal from ECMO, with O.D., 90% above baseline & extraction, 35% below baseline at 60 minutes post ECMO. These findings indicate that a marked reperfusion phenomenon occurs in the gut during the recovery phase from hypoxia while on ECMO. It could be speculated that enteral feeding on ECMO should be delayed for a period of time. The duration of this reperfusion phenomenon in the gut is yet to be determined.