Intestinal tissue oxygenation and tumor necrosis factor-alpha release during systemic blood flow changes in pigs with left ventricular assist devices

We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) inc reased following a reduction in systemic blood now to 60% or less of the or iginal cardiac output using a left ventricular assist device (LVAD). The ai m of this study was to investigate the effect of reducing systemic brood fl ow on tissue oxygenation in the gastrointestinal tract (GIT) and the conseq uences of this on TNF-alpha release. LVADs were implanted in 9 pigs. The ao rta was clamped, and thus the LVAD flow represented the entire systemic blo od flow. Plasma TNF-alpha of the superior mesenteric vein was measured at b aseline and during systemic blood flow changes. Simultaneously, pH, lactate , oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction (O2ER) in the GIT were measured. The pH decreased and the lacta te level increased significantly (p < 0.05) at a systemic blood flow of 50% or less. The VO2I was positively correlated with DO2I. The O2ER increased significantly (p < 0.05) with reductions in systemic blood flow to 30% or l ess. There was a significant (p < 0.01) correlation between TNF-<alpha> and O2ER at levels higher than 55%. These data demonstrate that the GIT oxygen ation is inadequate with a reduction in systemic blood flow to 50% and that GIT oxygenation becomes critical at a reduction of 30%. During LVAD weanin g, careful attention must be given to the GIT. The pH and lactate may be go od markers of the adequacy of tissue oxygenation in the GIT.