THE GASTROINTESTINAL-TRACT - AN UNDERESTIMATED ORGAN AS DEMONSTRATED IN AN EXPERIMENTAL LVAD PIG MODEL

Background. Although hemodynamic stability and renal function are impo rtant and are monitored closely in patients with implanted left ventri cular assist devices (LVAD), the gastrointestinal tract may be underes timated in the early postoperative period with regard to adequate perf usion. We investigated renal, intestinal, and whole body metabolic cha nges in response to variations in LVAD now and inspired oxygen concent ration (FiO(2)). Methods. Left ventricular assist devices were implant ed in 10 adult pigs (weight, 55 +/- 1.76 kg). Renal vein (RV), superio r mesenteric vein (SMV), and pulmonary artery (PA) blood oxygen satura tion and lactate concentration were measured and used as tissue perfus ion markers. These measurements were made at baseline and after change s in LVAD now or FiO(2). Results. Oxygen saturation in the PA, SMV, an d RV decreased significantly after a reduction in LVAD flow (p = 0.05) , with a greater reduction in the SMV than in the PA and RV (p < 0.05 at LVAD flow 3.5 L/min; p < 0.01 at LVAD flow 2.0 and 1.0 L/min). The lactate concentration in the PA and SMV increased significantly (p < 0 .01) with decreased flow, with a greater increase in the SMV than in t he PA (p < 0.05), whereas it remained unchanged in the RV. Oxygen satu ration in the PA, SMV, and RV decreased significantly after a reductio n in FiO(2) (p < 0.05). Lactate concentration in the PA, SMV, and RV i ncreased significantly at FiO(2) of 0.10 (p < 0.05). Lactate concentra tion in the PA and SMV was significantly higher than that in the RV at FiO(2) of 0.10 (p < 0.01). Conclusions. The results show that the gas trointestinal tract is at high risk during low perfusion or low FiO(2) , whereas the kidneys' metabolic function appears to be less disturbed . In clinical practice, this emphasizes the need to ensure adequate bl ood now and respiratory function, especially after extubation, in pati ents with implanted LVAD. This might avoid intestinal ischemia and sub sequent endotoxemia. Gastrointestinal tonometry may help in the assess ment of intestinal perfusion.