ANALYSIS OF NUTRIENT HEPATIC BLOOD-FLOW AFTER 8-MM VERSUS 16-MM PORTACAVAL H-GRAFTS IN A PROSPECTIVE RANDOMIZED TRIAL

BACKGROUND: In previous unrandomized studies, we demonstrated that pat ients undergoing 8-mm diameter portacaval H-grafts with collateral abl ation (partial shunts) have lower rates of portasystemic encephalopath y (PSE) postoperatively than patients undergoing total portacaval shun ts. We postulated that nutrient hepatic blood flow was greater after p artial shunts because 8-mm grafts preserved some portal flow. METHODS: To test this hypothesis, we analyzed hepatic hemodynamics in 18 of 30 randomized patients who consented to be studied after complete operat ive recovery, grouped according to shunt size. We measured nutrient he patic blood flow using 99m-Tc-Mebrofenin tracer elimination kinetics, and fractionated it into its portal venous and hepatic arterial compon ents. PSE was assessed by blinded observers. Stepwise logistic regress ion was used to select the variable that best predicted encephalopathy . From 1989 to 1993, we conducted a randomized, prospective trial of p artial (8 mm) versus total (16 mm) portacaval H-grafts. Group differen ces were compared using one-way analysis of variance (ANOVA). RESULTS: Hepatic encephalopathy occurred in 2 of 10 patients with partial shun ts versus 5 of 8 patients with total shunts. Nutrient hepatic blood fl ow Tvas significantly higher for partial shunts compared with total sh unts (403 +/- 601 versus 243 +/- 17 mL/min). Three variables-nutrient hepatic blood flow, portal blood flow, and hepatic arterial flow-were analyzed by stepwise logistic regression. Nutrient hepatic blood flow was selected as the best predictor of hepatic encephalopathy. In this series, PSE did not occur in any patient with more than 325 mL/min of nutrient hepatic blood flow. CONCLUSION: These findings provide a phys iologic basis for clinical observations demonstrating a lower incidenc e of PSE with partial shunts and indicates the superiority of partial over total shunts. Partial shunts, by preserving portal flow, maintain higher nutrient hepatic blood flow than total shunts and thus minimiz e PSE rates.