[Experimental study on orthotopic liver transplantation using veno-venous bypass in the pig--the evaluation of hemodynamic alterations and the estimation of appropriate bypass flow during the period of the ahepatic state].

This is the study on the estimation of appropriate bypass flow during an hepatic phase and on hemodynamic changes in orthotopic liver transplantation. Sixty six pigs weighing 16 to 25 kg were used. Experiment I (the estimation of correct bypass flow); The relationship between bypass flow and hemodynamics was evaluated in six pigs. Bypass model without transplantation was made by following procedures. The pig liver was isolated from the blood circulation and the systemic and splanchnic venous flow was shunted to the external jugular vein via the centrifugal pump. Experiment II (the hemodynamic changes of orthotopic liver transplantation); Evaluation of hemodynamic alterations was carried out in thirty orthotopic liver transplantations. It was concluded as follows; 1. General hemodynamics such as mean arterial pressure, cardiac output, central venous pressure, pulmonary arterial pressure, etc. have not changed significantly under veno-venous bypass, however, portal and vena caval pressure elevated up to 142 and 122 percent respectively, even though the maximum bypass flow was gained. 2. Hemodynamic profile associated with the reduction of bypass flow was the same as that of acute hypovolemic shock. Immediately after the bypass was closed, mean arterial pressure and cardiac output fell down to 42 and 30% of prebypass level respectively. 3. The statistical correlationship was found between bypass flow and cardiac output (r = 0.8565). The expressions; R = (2.454 x X + 0.034)/(4.829 x X + 1.823), was induced through the correlationship between bypass flow (BF, 1/min), the maximum bypass flow (BFmax, 1/min), and cardiac output(CO, 1/min),(e.g. R = BF/CO, X = BF/BFmax). 4. Orthotopic liver transplantation was succeeded in 80% of 25 cases with stable hemodynamics. In conclusion, cardiac output . bypass flow ratio(R) was proved to be useful in orthotopic liver transplantation. A appropriate bypass flow was able to be estimated systematically using this expression.