A study of the xenogeneic response in an isolated liver perfusion circuit--preliminary observations.

An isolated liver perfusion circuit was developed to study the xenogeneic reaction of human blood to porcine liver, and investigate the feasibility of using such a system for liver dialysis in fulminant hepatic failure. Three experimental groups were studied: a control group where pooled porcine blood was perfused through pig liver (n = 12), a xenogeneic group where banked human blood was perfused through porcine liver (n = 23), and a modified xenogeneic group where decomplemented human blood was perfused through porcine liver (n = 4). The following parameters of liver function were assessed: liver function tests, serum electrolytes, bile and ascites production. In addition, liver histology was assessed at the start and completion of each perfusion experiment. Control experiments established that the use of low perfusion pressures (mean inlet pressure of 29.5 +/- 7.4 mmHg), and low haematocrit of 20.5 +/- 8.9% (n = 14), enabled five hour perfusions to be consistently achieved with maintenance of normal acid base and electrolyte balance. Bile production over 5 hours was 18.8 +/- 8.0 ml in controls (n = 5) and 17.0 +/- 6.7 ml in the xenogeneic (human-pig) circuit (n = 11) (NS). Ascites production was 235.8 +/- 157.3 ml/hr in controls (n = 5) and 205 +/- 142.0 ml/hr in the xenogeneic circuit (n = 7) (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of protamine dose assay in reversal of heparin following extracorporeal circulation for open heart surgery.

The amount of protamine required for the neutralisation of heparin following cardiopulmonary bypass was determined by a Protamine Titration Assay using the principle of the dose--response curve and the patient's estimated blood volume. In 300 open heart surgery patients, infusion of the determined dose of protamine normalised the Activated Clotting Time (ACT) to baseline levels in 97% of these patients and produced adequate hemostasis. Our present study showed that the dose of protamine dropped to 75% of the dose calculated by conventional method of heparin to protamine ratio of 1:1. This had minimised the adverse effects of excessive protamine administration and optimised coagulation control after extracorporeal circulation.