Influence of cyclic guanosine monophosphate changes on hemodynamics after reperfusion in liver transplantation

Orthotopic liver transplantation (OLT) is often associated with hemodynamic instability upon reperfusion, recognized as postreperfusion syndrome. Changes in vascular tone due to humoral factors released upon reperfusion of the graft have been suggested as a possible mechanism. In this study, we looked at the perioperative changes in cyclic guanosine monophosphate (cGMP), a mediator of vascular smooth muscle relaxation, and investigated its relationship with hemodynamic parameters. cGMP was measured in the plasma of 14 patients undergoing OLT by radioimmunoassay serially at the preanhepatic and anhepatic phases, and after reperfusion at 30, 60, and 120 min. Hemodynamic data recorded were systemic and pulmonary arterial pressures, cardiac output, and pulmonary and systemic vascular resistance. cGMP decreased markedly after reperfusion from a baseline level of 5.33+/-0.7 ng/ml to 1.63+/-0.5 ng/ml (P<0.01). Pulmonary arterial pressure increased from 17+/-1.21 mmHg to 23.5+/-1.9 mmHg (P<0.05), and pulmonary vascular resistance increased from 62.8 +/-12.9 dynes/sec/cm5 to 135+/-42.7 dynes/sec/cm5 (P<0.01). Changes in cardiac output and systemic vascular resistance were not significant. The changes in cGMP correlated with pulmonary arterial pressure (r=0.74, P=0.005) and pulmonary vascular resistance (r=0.7, P=0.01). These data confirm the occurrence of hemodynamic changes during OLT, and provide evidence to suggest that the reduction in cGMP after reperfusion may mediate the vascular changes.