Serum vasopressin concentrations during orthotopic liver transplantation

We report measurements of the temporal response of serum vasopressin concentrations in the period after reperfusion of the liver graft during orthotopic liver transplantation (OLT).

Vasopressin concentrations were determined in 11 adult patients undergoing OLT by radioimmunoassay of samples collected after induction, at 5 minutes prior to reperfusion, and at 10, 20, 30, 40, 50, 60, 90, and 120 minutes after reperfusion.

Pre-incision vasopressin concentrations ranged from <0.5 to 2.6 pg/mL (reference serum vasopressin, <1.7 pg/mL). Overall, levels increased before reperfusion, but fell thereafter. Individual patients manifested elevated levels during the period after reperfusion. Values immediately before reperfusion exhibited most variability, ranging from 0.8 to 40 pg/mL (median, 15; interquartile range [IQR], 4-29) Median vasopressin concentrations 10 minutes postreperfusion were 7.6 pg/mL (IQR, 3-27). Only 3 of the 11 patients failed to generate vasopressin levels >20 pg/mL. In each of these patients, hemodynamics were satisfactory without the need for additional pressor infusion. Maximum vasopressin concentration measured in any patient was 85 pg/mL. There was no correlation between vasopressin concentration and mean blood pressure or systemic vascular resistance index.

Vasopressin concentrations during OLT vary widely and are elevated periodically during the anhepatic and postreperfusion stages, with no apparent relationship between vasopressin concentrations and blood pressure. Although vasopressin concentrations were not as high as those measured during some other clinical situations, these data suggest that a relative vasopressin deficiency is not a direct cause of hypotension during OLT.