Continuous monitoring of mixed venous oxygen saturation during orthotopic liver transplantation.

Hemodynamic management is an important issue concerning anesthesia for orthotopic liver transplantation (OLT). Mixed venous oxygen saturation (SvO2) is considered a good index of tissue oxygenation, but controversy exists about the usefulness of monitoring this parameter in different types of surgery. Therefore, a prospective study was performed to determine changes in SvO2 during OLT and to study the correlation between SvO2 and hemodynamic measurements. Thirty patients undergoing transplantation for end-stage liver disease were divided into two groups: group 1 (n = 15, aged 42 +/- 11 years [mean +/- SD]) without venovenous bypass (VVB), and group 2 (n = 15, aged 43 +/- 10 years) with VVB. SvO2 was greater than 74% throughout the procedure and remained stable during dissection and the anhepatic phase. There was a significant increase in SvO2 after unclamping the portal vein in group 1, whereas a significant decrease was observed during the first hour following reperfusion in group 2. There was no correlation among SvO2 and oxygen consumption, arterial oxygen saturation, (SaO2), or hemoglobin concentrations. A statistically significant correlation was found between SvO2 and cardiac index in both groups (group 1: r = 0.58, P = 0.01; group 2: r = 0.51, P = 0.01), but the correlation was relatively poor. Continuous monitoring of SvO2 may be useful, but cannot substitute for intermittent determinations of other hemodynamic or oxygenation parameters.