Indicators for global tissue perfusion in patients undergoing orthotopic liver transplantation: A pilot study

Background
Patients undergoing orthotopic liver transplantation are subjected to severe hemodynamic and metabolic derangements, close monitoring are always required. Mixed venous oxygen saturation (SVO) is often used to reflect supply/demand ration for oxygen in critically ill patients. Cardiac output (CO) and serum lactate levels are also sensitive markers for detecting early hemodynamic and metabolic changes. Patients with end-stage liver disease, possess hemodynamic and metabolic derangements that can render such tools insensitive. In the current trial we evaluated SVO, CO and serum lactate and since SVO can sometimes be misleading especially in hyperdynamic status we assessed oxygen delivery (DO) and oxygen consumption (VO).
Patients and methods
Twenty patients with end-stage liver disease scheduled for live related liver transplantation were enrolled, CO, SVO, serum lactate levels, VO and DO were recorded during the following times; dissection phase (T1), an-hepatic phase (T2) and neo-hepatic phase (T3).
Results
All recorded parameters were comparable among the three phases of liver transplantation except for serum lactate levels that had increased significantly during T2 (7.10 ± 3.5 mmol/l,  = 0.04) and T3 (9.42 ± 4.65 mmol/l,  = 0.001) compared T1 (3.28 ± 2.7 mmol/l), however serum lactate levels and T2 and T3 were comparable. There was no evidence of any correlation among CO, SVO, serum lactate levels, VO and DO.
Conclusion
Increase in serum lactate in this patient population is not necessarily due to increased production as a consequence of tissue hypoperfusion but rather may reflect improper lactate utilization since indicators of global tissue perfusion acted independently.