The Validity of Central Venous to Arterial Carbon Dioxide Difference to Predict Adequate Fluid Management during Living Donor Liver Transplantation: A Prospective Observational Study.

Abstract Background: Patients with End-stage liver disease undergoing orthotopic liver transplantation are prone to serious hemodynamic and metabolic derangements. The study aimed to assess the validity of central and pulmonary veno-arterial CO2 gradients to predict fluid responsiveness and to guide fluid management during liver transplantation. Methods: In adult recipients of liver transplantation, ASA III to IV, pulse pressure variations (PPV) guided intraoperative fluid management. PPV of ≥15% (Fluid Responding Status-FRS) indicated fluid resuscitation with 250 ml albumin 5% boluses repeated if required to correct PPV to <15% (Fluid non-Responding Status-FnRS). Samples from central venous and pulmonary artery catheters (PAC) were collected simultaneously to calculate both the central venous to arterial CO2 gap [C(v-a) CO2 gap] and the pulmonary venous to arterial CO2 gap [Pulm(p-a) CO2 gap]. Results: Primary outcome was the sensitivity of central venous CO2 gap to differentiate between fluid responding and non-responding states with 67 data points recorded (20 FRS and 47 FnRS). The discriminative ability of central and pulmonary CO2 gaps between the two statuses (FRS and FnRS) was poor with AUC of ROC of 0.698 and 0.570 respectively. The central CO2 gap was significantly higher in FRS than FnRS (P=0.016), with no difference in pulmonary CO2 gap between both statuses. The central and pulmonary CO2 gaps were weakly correlated to PPV [r=0.291, (P=0.017) and r=0.367, (P=0.002) respectively]. No correlation between both CO2 gaps and both CO and lactate could be seen. Conclusion: The Central and the Pulmonary CO2 gaps cannot be used as valid tools to predict fluid responsiveness and to guide fluid management during liver transplantation. CO2 gaps also do not correlate well with the changes in PPV or CO.