Discrepancy Between Pulmonary Artery Catheter and Co-Oximeter Value of Mixed Venous Oxygen Saturation After Graft Reperfusion During Living Donor Liver Transplantation.

Background: Monitoring tissue oxygenation is critical in liver recipients. The pulmonary artery catheter (PAC) provides continuous monitoring of mixed venous oxygen saturation (SvO₂) using fiberoptic reflectance spectrophotometry. Despite the need for in vivo calibration during liver transplantation, recalibration guidelines are absent, and we frequently observed a significant discrepancy between PAC and reference co-oximeter SvO₂ values after graft reperfusion. This study aimed to assess the incidence and risk factors of a significant discrepancy after reperfusion during living donor liver transplantation.

Methods: This retrospective study included 54 recipients who underwent living donor liver transplantation at our institution between October 2021 and April 2022. A PAC was inserted, and in vivo calibration was conducted using the co-oximeter SvO₂ value. We defined a significant discrepancy as a drift was ≥ 3% at 1 hour after reperfusion. Logistic regression analysis was performed to determine the association between perioperative variables and the risk of significant discrepancy.

Results: PAC SvO₂ was higher than co-oximeter SvO₂ in 51 recipients. A significant discrepancy was observed in 37 recipients (68.5%). The risk of significant discrepancy decreased with a high preoperative hemoglobin concentration (odds ratio [OR] = 0.65 [0.47-0.91], P = .011) and a high arterial oxygen partial pressure (PaO₂) at 1 hour after reperfusion (OR = 0.96 [0.94-0.99], P = .004) but increased with a high baseline co-oximeter SvO₂ value (OR = 1.29 [1.05-1.59], P = .015).

Conclusions: PAC SvO₂ significantly drifted from the reference co-oximeter value in over two-thirds of recipients after reperfusion. Therefore, in vivo recalibration is required for the reliable measurement of PAC SvO₂ during living donor liver transplantation.