Intraoperative cerebral tissue oxygenization changes in liver transplant recipients

Introduction and Purpose: NIRS (Near-infrared spectroscopy) is a noninvasive method that shows the adequacy of perfusion in the brain locally. NIRS is advantageous in that it can be applied in all age groups, is portable, and can be used together with other imaging methods. It is known that large hemodynamic changes occurring between different phases of liver transplant surgery will have effects on cerebral blood flow. Cerebral autoregulation describes that cerebral blood flow remains relatively constant within a mean arterial pressure of about 60-150 mmHg, but some patients with liver disease do not have effective cerebral autoregulation. In laboratory studies and clinical studies, they have found that regional cerebral oxygen saturation, as measured by NIRS, is a clinical tool suitable for cerebral blood flow for monitoring autoregulation. The aim of this study is to study the effect of large hemodynamic changes in different phases of transplant surgery on cerebral oxygenation via NIRS and its correlation with hemodynamic parameters. Equipment and method: In this study, after the approval of the Ethics Committee, 60 patients aged between 18 and 65 years, who were planned for elective liver transplantation, were included in the study. In addition to routine monitoring, BIS, near-infrared spectroscopy (NIRS) and pleth variable index (PVI), perfusion index (PI), oxygen reserve index (ORI), SpHb monitoring were performed. Input data saved (Tinput). Anesthesia was induced with thiopental 5-8 mg/kg, fentanyl 1-2 µ/kg, lidocaine 1 mg/kg, vecuronium 0.1 mg/kg, post-induction data (Tind) and post-intubation data were recorded (Tent). After invasive artery monitoring, cardiac output, stroke volume, stroke volume variation and dpmax were monitored by pulse contour analysis method. After the operation started, measurements were repeated in the dissection, anhepatic and neohepatic phases (Tdis,Tanh,Tneo). Results: 50 patients were included in the study. There was no significant difference between HR entry value and HRInd, HRent and HRdis values. HR entry value was significantly lower than HR Hanh and HRneo values. OAB entry value was significantly higher than OABdis, OABanh and OABneo values. There was no significant difference between OABdis, OABanh and OABneo values. In the anhepatic period, compared to other periods; There was a significant decrease in CI, CPI, DpMax, DO2, SVI, PI values, and a significant increase in PPV, SPV, SVV and PVI values. Hourly mean noradrenaline use was higher in the anhepatic period. In the anhepatic period, there was a 14% decrease in rSO2 values compared to the entry and other phases (p<0.001), and this decrease was highly correlated with the PI value at the level of 0.01. A significant correlation of 0.05 was found between this decrease in rSO2 values observed in the anhepatic period and PVI, OAB, CPI and SpO2 values, but no significant correlation was found between PPV, SPV, SVI, SVV, HR, CI, DpMax, DO2 and SVRI values. Conclusion: In this study, in which we investigated the effects of hemodynamic changes in different phases of surgery on cerebral tissue oxygenation in liver transplant recipients, we found that although there was no significant difference in mean arterial pressures between phases, brain perfusion varied. In the anhepatic period, the rSO2 value decreased by 14%. This decrease was most correlated with the PI value among the parameters we followed. Keywords: NIRS, Liver Transplantation, Pulse Contour Analysis