Ultrasonographic Optic Nerve Sheath Diameter Is Correlated With Arterial Carbon Dioxide Concentration During Reperfusion in Liver Transplant Recipients

Background. Cerebral blood flow and intracranial pressure (ICP) has been known to be increased after graft reperfusion during liver transplantation, which was correlated with arterial carbon dioxide concentration (PaCO2). Ultrasonographic measurement of optic nerve sheath diameter (ONSD) is a simple and noninvasive method for evaluating ICP. We investigated the correlation between ONSD and the PaCO2 during reperfusion in liver transplant recipients. Methods. Twenty liver transplant recipients with end-stage liver disease were enrolled. We measured ONSD and PaCO2 at 6 time points: preinduction, preanhepatic phase, anhepatic phase, 5 minutes after reperfusion, 30 minutes after reperfusion, and neohepatic phase. Pearson correlation analysis and receiver operating characteristics (ROC) curve analysis were performed. Results. ONSD measured 5 minutes after reperfusion was significantly higher compared with the other time points. Differences in ONSD between the anhepatic phase and 5 minutes after reperfusion demonstrated significant correlations with both PaCO2 at the anhepatic phase and 5 minutes after reperfusion (both P < .001). On the ROC curve analysis, PaCO2 of 35 mm Hg at the anhepatic phase could be used to indicate >= 20% changes in ONSD after reperfusion. There were significant increases in ONSD after graft reperfusion in liver transplant recipients with PaCO2 >= 35 mm Hg at the anhepatic phase (P = .004). Conclusion. ONSD was increased just after reperfusion, which demonstrated good correlation with PaCO2 during reperfusion in liver transplant recipients. This finding suggests that the carbon dioxide can play a key role in increasing ONSD during hepatic graft reperfusion.