Changes in pulmonary gas exchange and intrapulmonary shunt during orthotopic liver transplantation with non-venovenous bypass

Objective To study the changes in pulmonary gas exchange and intrapulm onary shunt during orthotopic liver transplantation (OLT) with non venovenous bypass. Methods Nineteen American Society of Anesthesiologists (ASA) ⅢⅣ patients (male 17,female 2) with terminal liver diseases w ere enrolled for study. Their age ranged from 2567 years. Anesth esia was induce d with midazolam 0.05 mg/kg, propofol 0.51.0 mg/kg, fentanyl 4 μg/kg,with v ecuronium 0.1 mg/kg, and it was maintained with isoflurane inhalation, fent anyl and vecuronium. All patients were mechanically ventilated with 100% O_2 during operation. After induction of anesthesia, SwanGanz catheter was ins erted via r ight internal jugular vein. Cardiac output (CO), mixed venous oxygen saturat ion and core venous temperature were continuously monitored with continuous card iac output monitor, and electrocardiogram (ECG), central venous pressure (CVP) , pulmonary arterial wedge pressure (PAWP), pulse oxygen saturation (SpO_2) an d endtidal carbon dioxide tension (P_ ETCO_2) were also continu ously monit ored during operation. Radial artery was cannulated for continuous direct blood pressure mo nitoring. Arterial and mixed venous blood samples were taken after induction of anaesthesia,and partial pressure of oxygen(PaO_2), partial pressure of carbon dioxide (PaCO_2), and cardiac index(CI) were determined after induction of anaesthesia, 30 minutes before anhepatic stage ,30 minutes during anhepatic stage,30 minutes during neohepatic stage and at t he end of operation. Alveolararterial oxygen partial pressure di ffer ence (P_ AaO_2 ) and intrapulmonary shunt(Qs/Qt) were calcu lated according to the standar d formula. Results After induction of anaesthesia, when the inspired oxygen flow (FiO_2) was 1. 00, PaO_2 was only (385.0±56.4) mm Hg (1 mm Hg=0.133), P_ A aO_2 and Qs/Qt were all higher than normal values. There were no significant changes 30 minutes before anhepatic stage as compared with that after induc tion of anaesthesia. CO, CI and Qs/Qt were decreased significantly during an hepatic stage compared with that after induction of anaesthesia. PaO_2, PaCO_2, CO an d CI were increased and P_ AaO_2 d ecreased significantly,but there were no significant changes in Qs/Qt 30 minu tes during neohepatic stage. CI and CO increased and Qs/Qt decreased significa ntly at the end of operation, but there were no significant difference in PaO_2 , PaCO_2 and P_ AaO_2. Conclusion There are obvious changes in pulmonary gas exchange and intrapulmonary shunt during OLT with nonvenovenous bypass.