Objective: Evaluation of haemodynamic and gas exchange modifications using propofolnitrous oxide anaesthesia after ketamine induction during experimental orthotopic liver transplantation (OLT).
Design: Measurements of haemodynamic and haemoximetric effects of two anaesthesiological conditions, differing each other for the different dose of propofol, performed in an experimental model characterized by temporary anhepatism followed by revascularization.
Setting: Surgical experimental laboratory of the University Hospital of Florence.
Animals: Thirty experimental OLT on female pigs (weight 30 +/- 2 kg) were performed.
Measurements and main results: The following haemodynamic: HR, MAP, MPAP, PCWP, CI, SI, RVSWI, LVSWI, SVR, PVR, RPP and gas-exchange parameters: PaCO2, etCO2, D(aA)CO2, PaO2/PAO2, VD/VTphys, HB, PaO2, SaO2, DO2, O2ER, VO2, SvO2, VO2/DO2 relationship were evaluated. Anaesthesia was induced by ketamine and maintained by N2O and propofol infusion using 0.28 mg x kg(-1)x min(-1) (Group 1) and 0.19mg x kg(-1) x min(-1) (Group 2). During the anhepatic phase we used cavalportal-jugular by-pass (CPJ). Haemodynamic preoperative data confirmed the absence of any myocardial depressant effect at the lower dose of propofol. During the most critical stages of surgery a progressive decrease of CI associated with low values of PCWP was observed. The decrease of etCO2 during the anhepatic phase is due to the VD/VT increase following CI reduction and CO2 production decrease. VO2 decreased significantly during the anhepatic phase and successively increased during the reperfusion phase whereas CI remained low, during both surgical phases. These results demonstrated that VO2 was largely independent from DO2 because cellular O2ER gradually increased as DO2 remained constantly low, thus indicating a good cellular metabolism reuptake. The decrease of SVO2 is related to the decrease of CI and to the increase of VO2 and O2ER.
Conclusion: The VO2/DO2 relationship showed a complete O2 supply-non-dependency suggesting an adequate cellular metabolism maintenance during the anhepatic and postanhepatic phases. According to these results, the authors suggest that propofol, within the two different anaesthesiological protocols at two different doses, surely favoured a good cellular perfusion also under low cardiac output conditions, undoubtedly contributing to the realization of stress-resistant conditions and influencing a good recovery and postoperative outcome.