ABSTRACT
The aim of this study was to assess hepatic function in elderly patients anaesthetized with sevoflurane - Nitrous oxide and to compare recovery and psychomotor performance after maintenance of anaesthesia with sevoflurane - nitrous oxide supplemented with remifentanil 80 patients. 70 to 90 yr old, were allocated randomaly to four groups, twenty patients each were allocated to maintenance of anaesthesia with sevoflurane only in concentration necessary to mentain adequate anaesthesia [Group I] with 1.5, 1.0, 0.5 MAC [end tidal] of sevoflurane supplemented with remifentanil. Measurement if cytosolic liver enzyme alpha glutathione S-transferase [alpha GST], the formation of the lidocaine metabolite monoethylglycinexylidide [MEGX] and gastric mucosal tonometery-derived variable as sensitive markers of hepatic function and splachnic perfusion. No significant changes in standard liver enzyme markers were seen throughout the study. Tonometric measurements showed a significant decrease from baseline in regional Pco[2]' regional to arterial difference in Pco[2] and intermucosal PH at 90 min after skin incision, alpha GST concentration increased significantly in group I. A return to base line values in tonometric values and alpha GST levels was seen 24 h postoperatively. MEGX formation did not charge significantly after surgery. The median dosage of ramifentanil required in the last three groups was 0.21, 0.25 and 0.34 mg/kg/min, respectively [P<0.05]. The median times to eye opening were 10.3, 12.7, 11.0 and 6.5 min in the four groups [P<0.05 between the 0.5 MAC and other groups] and for orientation 12.1, 14.9, 12.3 and 8.3 respectively [P<0.05 between 0.5 and 1.5 MAC groups]. There was no significant difference in the mini-mental state assessment scores on the actual discharge times from the recovery ward among the groups. Significantly greater numbers of patients could perform the critical thicker fusion test at 15 min in the group receving the lowest concentration of sevoflurane and the highest doses of remifentanil [p<0.05]. Patients in this group also showed the highest incidence of chest wall rigidity [P<0.003]. We conclude that, liver function in elderly patients is well preserved during sevoflurane anaesthesia, increased serum levels of alpha GST and changes of gastric tonometry-derived variables imply a reduction in splanchnic perfusion, leading to temporary impairment of hepatocyte oxygenation. Also the use of remifentanil with lower concentration of sevoflurane facilitate early recovery, it does not influence discharge time from recovery ward and may be associated with side effects as chest wall rigidity