The pharmacokinetics of propofol were studied in 12 healthy Chinese children, aged 4-12 yr, undergoing circumcision under inhalation anaesthesia. All patients received a single i.v. bolus dose of propofol 2.5 mg kg-1 and blood concentrations of propofol over the subsequent 24 h were measured using high pressure liquid chromatography with fluorimetric detection. Data were consistent with a three-compartment model with a mean (SEM) elimination half-life of 209 (29) min and total body clearance of 40.4 (3.6) ml min-1 kg-1. The mean (SEM) apparent volume of distribution at steady state was 5.0 (2.7) litre kg-1 and volume of the central compartment was 0.6 (0.1) litre kg-1. The mean (SEM) ratio of k12:k21 was 1.4 (0.2), suggesting that, after injection of a single bolus dose in children, propofol is distributed rapidly to the shallow compartment. The mean ratio of k31:k10 suggests that lipophilicity constrains return of the drug to the central compartment.

Sixty-four patients undergoing oesophageal surgery were randomly allocated to receive either a continuous lumbar epidural infusion of morphine or fentanyl, or, intramuscular morphine for postoperative analgesia. There was no statistical difference in analgesic requirements between the patients who underwent a thoracotomy for their procedure (n = 50) and those who did not (n = 14), as assessed by the total dose of opioid administered, visual analogue scale (VAS) and pain score (PS) comparison. However, by these criteria, epidural morphine infusion provided the most satisfactory analgesia (P < 0.05). Despite the variable quality of analgesia achieved with the three regimens, the postoperative lung function tests were similar for all groups, and we conclude that routine lung function tests are not an appropriate method of comparing analgesic efficacy. Prophylactic administration of loratadine to 15% of our patients was not shown to be effective in diminishing the incidence of pruritus.

We studied 30 children undergoing circumcision randomly allocated to receive either thiopentone 4 mg.kg-I , propofol2.5 mg.kg-I or midazolam 0.5 mg.kg-I (n=JO) IV over 30 seconds at induction of anaesthesia. Blood pressure and pulse rate during the first 15 minutes of induction were recorded by a Finapres 2300e and a Cardiocap CM-J04, and changes from preinduction baseline compared between the three induction agents and the two recording instruments. Postoperatively, blood levels of the induction agents were measured and recovery from anaesthesia was assessed by clinical criteria, mood and sedation scores and psychomotor performance. The Cardiocap data revealed no statistically significant haemodynamic differences between the three induction agents. Finapres data demonstrated that propofol caused a greater decrease in mean arterial pressure when compared to thiopentone at one minute (P=0.01) and the MAP remained significantly lower than midazolam at five minutes (P= 0.02), illustrating an advantage of continuous over intermittent non-invasive blood pressure monitoring. The midazolam group took longer to identify themselves compared to both the propofol (P= 0.005) and the thiopentone groups (P=0.02), but there was no difference in the groups in time to eye-opening. Psychomotor performance on awakening was significantly worse in the midazolam group compared to the propofol (P< 0.03) and thiopentone groups (P< 0.02). Most children had recovered to 80% of their best, practised, unmedicated, preoperative performance four hours after awakening, irrespective of the induction agent administered. Drug blood levels correlated weakly with both methods of psychomotor assessment (r ~ 0.6). Of the three induction agents, thiopentone caused the least haemodynamic perturbation on induction, and anaesthesia induced with midazolam caused the greatest psychomotor impairment on awakening. Within one hour patients in all drug groups were equally awake, co-operative and co-ordinated.