ICU admissions from an obstetrical hospital.

To ascertain the anaesthetic complications requiring post-anaesthetic respiratory support in a large obstetrical hospital, the hospital records of obstetrical patients admitted to an adjacent general intensive care unit (ICU) were studied. Obstetrical patients who required mechanical ventilation following anaesthetic complications were identified and their hospital records reviewed. In a ten-year period there were 61,435 women delivered at the Mater Mothers Hospital (MMH) in Brisbane, Queensland, Australia. Of these 24,161 had an anaesthetic associated with delivery including 7,452 general anaesthetics (GAs) and 16,709 regional anaesthetics (RAs). There were also 3,708 GAs and 17 RAs for procedures other than delivery. During this period there were 126 obstetrical admissions to the ICU. Sixteen were due to anaesthetic complications, twelve followed GA and four followed RA. Complications included anaphylaxis, high block and failure of tracheal intubation. The incidence of a major complication of a GA causing admission to the ICU was 1 in 932 and for RA was 1 in 4177 when these were given for delivery (P less than 0.01). If a complication requiring ICU admission and mechanical ventilation is used as the criterion of safety it appears that RA is safer than a GA for delivery.

Pharmacokinetics of alcuronium in elderly patients undergoing total hip replacement or aortic reconstructive surgery.

The pharmacokinetic behaviour of alcuronium was studied in three patients undergoing resection of an aortic aneurysm, and in another two patients undergoing total hip replacement (group I). A control group of five elderly patients undergoing relatively minor surgery was included (group II). In group I patients, the values of the pharmacokinetic parameters such as plasma clearance, elimination half-life and the apparent volume of distribution of the drug were found to be comparable to those obtained in normal young patients in previous studies. The group II patients, however, were found to have a prolonged elimination half-life as a result of reduced plasma clearance, possibly an age-related effect. The differences between these two groups of patients may be explained by the differences in the extent of haemorrhage and fluid replacement or changes in blood circulation, or both. However, alcuronium must still be used cautiously in both groups of patients, especially in the light of a recent finding that patients undergoing aortic reconstructive surgery have a high frequency of functional renal failure after operation.

Apple II program to simulate the response-time profile of non-depolarising muscle relaxants.

We have developed a BASIC program for the Apple II microcomputer which can simulate the effect (degree of paralysis) time curve obtained following bolus intravenous administrations of pancuronium. The program is based on a combined pharmacokinetic/pharmacodynamic model and has practical application to the anaesthetist under operating room conditions. Knowing the disease state of the patient and the doses and times of administration of pancuronium the microcomputer can predict the degree of paralysis which exists at any time and so assists in the timing of the next dose of relaxant and in deciding when to effect reversal.

Caesarean section and placental transfer of alcuronium.

The placental transfer of alcuronium was studied in twelve patients undergoing elective or emergency caesarean section. Umbilical cord vein and maternal plasma was analysed for alcuronium at dose-delivery time intervals ranging from 5 to 10.5 minutes. The mean umbilical vein concentration of the relaxant was 0.41 +/- 0.18 (SD) microgram/ml, and the mean foetal/maternal concentration ratio was 0.26 +/- 0.11. A positive correlation between foetal and maternal concentrations of alcuronium was demonstrated. Although alcuronium appears to cross the placenta rapidly and in reasonably high concentration, no apparent adverse effects on the neonates was evident as judged by measurement of Apgar scores.