Summary

A new method of administering Fluothane in closed circuit anaesthesia is presented. The Goldman’s drip feed is used to measure minute amounts of the drug accurately. In all, 809 cases were done. The simplicity and safety of the method are stressed, together with its economy.

Using amultiple gas phase equilibration technique, we determined the solubility of isoflurane in arterial blood at 37° C obtained from patients anaesthetized with isoflurane. Goodness of fit of individual sets of datato a predicted decline of isoflurane concentration in successive equilibrated gas phases and reproducibility of results indicate that the analytical technique was acceptably accurate. In blood samples taken from twenty-three patients undergoing minor surgical procedures, the blood/gas partition coefficient of isoflurane was 1.20 ± 0.08 (mean ± S.D.). Individual values were notdetectably related to absolute tension of isoflurane, preoperative haemoglobin concentration nor patient age. In samples taken from twenty neurosurgical patients, the blood/gas partition coefficient was slightly less, 1.14 ± 0.09 (p < 0.05), a difference we attribute to the effect of previously infused mannitol. In vitro, blood solubility of isoflurane was decreased by haemodilution with normal saline, mannitol 20 per cent or plasma, was increased by hypothermia(30° C) and was decreased by hyperthermia (40° C). We conclude that the solubility of isoflurane in human blood is approximately half that ofhalathane.

Summary

The Haloxair, a new anaesthetic apparatus usmg halothane m air or in au and oxygen, is described The apparatus is designed especially for emergency use or where portable, compact equipment is desirable A clinical trial of the unit is reported with observations on its special features

Summary

Urine excretion rates of norepinephrine were measured in 15 children with Tetralogy of Fallot and 25 with atrial septal secundum defects anaesthetized with halothane or morphine before, during and for two hours after surgical correction of their cardiac defects. All patients were paralyzed with d-tubocurarine, the tracheae were intubated and respiration was controlled. Urine was obtained for 90 minutes before induction, during induction, before, during and after bypass and post-operatively. Patients with TF had significantly higher pre-operative urine norepinephrine excretion rates than patients with ASD. In TF children anaesthetized with halothane norepinephrine excretion was significantly decreased during induction and during operation but increased post-operatively. Children with ASD and anaesthetized with halothane did not have urine norepinephrine excretion rates that were significantly different from pre-operative values until the postoperative period. ASD children anaesthetized with morphine had marked elevations in norepinephrine excretion during induction and all subsequent study periods. On the Other hand, morphine anaesthetized TF children did not have a significant increase in urine norepinephrine excretion until bypass had been established. Increased norepinephrine excretion was maintained in these patients during all subsequent study periods. These data, when combined with our results in patients with acquired heart disease, demonstrate that disease can alter norepinephrine responses to morphine anaesthesia. In addition our results suggest that dosage of morphine and morphine blood levels might also modify norepinephrine excretion.

Summary

At the Vancouver General Hospital the effectiveness of the system for decontamination of anaesthetic equipment was evaluated to determine the need for bacterial filters on anaesthetic machines.

Two groups of patients were studied. Group I consisted of 33 patients, none of whom had clinical symptoms of respiratory tract disease. Group II consisted of 17 patients who had lower respiratory tract secretions. In the latter group 16 had chronic bronchitis and one had cystic fibrosis.

Of 550 bacterial cultures taken from the anaesthetic equipment immediately before and after anaesthesia in our 50 patients, only five yielded a growth of non-pathogenic bacteria.

The results of this study indicate that bacterial colonization of anaesthetic equipment is of a low order and is adequately controlled by pasteurization even after use in patients with chronic lower respiratory tract disease. The use of bacterial filters does not appear justified if a strict regimen of cleaning and pasteurization is followed.

Summary

In conclusion, the data presented indicate that pregnant women of any age, during the course of any pregnancy or the early post-partum period have significant lower serum cholinesterase activity. With the currently available techniques we were able to demonstrate that this decline is not associated with any structural malformation of the enzyme molecule.

Alfentail, a new short-acting narcotic was clinically evaluated as an intravenous anaesthetic induction agent in 19 patients and compared to 20 patients receiving thiopentone, Alfentanil was superior to thiopentone in cardiovascular stability, both during induction of anaesthesia and tracheal intubation, However, alfentanil does not behave like a typical induction agent, time to unconsciousness is longer and more variable and is often accompanied by muscle rigidity. The results of this study suggest that alfentanil is more difficult to use as an induction agent than thiopentone, but alfentanil is recommended for short procedures when haemodynamic stability is important.

Summary

A scoring system has been devised to evaluate preoperative sedation in children. The system was tested in a double-blind trial comparing a placebo with diazepam (0.2 mg/kg), pentobarbitone (4 mg/kg) and pentobarbitone (2 mg/kg) in oral preparations. The total score (0–12) for each child was obtained by the addition of points acquired for subjective impressions and the changes in objective measurements of heart rate, blood pressure, and respiration when the children were given a standard stimulus. Scores of 0 to 5 indicated poor, 6 to 7 fair, and 8 to 12 good sedation. Of the drugs studied, pentobarbitone 4 mg/kg produced higher scores (mean 10.2) than the other groups, pentobarbitone 2 mg/kg and diazepam 0.2 mg/kg (mean scores 7.8) were superior to the placebo (mean score 6.2) but this difference was not significant in the numbers studied. This scoring system is thus capable of distinguishing between large and intermediate doses of sedative premedication and a placebo.