CHANGES IN OXYGEN SATURATION DURING INHALATION INDUCTION OF ANAESTHESIA IN CHILDREN

Changes in oxygen saturation (Sa_O2) were studied during inductionof anaesthesia in 48 healthy children receiving halothane orisoflurane for outpatient dental extractions. Substantial reductionsin Sa_O2 occurred in more than 50% of the children given isofluraneand were associated with the irritant effects of this agenton the airway. Sa_O2 was largely unaltered during the use ofhalothane. These findings indicate that the airway complicationscaused by isoflurane may be associated with decreases in Sa_O2.     

Effect of xylazine and ketamine on the pharmacokinetics of alfentanil during halothane anaesthesia

We measured plasma concentrations of alfentanil in two horsesafter three different randomly ordered treatments. Each horsereceived halothane in oxygen by mask followed by a bolus doseof alfentanil 60 µg kg^–1 i. v., halothane in oxygenby mask followed by an i.v. alfentanil infusion for 120 minand xylazine and ketamine followed by halothane and a bolusdose of alfentanil 60 µg kg^–1 i.v. Halothane wasmaintained at 1.05–1.07% end-tidal concentration witha Pa_co2 of 6–7.3 kPa. The plasma concentration-time curveswere similar after bolus and infusion doses of alfentanil withhalothane and could be fitted to a two-compartment open model.A plateau was noted in the plasma concentration-time curve inthe presence of xylazine-ketamine which could not be modelledadequately, but suggested a three-compartment open model withan additional input component. (Br. J. Anaesth. 1994; 72: 345–347)