The aim of this prospective, double-blind, randomized, placebo-controlled clinical trial was to investigate whether the administration of ketamine before induction with propofol improves its associated haemodynamic profile and laryngeal mask airway (LMA) insertion conditions. Ninety adult patients were randomly allocated to receive either ketamine 0.5 mg.kg-1 (n=30), fentanyl 1 µg.kg-1 (n=30) or normal saline (n=30), before induction of anaesthesia with propofol 2.5 mg.kg-1. Insertion of the LMA was performed 60 s after injection of propofol. Arterial blood pressure and heart rate were measured before induction (baseline), immediately after induction, immediately before LMA insertion, immediately after LMA insertion and every minute for three minutes after LMA insertion. Following LMA insertion, the following six subjective endpoints were graded by a blinded anaesthestist using ordinal scales graded 1 to 3: mouth opening, gagging, swallowing, movement, laryngospasm and ease of insertion. Systolic blood pressure was significantly higher following ketamine than either fentanyl (P=0.010) or saline (P=0.0001). The median (interquartile range) summed score describing the overall insertion conditions were similar in the ketamine [median 7.0, interquartile range (6.0-8.0)] and fentanyl groups [median 7.0, interquartile range (6.0-8.0)]. Both appeared significantly better than the saline group [median 8.0, interquartile range (6.75-9.25); P=0.024]. The incidence of prolonged apnoea (>120 s) was higher in the fentanyl group [23.1% (7/30)] compared with the ketamine [6.3% (2/30)] and saline groups [3.3% (1/30)]. We conclude that the addition of ketamine 0.5 mg.kg-1 improves haemodynamics when compared to fentanyl 1 µg.kg-1 , with less prolonged apnoea, and is associated with better LMA insertion conditions than placebo (saline).

Differences in sensitivity to anaesthetic drugs may exist among different ethnic groups. Allelic variants for drug metabolizing isoenzymes and pharmacokinetic differences may account for a variable response to some anaesthetic drugs. This study was designed to compare propofol consumption and recovery characteristics in four ethnic groups: Chinese, Malays, and Indians in Malaysia and Caucasians in Italy. Patients undergoing total intravenous anaesthesia with propofol and fentanyl were evaluated for propofol consumption and recovery time. The Bispectral Index (BIS) was used to maintain the same anaesthesia depth in all patients. The BIS value, the response to verbal stimuli and eye-opening time were used to assess recovery. After propofol discontinuation the BIS values returned to baseline in 11±4.2 min for Caucasians, in 12.5±5.1 min for Chinese, 15.9±6.3 min for Malays and 22.1±8.1 for Indians. Time to eye-opening was 11.63±4.2 min in Caucasians, 13.23±4.9 min in Chinese, 16.97±5.2 min in Malays and 22.3±6.6 min in Indians. The propofol consumption was significantly lower in Indians compared to the other three groups (P<0.01). The recovery of Indians was much slower compared to Chinese, Malays and Caucasians. The recovery time of Malays is significantly slower compared to Chinese and Caucasians. Differences in propofol consumption and recovery time were not significant between Chinese and Caucasians, but the ratio recovery time/propofol consumption was significantly lower in Caucasians compared to all the other groups.

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