SummaryIn II study of144 children aged 1-12 years, astempts were made to ussess the ED,, und ED,, o Key wordsAnae.~thrtics. intruvetzous; propofol. Aniirsth~sia; paediatric.Propofol i n an emulsion formulation that contains soyabean oil and a puritied egg phosphatide has been available for clinical evaluation since July 1983. Pharmacokinetic studies o f propofol in adults have demonstrated its high plasma ~l e a r a n c e l -~ and short elimination half-life. which suggests its suitability for daycase anaesthesia. Clinical studies have confirmed rapid postoperative recovery and it appears to be superior to m e t h~h e x i t o n e~-~ in this respect. Thc dose required in adults to induce anaesthesia in 95% of hcalthy, unprcmcdicated paticnts is 2.5 mg/kg.' However, there are very few published studies on the usc of propofol as an induction agcnt in ~h i l d r e n .~ Thc aim of this study was to dctcrmine the cffcctive dose of propofol for induction in premedicated and unpremcdicatcd children. Opportunity was taken to make general observations of efficacy and side effects of thc drug in this respect. MethodForty-six children were used in a pilot study to determine the range of doses which would be appropriate for use in a formal study to detect ED,, and ED,, (the ED,, was taken as that dose which would abolish the eyelash reflex in 50% of the studied subjects). It also became clear from this study that an unacccptably high proportion of children experienced severe pain on injection. Thereforc lignocainc was mixed with the propofol for the formal study. The dose uscd was 2% lignocainc 0.5 ml added to propofol 20 ml, according to the rccommendations of Brooker and Redfern.g The prepared mixture was uscd within 25 minutes of preparation.Inrormed parental consent and approval from the District Ethics Committee was obtained Tor both the pilot and definitive studies. In the definitive study 144 mentally normal children in ASA grades 1 and 2 and betwccn 1 and I2 years of age, were evaluated. The study split them into two groups. Group A consisted of 72 children who were premedicatcd with trimcprazinc 3.0 ingjkg up to a maximum of 100 mg. They also received atropine 30 pgjkg orally 2 hours pre-operatively. Group B's 72 children received no premcdication. The majority were undergoing surgery as day cases. Both groups had EMLA cream applied over a vcin on the dorsum of one hand 2 hours before operation. Each child was allocated randomly to one of the six dose rangc groups on arrival in the anaesthetic room. These were 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 mgikg for the premedicated group A and 1.5. 2.0, 2.5, 3.0, 3.5 and 4.0 mgikg for the unpremedicated group B.The allocated dose was administered over approximately 20 seconds through a 25-gauge indwelling needle in the dorsum of the hand. Twenty seconds after the injection two reactions were assessed. Firstly, an attempt was made to elicit the eyelash reflex and if it was lost, the patient was considered a responder. If not, increments of propofol 5-10 mg were given. If no e...

SummaryThe ef'ective dose qj' thiopentone in 90% (ED,,) of unpremedicated children is 10.5 mglkg. This is significantly greater (p < 0.01) than in premedicated children. The ED,, in children premedicated with TDP ( a mixture of trimeprazine, droperidol and physeptone with atropine) is 4.2 mglkg which is significantly less (p < 0.05) than with trimeprazine and atropine (ED,, 5.2 mglkg) or papaveretum and hyoscine (EDpo 5.0 mglkg). Key wordsInduction; anaesthesia. Premedication.It has been known for some time that premedication affects the induction dose of thiopentone in There is little information on the effect of premedication on the dose requirement of thiopentone in children although recent work indicates that children require less thiopentone than adults for induction of anae~thesia.~ Beeby and Morgan Hughes4 have shown that the frequency of satisfactory behaviour in unpremedicated children is similar to that in published trials of sedative premedication, using the same method of assessment., It is becoming fashionable to encourage the presence of a parent in the anaesthetic room. Many anaesthetists now prefer to anaesthetise unpremedicated children accompanied by a parent particularly as more day case surgery is done. The aim of this study was to compare the effect of different premedicants on the dose requirement of thiopentone and to determine the ED,, and ED,, for thiopentone with and without premedication. MethodObservations were made on 490 mentally normal children aged 1-12 years in the American Society of Anesthesiologists Physical Status grades 1-2. Children with needle phobia were excluded. There were four groups for premedication: trimeprazine 3 mg/kg and atropine 0.03 mg/kg orally I f hours pre-operatively (group I); T D P (trimeprazine 6 mg, droperidol 0.6 mg and physeptone 0.32 mg per ml) 0.25 ml/kg arid atropine 0.03 mg/kg orally 1+ hours preBarbara B

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