Use of essential oil to promote induction of anaesthesia in children (1998)

With the approval of Research Ethics Committee, we investigated the effect of essential oil of sweet orange on induction and recovery characteristics in a randomised blind trial of 120 unpremedicated children, ASA 1 or 2, of both sexes, aged between 5 and 14 years undergoing dental extraction under sevoflurane anaesthesia. Children were randomly allocated to one of two treatment groups of 60 patients: group 1, sevoflurane gaseous induction in 50% oxygen and nitrous oxide; group 2, sevoflurane gaseous induction in 50% oxygen and nitrous oxide with essential oil of sweet orange. A breathing filter (Intersurgical mini filter) was interposed between the breathing system and anaesthetic mask. In children belonging to group 2 the filter was impregnated with four drops of essential oil. The filter was removed soon after the child was asleep. A standard anaesthetic technique was used. Anaesthesia was induced via a face mask using the Humphrey ADE system and a Penlon calibrated vaporiser. After having two breaths of the gas mixture and 1% sevoflurane, the child was asked to rate the odour of the anaesthetic vapour which was graded as pleasant or nice; acceptable or all right; unpleasant or not nice; and horrid. The sevoflurane concentration was then increased rapidly in a stepwise fashion up to 8%. The quality of induction was assessed by the anaesthetist as good, adequate or poor depending on the resistance offered by the child on applying the face mask. Once the desired level of anaesthesia was achieved, the face mask was moved on to the nose and anaesthesia maintained with inhalation of 4% sevoflurane. A mouth gag was introduced and a throat pack inserted by the dentist before extractions were carried out. Induction time, duration of anaesthesia and emergence time were noted. The incidence of complications during induction and recovery, such as cough, breath holding, shivering, restlessness, nausea and vomiting, were recorded. Before discharge from the recovery room the children were asked to grade the acceptability of induction of anaesthesia and whether they would like to have similar techniques used again in future. We found that children were more relaxed and co-operative during induction in Group 2. The pleasant odour of the essential oil facilitated smooth induction of anaesthesia in 85% of children. Patient's grading of the odour of the anaesthetic vapour was significantly more favourable in the essential oil group (72% vs. 23%, p < 0.05) and so was acceptability of induction of children (p < 0.05). There were no significant differences between the groups regarding induction time, duration of anaesthesia and incidence of complications during induction and recovery. Although the mean emergence time was found to be significantly greater in the essential oil group (2.85 vs. 2.40 min), it was difficult to rule out breathing of air through mouth during maintenance of anaesthesia. This also explains the short emergence time in both groups than found by other workers (4.3 min or longer) [1, 2]. Children in the essential oil group were significantly more likely to say that they would like to have similar anaesthetic technique again in future (82% vs. 55%, p < 0.05). We conclude that use of essential oil offers several advantages during induction of anaesthesia with sevoflurane in children. We find it safe and recommend its use more widely.