A new route, jet-injection for anesthetic induction in children: I. Midazolam dose-range finding studies

In order to assure rapid anesthetic induction in children and to prevent the psychological and physical trauma associated with restraint during mask induction or intramuscular injection, we evaluated the utility of a jet-injector and the effectiveness of midazolam for anesthetic co-induction in a dose-range finding study. Forty children (age: 1-6 yrs), whose parents gave a valid consent approved by the Institutional Review Board (IRB) and who underwent minor surgery, were randomized into four equal groups: A. midazolam 100 micrograms/kg by jet-injection (JI); B. midazolam 150 micrograms/kg JI; C. midazolam 200 micrograms/kg JI; D. midazolam 80 micrograms/kg i.m by conventional syringe-needle. As a drying agent, atropine 20 micrograms/kg JI or i.m. was also added to the midazolam solution. The onset and full sedative effect of midazolam, the scoring of sedation and emotional state, the ease of placement of the intravenous catheter, the speed of recovery by Aldrete-scores and the time for safe discharge were evaluated. No demographic differences were observed among the four groups with similar mean duration of surgery and anesthesia. The mean sedation score was reduced in Group C the most, less in the B, A and D groups. The onset of sedation ranged from 3-5 min in groups A, B or C as compared to 5-9 min in D. Ideal conditions for the start of i.v. catheter were best achieved in group C (8:8) and B (8:10) in contrast to groups A (2:10) and D (0:10). Whereas no i.v. start was difficult in B and C, 6:10 were difficult in D and A. None of the children in the three JI groups (A, B and C) experienced unpleasant recall or pain from the injection during the whole procedure. Response to verbal stimuli recovered in 3 min after the end of anesthesia and the children were discharged 8-9 minutes afterward. None of the children needed a longer than 15-minute interval to reach an Aldrete score of 10. No differences among the groups were observed as to the time of recovery or discharge. This new route of midazolam administration with the jet-injector allows pain-free and stress-free induction of anaesthesia after rapid placement of an intravenous catheter and prevents the transmission of infections.