Ketamine and midazolam is an inappropriate preinduction combination in uncooperative children undergoing brief ambulatory procedures

Background: We prospectively studied the effects of intramuscular (i.m.) ketamine alone, or combined with midazolam, on mask acceptance and recovery in young children who were uncooperative during induction of anaesthesia. Methods: The Institutional Review Board (IRB) approval was obtained to study 80 children, 1-3 years, scheduled for bilateral myringotomies and tube insertion (BMT). Mask induction was attempted in all the children. Those who were uncooperative were randomly assigned to one of the four preinduction treatment groups: group I, ketamine 2 mg.kg(-1) ; group II, ketamine 2 mg.kg(-1) combined with midazolam 0.1 mg.kg(-1) ; group III, ketamine 2 mg.kg(-1) with midazolam 0.2 mg.kg(-1) ; or group IV, ketamine 1 mg.kg(-1) with midazolam 0.2 mg.kg(-1) . Anaesthesia was continued with nitrous oxide and halothane by facemask. Results: Children in all treatment groups achieved satisfactory sedation in less than 3 min following the administration of the preinduction drug(s). Compared with patients who received halothane induction (comparison group), the use of ketamine alone did not significantly (P > 0.0167, a Bonferroni corrected significance level) delay recovery and discharge times (18.8 +/- 2.5 and 82.5 +/- 30.7 min vs 12.6 +/- 4.6 and 81.0 +/- 33.8 min, P = 0.030 and P = 0.941, respectively). Patients who received ketamine/midazolam combinations, however, had significantly longer recovery and discharge times vs halothane (32.3 +/- 14.0 and 128.0 +/- 36.6 min, P = 0.001, P = 0.007, respectively). These times were so clinically unacceptable, that the study had to be terminated with only 17 patients receiving study drugs. Conclusions: It is concluded that ketamine/midazolam combination is not appropriate for preinduction of anaesthesia in paediatric ambulatory patients because of unacceptably prolonged recovery and delayed discharge times.