Oral Premedication for Pediatric Cardiac Surgery: A Comparison of Midazolam, Ketamine and Midazolam plus Ketamine

Background- Although midazolam and ketamine are widely administrated as oral premedications for children, only a few studies have investigated the cardiovascular, respiratory and sedative effects of these drugs in children with congenital heart disease (CHD). Methods- We compared three methods of administering midazolam and ketamine and a combination of these two drugs as an oral premedication in 165 children with CHD, ASA class II-III, aged 2-8 years, and candidates for cardiac surgery. In this prospective, randomized double-blinded study, we examined hemodynamics, respiratory rate, hemoglobin oxygen saturation, degree of sedation, adverse events such as nausea, vomiting, hallucinations and finally face-mask acceptance or IV line insertion reaction at induction time in three groups. Patients received midazolam 0.5 mg/kg, ketamine 6 mg/kg, or midazolam 0.25 mg/kg plus ketamine 3 mg/kg, 45 minutes before the induction of anesthesia. Results- Heart rate, respiratory rate and hemoglobin oxygen saturation were stable in all three groups. However, systolic and diastolic blood pressure were significantly higher in the ketamine group than those in the other two groups (p=0.001). Sedation score was gradually increased in all the groups, with maximum rate after 45 minutes. After 30 minutes, the midazolam+ketamine group had significantly higher sedation than the other groups (p=0.04). All patients in the three groups had satisfactory separation from their parents. At the time of induction, the cooperation score for face mask acceptance was 81 to 84% among the groups, with no significant differences. However, cooperation at IV line insertion time in the ketamine and the midazolam+ketamine groups (23%, 24%) was better than that in the midazolam group (12%, p=0.03).There were six episodes of emesis in the ketamine group and one episode of nausea in the midazolam+ketamine group. Conclusion- Midazolam and ketamine alone or as a mixed combination are safe oral premedicants in children with CHD undergoing cardiac surgery (Iranian Heart Journal 2007; 8 (4): 17-23).