Comparison of analgesic/sedative effect of racemic ketamine and S(+)-ketamine during cardiac catheterization in newborns and children

The hypnotic and analgesic effect of ketamine with maintained spontaneous breathing is used for analgesic/sedative anesthesia without the need of intubation. The intention of this study was to compare the efficacy and side effects of racemic ketamine and its enantiomer S(+)-ketamine during cardiac catheterization in newborns and children. One hundred children (ages 0-11 years) were randomly assigned to groups of equal size. The differences between the racemic ketamine/midazolam and the S(+)-ketamine/midazolam groups were investigated regarding the total dosage of sedative drugs, side effects, and the awakening period. The dosage of S(+)-ketamine (2.28 mg/kg/h) was significantly lower than that needed for racemic ketamine (3.12 mg/kg/h) (p = 0.037) with an analgesic/sedative potency ratio of 1.4:1. Balloon dilatation required significantly higher dosages in both groups (p = 0.043). Significantly more patients were excluded because of ineffective analgesia/sedation or severe side effects in the racemic ketamine group. The awakening period did not show significant differences between the two groups. S(+)-ketamine proved to be a more efficient analgesic/sedative drug in newborns and children. It was shown to be useful in diagnostic and interventional procedures and allows spontaneous breathing. Moderate side effects occurred in both groups; severe side effects seemed to occur more often with the racemic solution.