Objective: We have used the combination of midazolam, a short-acting benzodiazepine, and ketamine, a "dissociative anesthetic," to provide conscious sedation for invasive or lengthy procedures.
Methods: A total of 350 procedures (74 lumbar punctures, 97 bone marrow aspirations or biopsies, 84 radiotherapy sessions, and 95 imaging studies) were performed on 68 children, 4 months to 17 years of age, in both inpatient and ambulatory settings. All patients had an intravenous line in place and were monitored for heart rate and O2 saturation by pulse oximetry for the duration of the procedure and recovery time. Blood pressure was monitored periodically (every 5 to 30 minutes). Oxygen and suction equipment was available during the procedure. In addition to the individual performing the procedure, a second staff member trained in airway management (eg, physician, nurse practitioner, or registered nurse) was present to monitor vital signs and respiratory status. Patients were sedated initially with midazolam (0.05 to 0.1 mg/kg intravenously; maximum single dose of 2 mg, maximum total dose of 4 mg), followed by ketamine (1 to 2 mg/kg intravenously). During lengthy procedures, additional doses of ketamine (0.5 to 1 mg/kg) were given as necessary. Effectiveness of the sedation, recovery time, and adverse events associated with the sedative regimen were documented.
Results: All patients were effectively sedated with this regimen. Four patients experienced transient decrease in O2 saturation (<85%) requiring temporary interruption of the procedure and oxygen by blow-by; the procedure was subsequently completed without incident in each case. Two patients experienced significant agitation during recovery from sedation. This side effect resolved spontaneously after 5 to 10 minutes in one patient and was effectively treated with diphenhydramine hydrochloride in the other. Twenty-four lumbar punctures were associated with transient decrease in O2 saturation (88% to 92%), which improved by relief of neck flexion and/or blow-by oxygen. No hypotension, bradycardia, or respiratory depression requiring respiratory support or reversal of sedation was noted. Anesthesia recovery time ranged from <15 minutes to 120 minutes with >70% of patients recovering within 30 minutes. Most patients demonstrated an increase in oral secretions requiring occasional suctioning. Transient sleep disturbances were reported in only two patients.
Conclusions: This sedative regimen of intravenous midazolam and ketamine was found to be safe and effective. Its use has greatly reduced patient and parent anxiety for diagnostic and therapeutic procedures.