Dexmedetomidine and ketamine sedation for muscle biopsies in patients with Duchenne muscular dystrophy.

Background: Duchenne muscular dystrophy (DMD) possesses many potential challenges for anesthetic care. Invasive and noninvasive procedures with corresponding sedation or general anesthesia are frequent and necessary for affected patients. There remains a need for a better agent or agents for procedural sedation in patients with comorbid diseases. This study prospectively evaluated a combination of ketamine with two different doses of dexmedetomidine for sedation during muscle biopsy in patients with DMD.

Methods: Dexmedetomidine 1.0 or 0.5 μg·kg(-1) was administered as a loading dose over 3 min followed by a continuous infusion of 1.0 or 0.5 μg·kg·h(-1). Ketamine (1 mg·kg(-1)) was administered along with the dexmedetomidine loading dose. As the procedure commenced, additional doses of ketamine (0.5 mg·kg(-1)) were administered as needed. Sedation scores, hemodynamic data, operative times, and recovery times were recorded.

Results: The study cohort included a total of 53 bicep, deltoid, or anterior tibialis muscle biopsies in 19 boys including 24 in the dexmedetomidine 1.0 μg·kg(-1) group and 29 in the dexmedetomidine 0.5 μg·kg(-1) group. Mean age and weight were 9.7 ± 1.4 years and 33.3 ± 7.7 kg in the dexmedetomidine 1.0 μg·kg(-1) group and 8.8 ± 1.8 years and 30.2 ± 10.8 kg in the dexmedetomidine 0.5 μg·kg(-1) group. No significant changes in blood pressure were noted. A decrease in heart rate (HR) occurred after the loading dose of dexmedetomidine in both groups. The HR was significantly lower in the dexmedetomidine 1.0 μg·kg(-1) group compared with the dexmedetomidine 0.5 μg·kg(-1) group. Total recovery time to discharge was significantly shorter in the dexmedetomidine 0.5 μg·kg(-1) group than the dexmedetomidine 1.0 μg·kg(-1) group (146 ± 65 vs 174 ± 58 min; P = 0.03), although the total ketamine dose was significantly greater in the dexmedetomidine 0.5 μg·kg(-1) group (3.7 ± 1.0 vs 2.0 ± 0.5 mg·kg(-1); P < 0.01). There were no episodes of apnea or hypoventilation; however, a jaw thrust was needed in one patient in the dexmedetomidine 1.0 μg·kg(-1) group.

Conclusion: The combination of dexmedetomidine and ketamine is safe and effective for moderately painful procedures with limited respiratory and cardiovascular effects in a high-risk patient population. Dexmedetomidine 0.5 μg·kg(-1) as a loading dose with ketamine followed by a continuous infusion of dexmedetomidine at 0.5 μg·kg(-1) ·h(-1) achieved an adequate sedation level with shorter total recovery times in the perioperative unit compared with a higher dose regimen of dexmedetomidine (1.0 μg·kg(-1) loading dose followed by an infusion at 1.0 μg·kg(-1) ·h(-1)).