Pilot study of continuous co-infusion of morphine and naloxone in children with sickle cell pain crisis.

Patients with sickle cell disease experience painful crises that often require hospitalization for a continuous infusion of morphine that may cause significant pruritus. We conducted a pilot study to determine the feasibility of simultaneous continuous co-infusion of naloxone with morphine, test novel assessment instruments for pruritus, and explore whether pruritus could be reduced while maintaining effective analgesia. Patients with sickle cell disease and painful crisis requiring continuous infusion morphine received continuous co-infusion of naloxone at 0.25 (low dose) or 1.0 mcg/kg x hr (high dose). Pain scores were obtained using the FACES scale and a 100-mm visual analog scale (VAS). Itching was quantified by a modified VAS score. Evaluable data were obtained on 16 patients. Simultaneous co-infusion of naloxone and morphine was feasible, did not seem to reduce the analgesic efficacy of morphine, and was associated with no adverse effects. The high dose group reported a lower median "VAS worst itch" score than the low dose group (4.8 vs. 7.3, P = 0.08). Simultaneous continuous infusion of naloxone with morphine in pediatric patients with sickle cell disease and pain crisis was feasible and well tolerated. A quantitative pruritus score allowed us to systematically measure pruritus. Further evaluation by randomized, placebo-controlled study of 1 mcg/kg x hr naloxone in this setting is required.