Analgesia for acute musculoskeletal trauma: low-dose subcutaneous infusion of ketamine.

Low-dose ketamine by subcutaneous infusion (0.1 mg/kg/h) was compared in double-blind fashion with intermittent morphine (0.1 mg/kg intravenously, four-hourly) as analgesic regimen in 40 ASA-I adults after acute musculoskeletal trauma. Pain was assessed using visual analogue scales and sedation was graded on a four point rank drowsiness score. Objective cardiovascular and respiratory parameters and patient acceptability in terms of supplementary analgesia and early mobilization were also recorded. Pain relief was better with the ketamine infusion than with intermittent morphine (P < 0.001). Patients were more awake and alert with ketamine infusion as evidenced by the drowsiness score (P < 0.001). Peak expiratory flow rate improved significantly with the ketamine infusion (P < 0.05). None of the patients in ketamine group required supplementary analgesia (P < 0.001) and the patients could be easily mobilized for traction/splintage as compared with patients in the control group (P < 0.001). The incidence of nausea and vomiting in the morphine group was high (P < 0.01). The study shows that subcutaneous infusion of ketamine provides safe and effective analgesia in acute musculoskeletal trauma.