The effect of combined treatment with morphine sulphate and low-dose ketamine in a prehospital setting

BACKGROUND: Pain is a common condition among prehospital patients. The present study is designed to determine whether adding low-dose ketamine as additional analgesia improves the pain/nausea scores and hemodynamic parameters compared to morphine sulphate alone among patients with bone fractures. METHODS: Prospective, prehospital clinical cohort study. Twenty-seven patients were included with acute pain. Eleven patients received morphine sulphate 0.2 mg/kg (M-group) and 16 patients received morphine sulphate 0.1 mg/kg combined with 0.2 mg/kg ketamine (MK-group). Scores for pain, nausea, sedation (AVPU) and the haemodynamic parameters (systolic blood pressures (BP), heart rate (HR) and peripheral oxygen saturation (SpO2) were recorded at rescue scene before the start of analgesia and subsequently to admission at hospital. RESULTS: Mean treatment time 46 ± 17 minutes in the M-group and 56 ± 11 minutes in the MK-group, respectively (ns). Mean doses of morphine sulphate in the M-group were 13.5 ± 3.2 mg versus 7.0 ± 1.5 mg in the MK-group. The mean additional doses of ketamine in the MK-group were 27.9 ± 11.4 mg. There were significantly differences between the M- and the MK-group according to NRS scores for pain (5.4 ± 1.9 versus 3.1 ± 1.4) and BP (134 ± 21 mmHg versus 167 ± 32 mmHg) at admission at hospital, respectively (P < 0.05). All patients were Alert or respond to Voice and the results were similar between the groups. One patient versus 4 patients reported nausea in the M- and MK-group, respectively, and 3 patients vomited in the Mk-group (ns). CONCLUSION: We conclude that morphine sulphate with addition of small doses of ketamine provide adequate pain relief in patients with bone fractures, with an increase in systolic blood pressure, but without significant side effects.