Hot water immersion v icepacks for treating the pain of Chironex fleckeri stings: a randomised controlled trial

Objective: To investigate the effectiveness of hot water immersion for relieving the pain of major box jellyfish (Chironex fleckeri) stings. Design, interventions: Open label, randomised controlled trial comparing the effects of hot water immersion (45 degrees C) and icepacks. Setting, participants: 42 patients with suspected C. fleckeri stings treated in the emergency department of the Royal Darwin Hospital during September 2005 - October 2008. Main outcome measures: The primary outcome was pain severity, assessed with a visual analogue scale (VAS). Secondary outcomes included crossover to the alternative treatment, use of opioid analgesia, emergency department length of stay (LOS), and delayed urticaria. Results: Of 42 patients (26 males; median age, 19 years; IQR, 13-27 years), 25 were allocated to icepack treatment and 17 to hot water immersion. The demographic and baseline VAS data for the two groups were similar. After 30 minutes of treatment, 11 patients (65%) treated with hot water and 14 (56%) treated with icepacks had clinically improved pain scores (absolute difference, 9%; 95% CI, -22% to 39%; P = 0.75). One patient treated with icepacks crossed over to heat immersion. Two patients in each arm received intravenous opioid analgesia. Median emergency department LOS was 1.6 h (IQR, 1.0-1.8 h) for icepack patients and 2.1 h (IQR, 1.6-2.8 h) for heat immersion patients (P = 0.07). Five of seven patients who were followed up developed delayed urticaria. Conclusion: Hot water immersion was no more effective than icepacks for reducing the acute pain of box jellyfish stings, but increased emergency department LOS by about 30 minutes.