A randomised controlled trial of hot water (45°C) immersion versus ice packs for pain relief in bluebottle stings

Abstract

Objective: To investigate the effectiveness of hot water immersion for the treatment of Physalia sp. (bluebottle or Portuguese Man‐of‐War) stings. Design: Open‐label, randomised comparison trial. Primary analysis was by intention to treat, with secondary analysis of nematocyst‐confirmed stings. One halfway interim analysis was planned. Setting: Surf lifesaving first aid facilities at two beaches in eastern Australia from 30 December 2003 to 5 March 2005. Participants: 96 subjects presenting after swimming in the ocean for treatment of an apparent sting by a bluebottle. Interventions: Hot water immersion (45°C) of the affected part versus ice pack application. Main outcome measures: The primary outcome was a clinically important reduction in pain as measured by the visual analogue scale (VAS). Secondary outcomes were the development of regional or radiating pain, frequency of systemic symptoms, and proportion with pruritus or rash on follow‐up. Results: 49 patients received hot water immersion and 47 received ice packs. The two groups had similar baseline features, except patients treated with hot water had more severe initial pain (VAS [mean ± SD]: 54 ± 22 mm versus 42 ± 22 mm). After 10 minutes, 53% of the hot water group reported less pain versus 32% treated with ice (21%; 95% CI, 1%–39%; P = 0.039). After 20 minutes, 87% of the hot water group reported less pain versus 33% treated with ice (54%; 95% CI, 35%–69%; P = 0.002). The trial was stopped after the halfway interim analysis because hot water immersion was shown to be effective (P = 0.002). Hot water was more effective at 20 minutes in nematocyst‐confirmed stings (95% versus 29%; P = 0.002). Radiating pain occurred less with hot water (10% versus 30%; P = 0.039). Systemic effects were uncommon in both groups. Conclusions: Immersion in water at 45°C for 20 minutes is an effective and practical treatment for pain from bluebottle stings.

Assessing the Efficacy of First-Aid Measures in Physalia sp. Envenomation, Using Solution- and Blood Agarose-Based Models

“…Lastly, these results bolster previous studies that support the use of heat in the treatment of Physalia stings [34,35], as the application of heat significantly reduced hemolysis in the TBAA (Figure 3A, red line versus black line). The application of cold not only failed to reduce hemolysis, it worsened stings (Figure 3, blue lines).…”

Heated Debates: Hot-Water Immersion or Ice Packs as First Aid for Cnidarian Envenomations?

“…Loten et al [7] compared the pain reported from 96 sting victims which were randomized to receive either hot-water immersion (49 subjects) or ice packs (47 subjects). A significantly larger percentage of the hot-water group reported less pain at 10 and 20 min of treatment (53% and 87%, respectively).…”

Cubozoan Sting-Site Seawater Rinse, Scraping, and Ice Can Increase Venom Load: Upending Current First Aid Recommendations

“…Sting severity varies based on several factors, the most important of which are the species involved and the dose of venom delivered [8,9]. Studies have shown that the outcomes also vary based on first-aid and clinical-care measures [10,11,12,13]. The activity of venom, which is already deposited into the tissue of the victim at the sting site, can be markedly reduced by using venom-inhibiting treatments, such as hot-water immersion [10,11,14,15] and dermal-permeating inhibitors [15].…”