Efficacy of Topical Treatments for Chrysaora chinensis Species: A Human Model in Comparison with an In Vitro Model.

OBJECTIVES: This study sought to create a model for testing topical treatment of jellyfish stings. It sought to determine which treatments 1) stimulate/inhibit nematocyst discharge; 2) decrease pain; and 3) decrease skin inflammation; it also sought to discover whether there is a clinical correlation between stimulated nematocyst discharge observed in vitro to the pain and erythema experienced by humans stung by a particular species of jellyfish, C chinensis. METHODS: Chrysaora chinensis stung 96 human subjects, who were then treated with isopropyl alcohol, hot water, acetic acid, papain meat tenderizer, lidocaine, or sodium bicarbonate. Pain and erythema were measured. In a separate experiment, nematocysts were examined microscopically after exposure to the same topical treatments used in the human experiment. RESULTS: Forearms treated with papain showed decreased mean pain over the first 30 minutes after being stung, relative to placebo, although only by a small amount. The other topical treatments tested did not reach statistical significance. Sodium bicarbonate may reduce erythema after 30 minutes of treatment; sodium bicarbonate and papain may reduce erythema at 60 minutes. The other topical treatments tested did not reach statistical significance. Nematocyst discharge in vitro occurred when tentacles of C chinensis were exposed to acetic acid or isopropyl alcohol. Sodium bicarbonate, papain, heated water, and lidocaine did not induce nematocyst discharge. CONCLUSIONS: Papain-containing meat tenderizer used as a topical treatment for C chinensis stings may decrease pain. Although there is published experimental support for the concept that in vitro nematocyst discharge correlates with in vivo human pain perception, no definitive randomized controlled trial, including ours, has yet provided incontrovertible evidence of this assertion. Despite this study's limitations, it presents a viable basis for future human studies looking at the efficacy of topical treatments for jellyfish stings.

A Chemical Heat Pack-Based Method For Consistent Heating of Intravenous Fluids.

BACKGROUND: Transfusion of cold intravenous fluids (IVF) can exacerbate hypothermia. Civilian and military guidelines recommend heated IVF for hypothermic patients; however, there is currently no ideal IVF heating system for use in resource-limited settings. OBJECTIVE: Development of a system that uses flameless ration heaters (FRH) and an insulated sleeve for the consistent delivery of IVF at physiologically appropriate temperatures (40°-42°C) over the range of ambient conditions typical of the prehospital and wilderness environments. METHODS: The temperatures of 0.9% normal saline (NS) 1-L bags were measured under 3 ambient conditions: 3°C, 10°C, and 20°C. The IVF was placed in an insulated pouch along with a predetermined number of activated FRH (5 FRH for 3°C, 4 FRH for 10°C, and 3 FRH for 20°C) for 10 minutes before removing the FRHs. The insulated IVF bag was drained through 280 cm of intravenous tubing at a flow rate of 77 mL/min. Raw temperature data for internal and delivery temperatures were collected and analyzed. RESULTS: The temperature of the IVF throughout the delivery of 1 L of NS under the 3 ambient conditions was as follows (mean ± SD): at 3°C ambient, 47° ± 2.1°C internal and 42.6°C ± 1.4°C at delivery; at 10°C ambient, 52.3° ± 2.7°C and 45.2° ± 1.6°C; and at 20°C ambient, 45.5° ± 1°C and 39.7° ± 0.7°C. CONCLUSIONS: The IVF heating system described here reliably delivered physiologically appropriate temperature intravenous fluids in 2 of the 3 ambient treatment conditions. With the appropriate number of FRH for the ambient conditions, this system enables the delivery of warmed IVF to provide active warming, which may be clinically beneficial in the prevention and treatment of hypothermia.

A review of emergency medical services events in US national parks from 2007 to 2011.

OBJECTIVE: Outdoor recreation is growing in the United States, with more than 279 million annual visitors to areas controlled by the National Park Service (NPS). Emergency medical needs in these parks are overseen by the National Park's rangers within the NPS Emergency Medical Services (EMS) system. This study examines medical and traumatic emergencies throughout the NPS over a 5-year period to better understand the types of events and fatalities rangers encounter, both regionally and on a national scale. METHODS: This is a retrospective review of the annual EMS reports published by the 7 NPS regions from 2007 to 2011. The following were compared and examined at a regional and national level: medical versus traumatic versus first aid events, cardiac events and outcomes, use of automated external defibrillators, and medical versus traumatic fatalities. RESULTS: The national incidence of EMS events was 45.9 events per 1 million visitors. Medical, traumatic, and first aid events composed 29%, 28%, and 43% of reports, respectively. Of medical episodes, 1.8% were cardiac arrests, of which 64.2% received automated external defibrillator treatment; 29.1% of cardiac arrests survived to hospital discharge. Of fatalities, 61.4% were traumatic in nature and the remaining 38.5% were nontraumatic (medical). Regional differences were found for all variables. CONCLUSIONS: On a national level, the NPS experiences an equal number of medical and traumatic EMS events. This differs from past observed trends that reported a higher incidence of traumatic events than medical events in wilderness settings. Cardiac events and automated external defibrillator usage are relatively infrequent. Traumatic fatalities are more common than medical fatalities in the NPS. Regional variations in events likely reflect differences in terrain, common activities, proximity to urban areas, and access to definitive care between regions. These data can assist the NPS in targeting the regions with the greatest number of incidents and fatalities for prevention, ranger training, and visitor education.