Wilderness Medicine Podcast · Wilderness Medical Society

#29: Solar Water Disinfection, Hypothermia, Mountain Rescue, and Marine Medicine

March 15, 2023·1 hr 20 min·5 clips

A 20-year-old woman in persistent V-fib at 21°C required improvised warming with hot water bags during CPR.

This episode of the Wilderness Medicine Podcast, hosted by Daryl, covers a complex hypothermia resuscitation case and new research on solar water disinfection. The host is joined by Dr. Kylie Van Heusden and Dr. William Mundo to discuss their study, and later by Dr. Dylan P. Collins to review a search and rescue paper. The host details a case of a 20-year-old woman found pulseless and in ventricular fibrillation with severe hypothermia, a core temperature of 21°C. Resuscitation efforts included mechanical CPR, attempts at rewarming with an Arctic Sun device, and consideration of ECMO. The team employed an improvised rewarming method using hot water in plastic bags placed on her head and chest, a technique attributed to Dr. Giesbrecht. They attempted a double sequential defibrillation technique, referencing a 2022 New England Journal of Medicine study showing a 30% survival to discharge rate with this method. The team also administered esmolol, considering its potential synergistic effect with defibrillation in a cold heart. The patient's end-tidal CO2 rose to 20, and her potassium was 4.3, contributing to a calculated hope survival probability of 93%. She was ultimately rewarmed, achieved a perfusing rhythm, and was found neurologically intact two days later. The solar disinfection (SODIS) study evaluated E. coli inactivation at high altitudes, comparing sites near Denver at 1,600 meters and Leadville above 3,000 meters. Researchers found SODIS effective at high altitude, with faster bacterial inactivation in the first two hours at higher elevation but equivalent results after six hours. They discovered standard plastic water bottles were 1.4 log more effective at disinfection than clear Nalgene bottles, while plastic bags performed equally to plastic bottles. The mechanism is primarily bacteriostatic, damaging bacterial DNA with UVA and UVB radiation to prevent replication. Dr. Collins's paper analyzes 25 years of data from the volunteer North Shore Rescue group near Vancouver, which operates in rugged mountains close to a major city. The tone is conversational and educational, blending a detailed clinical narrative with interview segments discussing research methodologies. Listeners interested in frontline emergency medicine, improvisation in austere care, and practical wilderness science will find this episode compelling. Those seeking a purely recreational outdoor skills focus may find the detailed hospital case less directly applicable.

As heard by us

Practical wilderness medicine that keeps the cautions plain.

The episode plays like a field guide to wilderness medicine. It starts with a March 2023 check-in from the WMS Winter Conference in Tahoe, then moves through high-altitude solar water disinfection, mountain rescue in British Columbia, and a brief marine-medicine segment.

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Why you'd press play

You want the water and rescue basics before your next cold-weather trip.

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