Over the last few months, several people have put together wonderful in-class presentations on heat emergencies. With no slight intended to those fine folks, Dr. Richard Payden has also written a pretty good article on the subject for Wilderness Medicine Magazine. If you'd like to skip my rambling commentary, the link to that article is at the end of this post.
A few particularly interesting points…
Dr. Payden focuses on prevention - including recognizing risk factors - more than it does on treatment. (If you have taken our wilderness first aid class before, you will notice this is in line with current thinking on other environmental emergencies, such as hypothermia and altitude emergencies.) Few will be surprised to see dehydration on the list of risk factors, but it is a surprise to see the risk quantified: for every 1% of fluid weight loss, body temperature increases by 0. 22°C. That means, for a 150 lb person, losing 7.5 lbs of water – about 3 litres – will raise body temperature by about 1°C. This seems like a lot of water, but in the context of wilderness activity, where we tend to participate in sustained activity over the course of many hours or days, water loss can add up - especially when you consider that most people tend to underestimate how much water they need!
I also enjoyed Dr. Payden’s discussion of acclimatization to prevent heat illness - similar to the conversation we usually have around altitude. Among the body’s adaptation techniques, Dr. Payden describes “lowering the salt concentration of sweat.” This suggests that following a good acclimatization program will also mitigate the risk of electrolyte imbalances!
Finally, Dr. Payden’s prescription for very aggressive treatment of heat illnesses is nothing new, and will certainly be familiar to students of our wilderness first aid courses. The article compares the effectiveness of various treatments – not surprisingly, immersion in ice water is most effective, but since it is rarely practical, it's nice to know how the alternatives measure up.
As we enter the hottest part of summer, with the race and festival seasons well underway, heat emergencies are a very real threat. Hopefully this information will help you to protect yourself, and to act quickly when you suspect someone around you is having a heat emergency. This is one of those situations where you can potentially save someone’s life.
Read the full article at wms.org/magazine/1202/EHI.