Hypothermia

[Thomas Linton]

I had always heard that hypothermia was "a leading cause of death in the wilderness" -- if not "the" leading cause. That didn't match my SAR experience, but one person's experience is a pretty poor sample.

Lately, I have been searching for statistical studies of wilderness mortality. I can't find much. What I found reveals hypothermia to be pretty far down the list of wilderness death.

A study of 437 SAR cases revealed a mortality rate of 14%. Of those deaths, 32.8% were due to drowning. Heart attacks caused 23.4%. Hypothermia was not listed.

The 1998 Montalvo study of eight California National Parks found 61 total fatalities for the period studied. One was due to hypothermia, the same number as for shark attack and volcano. The three leading causes of death were: a) Cardiac incidents (11); b) drowning (11); and c) falls (8).

Apparently, about 725 people a year die of hypothermia in the U.S. - the vast majority in urban areas.

Anyone out there know of statistical studies on the casues of death or injury in the wilderness?

 

[skammer]

Thomas,

Maybe the correct stats should say the % of "LOST" people who die of exposure and not just wilderness deaths of those who aren't lost.

Stats are subjective no matter what they say.

Skam

 

[longbow50]

One thing about statistics is that they are rarely complete. Not arguing with them, only saying that they don't cover all the bases that need to be covered. Hypothermia can be directly related to a fall, a drowning and most certainly cardiac arrest, but the deaths may not list exposure, because of the obvious reasons related to the death. I suspect that there are many more deaths that can be attributed directly or indirectly to hypothermia and hyperthermia (exposure?) and they just aren't being reported.

 

[Thomas Linton]

The deficiencies of statistics are acknowledged. Nevertheless, that's what I am interested in.

The statistics measure deaths, not risks. It may be that folks are simply better prepared and thus avoid the consequences of the risk.

California National Parks are probably drier, over a year, than locations in BC or Michigan, for example. But they include some very high altitudes (over 3000 meters) and substantial winds.

Where is the proof that hypothermia is a significant wilderness killer? That is the oft-repeated claim. Indeed, I find many statements that it is "the" killer. On what basis?

Of the study of 457 SAR cases (in a cold/wet claimate), 41.4% involved lost persons. 39.3% were injured to some extent. 33.7% had fractures. 14% died. 32.8% from drowning - which may actually be death by hypothermia. 23.4% died of heart attacks.

The National Park survey simply measured deaths. If you include all drownings, it would still represent less than 20%.

Someone named Syrotuck claimed that he studied 200+ SAR cases in New Jersey and Washington. He named hypothermia as the greatest killer -- usually in first 24 hours, but he never published his study or revealed his sources. He gets cited repeatedly for "the killer" claims.

(OT 363/yr. die in U.S. due to hyperthermia.)

In an Alaskan National Park study, the two leading causes of death are influenza and motor vehicle accident.

 

[Moine]

IMHO, while hypothermia itself is not often THE cause of death, it's a great helper. Getting cold, we lose IQ points, rush to do things, make mistakes, and thus slip, fall, take a dip or get a heart attack more easily.

Another thing is that most people just try to walk out when lost. The are afraid to stay in there and try to escape by themselves, pushing their limits and trying their luck. As long as they walk/trash in the bush, the main risk is not hypothermia. It's falling, slipping, falling into water, getting a heart attack, etc. That being said, spend a night sitting int he bush without appropriate clothing, shelter or fire, and then we'll talk about what you felt your worse problem was

We, survival instructors, stress hypothermia so much for two main reasons... which are basically the two sides of a same coin.

1... we do so in the context of STAYING PUT. Because we all know you SAR guys will find people quicker if they stay put, get comfy and prepare to make themselves audible and visible. But staying put means little heat production and thus the need for greater insulation, even is relatively warm conditions. So stressing hypothermia so much is something to put back into a context.

2... People who are NOT equipped to prevent hypothermia will HAVE to walk and trash in order not to freeze in cold temps. People who prepare for this and carry shelter, fire, clothing and all will set up camp, light a fire, brew a hot chocolate and wait for you SAR guys.

In my own limited experience, the main risk of death or injury while staying put IS hypothermia, even in summer if you're exhausted and dehydrated enough (which, after 1-2 days of serious bushwhacking, is very possible in a real life scenario).

Cheers

David

 

[Cliff Stamp]

Interesting numbers, but I would agree that many of the deaths might be exposure related, if your fingers go numb and your feet are frozen the probability of a fall would be higher, similar with a heart attack, I don't imagine that someone with a heat condition would react well to a continued loss of body temperature and no way to prevent it. What would be interesting is to see the health of the person, were they suffering from exposure at the time of death.

-Cliff

 

[Watchful]

Apparently, about 725 people a year die of hypothermia in the U.S. - the vast majority in urban areas.

Sorry if I'm echoing someone else's question--I don't think I did--but what's the source of that specific stat?

Seems to me that's easy to believe, if you count homeless people or elderly folks frozen in the city. Here in Chicago, we get quite a few every year... and that's hypothermia, but not at all aligned with the research you're after (wilderness situations).

 

[Thomas Linton]

1979-1989 739/yr. American Jour. of Forensic Med.

1972-1992 10,550, or 754/yr. (CDC)

1. Illinois (660)
2. Alaska
3. Alabama
4. Arizona
5. New Mexico
6. N. Car.
7. Okla.
8. S. Car.
9. Tenn.
10. Vir.

2002 - 646 (CDC)
1. Alaska
2. New. Mex. and N. Dakota
4. Montana

2001 - 599 (CDC)
1. Montana
2. Alaska
3. New Mexico

The CDC states, in several places and times, that "most" such deaths are in an urban setting. They give examples of homeless, chemically impaired, and aged as typical urban victims.



So, to this point, no other statistics regarding death from hypothermia.

 

[gutsy]

ive been a whitewater raft guide for 4 years and i can say from experience that its been all to common for clients to underestimate the power of weather even / especially in summer . mt. leconte in the smokies claims someone every year it seems, particularily in summer or in warmer temperatures. you might have to start looking for stats based on individule departments and jurisdictions maybe . i believe hypothermia actually claims more people every year than wht we think and it either doesnt get talked about or is catagorized as something else . i personally can confirm 2 cases in wich that happend .

 

[SubaruSTi]

We all have computers, central air, tvs and most people dont die of exposure these days. most people put in a survival situation would die of hypothermia in temps below 20 with out the right gear. every case is different and humans dont have any tools but their mind to survive.

 

[Thomas Linton]

I'm still looking.

The National Outdoor Leadership School has some statistics, but they are from an unusual venue. Experienced leaders are with each group, they know about proper clothing and boots, and they lack the middle-aged male cohort. Probably, they are never lost, if sometimes confusion is deliberately allowed. Still, some interesting numbers.

1999-2002 Total Injuries

Hypothermia 2.3% (1/61 in the Montalvo study of fatalities)
Frostbite 1.3%
Drowning none (12/61 in the Montalvo study of fatalities)


1999-2002 Contributing factors for injuries:

Falls 28.2% (12/61 in the Montalvo study of fatalities)




Wilderness, expedition-based outdoor programs reportedly have an injury/fatality rate equivalent to school PE programs and non-contact school sports. Neill, "Outdoor Education Injury/Fatality Rates & Comparative Statistics, 12 feb. 2005.

 

[Thomas Linton]

I fanially founf the full text of the study of 457 SAR cases (Epidemiology of Wilderness Search and Rescue in New Hampshire, 1999-2001)

These were cases where the subject voluntarily went into the "woods."

57.3% od the subjects were hiking.

14% died

The most dangerous class of activity was swimming, boating, canoeing, or fishing [from a boat?].

Drowning was the COD for 32.8%, cardiac incidents for 23.4%, and hypothermia for 3.1%.

Falls were involved in 30.1% of the cases, "poor judgment" in 19.9%, and intoxicants in 4.5%.

Assuming as I must that many "drownings" took place because hypothermia ended the ability of the subject to stay above water, the relative percentage of cases of drownings has implications for education of folks to prevent death in the wilderness.

Do you favor a "large" PFD or a "smaller" PDF?

 

[dartanyon]

Just wanted to share an experience with you..

I remember caving with 7 friends and hypothermia becomming a real threat.

We were following notes on a cave (Wallandilli) where the exit was at a different place to the entry and the cave was to take the whole day.
After gearing up we walked down to the cave from the vehicles and arrived at the entry first where I assisted in setting up the abseil and 4 others took the ladders to the exit to set up there. When they returned we entered the cave. Six hours later we arrived at the final chamber where the exit ladder was supposed to be ... but not!
I climbed to a chimney in the roof of the chamber and was able to reach a handhold that the others could not. After discovering the exit ladder was nowhere to be found, we planned that I would climb out and get another ladder so they could exit the last chamber. Approximately 90 minutes later I found the ladder they had dropped into a large chamber near the exit, nowhere near the chamber they were in. I climbed out to find it dark outside and my batteries running low. I then walked up the hill not able to find the cave entry. I was walking up the wrong hill!! Another 90 mins later I sat down, lost and tried to gather my thoughts. After about 15 minutes and trying to use the stars to work out what to do, I saw some headlights on the opposite hill! Off I went trying to keep sight of a gap in thr tree line. About 20 mins later I nearly fell in the cave entry! Was good though as I now knew where the vehicle was. I found the spare ladder and an old set of batteries to take. About another one hour later I got back to the others who were now suffering fron the early simptoms of hypothermia. About 4 or 5 hours later I had returned to their waiting place. Out of the 3 girls, 2 of them were shivering and the other hysterical when I arrived. 2 of the guys were very sleepy and had to be assisted.
The situation was never spoken about again.
Why weren't they moving around rather than huddled in a group?
Why diddn't we carry a spare rope?
I was 19 then and have learned some great lessons from that experience.