Death from Exposure

 “Died of exposure” is a phrase one might have  read in the newspapers fifty years ago.   Nowadays it might mean one of two things – hypothermia or hyperthermia.   Here are some tales and observations of these two risks to backpackers, kayakers, and the like.

            I once heard someone talk about selecting kayaking buddies.   There was a litmus test question, “Have you ever capsized?”   If the answer was “No”, then run like hell and don’t paddle with them.   If “Yes”, proceed. The point is that the only way to get experience is to make mistakes.    Likewise, when looking to an outdoor buddy, you might consider asking him or her if they’ve ever been hypothermic or hyperthermic.    If the answer is “No,” or worse yet, “what’s that?”, you probably don’t want to venture out with them.  

            It’s one thing to learn about or study a condition as a detached clinician might, and quite another to experience it.   When you experience hypothermia or hyperthermia, you know what it feels like, and you can put yourself in the victim’s shoes, recognize it, say, “yeah, I see that, let’s get you some help.”  

            One exposure to a hypothermia case was during a training paddle off of Nantasket Beach, which is just the south of Boston.   It was mid-April, and definitely dry-suit weather.   A bunch of us were getting training on the American Canoe Association instructor syllabus.   The wind was pretty brisk, and I don’t recall the water temperature, but it must have been in the high 40’s.   Upon launching one of the guys in the group capsized.   We sprung into action and he was righted and back into the kayak within a minute.   He seemed OK at the time, but I noticed that his dry suit didn’t seem very solid.  

            We paddled along the breakers, and I wasn’t really paying attention to him, just focusing on my bracing in the waves.    Before long, the instructors told us to land, which we did.   They said that the guy who capsized was now hypothermic, which he denied, but they insisted that we pull-up on the beach.   We set up a quick shelter and huddled under it.   One of us produced a thermos with hot broth and fed it to the hypothermic guy.  

            One of the instructors then paddled back to the cars where we launched and drove up to our shelter, picking up the victim, and carting his kayak back to the cars.   The rest of us paddled back on our own.  

            We moved fairly swiftly and got indoors to a Dunkin Donuts, which is a favorite spot for the kayak guides, John Carmody and Peter Casson.   John and Peter said that the victim had been moving sluggishly and they were already concerned about him when he was recovering from his capsize.   Initially when we were out in the shelter, the victim didn’t think he had any problem and didn’t understand.   Upon reflection once he warmed up, he said he found that movements that he thought should be easy were difficult and he couldn’t understand why.  His thinking was sluggish, upon reflection.  

            One of the problems about the onset of hypothermia is that the victim is often unaware of it hitting.   A frequent set of warning signs taught are called the “umbles” – meaning that the victim fumbles, stumbles, and mumbles – basically impaired functionality.   I will confess that I’ve experienced this quite recently.   I bicycle commute in and out of work.  There is an annual ritual of gearing up for the cold, including putting snow tires on my bike.    The tricky part for me is the temperatures where long underwear is called for.

            Normally when I go running, I only start putting on long underwear when the temperature dips below about 22 degrees F.   I was working under those rules one day in early December.   Unfortunately, I failed to factor in the effect of the wind generated from riding, and also the fact that my trousers were thinner than my normal running pants.   It was about 25 degrees on my ride home, and I noticed toward the end of the ride that it was becoming unusually difficult.   I attributed this to being tired from my ride the day before, but it didn’t occur to me that I ride nearly every day, so this didn’t make any sense.  

            There’s one last hill on the commute that involves cresting a gravel, pot-holed section, followed by a steep incline.   For some reason, the road seemed a lot more discombobulated to my eyes than normal, and the last uphill bit made me wonder “Why is this road so messed up?   It’s making me ride erratically.”   Of course, it’s the same stretch of road I ride every day.  

            I got home and usually take a ‘cool-off’ period of 15 minutes or so before showering.    While I was ‘cooling off’, I noticed that I was distinctly cold and that sensation in the core of my body wasn’t going away.   All of a sudden it dawned on me:  I had become hypothermic during my bike ride home.    A good shower was all it took to regain my core body temperature, but the sensation of that struggling feeling stuck with me.  

            Another encounter with hypothermia involved ice baths.    While running, I had pulled my psoas muscle, which runs from the lumbar region of the spine, connects with the hip and then the femur.    It’s deep inside the body and I figured that the only way to get relief was to take ice baths.    I got an outdoor thermometer and a 10-pound bag of ice, filled the tub with cold water, and then dumped the ice bag in.   In October, this got the tub down to about 55 degrees F.    Getting into the tub at first was quite painful, but after a couple of minutes of immersion, it felt tolerable.   I poured myself a big glass of white wine and read books about Arctic exploration, which not only seemed appropriate, but the suffering of the explorers gave me cold comfort.    I typically stayed in for thirty minutes, and when I got out of my first tub, felt refreshed.

            As October wore into November, the temperature of the cold water coming out of the faucet dropped and I was getting into 53 degree, then 52 degree, then 51 degree baths.  I continued with the program, figuring ‘colder is better’ in some deranged logic.   Finally, I reached 48 degrees.    OK, now this one was too much.   I managed to stay immersed for 30 minutes, but when I got out, I could tell my core temperature had dropped.   I cooked dinner for my family, but I felt that something wasn’t right.   After about two hours, I finally warmed up enough to fell like my normal self again.   So, this little experiment gave me some indication of how long an exposure in water was enough to create problems around 50 degrees F.  

            Now, in kayak circles, we’re sometimes taught something called the 50-50-50 rule.  The rule goes something like this:  you have a 50% chance of surviving a 50 meter swim in 50 degree water.    Although a 30 minute immersion in 48 degree water isn’t equivalent to a 50 meter swim, I’d submit that 30 minute in 48 degree water is more severe than the minute it takes to swim 50 meters, even accounting for some pocketing of local water heating up near the body in the tub (which maintained 48 degrees throughout the 30 minutes).  

           

            I looked up the Coast Guard charts on hypothermia survival probability and the 50% mark is around 2 hours in 50-degree water, which made me doubt the 50-50-50 rule.   There is another factor that comes into play.   If you jump into 50 degree water without a PFD and try to swim, it isn't easy.   There's a gasp reflex that you have to fight, and then the constriction of blood vessels in the limbs makes them difficult to use to actually swim.   Here's where a lot of differences from one person to the next comes into play - there are plenty of swimmers who can brave swimming in 50 degree water for an extended period of time, and others who flounder about almost immediately.   On the other hand, I have to say that it takes a huge amount of time to rewarm someone who has hypothermia, and it’s far better to avoid it in the first place.

Typical hypothermia chart.   This tracks reasonably well with many other charts.  This is for a person in a huddling position in water.   Mean immersion time for death swimming in 50 degree F water is more like 40 minutes.    From the chart, one would surmise that the 50% probability of survival in 50 degree F water is around 2 hours and 15 minutes.

            Hyperthermia is a different creature, at least for me.  While the onset of hypothermia causes confused thinking and a lack of awareness that it’s hitting, hyperthermia is more obvious to me.   Once I was hiking in southeast Washington State along an exposed trail in August.   I don’t know the temperature precisely, but I reckon it was pushing 100 degrees F.   On my way back to camp, I felt distinctly light-headed, and this scared the bejeezers out of me.   I took every opportunity to obsessively stop in the shade, sip water, and even rub some water in my hair and on a kerchief I had around my neck.  

            I don’t understand what causes the cognitive differences in hypothermia versus hypothermia, but I wonder whether hypothermia doesn’t produce a kind of anesthetic effect that dulls the senses, while the dizziness I associate with hyperthermia is quite obvious.

            One other strange effect that I’ve never understood with hypothermia is the phenomenon known as ‘paradoxical undressing”.  In very advanced stages of hypothermia, the victim suddenly feels extremely warm and wants to ‘cool off’, which causes them to shed their clothes.  

            Over this past Thanksgiving, I was talking with a relative, Gersh, who is an anesthesiologist at San Francisco.   He’s something of a fan of outdoor medicine and told me what was going on in paradoxical undressing.    Normally, the body constricts the blood vessels in the limbs when it gets cold to preserve core temperature.   Now, the act of constriction burns energy, as the vessel walls have to actively contract.   If a person has been in this condition for a long time, the blood vessel walls burn up all their stored energy and then they relax.   The relaxation of the blood vessels causes the core blood to flood back into the limbs and this produces a burning warm sensation, which leads to the paradoxical undressing. Gersh said that when search and rescue personnel on the trail of a lost person encounter shed clothes, they know they’ll soon come across a dead body.

            I can’t say that I have a universal take-away message.   For hypothermia, the obvious answers are to dress to stay warm and dry, but this takes some judgment about likely conditions that will be encountered.   For me, I realized that I probably need long underwear when I bike in temperatures below about 30 degrees F.    I know from other experience that I switch into dry suits when kayaking when the water temperature dips below about 52 degrees, and wet-suit temperature is about 52 to 64 degrees F.  

            Some conditions can generate a real challenge.   The waters in downeast Maine in the summer can be quite cold – in the 50-55 degree range.   On the other hand, the air temperatures can be very warm, even downright hot.    Once I was at a kayaking symposium in Bar Harbor where the water temperature was around 55 degrees and the air temperature reached to 90.   We had no choice but to wear dry-suits, as our instructors insisted that we dress for the water.    For the latter half of the day, I thought I’d sprung a leak in my dry-suit, as both of my feet felt soggy.    When I got back to my hotel, I reckon I drained maybe a liter and a half out of my dry-suit.    Only when I found that my thermal underwear smelled like an ammonia factory, did I realize that it was sweat, and not seawater that had been puddling in my boots.  

            The very next day, I went out again in a dry-suit.   Fog rolled in this time along with some wind.   During a break, I got chilled from the wind blowing over the sweat-filled clothing.  There’s no perfect answer, really.   As always, experience seems to be the best guide, and one has to be careful about simply falling back on generalities.