It is that time of year at the Grand Canyon. I found it interesting to follow up the linked wikipedia article on hyponatremia, especially when it mentions how common a condition it can be. My understanding is that one way HN occurs is when you ingest too much water, especially without electrolytes, which is difficult to do in the desert Southwest, typically because of the low humidity......


Grand Canyon National Park (AZ)
Ailing Hiker Rescued Via Helicopter Short-Haul

Late in the day on Tuesday, June 4th, visitors found a 29-year-old man in severe distress on the North Kaibab Trail. The hiker reportedly drank large amounts of water, but had eaten very little food. This, coupled with the expected increased perspiration while hiking in hot temperatures, lead rangers to believe this visitor was suffering from a potentially life-threatening condition due to low blood sodium levels known as hyponatremia. Responding via helicopter, ranger/medic Brian Bloom utilized a portable blood chemistry instrument (iStat) to confirm his suspicions and begin appropriate field treatment. Due to the serious nature of the man’s condition and the lack of nearby landing zones, he was helicopter short-hauled with Bloom from switchbacks in the Redwall to the North Rim helibase. He was then placed inside the helicopter, flown to the South Rim, and taken from there to Flagstaff Medical Center. Heis expected to recover.
[Submitted by Brandon Torres, Branch Chief of Emergency Services]

Hyponatremia was discussed at the WFR recert I recently attended. According to the instructor there have been more issues during hot weather marathons from hyponatremia than from heat stroke.

The issue is consuming a lot of water AND not replacing electrolytes. You basically sweat off all the sodium in your system. Because it is hot you don't feel so good, so you drink more water, thinking that will make you feel better. That causes you to sweat off even more electolytes, so you feel worse, so you drink more water .... repeat until you go into seizures. People do die from it. One of the issues is that early symptoms can look a lot like heat exhaustion, and late symptoms can look like heat stroke. However, just giving more water makes the problem worse.

Through the magic of Google I found a back issue of Boatman's Quaterly with a good discussion of Exertional Hyponatremia.

As with most things, the best treatment is prevention. When you are hot and sweating a lot, drink lots of water, but also eat salty snacks to maintain your electrolyte level!

Wow!

All those salt tablets we were fed actually had a rational purpose!

Hmm! Live and learn. I always thought potassium was the biggie in terms of becoming incapacitated via electrolyte depletion. Based on that, I assumed that the "salt pills" routine from ~50 years ago was a roundabout (archaic) way of getting trace amounts of potassium that are in most sodium salts.

Dealing with hyponatremia can be a very fluid situation, but any first aider worth their salt should be able to handle it.

Interesting. I'm surprised that in a situation where you're packing your own water, someone could drink enough plain water to induce hyponatremia.

It's a combo of drinking free water and losing salty water. Relatively easy to fix, a real PITA to diagnose, since it looks pretty close to heat exhaustion. In fact, a lot of times with patients I'll just recommend gatorade alternating with water for active folks.

Early on in our hiking adventures, a friend became very nauseous toward the end of a big hike on a hot humid day. That's when we became aware of hyponatremia.

On the hottest (90s), muggiest days hiking in Shenandoah National Park (Virginia), we've each packed a gallon of water/gatorade for a 9-10 miler with 2000-2500 foot elevation gain. We learned the hard way to go 50-50 with Gatorade/water.

On those hikes I've consumed 96 oz of water (3 Nalgenes) and sweated it all out.

I mean all of it -- no need to empty my bladder.



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For the sake of clarity, respiration uses a lot of water too. So you panted a bit out too.

Electrolyte packets ( gatorade powder) and bananas.