Warming cold swimmers (not hypothermia)

This article is written for rescuers/helpers when a swim has not gone to plan and the swimmer has got a little colder and needs a little more help than expected.

As an experienced Adventure Racer – Dan has looked after himself in a variety of states of (dis)repair. As a WEMSI Wilderness Emergency Medical Technician, and former Mountain Rescue team member – he has also looked after others in a variety of states of disrepair too. Indeed, once or twice he has had hypothermia.

Generally, a newbie swimmer’s biggest concern is the cold, and getting people warm again – I often hear about people worrying about hypothermia.

One of my pet peeves is the use of “space blankets” – those foil blankets you see at the end of marathons. These are designed to reflect radiated heat. Hot runners radiate lots of heat, and cool down quickly – so they are great for them. Cold swimmers do not radiate much heat at all. When placed against bare skin, this foil sheet actually actively conducts heat away from the body – the exact opposite of what we’re trying to achieve.

Remember, that if the swimmer was still swimming then they are almost certainly not suffering from hypothermia.  They are certainly cold wet and sad, but not hypothermic. People usually drown from swim failure long before they get clinically hypothermic (there may be very few exceptions in extremely well adapted & well trained individuals who can swim into hypothermia… however, without taking arterial blood temperature… we don’t really know for sure).

Anyway – with that rant out of the way… on course, I carry a variety of equipment to warm somebody up. So let’s talk through how we are warming someone up who is really cold (and remote from any building or vehicle). First things first, get them dry. Heat loss through evaporation is this persons biggest problem – they are coming out of their swimwear, and getting dry. Once dry – heat loss through convection is now the biggest problem. Get them layered up. Plenty of warm clothes on, and a warm hat.

At this point, a tasty hot beverage (and a slice of cake) is just what that person needs to give them the energy boost they need to get going again. The warm mug might make your fingers feel nice, but that’s about it in terms of thermal benefit.

Hopefully, by this point – the person should be feeling better – but if the wind is blowing and the rain is battering down – maybe you need to pull out a few extra bits. However, if you’re remote… getting moving at a brisk pace is the best way to get the muscles working (generating heat), blood pumping (moving the heat around) and generally getting the person feeling a bit better.

Extra equipment for cold & hypothermia

Unfortunately, if you’re in the situation where things have gone really wrong… and the person isn’t feeling up to marching back to the car (yet), you’ll need work fast. Or maybe, they’ve been injured and you’re now waiting for Mountain Rescue to arrive (and cooling down whilst you wait).

First up – a survival bag. A big orange plastic sack – cheap from any outdoor shop. This is great, and a lot more effective than a foil blanket. Popping the cold swimmer inside that (now that they are dry and have dry clothes on) and getting them to pull it tight over their head is going to help warm them more rapidly. The objective is to trap air inside it – and avoid too much movement of that air. It will then start to warm up and humidify – effectively making a personal sauna for the cold swimmer.

Get them to sit on a foam bum-pad to insulate them from the floor, and avoid heat-loss through that route as well.

Whilst working on the cold swimmer – don’t forget about the rest of the group (and yourself), as they are all standing around starting to get cold themselves. Next up – the group shelter. This is big enough for 4-10 people to get inside. Basically, it’s a waterproof fabric dome – a tent with no frame. The frame is made by the people inside. Everybody stands in a circle, and pulls it down under their bum – they then sit down. Suddenly, the world has a orange glow and the trapped heat and hot air from all the people means that it gets very warm very quickly. Sheltered from the wind & rain – sort everything out inside the shelter & get the cold person warm enough to get on their feet and get moving.  As mentioned above, the movement of walking back to safety will also help to warm them up – as long as they can stay dry.  If they are still wet by this point, then hypothermia is starting to become a serious risk.

Warm drinks do not do much to heat up cold people – they are a good psychological boost, but that’s about it. Urban medical advice is not to give people anything to eat/drink – and that’s fine when they are a few minutes from hospital. Wilderness medical advice is to feed people – they need the energy to get off the hill. If the person is conscious and able to swallow normally, then giving them a hot drink after you have done all of the things above is not going to do any harm. In the big picture, getting the person dry and dressed is far more important than giving them a brew.

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