Caving has many dangers associated with it: not being in contact with the outside world, a real possibility of injuries, such as falls, concussions, lacerations and fractions, getting trapped, a limited amount of food and water, the list goes on. Today, we look at a silent but deadly danger: hypothermia.
What Is Hypothermia
It’s normal to experience cold temperatures while caving: after all, you are underground, the walls are usually solid rock, and there is no sun anywhere to warm things up. Being somewhat cold is not unusual, but more often than not, you get enough physical activity to keep you warm. Hypothermia happens when the body is not able to stay warm. For humans, this means body temperature dropping below 95.0 °F (35.0 °C). This decrease in body temperature adversely affects many bodily functions such as the normal work of the heart and lungs and, in extreme cases, can result in death.
Most of us have experienced mild hypothermia (body temperature under around 95 °F (35 °C)) – this is when you feel shivers. In most cases, we are in a situation where we can fix this – go home, turn the heat up, add more clothing, etc. Unless being in this state for an extended period, it is usually harmless. When caving, the options are somewhat limited, as you can only warm yourself up with whatever you brought along. When experiencing shivers in the cave, either put on warmer clothes or start thinking about ending the trip early to leave and get yourself warm.
After a while, mild hypothermia may progress into moderate hypothermia (body temperature under around 89 °F (32 °C)) – this is when a person is so cold that their shivering is reduced or stops entirely. Moderate hypothermia is dangerous and should be avoided at all costs. In addition to a reduction in shivering, a person may develop mental confusion – he or she may seem a bit “out of it”, not responding to questions or giving answers that make no sense, looking around confused, disorientated, etc. They may see hallucinations and appear agitated. If you see a fellow caver with these symptoms, immediately stop whatever you’re doing, try to keep them warm, and seek help.
If untreated, moderate hypothermia will progress into severe hypothermia (body temperature under around 82 °F (28 °C)) – this is obviously the most dangerous form of hypothermia; the person may become unresponsive, all shivering is ceased, the cold will start to affect the heart and other organs, threatening shock and cardiac arrest. There are many known cases (in some estimates, 20-50% of hypothermia deaths) where people start to undress when suffering from severe hypothermia. The exact reasons for this are unknown but thought to be related to the hypothalamus, which regulates human body temperature and which in the extreme cold may start to malfunction, resulting in people mixing being super cold with being overheated. Like with moderate hypothermia, do whatever you can do get the person warmer and seek help immediately.
How to Avoid Hypothermia
Yup, you guessed it – you can avoid hypothermia by staying warm. No two caves are exactly the same, and you should prepare yourself appropriately for each cave you go in. Always go with a more experienced caver who knows the ins and outs of the cave, which includes the average temperature. The average temperature of the cave depends on where the cave is located and is usually, but not always, the same as the annual average temperature on the surface in that region. The bedrock retains heat very well, so the caves are usually at a constant temperature throughout the year.
If the cave you plan to visit is colder, you should wear warm, light clothing (think layers, such as long polypro underwear, wool socks, etc.), and you should bring extra clothing in your cave pack. Most cavers also recommend keeping an extra set of clothes in your car, so once you exit the cave, you can quickly take off your dirty wet clothes and get warmer by putting on some dry ones (don’t forget to bring a garbage bag for your dirty clothes!). For your cave pack, prefer lighter clothes that have good heat retention properties and which you can wear as layers. Avoid bulky and heavy clothing that takes up a lot of space. Avoid cotton clothing; cotton attracts moisture and keeps the moisture close to the skin, actively increasing the heat loss. Also include a garbage bag in your cave pack, which may be used in various ways, one of which is its potential function as a makeshift poncho.
Avoid alcohol and caffeine
Drinking booze in caves is generally a bad idea, but especially when one is suffering from hypothermia. Drinking when struggling to keep warm is a no-no as alcohol, as well as caffeine, dilates the blood vessels, allowing for more significant heat loss. Instead, bring an insulated flask with hot tea that will help you keep warm.
Stay away from water
If the cave has underground lakes or streams and you already feel cold, stay away. Heat is lost much more quickly in water than in air, and you continue to lose heat once you exit the water and have no option of drying yourself.
Bring a space blanket
A space blanket (also known as a thermal blanket or a first aid blanket) can be quite handy when it is necessary to wait (after receiving an injury, for example) and stay warm. Space blankets are cheap and light and should be included in your cave pack.
Don’t sit on the bedrock
Keep yourself or the person suffering from hypothermia insulated by putting something between the person and the ground, e.g., such as some extra clothing, a space blanket, a cave pack, etc.
If possible (i.e., there are no injuries, and there is enough space), engage in some physical activity when cold, such as push-ups, crunches, etc. Keep moving and use your common sense – if it’s so cold that you need to do push-ups, maybe it’s time to exit the cave.
If you have any other ideas on how to keep warm and avoid or prevent hypothermia, let us know in the comments!