Heat waves steal headlines for their deadly spikes, but, globally, more deaths are caused by the cold than heat. When it comes to heat, our bodies do a pretty good job of regulating our core temperature without any help. But when the temperature drops, even to a mild 60 degrees F, our bodies rely on heaters and extra clothes. This human weakness is especially dangerous in subzero temperatures, where a few minutes in wet clothing or little clothing can cause severe hypothermia or even death if left untreated. Tragically, this past week nine Wisconsinites lost their lives to hypothermia.
Doctors divide hypothermia into three stages: mild, moderate, and severe. But what we call mild hypothermia is a already drop in the body temperature below 95 degrees F (normal body temperature is about 98.6) and not actually very “mild.”
Unlike heat stroke or other problems with high temperature, mild hypothermia has more subtle symptoms. You might just feel off or slow, have some memory loss and confusion, or feel angry and become combative. You also might notice the skin on your belly or inner thigh feeling cooler, and even if you don’t notice this, your brain will detect the low temperature and start sending signals to make heat by shivering.
Shivering jacks up your metabolism 4 to 6 times, so it costs a lot of energy and isn’t a good long-term solution. Your breathing and heart rate speed up to help fuel the shivering and also to make sure the rest of your organs are getting enough oxygen. But once the core body temperature gets below 91.5 degrees F, your brain starts to malfunction. This is known as the “transition zone.” Everything starts to slow down, including your heartbeat and breathing. This is a time when arrhythmias—abnormal heart beating that could lead to death—are likely to occur. It’s a very dangerous emergency that could require intensive care in the hospital.
WATCHING FOR SIGNS AND PREVENTION
If you or someone you know has been outside or in wet clothes and appears confused, is slowing down mentally and physically, and/or is shivering, take a temperature. If the temperature reads 95 degrees F or below, GET EMERGENCY HELP immediately. While you wait for help, or if the temperature is above 95, take off any wet clothing and wrap the person in warm, dry blankets. Prioritize keeping the core warm rather than the arms and legs. Do not take a hot bath as this might actually cause the temperature to drop further (known as the “after drop”). If the person is talkative or interactive, encourage drinking fluids. Do not force any drinks down if the person is losing consciousness.
For older adults, a slight decrease in temperature can be even more problematic because the body’s shivering mechanism is weaker, and the perception of cold may be less sensitive. In addition, older adults are more likely to have other medical problems that are exacerbated by slight fluctuations in temperature.
Here are three non-commercial websites with more information about hypothermia prevention and care.
For all age groups: https://www.cdc.gov/disasters/winter/staysafe/hypothermia.html
For older adults:
TREATING FROST BITE
Frostbite is when the skin or another part of the body temperature reaches 32 degrees F, literally freezing. Unlike hypothermia, frostbite should be rewarmed with warm water (99 to 104 F). Rewarming a frost bitten hand can be very painful as sensation returns to the hand.
HYPOTHERMIA AND CHRONIC PAIN
Some patients with chronic pain sense that things are worse when there is a sudden temperature change. And in the winter they seem to be extra sensitive to cold air. Well, a research team in Australia was interested in looking at this topic and asked the question: do chronic back pain suffers have a lower threshold for pain from cold or heat than other people without low back pain?
Turns out that pain sensitivity from cold stimulation may be worse in those patients with chronic low back pain when compared with patients with no chronic pain. By using a cold stimulus that gradually got colder, a thermometer, and a button, subjects would push when they wanted the pain to stop, researchers measured the difference in cold pain tolerability. When the cold stimulus was on their arm, subjects with chronic back pain asked to stop the cold stimulus at 57 degrees F, on average, while subjects without low back pain averaged at 46 degrees F. And this difference was statistically significant.
The above does not constitute professional medical advice. Please contact your doctor or health care provider for personal medical attention. Seek immediate medical help for anyone with suspected hypothermia or frostbite. Call 911 if you suspect severe hypothermia or notice any change in mental alertness.
Angelie Singh, MD, MPH, MS
Angelie Singh, MD, MPH, MS