We lose 45 percent of our heat through our head, is a myth! Cold related injuries range from mild frostnip to life threatening frostbite. Proper gear and awareness are key to preventing cold related injuries.
Dear Doc, Q. I recently bought a book on enjoying winter in Upstate NY. I took my son sledding but before leaving, he gave me a hard time about wearing a hat and gloves. I told him we lose 45 percent of our heat from our head and he agreed to wear a hat. Unfortunately, he took his gloves off and came back with some cold sore hands that felt better in a few hours. Do you think he had frostbite?
A. Living in Upstate NY, you better learn to play in the winter. You gave good advice to cover up with hats and gloves. Part of your advice, although good, is based on a myth! The origins of this myth have been traced to the advice of an US Army Survival Manual in the 1970s which recommended covering the head when in the cold since “40 to 45 percent of body heat” is lost from the head. The Army based this on a flawed study that had volunteers dressed in Artic suits and exposed them to bitter cold conditions. Because it was the only part of their body uncovered most of their heat was lost through their heads! If they had been naked, their bodies would have lost only about 10 percent of their heat through their heads, as the remaining 90 percent would escape through the rest of their exposed body.
Don’t worry, the advice of wearing a hat is still sound, and considering the advice I give my own children, you get a total pass.
When enjoying winter, it is important to protect against the elements to avoid cold weather injuries, which may occur even if the temperature is above freezing. There are injuries that occur without the freezing of body tissue, such as chilblains, trench foot, and frostnip. Frostbite occurs when there is freezing of body tissue.
Chilblains typically develop because of an abnormal blood vessel response that occurs after being exposed to the cold and then being rewarmed. Chilblains are itchy, painful, reddish areas that may develop on the fingers, toes, nose or ears. They may last for several days to weeks. The affected area may remain sensitive to the cold but there is usually no permanent damage.
Trench foot was named after the condition that developed in soldiers who spent time in the trenches of World War I. Trench foot develops after feet have prolonged exposure to a wet, cold environment. Pain, itching, numbness and swelling may occur as the foot may turn red or pale. Trench foot may take weeks to resolve and can lead to more severe tissue injury.
Frostnip is a mild injury that typically affects the face, ears, toes and fingers. After exposure to cold the affected area may appear pale and have a sensation of burning, numbness or tingling. Simple rewarming restores normal color and sensation without permanent damage.
Frostbite, a more serious cold weather injury, occurs when there is freezing of body tissue. This type of injury results from decreased blood flow to the affected area resulting in damaging ice crystal formation, which leads to skin cell death and tissue damage. Skin turns white or blue and feels hard and frozen. There may be significant numbness initially with significant discomfort upon rewarming of the area. Severe frostbite may lead to loss of digits and can be a life threatening emergency if infection develops.
Cold weather gear, staying dry, and being aware of signs and symptoms are key to preventing cold weather injuries. If a cold injury does develop, treatment consists of moving out of the cold, removing wet clothing and rewarming the affected area. For the more severe frostbite, early medical attention is recommended to prevent permanent damage to tissues.
From your description it sounds like your gloveless son had a case of frostnip that resolved with simple re warming. Hopefully, as you continue to use your new book to enjoy the winter, your son will glove up to avoid future cold weather injury. In the meantime, I will be by a warm fire reading a book on how to be a better parent!
Stay healthy and remember the quote by Anthony D’Angelo, “Wherever you go, no matter what the weather, always bring your own sunshine.”
— Dr. Arun Nagpaul is a medical doctor and is board-certified in Internal Medicine. He currently is the Medical Director at Newark-Wayne Community Hospital and also serves as the Medical Director for Wayne County Public Health, Wayne County Nursing Home and Blossomview Nursing Home. This column is meant to be educational and not intended to be used to make individual treatment decisions. Prior to starting or stopping any treatment, please confer with your own health care provider. To send questions, please email Dr. Nagpaul at Arun.Nagpaul@rochestergeneral org and put “Ask a Doc” in the subject line.