This third and final article about the review by Haman et al. discusses, among other things, the prevention or limitation of cold injuries. This requires insight into the different cold conditions that can lead to these injuries. To work safely in the cold, it is necessary to combine information about temperature, humidity, wind strength, duration of exposure and the type of activity being performed.

This is a follow up to:

• Cold injuries and regulation mechanisms (2)
• Individuals and cold conditions (1)

Watch for signals

It is also important to pay attention to signs: if you start shivering, you run a direct risk of hypothermia and cold injury if the cause of the heat loss is not addressed. It is a signal to take action in the form of better clothing or seeking protection in a warmer environment. Early detection of signs of cold injury such as cooling, pain and loss of feeling in hands and feet are important as a sign of greater vulnerability. Timely treatment of cold injuries can prevent a lot of suffering in the future.

Balance in clothes

When looking for the most suitable clothing that protects against the cold, it is important to find a balance between insufficient protection against heat loss and sufficient possibility to remove perspiration as a result of physical exertion. Good protective clothing can be sufficiently permeable to wick away moisture during exercise, but must insulate sufficiently to optimally protect against cooling in strong winds (wind chill). It is also very important to prevent cooling of the head, ears, cheeks, feet and hands as much as possible.

Cold injuries without frostbite

To prevent cold injuries without frostbite, people should be aware of the risk and avoid prolonged periods of exposure to cold and wet. According to research, for example, you should think of 12 hours a day and four days in a row. It is important to keep hands and feet dry: so when working wet, put on dry socks and gloves regularly and air-dry hands and feet for at least 8 hours a day. The latter advice also applies to exposure to warm, wet conditions. (see for example Trench foot in the car wash)

Protection of the feet and hands in the cold should not be too tight. Shoes and clothing that are too tight can restrict blood flow and should be avoided. It is also important to remain physically active when exposed to low temperatures. Research has shown that 15-20 minutes of physical activity is enough to increase foot and toe temperature. It is not entirely clear whether previous experience of a cold injury has an influence on this.

Cold injuries with frostbite

Where the damage from cold injuries without frostbite is often difficult to determine, cold injuries with frostbite cause permanent tissue damage. In severe cases, this can lead to, for example, gangrene and amputation may be necessary. In the tissue that does recover, signs of neuropathy and damaged blood vessels often remain. These deviations mean that you are less well protected against new cold exposure.

Thermal sensation and thermal comfort

Of major importance to the psychological response to cold exposure is thermal sensation and thermal comfort. Thermal sensation is the comfort experienced by people at a certain (usually indoor) temperature: how hot or cold does the body feel under the given circumstances. Thermal comfort is mainly related to body temperature and says something about satisfaction with the ambient temperature. They are subjective measures that are difficult to define, but they do determine the behavior of people (and animals).

Although thermal sensation and thermal comfort are closely related, they are somewhat different. For example, thermal comfort mainly receives feedback on core temperature, while thermal sensations also respond to cooling of certain parts of the body. Nevertheless, a 1°C decrease in core temperature or skin temperature produces a similar change in perceived thermal comfort. This despite the large differences in responses to these temperature drops (such as shivering versus vasoconstriction). There are large differences between individuals in perceived thermal sensation, thermal comfort and responses to cold.

Conclusions of the review in its entirety

The review by Haman et al. shows that:

1. Every person runs a high risk of cold injury without adequate knowledge and protective equipment
2. It is essential to understand that there is a wide variation between individuals in physique, body composition and metabolism, which means that there are also large differences in cold injury risks.

When the body is exposed to cold, it has to find a balance between heat production and heat loss. In the first instance, these are circumstances that are compensable and where cold injuries can be prevented. Individual characteristics such as age, race, sleep deprivation, dehydration and previous cold injuries can make people vulnerable to cold exposure. To prevent problems, protection against the cold (clothing, shelter), food, sufficient moisture, etc. is necessary. In addition, people can adapt (to a limited extent) to cold conditions through acclimatization.

Cold injuries

The main causes of cold injuries without frostbite are sustained exposure to temperatures between 10 and 25 degrees Celsius with or without wet conditions. The injuries can occur anywhere, but the feet are the most vulnerable. Diagnosis is based on history, physical examination and classification of the lesion. Cold injuries without frostbite have four stages depending on the duration of exposure, color of the skin, etc. Treatment can only be done by taking people out of the cold and moisture in these injuries. To prevent the development of severe cold sensitivity, prevention of cold injuries without frostbite is the most important approach.

Cold injuries with frostbite are associated with temperatures around the freezing point of tissues, which is −0.55 °C. These injuries can also have four stages, two of which are superficial and two are deep and therefore more serious. The tissue damage must be mapped, but in the end a lot depends on the first aid that is given. This largely determines the prognosis. Prevention is also very important in these cases and it is good to know that individual sensitivity to cold can vary greatly.

Source

Haman, F., Souza, SC, Castellani, JW, Dupuis, MP, Friedl, KE, Sullivan-Kwantes, W., & Kingma, BR (2022). Human vulnerability and variability in the cold: Establishing individual risks for cold weather injuries. Temperature, 1-38.

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