It is general knowledge that extreme cold temperatures have negative effects on our bodies. As I switched on the television this morning, and browsed through the channels, there was one topic that was shared by most of the channels; the Arctic Blast that is affecting about two thirds of the American population during this Christmas holiday period. None of the warnings mentioned in these channels were about the health hazards of extreme cold temperatures, and so I decided to write and inform my readers about the medical implications of exposure to cold temperatures, especially extreme ones.
Death from accidental exposure to extreme cold temperatures occurs throughout the world in the winter season. It can also occur in regions with milder climates when individuals are not adapted to cold temperatures. The rate of survival and being neurologically intact in individuals whose body temperature has dropped, medically known as hypothermia, is about 60%. Hypothermia is defined as a core body temperature below 35°C (95°F), and there are 4 stages, which have important implications on diagnosis and treatment. Mild hypothermia is defined as core body temperature between 32 to 25 °C (90 to 95°F), moderate hypothermia is core temperature of 28 to 32 °C (82 to 90°F), severe hypothermia is core body temperature of < 28°C (82°F), and profound hypothermia is core body temperature of < 24 °C (75°F).
There are also clinical stages that can give an indication of the core body temperature. Cold stress (not hypothermia) presents with shivering and normal mental status, and the individual is able to function normally, and the estimated temperature would be 35 to 37 °C (95 to 98.6°F). Mild hypothermia individuals are alert but the mental status might be altered, functioning abnormally and shivering is present. These individuals are not able to care for themselves and the estimated body core temperature is 32 to 35 °C (90 to 95°F). Moderate hypothermia presents with a decreased level of consciousness, and might be unconscious, with or without shivering, and the estimated core body temperature would be 28 to 32 °C (82 to 90°F). Severe and profound hypothermia patients are unconscious and do not shiver and the estimated core temperature would be < 28°C (82°F)
Apart from exposure to cold temperature outdoors, hypothermia can also occur secondary to cold water submersion, medical conditions such as underactive thyroid, alcohol abuse and medications such as sedatives, hypnotics and those used to lower blood glucose. Medications lead to an inability to autoregulate the core body temperature and is common among older people.
Hypothermia is diagnosed by using low reading electronic or glass thermometers. The standard thermometers generally do not read below 34°C (93°F). Mild to moderate hypothermia can cause the heart to go into serious abnormal rhythms leading to cardiac arrest. The initial management is directed towards resuscitation and rewarming. Patients with respiratory distress or who cannot protect their airway will need endotracheal intubation. Drop in blood pressure is common, and aggressive fluid resuscitation is frequently required.
Mild hypothermia patients will require passive external rewarming. The patient is covered with blankets or other insulation materials and the room temperature should be maintained at around 28°C (82°F). In moderate hypothermia, active external rewarming is required, and this consists of a combination of warm blankets, radiant heat or warm air applied directly to the patient. Rewarming of the trunk should be done first before rewarming the legs and arms to reduce the risk of drop in blood pressure.
In severe hypothermia, warm intravenous fluids will be required, and endovascular rewarming catheters might be required. In patients who fail to rewarm, extracorporeal blood rewarming techniques might be used, in addition to other invasive techniques like extracorporeal membrane oxygenation and cardiopulmonary bypass. Patients with severe hypothermia can easily develop cardiac arrest and cardiopulmonary resuscitation should continue until the patient is rewarmed to 30°C (86°F)
It is obvious from the above information about hypothermia, that prevention is better than cure. With that being said, I wish you Happy Holidays and a Happy New Year and stay safe.