Human body temperature is tightly controlled between 36.5 degree Celsius to 37.5 degrees Celsius by the thermoregulatory zone in the hypothalamus. Heat is constantly produced in the body by processes like metabolism, muscle work and is lost through radiation, conduction, convection, and evaporation. The balance of core body temperature around 37 degrees Celsius is possible due to the constant balance of heat production and loss via the aforementioned mechanisms.
Hypothermia is a condition where the body’s core temperature drops below 35 degrees Celsius. In this condition, the body’s mechanism of mentioning core body temperature is overwhelmed. The two most active heat-producing organs-liver and heart- produce less heat lowering the body temperature by giving out more heat than what is produced in the body.
This imbalance of temperature is s most common during the autumn and winter months of October to February.
Cold kills more people than hot weathers do. Every year in the United States alone more than 700 people die due to hypothermia and this morbidity is seen more in infants and old age rather than other age groups.
What are the different classifications and causes of hypothermia?
Hypothermia is classified based on its cause into accidental or intentional the reason of its onset by primary or secondary.
Accidental Hypothermia occurs from an unanticipated exposure to cold temperature. It occurs to a person poorly prepared for his/her exposure in the cold air, water, wind, or rain. Some of the common situations that a person might accidental hypothermia are someone caught in a snowstorm and a homeless person.
Intentional hypothermia is a medically induced state to lower body temperature. This is usually done to avoid complications related to hypothermia. It is usually induced in patients after a life-threatening emergency like cardiac arrest and severe head injury. It is induced in a body by two general methods; surface cooling and endovascular cooling.
Primary and secondary hypothermia is classified based on its onset in a human body. If the hypothermia is caused due to environmental factors and the person has no underlying medical condition that might have disrupted the homeostasis of temperature, it is called primary hypothermia.
If the body temperature lowers due to medical illness then it is classified as secondary hypothermia. The medical conditions that usually result in secondary hypothermia are the conditions that interfere with the hypothalamus’s control. Examples of these medical conditions are poisoning, metabolic disorder, or central nervous system disorder.
How does hypothermia develop?
Failure to produce enough heat to maintain the body temperature stressed the body and if the factor lowering the body temperature continues the body becomes fatigued and is unable to generate heat.
Stages of hypothermia
When a body’s temperature decreases below its normal range, the thermoreceptors direct the brain to take necessary measures to maintain homeostasis. Failure to do so will result in hypothermia which proceeds in a body in five stages.
Stage One – Mild Hypothermia
The core body temperature during this period is between 35 degrees Celsius to 37.5 degrees Celsius. The person will feel cold and a little numbness in the body’s extremities. Minor muscular impairments might also be experienced but the mental state of the person is normal.
Sage Two – Moderate Hypothermia
The core body temperature during the second stare is between 32 degrees Celsius to 35 degrees Celsius. The body shivers to produce heat to maintain the core body temperature. The person will feel fatigued and will experience difficulty in coordination. It appears as if the person is drunk in this stage.
Stage Three – Moderate Hypothermia
The core body temperature reaches between 32 degrees Celsius to 28 degrees Celsius. The body uncontrollably shivers in response to the lowering body temperature. The patient experiences increase mental confusion and difficulty to stand or move. The skin appears pale and the heart rate and respiration increase.
Stage Four – Severe Hypothermia
The estimated core body temperature drops below 28 degrees Celsius. There is no shivering. The skin turns blue and the body collapses. The pulse rate and breathing are very difficult to detect during this stage. The body does not respond to pain. This stage is also termed as ‘apparent death’.
Stage Five – Severe hypothermia
In this last stage of hypothermia, the body temperature drops so low that it is almost impossible to resuscitate. The hypothermia is irreversible and the person usually goes under a cardiac arrest and dies.
What are the symptoms of hypothermia?
The symptoms of hypothermia are very subtle and are usually mistaken for other medical conditions. In the case of mild to moderate hypothermia, the symptoms match with alcohol intoxication and stroke whereas, for severe hypothermia, the symptoms match with cardiac arrest and coma.
The most important symptom to be checked to rule out hypothermia is to check the core body temperature, usually through a rectal thermometer. The other common early symptoms of hypothermia include:
- Felling Cold
- Altered muscle coordination
- Pale or blue-gray skin
- Slurred speech
- Numbness in body extremities
The late symptoms of hypothermia include:
- The whole body is very cold, even the trunk
- The person is unable to move muscles
- Slow pulse
- Slow breathing
- Loss of consciousness
- Shivering may stop
What are the investigative methods for hypothermia?
Hypothermia is a condition where the temperature of the body is lower than 37.5 degrees Celsius. This drop in temperature is the main way this condition expresses itself in the body but to confirm if the patient has hypothermia there are a few tests that can be done.
- A full blood count is done to check the packed cell volume of the patient. This volume increases as the core body temperature decreases.
- Hypothermia usually causes coagulopathy. This is why a patient suspected of hypothermia is tested for coagulation of his/her blood.
- Electrolytes of a body are also tested as hypothermia in many causes renal failure due to low cardiac output.
- Electrocardiography is also performed to detect the J wave which confirms atrial fibrillation. Hypothermia decreases depolarization of the pacemaker in the heart decreasing the mean arterial pressure and output.
- The functioning of thyroid glands is testes as hypothyroidism is a common precipitant of hypothermia.
- Glucose level is checked as acute hyperthermia causes hyperglycemia
Adequate preparation is the main preventive method to avoid accidental hypothermia. Clothing according to the weather helps in insulating the body from the cold and thus prevents excessive loss of body heat to the environment.
1. In addition to choosing the proper clothing material, it is also important to make sure that the clothes are not tight.
2. Tight clothing reduces the circulation of warm blood and may aid hypothermia.
3. The heating system should be managed to keep the environment warm.
4. A fire or house heating system should be managed. It is also advised to sip a warm drink when exposed to cold temperatures.
5. Another important thing to keep in mind is to not overexert our body as it will cause loss of heat rather than conserve it. Avoiding alcohol is also advised as it can disrupt temperature homeostasis.
How is hypothermia treated?
The main aim while treating any stage of hypothermia is to prevent further loss of heat by radiation, convection, conduction, or evaporation. The intensity of treatment of hypothermia changes according to the patient stage. Mild to moderate hypothermia can be treated by
- Changing wet clothes for dry alternatives
- Insulating the person with layers of warm clothes and blankets
- Providing hot beverages
- Encourage gentle exercise
- Provide hot packs and external heat sources if the person is unable to move
- Skin to skin heat is also effective
Once the patient goes beyond moderate hypothermia, these simple treatments will no longer produce enough heat to warm their bodies. The body will have started collapsing and therefore specialized care is needed.
The treatment for severe hypothermia are:
- The pulse and respiration has to be monitored closely for a full minute as it is difficult to detect
- All the measures to reduce heat loss should be adopted for mild hypothermia.
- Handling of these patients should be done gently to prevent arrhythmias
- Warmed intravenous fluids also help in bring up the body temperature
- Inhaling warm air
- Application of extracorporeal rewarming
How to provide first aid to a hypothermic body?
Hypothermia occurs due to a loss in body heat and therefore while providing first aid to a person suffering from hypothermia the following steps must be followed until help arrives:
- Take the person to a safer place and change any wet cloth
- Cover their body with warm blankets and ask them to add layers of clothing
- If the person is conscious and able to move, ask them to perform light exercises that will help in heat production but make sure that the person is not sweating as this furthers heat loss
- Give them warm fluids if possible
- Rub the extremities like hands and sole of their foot
- If no other means of additional heat is available, skin to skin heating also helps a hypothermic person
- Check for their breaths and pulses. If the person shows no sign of heartbeat or respiration for one full minute, perform CPR.
Further heat loss must be avoided as the degrading condition in hypothermia causes reduced blood flow and the body’s organs start shutting down. The brain will grow colder and is at risk of permanent brain damage.
What is the difference between Hypothermia vs Hyperthermia?
Hypothermia and hyperthermia sound similar but are two contrasting temperature conditions in a body. As seen in the component of the two words, hypo, and hyper, it means low and high respectively. Consequently, it means that a person has hypothermia, he/she has a body temperature lower than the temperature at homeostasis but a person suffering from hyperthermia has a body temperature higher than expected.
Hypothermia occurs when a person is exposed to cold temperature for a period that exhausts the body compensating for the heat loss and is no longer able to keep up the heat production. As a consequence, the core body temperature decreases and causes symptoms like shivering, pale or blue skin, slurred speech, and low pulse and treating.
Hyperthermia on the other hand occurs on hot humid days and usually when a body is physically exerted. The body loses a lot of electrolytes and fluids during hot days. The body then becomes dehydrated and is no longer able to release enough heat. People suffering from hyperthermia will have an elevated body temperature with other symptoms like heat cramps, exhaustion, and heatstroke.
How hypothermia and shock differ?
The symptoms of severe hypothermia and shock are similar as the patient has an irregular heartbeat, unable to stand, breaking is altered, and eventually loses consciousness. Both of these conditions create dysfunction of the brain, muscle, and heart but these are two completely different things occurring in a body.
Hypothermia occurs as the body is no longer able to compensate for the heat it is losing whereas shock occurs due to trauma caused in the body. It can occur at any temperature, hot or cold, and the body does not respond to additional heat being provided.