Hypothermia

What is Hypothermia : Definition

Hypothermia is a medical condition in which the body’s core temperature drops below 35.0 °C or 95.0°F. When this occurs, the body experiences faster heat loss than being able to produce heat. This results to significant and dangerously low body temperature [1].


Usually, this happens as the body’s compensatory mechanism to overwhelming cold stressor.[2] The body’s normal body temperature is about 37°C or 98.6°F.[1]

Hypothermia Stages

The stages of Hypothermia are based on how low the body temperature is and the symptoms felt by an individual with this condition. Here are the stages of Hypothermia:

Mild Hypothermia

  • Body Temperature: 32-25°C
  • Persistent shivering
  • Pallor
  • Cold skin
  • Fatigue
  • Hyperventilation (fast breathing)

Moderate Hypothermia

  • Body Temperature: 28-32°C
  • Uncontrollable shivering
  • Hypoventilation (shallow and slow respiration)
  • Drowsiness
  • Incoherent or confusion
  • Slurring of speech
  • Unable to focus
  • Reasoning and judgement problems
  • Coordination problems
  • Unable to move freely

Severe Hypothermia

  • Body Temperature: lower than 28°C
  • Comatose
  • Absence or shallow respiration
  • Irregular weak pulse or absence of pulse
  • Irregular heart rhythm (dysrhythmia)
  • Pupil dilation
  • Death[3]

Hypothermia Causes

Decreased Heat Production

1. Endocrine DisordersSome of the problems with the endocrine system cause decreased production of heat in the body. These include:

  • Hypothyroidism
  • Hypopituitarism
  • Hypoadrenalism

2. Other causes of decreased production of heat:

  • Hypoglycemia
  • Severe malnutrition
  • Neuromuscular problems common in elderly

Increased loss of heat

1. Accidental Hypothermia

This is considered as the most common cause of Hypothermia.

  • Immersion: Diving or swimming in cold water, inadequate warming prior to repetitive diving, boating accidents
  • Non-immersion: Dehydration, anorexia, alcohol and substance abuse, poor clothing, cold environment, homelessness

2. Induction of vasodilation

  • Toxicologic agents
  • Pharmacologic agents

3. Skin conditions

Certain conditions of the skin may lead to impairment in the body’s ability to preserve heat. These are:

  • Psoriasis
  • Burns

4. Iatrogenic etiologies

  • Emergency deliveries
  • Over treatment of heatstroke
  • Cold infusions

Impaired Thermoregulation

1. Hypothalamic problems

This is commonly associated with impaired thermoregulation of the body due to the inability of the hypothalamus to normalize it.

  • CNS disorders: stroke, CNS tumors, Wernicke disease, Multiple Sclerosis, Parkinson’s Disease, intracranial bleeding
  • Metabolic disorders
  • Toxicologic agents

Other Causes

1. Drug administration

There are certain medications that impair the body’s ability to react properly to low temperatures.

  • Betablockers
  • Neuroleptics
  • General anesthetic agents
  • Sedatives

2. Chronic medical conditions

  • Prolonged cardiac arrest
  • Sepsis
  • Uremia[1, 2, 4]

Hypothermia Pictures

Picture 1: How the body losses heat
Source: Princeton.edu

Picture 2: A patient with Hypothermia
Source: alliedhealthworld.com

Picture 3: Progression of Hypothermia
Source: cbc.ca

Picture 4: Hypothermia in cold water immersion
Source: mail.boat-ed.com

Picture 5: Hypothermia first-aid treatment
Source: videojug.com

Hypothermia Treatment Protocol

The management of Hypothermia depends on its severity[4]. There are various treatment regimens which are directed towards rewarming the patient, close monitoring, and treatment of complications.

First Aid Treatment

1. Moving of the patient

  • Be gentle in handling a person with hypothermia.
  • Make sure to limit moving the person to prevent cardiac arrest from occurring.
  • Don’t rub or massage the person.
  • Remove the person from the cold location. Place the person in a dry and warm environment.

2. Maintain/Preserve the person’s body heat.

  • Remove wet clothes.
  • Cover the person with several layers of dry fabric (coats or blankets).
  • Apply dry and warm compress on the areas such as chest, neck, or groin. Remember to avoid from applying it directly to the skin.
  • Shield the body from the cold ground. Use a blanket to protect the body from the cold surface.
  • Share body heat by making skin-to-skin contact.
  • If the hypothermic person is conscious and can swallow, make the person drink warm beverage with no alcoholic and caffeine contents.

3. Monitor closely.

  • Look for absence of the breathing or pulse.
  • If the person is pulseless or not breathing, perform CPR.[1]

Emergency Management

1. Address airway, breathing, and circulation

  • Cardiopulmonary Resuscitation
  • If with respiratory failure, endotracheal tube is inserted. Then, the patient will be placed on mechanical ventilator.
  • Oxygen therapy through bag reservoir device

2. Rehydration

  • Intravenous Therapy

3. Restoration of body heat

  • Removal of the patient from cold environment to prevent rapid loss of heat. Also, wet clothing is replaced with dry one.
  • Placing of warm blankets to the patient.
  • For conscious patients, warm, sweet, and non-alcoholic drinks are given.[2, 5]

Hospital Care Management

1. Cardiac Drugs

  • Bretylium tosylate: Given for treating dysrhythmias
  • Dopamine: An inotropic drug administered for a hypothermic patient.

2. Oxygen therapy

  • 100% oxygen is given during the rewarming process
  • Administered for prolonged period of time.
  • This is performed to improve the patient’s cardiac perfusion.

3. Rewarming technique

  • Passive external warming: This is the generation of an individual’s ability to produce own heat. Examples include moving to warm environment and wearing of insulated dry clothes. This is advised for those who have mild hypothermia.
  • Active external warming: This type of rewarming process includes the use of warming devices like warmed forced air.
  • An alternative to this is hot water bottle. This is indicated for those who have moderate hypothermia.
  • Active core warming: Includes the usage of irrigation of body fluids with warmed fluids, warm humidified air, warmed intravenous fluids, and extracorporeal rewarming (heart lung machine).[2, 4, 5]

Therapeutic Hypothermia

There are some cases in which hypothermia is induced for the patient’s treatment. This is referred to as Therapeutic Hypothermia[3]. This medical treatment is performed to decrease the chances of obtaining ischemic tissue injury due to impairment of blood flow.

Mechanism of Treatment

There have been studies which suggest that small drop in the body’s temperature results in the stabilization of the cell membrane. When the body is deprived of oxygen supply, hypothermia minimizes the disruption of the body’s normal functioning, caused by lack or blockage of blood supply. Therefore, it minimizes ischemic injuries to the tissues.

Indications of Treatment

  • Cardiac Arrest
  • Cerebrovascular Accident (stroke)
  • Neurogenic Fever
  • Traumatic injury to the brain or spinal cord
  • Neonatal encephalopathy

Methods of Treatment

1. Invasive

  • Trans Nasal Evaporate Cooling
  • Cooling Catheters

2. Non-invasive

  • Leg wraps
  • Torso vest
  • Cool caps
  • Water blankets [6]

References:

  1. http://www.mayoclinic.com/health/hypothermia/DS00333
  2. http://emedicine.medscape.com/article/770542-overview
  3. http://www.nhs.uk/Conditions/Hypothermia/Pages/Symptoms.aspx
  4. https://en.wikipedia.org/wiki/Hypothermia
  5. http://www.patient.co.uk/doctor/Hypothermia.htm
  6. https://en.wikipedia.org/wiki/Therapeutic_hypothermia#Mechanism_of_neuroprotection

Published on by under Diseases and Conditions.
Article was last reviewed on September 7th, 2016.



Leave a Reply

Back to Top