Hypothermia Flashcards
What is hypothermia?
an unintentional reduction of core body temperature below the normal physiological limits
Pathophysiology of hypothermia?
initial stages: thermoreceptors in the skin and subcutaneous tissues sense the low temperature and cause regional vasoconstriction
This cause the hypothalamus to stimulate the release of TSH and ACTH
also stimulates heat production by promoting shivering
Mild hypothermia temperature range?
32-35 degrees
Moderate or severe hypothermia?
<32 degrees
Epidemiology of hypothermia?
In the UK, the estimated annual number of hypothermia-related deaths is 300/year, whereas in Canada, it is 8000/year.
Hypothermia is most common during the winter, and the elderly are particularly susceptible (see further risk factors below). Many cases of hypothermia also occur indoors, due to poor heating facilities.
Causes of hypothermia?
Exposure to cold in the environment is major cause
inadequate insulation in the operating room
cardiopulmonary bypass
newborn babies
Risk factors of hypothermia?
General anaesthesia
Substance abuse
Hpypothyroidism
Impaired mental status
Homelessness
Extremes of age
Signs of hypothermia include?
shivering
cold and pale skin
slurred speech
tachypnoea, tachycardia and hypertension (if mild)
respiratory depression, bradycardia and hypothermia (if moderate)
confusion/impaired mental state
what is frostbite?
when the skin and subcutaneous tissue freeze, causing damage to cells
Babies in hypothermia?
they can look healthy
however, they may be limb, unusually quiet, refuse to feed
head loss in newborns is extremely common, hence a hat and clothing/blankets should be applied soon after birth
Investigations for hypothermia?
Temperature: tracked over time
12 lead ECG: as the core temperature approached 32 to 33, acute ST-elevation and J waves or Osborn waves may appear
FBC, serum electrolytes. Hb and haematocrit can be elevated. platelets and WBCs are low due to sequestration in the sleep. monitoring potassium is advised as hypothermic patients can be hypokalaemic due to a shift of potassium into the intracellular space
Blood glucose. stress hormones are increased, and the body can have more peripheral resistance to insulin
Arterial blood gas
Coagulation factors
Chest X-ray
Initial management of hypothermia?
Removing the patient from the cold environment and removing any wet/cold clothing,
Warming the body with blankets
Securing the airway and monitoring breathing,
If the patient is not responding well to passive warming, you may consider maintaining circulation using warm IV fluids or applying forced warm air directly to the patient’s body
Rapid re-warming can lead to?
peripheral vasodilation and shock
in severe cases, be prepared to conduct CPR.
IV drugs should be avoided if possible, as the patient is more likely to have a drastic response to the drug
For reference, the NHS also provides advice to the public for what NOT to do when a person has hypothermia (due to the risk of cardiac arrest):
Don’t put the person into a hot bath.
Don’t massage their limbs.
Don’t use heating lamps.
Don’t give them alcohol to drink.
