Body temperature

Question 1

hypothermia definition

Answer 1

Mild hypothermia: 32-35°C

Moderate or severe hypothermia: < 32°C

Question 2

causes of hypothermia

Answer 2

Exposure to cold in the environment is the major cause

Inadequate insulation in the operating room

Cardiopulmonary bypass

Newborn babies.

Question 3

risk factors for hypothermia

Answer 3

General anaesthesia

Substance abuse

Hypothyroidism

Impaired mental status

Homelessness

Extremes of age

Question 4

signs of hypothermia

Answer 4

shivering

cold and pale skin. Frostbite occurs when the skin and subcutaneous tissue freeze, causing damage to cells.

slurred speech

tachypnoea, tachycardia and hypertension (if mild)

respiratory depression, bradycardia and hypothermia (if moderate)

confusion/ impaired mental state

Question 5

babies with hypothermia features

Answer 5

Babies with hypothermia can look healthy. However, they may be limp, unusually quiet and refuse to feed.
Heat loss in newborns is extremely common, hence a hat and clothing/ blankets will be applied soon after birth.

Question 6

investigations for hypothermia

Answer 6

Temperature. Special low-reading rectal thermometers or thermistor probes are preferred for measuring core body temperature. The patient’s temperature should be tracked over time, to check for improvement.

12 lead ECG. As the core temperature approaches 32°C to 33°C, acute ST-elevation and J waves or Osborn waves may appear

FBC, serum electrolytes. Haemoglobin and haematocrit can be elevated (due to haemoconcentration). Platelets and WBCs are low due to sequestration in the spleen. 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

Question 7

ECG of hypothermia

Answer 7

bradycardia

‘J’ wave (Osborne waves) - small hump at the end of the QRS complex

first degree heart block

long QT interval

atrial and ventricular arrhythmias

Question 8

initial management of hypothermia

Answer 8

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

Question 9

management of severe hypoglycaemia

Answer 9

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.

Question 10

causes of malignant hyperthermia

Answer 10

The most common cause is an autosomal dominant mutation in the ryanodine receptor 1, increasing calcium levels in the sarcoplasmic reticulum and increasing metabolic rate.

causative agents: halothane, suxamethonium, antipsychotics

Question 11

presentation of malignant hyperthermia

Answer 11

Patients typically present at the induction of general anaesthesia with increased body temperature, muscle rigidity, metabolic acidosis, tachycardia, and increased exhaled carbon dioxide.

Question 12

management of malignant hyperthermia

Answer 12

Malignant hyperthermia is managed by: stopping the triggering agent, administrering intravenous dantrolene (a ryanodine receptor antagonist) and restoring normothermia.

Question 13

definition of malignant hyperthermia

Answer 13

Malignant hyperthermia is a life-threatening syndrome triggered by inhalation anaesthetics or suxamethonium.

Question 14

investigations of malignant hyperthermia

Answer 14

CK raised

contracture tests with halothane and caffeine