Hypothermia Flashcards
Define hypothermia.
Hypothermia is defined as a core body temperature < 35 degrees celsius and is divided into categories based on severity.
Mild = 32 - 35 degrees
Moderate = 28 to 32 degrees
Severe = < 28 degrees
What are the clinical features of mild hyperthermia?
- Shivering
- CNS - confusion, slurred speech
- Tachypnea
- Activation of SNS (tachycardia)
- Diuresis
What are the clinical features of moderate hyperthermia?
Temperature between 28 and 32 degrees
- Loss of shivering
- CNS - stupor
- Dilated pupils
- Hypoventilation
- Increased risk of arrhythmias
- Bradycardia, hypotension, decreased CO2, peripheral vasoconstriction
- ECG - J or Osborne waves
- Coagulopathy - decreased platelet function, decreased coagulation cascade activation
What are the clinical features of severe hyperthermia?
- CNS - coma
- Decreased EEG activity
- Fixed pupils
- Pulmonary edema
- Arrhythmias - spontaneous asystole/VFib
- Decreased myocardial contractility, hypotension
- Oliguria
What is the differential diagnosis for hypothermia?
- Decreased heat production (hypopituitarism, adrenal insufficiency, hypothyroidism, malnutrition, hypoglycemia)
- Increased heat loss (exposure, iatrogenic, burns, drug-induced)
- Impaired thermoregulation (CNS trauma, strokes, intracranial bleed, Parkinson’s)
- Therapeutic hypothermia (postcardiac arrest, post stroke)
Who is at elevated risk for perioperative hypothermia?
Very young or elderly
Those undergoing emergency surgery
Prolonged surgery
Low preoperative temperature
What is the management of hypothermia?
- Verify temperature and severity of hypothermia
- Assess need for intubation or hypothermia
- Rewarm (forced-air warming systems), warmed IV fluids, warm fresh gas flow
- Correct electrolytes as required (hypo or hyperkalemia; hypo or hyperglycemia)
- Correct fluid deficit
- Treat coagulopathy as required
- Consider need for invasive core rewarming: gastric/peritoneal/thoracic lavage, CPB, ECMO
- If Vfib - perform CPR and treat with defibrillation and antiarrhythmics but these may be ineffective at core temperatrures < 30 degrees C - consider CPB if available.
- Postoperative shivering - rewarm, treat with opioids or alpha-2 agonists
How would you treat ventricular fibrillation in a hypothermic patient?
Perform CPR and treat with defibrillation and antiarrhythmics but these may be ineffective at core temperatrures < 30 degrees C - consider CPB if available.
