Mild hypothermia = core temp 32-35C
Moderate hypothermia = 28-32C
Severe = <28C
Consequences of hypothermia
CNS effects
- Confusion, sedation, increased seizure threshold
Respiratory effects
- Decreased MV
- Alkalosis
- Increased O2 solubility and OHDC left-shift
Cardiovascular effects
- \(\downarrow\)HR and inotropy \(\to \ \downarrow\)CO
- QT prolongation, osborn waves
- Defibrillation-refractory arrhythmias
Haematological effects
- Increased viscosity
- Coagulopathy
Metabolic effects
- Decreased metabolic rate, VO2
- Hyperglycaemia due to \(\downarrow\)consumption
Pharmacological effects
- Decreased absorption
- Decreased metabolism
- Decreased renal/hepatic clearance
- Poorer receptor affinity (e.g. catecholamines)
Renal effects
- Impaired ADH synthesis \(\to\) diuresis
Attempts at thermoregulation
- Shivering
- Dermal vasoconstriction
- With prolonged hypothermia, dermal tissue damage \(\to\) reactive hyperaemia \(\to\) vasodilation \(\to\) decompensation