Perioperative hypothermia during regional anaesthesia can be as severe as that seen with general anaesthesia, because it also significantly impairs thermoregulatory responses.
- Central effect. Loss of afferent input from cold receptors impairs the central thermoregulatory response.
- Redistribution. Blockade of sympathetic vasoconstriction causing redistribution hypothermia in the lower half of the body, means that the initial temperature drop will be about half that seen with GA. Blockade of motor nerves impairs shivering.
- Lack of core temperature plateau because of blocked vasoconstriction