Thermoregulation in the Perioperative Period

Question 1

why are patients more likely to become hypothermic whilst under anaesthetic?

Answer 1

• cannot mount their normal behaviour responses to the cold
• minimum clothing in surgery

Question 2

what are the risk factors for perioperative hypothermia?

Answer 2

• ASA grade of 2 or above
• major surgery
• low body weight
• large volumes of unwarmed IV infusions
• unwarmed blood transfusions
• use of muscle relaxants (prevents shivering)
• spinal or epidural anesthesia (prevents peripheral vasoconstriction)

Question 3

what can be done intra-operatively to avoid hypothermia?

Answer 3

• ‘bair hugger’ = forced air warming device
• warm fluid volumes

Question 4

what are the complications of perioperative hypothermia?

Answer 4

• coagulation - reduces clotting
• prolonged recovery from anaesthesia
• reduced wound healing
• infection
• shivering

Question 5

how does spinal or epidural anaesthetic increase risk for hypothermia?

Answer 5

• prevents peripheral vasoconstriction via reduced sympathetic tone
• inceased heat loss at the peripheries