Epidural anesthesia decreases the core temperature triggering vasoconstriction and shivering, presumably by increasing apparent lower-body temperature. We therefore tested the hypothesis that epidural anesthesia in cesarian delivery patients decrease forearm-fingertip skin-surface temperature gradient and it is cause of shivering.

Twenty-two healthy pregnant women were studied. Epidural anesthesia was induced by 2% lidocaine and 0.75% ropivacaine 24 ml (T4 level) at 25℃ ambient temperature. Shivering were evaluated by observation. Core temperature was recorded in the external auditory canal using a compensated infrared thermometer. Arteriovenous shunt tone was evaluated with forearm- fingertip temperature gradients; gradients less than 0 were considered evidence of vasodilation. Skin-surface temperature, skin- temperature gradients (forearm-fingertip, calf-toe) and the presence or absence of shivering were measured.

Shivering was observed in seven of twenty two patients. Sixty minutes after induction, Tympanic temperature decreased for 0.8 ± 0.1℃ in non-shivering patients and 0.9 ± 0.1℃ in shivering patients. Forearm temperature decreased for 0.2 ± 1.7℃ in non-shivering patients, but increased for 0.5 ± 0.6℃ in shivering patients. Upper limb (Forearm-fingertip) skin Temperature gradients continues the plus in non-shivering patients, but maintain minus (45 minutes after induction) in shivering patients. Low limb skin temperature is increases in both group.

We failed to confirm our hypothesis, but for an expected reason: shivering was preceded by hypothermia and vasoconstriction in the arm. For prevention of hypothermia in epidural anesthesia, not to be monitored core temperature, but also upper limb skin temperature gradients.