I found some information in regards to Anesthesia, Microsvascular flap surgery, and temperature:


Temperature

In addition to vasoconstriction, hypothermia is also responsible for increased viscosity and hematocrit, platelet and red blood cells aggregation, which can reduce the microcirculation in the flap. Thus, the patient should be kept warm in the operating room, ICU, and the first 24 to 48 hours. This can be achieved by increasing the room temperature and using forced air heater. Active heating should start before the onset of anesthesia, as the patient rapidly cools after induction6.

Warming

Intuitively, it makes sense to keep these normothermic patients with active warming to prevent increased viscosity and vasoconstriction. Normothermia maintenance may be difficult with large areas exposed for prolonged periods, associated with fluid and blood loss. Furthermore, anesthesia changes the thermoregulatory mechanisms.

In the '80s, some studies of animals have confirmed the deleterious effects of hypothermia on viscosity and flow of pedicle and free flaps20. There are few studies of the effects of hypothermia on flap blood flow in humans, perhaps because it may be unethical. However, there are reports of flaps that survived hypothermia associated with cardiac bypass 14.

Central and peripheral temperature must be monitored and the ideal difference (Δt) between them should be less than 1ºC. The (Δt) can reflect the volemic status of a patient4.

Active heating (solution heaters, blanket with forced hot air) should be initiated as soon as possible and cover the greatest possible extent. If possible, the room temperature must be increased to 22º-24ºC, a temperature that reduces heat loss from the patient and is not uncomfortable for the surgical team 6.

You can read the full article here:

http://www.scielo.br/pdf/rba/v62n4/en_v62n4a11.pdf