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ers. Coagulopathy, for example, is presumably related to intraopera-
tive hypothermia, since platelet function — the initial defense against
surgical bleeding — is reduced at lower temperatures. In contrast,
vasoconstriction, which possibly facilitates myocardial injury and
wound infections, is likely largely a post-operative effect.
Rising to the challenge
Keeping patients normothermic intraoperatively remains a challenge,
especially when patients are neither prone nor supine. The lithotomy
position, for example, leaves a lot of skin exposed and with all surface-
warming methods, there is a direct relationship between the amount of
surface covered and the efficacy of the warming. To help meet the chal-
lenge, here's what I recommend:
1. Monitor diligently.
Temperature monitoring is the standard of care in
patients having general anesthesia lasting more than 30 minutes. The
only way to determine a patient's temperature is to measure it. In intu-
bated patients, the distal esophagus is an excellent monitoring site.
2. Warm effectively.
Actively warm patients under general anesthesia
throughout surgery in all but the shortest cases. Maintaining normother-
mia is the standard of care, but there is no requirement to use any spe-
cific method or combination of methods. Any method is suitable, so
long as it works. But that said, surgical patients rarely remain normoth-
ermic without some form of active warming.
3. Consider fluid warming.
Use fluid warming as a secondary warming
strategy for patients being given large amounts of fluid (1 to 2
liters/hour or more, for example).
The bottom line
Is there a magic number to strive for in warming? While people tend
to consider 36ºC (96.8ºF) the threshold for hypothermia, it should be
viewed as a laudable goal, rather than a cliff. It is just not the kind of
P A T I E N T W A R M I N G
