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patients begin to emerge from anesthesia, we may be overlooking the
importance of temperature fluctuations during the hours leading up to
that point. The fact that a patient is normothermic at the end of sur-
gery doesn't tell us much about temperature changes that might have
occurred during surgery, or how long they might have lasted.
More common than you think
Many randomized studies show that hypothermia increases the risk of
various serious complications, including coagulopathy, wound infec-
tion and prolonged hospitalization. This explains why active intraop-
erative warming is now the standard of care. A reasonable question,
though, is how well active warming maintains core temperature in
typical clinical environments.
We evaluated core temperatures in more than 50,000 adults who had
non-cardiac surgery at the Cleveland Clinic (results presented at the
2013 annual meeting of the American Society of Anesthesiologists).
None were pre-warmed, and all were warmed intraoperatively with
forced air. Nearly all patients were at 36°C or higher at the end of sur-
gery. But what we found was that hypothermia was surprisingly com-
mon during surgery.
• 29% of the patients were less than 35.5
°
C at some point during sur-
gery.
• Nearly half of the patients had continuous core temperatures
below 36
°
C for more than an hour, and 20% were below 35.5
°
C for
more than an hour.
• 20% of patients had continuous core temperatures below 36
°
C for
more than 2 hours, and 8% were below 35.5
°
C for more than 2 hours.
These results are sobering, since most clinicians assumed that
forced-air warming kept nearly all patients normothermic. A more
accurate statement is that patients warmed with forced air are usually
P A T I E N T W A R M I N G
