THURSDAY, July 8 (HealthDay News) -- Inhaled anesthetics used to
put patients to sleep during surgery contribute to global climate
change, according to a new study.
Researchers determined that the use of these anesthetics by a
busy hospital can contribute as much to climate change as the
emissions from 100 to 1,200 cars a year, depending on the type of
anesthetic used, said University of California anesthesiologist Dr.
Susan M. Ryan and fellow study author Claus J. Nielsen, a computer
scientist at the University of Oslo in Norway.
The three major inhaled anesthetics used for surgery --
sevoflurane, isoflurane, and desflurane -- are recognized
greenhouse gases, but their contribution to climate change has
received little attention because they're considered medically
necessary and are used in relatively small amounts.
These anesthetics undergo very little metabolic change in the
body, the researchers noted. When they're exhaled by patients,
they're almost exactly the same as they were when administered by
anesthetist. The anesthetics "usually are vented out of the
building as medical waste gases," the study authors wrote in a news
release. "Most of the organic anesthetic gases remain for a long
time in the atmosphere where they have the potential to act as
greenhouse gases."
Desflurane has a 10-year "lifetime" in the atmosphere, compared
with 3.6 years for isoflurane and 1.2 years for sevoflurane. When
they factored in the flow rates at which the different anesthetics
are given, the researchers calculated that desflurane has about 26
times the global warming potential as sevoflurane and 13 times the
potential of isoflurane.
Using desflurane for one hour is equivalent to 235 to 470 miles
of driving, according to the study.
The environmental impact of anesthetics can be reduced by not
using nitrous oxide unless there are medical reasons to do so,
avoiding unnecessarily high anesthetic flow rates (especially with
desflurane) and by developing new methods of capturing anesthetic
gases for reuse, rather than releasing them into the atmosphere,
the researchers suggested.
The study appears in the July issue of the journal
Anesthesia & Analgesia.
More information
The American Society of Anesthesiologists has more about
anesthesia.