The environmental impact of using desflurane to anesthetize a surgical patient for 1 hour is equivalent to 235 to 470 miles of driving, according to a new study measuring the global warming potential of 3 popular inhaled anesthetics.

A busy hospital, where the anesthetics desflurane, sevoflurane and isoflurane may be in wide use for surgical procedures, can contribute as much to global warming as auto emissions from as many as 1,200 cars, write anesthesiologist Susan Ryan, MD, of the University of California and computer scientist Claus J, Nielsen of the University of Oslo in a study published in the journal Anesthesia & Analgesia. All 3 anesthetics are recognized as greenhouse gases, but because they are considered medically necessary there is little research on their actual environmental impact.

Dr. Ryan and Mr. Nielsen found that desflurane remains in the atmosphere longest and has the highest global warming potential (GWP) of the 3 agents — 26 times more GWP than sevoflurane and 13 times more than isoflurane. Nitrous oxide, "delivered as a carrier gas for volatile anesthetics or as a supplemental anesthetic with IV drugs, can have a relatively large impact" as well, and it also significantly increases the impact of sevoflurane and isoflurane when used in conjunction with those anesthetics.

The authors suggest 2 ways anesthesia providers can minimize the environmental impact of these inhaled anesthetics: