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:
Avoid the use of nitrous oxide unless there is a clinical necessity for it.
Avoid "unnecessarily high" anesthetic flow rates, particularly with desflurane. "For now, based on the results of the study," they suggest, "reduction of FGF to 2 L/min with sevoflurane (the lowest in common clinical usage currently) and 0.5 to 1 L/min with desflurane and isoflurane would be the best approximations of ideal FGF rates, unless particular anesthesia machine characteristics dictate higher flows."
Ultimately, the best way to reduce the GWP of inhaled anesthetics will be to employ new technologies that capture and reuse expelled gases instead of releasing them into the atmosphere, write the study authors.
Irene Tsikitas
