Desflurane Has the Highest Global Warming Potential
Desflurane has by far the highest global warming potential among the three inhaled anesthetic agents, being approximately 20-27 times more potent than sevoflurane and 5 times more potent than isoflurane. 1, 2
Global Warming Potential Rankings
The 20-year global warming potential (GWP₂₀) values clearly establish the hierarchy:
When expressed as carbon dioxide equivalents (CDE₂₀) for 1 MAC-hour at 2 L fresh gas flow, the differences become even more striking:
- Desflurane: 187,186 g CO₂ equivalent 1
- Isoflurane: 15,551 g CO₂ equivalent 1
- Sevoflurane: 6,980 g CO₂ equivalent 1
This translates to a ratio of sevoflurane 1 : isoflurane 2.2 : desflurane 26.8 1
Why Desflurane Is Worse
The dramatically higher environmental impact of desflurane stems from several factors:
- Minimal metabolism: 99.98% of desflurane is exhaled unmetabolized and released directly into the atmosphere 3
- Long atmospheric lifetime: 9-21 years compared to 1-5 years for sevoflurane and 3-6 years for isoflurane 4
- Intrinsically higher potency as a greenhouse gas: The molecular structure makes it a more potent heat-trapping agent 1, 5
In contrast, sevoflurane has 4-5% metabolism and isoflurane has 0.2% metabolism, meaning slightly less unmetabolized gas is released 6, 4
Clinical Guideline Recommendations
The French Society of Anesthesia and Resuscitation (SFAR) provides a strong recommendation: "With equal clinical benefit for the patient, anesthesia professionals prefer sevoflurane to desflurane or isoflurane." 3
This guideline explicitly prioritizes sevoflurane over both other agents when clinical outcomes are equivalent, reflecting both environmental concerns and clinical considerations 3
Important Caveats
Nitrous Oxide Amplifies the Problem
When nitrous oxide (N₂O) is used as a carrier gas, the environmental impact calculations change substantially:
- With 60% N₂O, sevoflurane's CDE₂₀ increases 5.9 times 1
- With 60% N₂O, isoflurane's CDE₂₀ increases 2.9 times 1
- With 60% N₂O, desflurane's CDE₂₀ actually decreases 0.4 times (becomes relatively better) 1
However, N₂O itself is a potent greenhouse gas with a 114-year atmospheric lifetime and depletes the ozone layer, making it an environmentally unsound choice regardless 1, 4
The SFAR strongly recommends against using nitrous oxide when choosing an inhalational anesthetic. 3
Fresh Gas Flow Matters
The environmental impact can be reduced by approximately 50% by using minimal fresh gas flow (≤1 L/min) during wash-in and metabolic fresh gas flow (0.35 L/min) during maintenance 2. The SFAR strongly recommends using low fresh gas flow 3
Bottom Line for Clinical Practice
From an environmental perspective alone, the ranking is clear: sevoflurane has the lowest global warming potential, followed by isoflurane, with desflurane having dramatically the highest impact. 1, 5 Life cycle assessments confirm that desflurane accounts for 15-20 times the greenhouse gas impact of sevoflurane per MAC-hour 5. Desflurane should be restricted to cases where it may reduce morbidity and mortality over alternative agents 5, and sevoflurane should be preferred when clinical benefits are equal 3.