System-Level Reduction in Anesthetic Greenhouse Gas Emissions: Central Nitrous Oxide Deactivation, Clinical Decision Support, and Secular Change in a Multicenter Interrupted Time-Series Study
Authors' conclusion
Central N2O pipeline deactivation was associated with the largest reduction in the N2O-attributable hourly CO2e emission rate; the association with total emissions in the primary model was not statistically significant (P = .069). Concurrent secular declines in N2O and desflurane use contributed additionally, whereas the clinical decision support Advisory was associated with a modest but statistically significant reduction in FGF rate and total hourly CO2e emission rate.
Study context
- Population
- General anesthetic cases at 11 NYC Health + Hospitals facilities, April 1, 2022 – December 31, 2025of 158,881 screened cases analysed
- Participants
- 148,762 cases
- Exposure
- Clinical decision support Advisory prompting fresh gas flow (FGF) reduction and central nitrous oxide (N2O) pipeline deactivation vs pre-intervention
- Outcome
- Hourly CO2e emission rate from N2O and volatile agents
Methodological detailscase-level data aggregated to monthly group-level observations
- Case-level data aggregated to monthly group-level observations
Main finding
As reported in the abstract
Step reduction in total hourly CO2e emission rate
0.78 kg CO2e·h-1
95% CI 0.24–1.32; P = 0.006
Advisory
Reduction in N2O-attributable hourly emission rate (complete deactivation, group level)
1.67 kg CO2e·h-1
95% CI 1.23–2.12; P < 0.001
N2O pipeline deactivation · association with total emissions in primary model not significant (P = .069)
- System-level hourly CO2e emission rate decline over study period, per month
- 0.143 kg CO2e·h-1 (95% CI, 0.11-0.18; P < .001)
Observational data: associations, not effects.
Further findings
| Outcome | Step reduction (L·min-1) (95% CI) | P value |
|---|---|---|
| FGFAdvisory vs Phase 1 | 0.163 (0.11–0.21) | P < 0.001 |
- Baseline anesthetic gas use (Phase 1)
- 3.90 · median · L·min-1
- Baseline anesthetic gas use (Phase 1) — N2O annualized CO2e impact equivalent to share of all volatile agents combined
- 77%
Central N2O pipeline losses at Bellevue
- Centrally supplied N2O lost before reaching patients
- 94.6%
- CO2e generated annually (approximately), metric tons
- 2136
- Multiple of combined annual emissions from all clinically administered anesthetic gases across 11-hospital system
- 2.58
Original publication
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