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
Kenneth M. Sutin, Sudheer Jain, Zoran Z. Gajic, Mark J. Young, Anthony Chang, Michaela Klesitz, Elie Geara, Nicolai P. Ostberg, Barbara M. Dilos, Leonard Golden, Bret W. Robinson, Mark E. NunnallyBACKGROUND:
Volatile anesthetic agents and nitrous oxide (N 2 O) are greenhouse gases and a modifiable source of health care-related carbon dioxide equivalent (CO 2 e) emissions; losses from central N 2 O pipeline systems are a major contributor. We evaluated anesthetic gas use and assessed system-level emission-reduction strategies across a large public health system.
METHODS:
We conducted a multicenter observational interrupted time-series study of case-level data aggregated to monthly group-level observations from 11 NYC Health + Hospitals facilities between April 1, 2022, and December 31, 2025. After exclusions, 148,762 of 158,881 screened general anesthetic cases (93.6%) were analyzed. Fresh gas flow (FGF) rate and time were recorded, and hourly CO 2 e emission rate from N 2 O and volatile agents was calculated. Two interventions were evaluated: a clinical decision support Advisory prompting FGF reduction and deactivation of central N 2 O pipelines at three hospitals.
RESULTS:
During Phase 1 (pre-intervention), median FGF was 3.90 L·min
−
,
1
N
2
O was used in 27.2% of cases, and sevoflurane in 97.8%. N
2
O generated an annualized CO
2
e impact equivalent to 77% of all volatile agents combined. System-level hourly CO
2
e emission rate declined over the study period by 0.143 kg CO
2
e·h
−
1
per month (95% confidence interval [CI], 0.11–0.18;
CONCLUSIONS:
Central N
2
O pipeline deactivation was associated with the largest reduction in the N
2
O-attributable hourly CO
2
e emission rate; the association with total emissions in the primary model was not statistically significant (