Sustainability
Workgroup
April 28, 2025
1000 am - 1100 am Eastern Time
Introductions and goals for the meeting
Measures to discuss:
-SUS-01: Fresh Gas Flow, less than or equal to 3 L/min
- SUS-04: Fresh Gas Flow, less than or equal to 2 L/min
- SUS-02: Global Warming Footprint, Maintenance
- SUS-05-Peds: Nitrous Avoided, Induction
Measures for next meeting:
SUS-03: Global Warming Footprint, Induction
SUS-06-Peds: Low Fresh Gas Flow, Pediatric Induction
SUS-07: Nitrous Oxide Avoided
Modify measures
- Identify areas identified by the coordinating center to modify measures
- Identify opportunities identified by workgroup to modify measures
Review Literature Updates
Summary and next steps
Agenda
Sustainability Workgroup Members
Name Institution
Brady Still, MD UChicago
Seema Gandhi, MD UCSF
Ben Stam, MD Corewell West & UM West
Eva Lu Boettcher, MD University of Wisconsin
Katie O'Conor, MD, MBA Johns Hopkins
Nick Dalesio, MD Johns Hopkins
Lucy Everett, MD Mass General
Liz Hansen, MD Seattle Children's
Jonathan Paul, D.O. Columbia University
Jodi Sherman, MD Yale
Measure Review: SUS-01
SUS-01: Fresh Gas Flow, less than or equal to 3 L/min
Description: Percentage of cases with mean fresh gas flow (FGF) equal to, or less than 3L/min, during
administration of halogenated hydrocarbons and/or nitrous oxide.
Threshold: 90%
Exclusions:
● Cases without an ETT or LMA placed
● Cases without halogenated hydrocarbons or nitrous oxide administration
● Cases with < 30 minutes of halogenated hydrocarbons and/or nitrous oxide administered between
intubation and extubation
● Cases with documentation of Nitric Oxide use
● Cases with only manually documented fresh gas flow values (fresh gas flow values must be
automated to be considered for this measure)
Success: Mean FGF equal to, or less than 3 L/min when inspired halogenated hydrocarbons is > 0.2% or
nitrous oxide FGF > 0.2 L/min, during the maintenance period of anesthesia
SUS-01: Fresh Gas Flow, less than or equal to 3 L/min
Other Measure Details:
● If Fresh Gas Flow Total (Concept ID:3214) is documented for the case, this concept will be used to
determine success of halogenated agents or nitrous oxide use
● If Fresh Gas Flow Total (Concept ID:3214) is not documented for the case, MPOG will calculate
Fresh Gas Flow: Flows Oxygen (ID:3215) + Flows Air (ID:3220) + Flows Nitrous Oxide (ID:3225)
Current SUS-01 Performance, All MPOG Institutions, April 2024 - March 2025
Performance: 15% - 100%
Measure Review: SUS-04
SUS-04: Fresh Gas Flow, less than or equal to 2 L/min
Description: Percentage of cases with mean fresh gas flow (FGF) equal to, or less than 2L/min, during
administration of halogenated hydrocarbons and/or nitrous oxide.
Threshold: 90%
Exclusions:
● Cases without an ETT or LMA placed
● Cases without halogenated hydrocarbons or nitrous oxide administration
● Cases with < 30 minutes of halogenated hydrocarbons and/or nitrous oxide administered between
intubation and extubation
● Cases with documentation of Nitric Oxide use
● Cases with only manually documented fresh gas flow values (fresh gas flow values must be
automated to be considered for this measure)
Success: Mean FGF equal to, or less than 2 L/min when inspired halogenated hydrocarbons is > 0.2% or
nitrous oxide FGF > 0.2 L/min, during the maintenance period of anesthesia
SUS-04: Fresh Gas Flow, less than or equal to 2 L/min
Other Measure Details:
● If Fresh Gas Flow Total (Concept ID:3214) is documented for the case, this concept will be used to
determine success of halogenated agents or nitrous oxide use
● If Fresh Gas Flow Total (Concept ID:3214) is not documented for the case, MPOG will calculate
Fresh Gas Flow: Flows Oxygen (ID:3215) + Flows Air (ID:3220) + Flows Nitrous Oxide (ID:3225)
Current SUS-04 Performance, All MPOG Institutions, April 2024 - March 2025
Performance: 1% - 98%
Measure Review: SUS-02
SUS-02: Global Warming Footprint, Maintenance
Description: This measure analyzes the percentage of cases where carbon dioxide equivalents (CO2
eq) normalized by hour for case receiving inhalational anesthetic agents (desflurane, isoflurane, or
nitrous oxide) is less than CO2 eq of 2% sevoflurane at 2L FGF = 2.83 kg CO2/hr or the total CO2 eq is
less than 2.83 kg CO2 for the maintenance period of anesthesia.
Threshold: 90%
Exclusions:
● Cases without an ETT or LMA placed
● Cases without inhalational agent (desflurane, sevoflurane, isoflurane, or nitrous oxide)
administration
● Cases with documentation of Nitric Oxide use
● Cases with only manually documented fresh gas flow values (fresh gas flow values must be
automated to be considered for this measure)
SUS-02: Global Warming Footprint, Maintenance
Success: For maintenance phase of anesthesia:
● Mean CO2 equivalents for a case is < 2.83 kg CO2/hr. This is equivalent to administering 2%
sevoflurane at 2 L/min FGF,
● Total CO2 equivalents are less than or equal to 2.83 kg/CO2
Other Measure Details:
● If Fresh Gas Flow Total (Concept ID:3214) is documented for the case, this concept will be used to
determine success of halogenated agents or nitrous oxide use
● If Fresh Gas Flow Total (Concept ID:3214) is not documented for the case, MPOG will calculate
Fresh Gas Flow: Flows Oxygen (ID:3215) + Flows Air (ID:3220) + Flows Nitrous Oxide (ID:3225)
Current SUS-02 Performance, All MPOG Institutions, April 2024 - March 2025
Performance: 1% - 100%
Measure Review:
SUS-05-Peds
SUS-05-Peds: Nitrous Avoided, Induction
Description: Percentage of pediatric patients < 18 years old undergoing general anesthesia where nitrous oxide was avoided
during induction.
Threshold: 90%
Exclusions: Age ≥ 18 years
Success: Nitrous oxide was not administered during the induction period of anesthesia
Modifications to Consider: Pass cases with nitrous oxide used during induction AND
1. Flows lower than ____.
2. For less than ____ minutes.
3. Patients < 3y
Rationale: “...can justify avoiding nitrous oxide for pediatric inhalational inductions when preop versed is administered or for
patients 2/2.5 years old and younger but would prefer to continue using it for the older children who do not receive preop
anxiolytic/amnestic agent”
Current SUS-05-Peds Performance, All MPOG Institutions, April 2024 - March 2025
Performance: 17% - 100%
Feedback we’ve
received
Should MPOG Change kg CO2 equivalents calculation?
● MPOG currently uses GWP100 for kg CO2 equivalents calculations
● Should we consider using GWP20 ?
Global Warming Potential ( IPCC report)
GWP20 GWP100
Desflurane = 7020 * Desflurane = 2,590 (MPOG uses 2540)
Isoflurane = 1930 Isoflurane = 539 (MPOG uses 565)
Sevoflurane = 702 Sevoflurane = 195 (MPOG uses 144)
Nitrous = 273 Nitrous = 273 (MPOG uses 282)
* 1kg of desflurane has the same effects as 7,020 kg of carbon dioxide over a period of 20 years
GWP Discussion
GWP100 significantly underestimate the climate effects in the coming decades. The 20 year time
horizon values much better reflect the climatological reality for the next 50 years.
Our GWP values don’t currently use the latest GWP values from the IPCC.
All-Inclusive Carbon Footprint of Inhalation Anesthesia
GWP100 and GWP20 values for all volatile anesthetics can be found in the IPCC report (isoflurane =
HCFE-235da2 ; desflurane = HCFE-236ea2 ; sevoflurane = HFE-347mmz1).
Additional background on GWP100 and GWP20
The future is now—it’s time to rethink the application of the Global Warming Potential to anesthesia
Additional information…
The science of climate change and the effect of anaesthetic gas emissions
“On the basis of GWP, anaesthetic gases appear to be very 'damaging'. However, this conclusion is
scientifically unsound: their lifetimes are short; their emissions, accumulation and resulting atmospheric
concentrations are minute; and their actual radiative forcing is vanishingly small."
and.. "A key reason that CO2e values are misleading is that long- and short-lived gases affect atmospheric
concentrations, and thus the planet's energy budget, in fundamentally different ways."
…halogenated hydrocarbons such as sevoflurane, desflurane and other inhaled anesthetic vapors are
near term climate forcers and hence shorter GWP numbers (GWP-20) needs to be employed while the
GWP-100 numbers are better suited for long term climate forcers such as Nitrous Oxide."
Method to calculate kg CO2 equivalents
Gold Standard: agent consumption from the anesthesia machine
Current MPOG methodology uses Fresh Gas Flow x Inspired Agent
Cuveele Method: Use FGF, minute ventilation (MV), agent inspired concentration (FIN),
agent end-expired concentration (FET)
MPOG Method will generally underestimate use compared to Cuveele.
In a soon to be published analysis, compared to what the machine estimates, Median
Absolute Prediction Error (%) was 16% for MPOG and 6% for Cuveele. 90% of the time
Cuvelle was within 20% of what the machine estimated, this was only 57% of the time for
the MPOG method
Not all sites are able to send MPOG FET and MV
Cuveele’s method to calculate anesthetic agent
● If both fresh gas flow (FGF) and vaporizer dial setting (dialed FVAP) are available, anesthetic agent
consumption can be calculated as a product of FGF and FVAP
● If FVAP is unknown, theoretical model for calculating FVAP, based on FGF, minute ventilation (MV), agent
inspired concentration (FIN), agent end-expired concentration (FET) and dead space ventilation (VD)
● FVAP = [FIN − (dead space fraction * FIN + (1 − dead space fraction) * FET) * (1 − FGF/MV)]/(1-(1 − FGF/MV))
● Dead space fraction for sevoflurane, desflurane, and isoflurane was therefore determined empirically
Other changes to
consider
Should we measure very low FGF (< 1 l/min)?
● SUS-01: Fresh Gas Flow, less than or equal to 3 L/min
● SUS-04: Fresh Gas Flow, less than or equal to 2 L/min
● SUS-08?: Fresh Gas Flow, less than or equal to 1 L/min?
Should we identify short cases with high maintenance
flows?
● Some of these cases have < 2.83 kg CO2
● Would have to choose a value lower than 2.83 kg CO2 or use some other method to identify these
cases
● For example, we could calculate the kg CO2 per minute instead of per hour
Thank You!
