Sustainability Workgroup Meeting

Date: April 28, 2025, 10am EST via Zoom

Attendance

Henrietta Addo, MSN, RN

MPOG QI Specialist

Eva Lu-Boettcher, MD

University of Wisconsin

Kate Buehler, MS, RN

MPOG Clinical Program Manager

Katie O’ Connor, MD, MBA

Johns Hopkins

Nick Delasio, MD

Johns Hopkins

Nirav Shah, MD

MPOG Quality Director

Tony Edelman, MD, MBA

MPOG Associate QI Director

Ben Stam, MD

Corewell West and UM West

Lucy Everett, MD

Massachusetts General

Meridith Wade, MSN, RN

MPOG Pediatric Program Manager

Summary of meeting:

SUS 01 and 04

 Group generally supported a low flow measure (ie flow < 1 l/min), should be

accompanied by a lower carbon footprint measure (update to SUS 02). Consider retiring

SUS 01

 Group generally agreed that we should remove exclusion for < 30 minutes so that we

can encourage lower flows for short cases

SUS 02

 Cuveele method – more accurate but likely fewer sites can participate. Coordinating

center to see if more sites can send MV and end tidal agent concentration

 Change GWP from GWP 100 to GWP 20. Group agreed with plan to change to GWP

20, given that relative performance and trend over time should not change much as this

doesn’t change recommendations about the choice of anesthetic agents or flows

administered.

 The group generally agreed that we should figure out a way to analyze shorter cases (ie

less than hour) in a more granular way. One way is for shorter cases to compare

against the recommended per minute (instead of per hour) kg CO2 equivalents of 2%

sevoflurane at 2 l/min.

SUS 05 - PEDS

 Consider trying to isolate inhalation induction cases from IV induction

 Update rationale to include information about why nitrous shouldn’t be used during

induction (ie inability to adequately preoxygenate)

 Meridith to look through Peds SC notes regarding SUS 05

Next Meeting:

 SUS-03: Global Warming Footprint, Induction

 SUS-06-Peds: Low Fresh Gas Flow, Pediatric Induction

 SUS-07: Nitrous Oxide Avoided

Meeting Transcript:

Meeting Start: 1004

I) Measure Review: SUS-01: Fresh Gas Flow, less than or equal to 3 L/min

a. Description: Percentage of cases with mean fresh gas flow (FGF) equal to, or

less than 3 L/min, during administration of halogenated hydrocarbons and/or

nitrous oxide

b. Threshold: 90%

c. Exclusions:

i. Cases without an ETT or LMA placed

ii. Cases without halogenated hydrocarbons and/or nitrous oxide

administration

iii. Cases with < 30 minutes of halogenated hydrocarbons or nitrous oxide

administered between intubation and extubation

iv. Cases with documentation of Nitric Oxide use

v. Cases with only manually documented fresh gas flow values (fresh gas

flow values must be automated to be considered for this measure)

d. 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

e. Other Measure Details:

i. 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

ii. 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)

f. Current SUS-01 Performance across All MPOG Institutions between April 2024

and March 2025: 15% - 100%

II) Measure Review: SUS-04: Fresh Gas Flow, less than or equal to 2 L/min

a. Description: Percentage of cases with mean fresh gas flow (FGF) equal to, or

less than 3 L/min, during administration of halogenated hydrocarbons and/or

nitrous oxide

b. Threshold: 90%

c. Exclusions:

i. Cases without an ETT or LMA placed

ii. Cases without halogenated hydrocarbons and/or nitrous oxide

administration

iii. Cases with < 30 minutes of halogenated hydrocarbons or nitrous oxide

administered between intubation and extubation

iv. Cases with documentation of Nitric Oxide use

v. Cases with only manually documented fresh gas flow values (fresh gas

flow values must be automated to be considered for this measure)

d. 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

e. Other Measure Details:

i. 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

ii. 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)

f. Current SUS-01 Performance across All MPOG Institutions between April 2024

and March 2025: 1% - 98%

III) Measure Review: SUS-02: Global Warming Footprint, Maintenance

a. 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

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

b. Threshold: 90%

c. Exclusions:

i. Cases without an ETT or LMA placed

ii. Cases without inhalational agent (desflurane, sevoflurane, isoflurane, or

nitrous oxide)

iii. Cases with documentation of Nitric Oxide use

iv. Cases with only manually documented fresh gas flow values (fresh gas

flow values must be automated to be considered for this measure)

d. Success: For maintenance phase of anesthesia:

i. Mean CO2 equivalents for a case is < 2.83 kg C02/hr. This is equivalent

to 2% sevoflurane at 2 L/min FGF

ii. Total CO2 equivalents are less than or equal to 2.83 kg/CO2

e. Other Measure Details:

i. 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

ii. 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)

f. Current SUS-02 Performance across All MPOG Institutions between April 2024

and March 2025: 1% - 100%

g. Discussion:

i. Ben Stam (Corewell West &UM West): If you pass SUS-01 you then you

pass SUS-01. When you look at SUS-02 and SUS-04, what does the

Venn diagram look like for mutual inclusivity and exclusivity? Are there

cases where SUS-04 is passed but failed in SUS-02? And vice versa? Do

we need to do that analysis?

ii. Tony Edelman (MPOG Associate QI Director): Conceptually, think about

using desflurane at 2 L/min - desflurane has a high global warming

potential, so your CO2 eq would still be high even if you pass SUS-04.

They are similar measures, but not the same because they target

different metrics

iii. Kate Buehler (MPOG Quality Manager): SUS-01 and SUS-04 have a 30-

minute exclusion, but SUS-02 does not. So, there could be cases that are

excluded from SUS-01 and SUS-04 but included in SUS-02 that could

impact passing rates, especially for short cases depending on which

anesthetic agent you use.

IV) Measure Review: SUS-05-Peds: Nitrous Avoided, Induction

a. Description: Percentage of pediatric patients < 18 years old undergoing general

anesthesia where nitrous oxide was avoided during induction

b. Threshold: 90%

c. Exclusions:

i. Age > 18 years

d. Success: Nitrous oxide was not administered during the induction period of

anesthesia

e. Modifications to consider: pass cases with nitrous oxide used during induction

AND

i. Flows lower than _________

ii. For less than ________ minutes

iii. Patients < 3 years

iv. 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 older children

who do not receive preop anxiolytic/amnestic agent”

f. Current SUS-05-Peds Performance across All MPOG Institutions between April

2024 and March 2025: 17% - 100%

g. Discussion:

i. Lucy Everett (Mass Gen): For nitrous use in peds, since the age cut off is

under 18, are we targeting only inhalation inductions? A lot of teens would

have IV inductions, meaning no nitrous by default.

ii. Tony Edelman (MPOG Associate QI Director): No, it is not specific to

inhalational induction; it is for the induction period in general

iii. Lucy Everett (Mass Gen): Including all teens in the measure might skew

performance rates higher because many undergo IV inductions without

nitrous

iv. Eva Lu-Boettcher (University of Wisconsin): Yes, many patients 12 years

and older, or over 40 kg, get IV inductions. One idea floated was to

exclude cases where muscle relaxants are given early, suggesting IV

induction. It is harder to differentiate clearly because propofol boluses are

common even with inhalational inductions.

v. Tony Edelman (MPOG Associate QI Director): The thought is to capture

only true inhalational inductions for more accurate performance data?

vi. Eva Lu-Boettcher (University of Wisconsin): Exactly. Otherwise, it

overstates high success rates – masking true performance differences

among providers

vii. Meridith Wade (MPOG Pediatric Program Manager): I'll check old Peds

subcommittee notes. Originally, we just wanted a broad baseline to see

overall nitrous use. But now we could refine it. We have phenotypes

separating IV vs mask induction, so could use those.

viii. Tony Edelman (MPOG Associate QI Director): Even under current

definitions, there's huge variability. Tightening definitions would be an

improvement.

ix. Eva Lu-Boettcher (University of Wisconsin): Recent literature also

discourages nitrous due to oxygenation concerns — especially not

preoxygenating 100% FiO₂ in peds. We could update the rationale to

reflect that.

x. Nirav Shah (MPOG QI Director): What the feedback/site is saying is that

there's still a population of patients they'd like to use nitrous on. And I

think that should probably be debated in the Peds subcommittee: is that

reasonable, or are we saying — even with the newer literature and

climate change data — that we still want to avoid nitrous use broadly?

This sounds a little bit like personal preference, but maybe there’s more

to it.

xi. Eva Lu-Boettcher (University of Wisconsin): The threshold is set at 90%,

so it’s not like sites can't ever use nitrous. I can think of a few cases

where nitrous might be more stable for specific patients, but it really

doesn’t exceed 10% usage. I think the 90% threshold is very generous.

Not sure if that site has a specific number in mind they want us to

consider — maybe we can discuss during the Peds subcommittee, but I

think our threshold is very reasonable.

xii. Lucy Everett (Mass Gen): I was just going to add: the ASA’s

recommendation was to eliminate central pipelines for nitrous — but they

did note that it’s informational. So, I think this measure can be seen that

way: if a site wants to eliminate it, great, but they’re not forced to.

xiii. Tony Edelman (MPOG Associate QI Director): The goal is to make the

activation energy higher — make using nitrous more intentional. You

have to consciously turn it on rather than having it available by default.

xiv. Eva Lu-Boettcher (University of Wisconsin): 90% of the nitrous waste

comes from leaks in central supply systems. So simply removing central

supply saves most of the environmental impact. From the pediatric side,

newer literature says the safety profile of nitrous isn’t as good as once

thought. You're not preoxygenating 100% FiO₂ during induction, which

increases risks of desaturation and cardiopulmonary arrest. Adults

wouldn’t be induced without 100% oxygen, so why are we doing that to

children? It’s a habitual practice — but the true clinical benefit of using

nitrous in young, combative patients is questionable. Diane Gordon and

Jeff Feldman have written reviews about this. It’s worth rethinking the

risk-benefit calculation.

xv. Nick Delasio (Johns Hopkins): My biggest nitrous problem is with adult

neuro colleagues — not peds. We just gave a talk yesterday. They like

nitrous for fast wakeups. Our peds group has moved away from nitrous

for inductions. Diane Gordon wrote a nice paper about inhalational

induction without nitrous. We did a study on decentralizing nitrous at

Hopkins — we’re doing slightly better than Washington’s numbers. About

13% of our liquid nitrous gets to patients — instead of 10%. We are

moving to E-cylinders to make nitrous harder to get.

(https://pedsanesthesia.org/wp-content/uploads/2021/08/Low-Flow-

Anesthesia-in-Pediatric-Patients.pdf)

xvi. Tony Edelman (MPOG Associate QI Director): There’s been discussion

about whether to move from GWP-100 to GWP-20 for CO₂ equivalent

calculations. GWP-20 increases the relative impact of shorter-lived gases

— reflecting reality more accurately. Has anyone read much about this?

Thoughts?

V) Feedback we’ve received

a. Should MPOG change kg CO2 equivalents calculation?

i. MPOG currently uses GWP100 for kg CO2 equivalents calculations

ii. Should we consider using GWP20?

Global Warming Potential (IPCC report)

GWP20

GWP100

Desflurane = 7020*

Desflurane = 2590 (MPOG uses 2540)

Isoflurane = 1930

Isoflurane = 539 (MPOG uses 565)

Sevoflurane = 702

Sevoflurane = 195 (MPOG uses 144)

Nitrous = 273

Nitrous = 273 (MPOG uses 282)

iii. *1 kg of desflurane has the same effects as 7,020 kg of carbon dioxide

over a period of 20 years

b. Discussion:

i. Nirav Shah (MPOG QI Director): GWP-20 is more accurate, and it won’t

dramatically change relative rankings between gases like sevo, des, or

iso –the trends still look the same. Only the absolute CO₂ equivalent

numbers would shift. We would need to update the 2.83 kg/hr SUS-02

threshold accordingly, but that's just math. It won't change behaviors or

recommendations drastically.

ii. Lucy Everett (Mass Gen): Only concern is that Epic’s dashboards were

built around GWP-100 because we aligned it with MPOG. People may get

frustrated seeing different numbers from different systems. We could

update Epic.

iii. Ben Stam (Corewell West &UM West): Could we use GWP-100 for

nitrous and GWP-20 for the other gases?

iv. Nirav Shah (MPOG QI Director): The numbers stay the same for nitrous

either way.

c. GWP Discussion

i. GWP100 significantly underestimates the climate effects in the coming

decades. The 20-year time horizon values much better reflect the

climatological reality for the next 50 years

ii. Our GWP values don’t currently use the latest values from IPCC

iii. All-Inclusive Carbon Footprint of Inhalational Anesthesia

iv. GWP100 and GWP20 values for all volatile anesthetics can be found in the

IPCC report (isoflurane = HCFE-235da2; desflurane = HCFE-236ea2;

sevoflurane = HFE-34mmz1)

v. Additional background on GWP100 and GWP20

vi. The future is now – it's time to rethink the application of the Global

Warming Potential to anesthesia

d. Additional information...

i. The science of climate change and the effects of anesthetic gas

emissions

ii. “On the basis of GWP, anesthetic 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”

iii. 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.”

iv. ...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 forces such as

Nitrous Oxide.”

e. Method to calculate kg CO2 equivalents

i. Gold Standard: agent consumption from the anesthesia machine

ii. Current MPOG methodology uses Fresh Gas Flow x Inspired Agent

iii. Cuveele Method: Use FGF, minute ventilation (MV), agent inspired

concentration (FIN), agent end-expired concentration (FET)

iv. MPOG Method will generally underestimate use compared to Cuveele

v. 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 Cuveele was within 20% of what the

machine estimated, this was only 57% of the time for MPOG method

vi. Not all sites are able to send MPOG FET and MV

vii. Discussion:

1. Kate Buehler (MPOG Quality Manager): If sites have that data, it's

usually not mapped. Most just don’t have it coming into their EHRs

from the anesthesia machine at all. It would require the same kind

of push we did for inspired agents and fresh gas flow — getting

anesthetic machine data to flow into EHRs minute-by-minute. We

could reassess now — it’s been a year or two — maybe more

sites have improved, but originally, hardly anyone had minute

ventilation and expired agent mapped, even U of M.

2. Ben Stam (Corewell West &UM West): Can be information be

extracted? Or would it take some work to pull it?

3. Nirav Shah (MPOG QI Director): I think the latter. It will take work

and political effort.

4. Ben Stam (Corewell West &UM West): The balance is, is

tolerating a 10% error rate acceptable? If not, is it worth the time,

effort, and ticketing with IT to pull this data?

5. Kate Buehler (MPOG Quality Manager): We could start by

reanalyzing what data gaps exist now and then work over the next

year encouraging sites to map it. If we push it too fast, people

might get frustrated because we just got everyone on board with

the sustainability data they have now.

6. Tony Edelman (MPOG Associate QI Director): Minute ventilation

can be calculated from tidal volume × respiratory rate, correct?

7. Nirav Shah (MPOG QI Director): Yes, for most sites we get actual

tidal volume and respiratory rate (not just set values). But we still

need end-tidal anesthetic agent concentrations, and that’s less

common.

8. Ben Stam (Corewell West &UM West): At Corewell West, we have

mapped both inspiratory and expiratory agent concentrations. At

University of Michigan Health West, only inspiratory is mapped.

f. Cuveele’s method to calculate anesthetic agent

i. 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

ii. If FVAP is unknown, theoretical model for calculation FVAP, based on FGF,

minute ventilation (MV), agent inspired concentration (FIN), agent end-

expired concentration (FET) and dad space ventilation (VD)

iii. FVAP = [FIN - (dead space ventilation * FIN + (1 – dead space fraction) *

FET) * (1 – FGF/MV)] / (1 – (1 – FGF/MV))

iv. Dead space fraction for sevoflurane, desflurane, and isoflurane was

therefore determined empirically

VI) Other changes to consider

a. SUS-01: Fresh Gas Flow, less than or equal to 3 L/min

b. SUS-04: Fresh Gas Flow, less than or equal to 2 L/min

c. SUS-08?: Fresh Gas Flow, less than or equal to 1 L/min

d. Should we identify short cases with high maintenance flows?

i. Some of these cases have < 2.83 kg CO2

ii. Would have to choose a value lower than 2.83 kg CO2 or use some other

method to identify these cases

iii. For example, we could calculate the kg CO2 per minute instead of per

hour

e. Discussion:

i. Eva Lu-Boettcher (University of Wisconsin): Absolutely. Since 2020, the

ASA’s "Greening the OR" recommendations have pushed for low flows.

Three liters isn’t aspirational anymore. Two liters is very safe for

Sevoflurane. Flows over two liters should only happen rarely, e.g.,

hypermetabolic or extremely obese patients. And with a 90% success

threshold, it’s already generous.

ii. Lucy Everett (Mass Gen): There’s interest among Epic BPA users too.

Some want an even lower flow target (<2 L/min). One complaint, if the

measures include flows during wakeup, people feel unfairly "dinged." I tell

them if they manage transitions correctly, the impact is small.

iii. Ben Stam (Corewell West &UM West): I agree with retiring the three-liter

measure too. But — what is our goal with a potential SUS-08 measure at

one liter? Is it low-flow anesthesia for its own sake? Or is it environmental

stewardship? Because if the goal is stewardship, refining SUS-02 (CO₂

equivalents) is more meaningful than just pushing flows lower.

iv. Nirav Shah (MPOG QI Director): Low flow is a means to an end. If we had

an aspirational SUS-02 metric (gold standard CO₂ footprint), flow would

be one lever among others (like gas choice).

v. Tony Edelman (MPOG Associate QI Director): Low flow measures inform

us, but SUS-02 reflects the true sustainability outcome — just like in other

QI efforts, intermediate metrics help guide improvements.

vi. Ben Stam (Corewell West &UM West): Yes, it homogenizes comparisons

across sites with heterogeneous practices.

vii. Meridith Wade (MPOG Pediatric Program Manager): SUS-02 focuses on

the maintenance phase. SUS-03 covers induction. Would there be

interest in a new measure evaluating sustainability across the entire

anesthetic (induction + maintenance)?

viii. Lucy Everett (Mass Gen): I would prefer keeping them separate. The

periods are so different, especially for peds cases. Inductions are short

and messy, while maintenance is more stable. Also — for induction —

training issues could arise around awareness risk if flows are dropped too

fast.

ix. Tony Edelman (MPOG Associate QI Director): Another question or

feedback we received: Should we try to identify shorter cases with high

maintenance flows? Is calculating CO₂ equivalents per minute — instead

of per hour — a better approach? Is the current 2.83 kg threshold the

right number for all case lengths?

x. Nirav Shah (MPOG QI Director): Some shorter cases pass the CO₂

threshold even if they have relatively high flows — just because the

maintenance period is short. It makes sense — if your maintenance is

short, a brief period of higher flow disproportionately affects the footprint.

We could: Set a lower CO₂ threshold for short cases, for example, less

than 30 minutes, or calculate CO₂ equivalents per minute, or just leave it

alone.

xi. Ben Stam (Corewell West &UM West): I prefer more granular data. I’d like

to know how short cases compare to long cases in overall anesthetic gas

use. If you leave flows at 10 L/min for even five minutes after intubation,

you’ve already blown through any sustainability gains you’d get later. So

yes — I think minute-by-minute CO₂ consumption would give a much

more accurate picture.

xii. Nirav Shah (MPOG QI Director): I was with a resident recently who

intubated and immediately dropped to low flow — adjusted for gas value,

without missing a beat. She had internalized that workflow already. So,

it’s possible. It is teachable.

xiii. Tony Edelman (MPOG Associate QI Director): At Michigan, with end-tidal

control turned on immediately after confirming the tube, the machine

quickly gets you to your target anesthetic concentrations with minimal

flows. Since people are becoming more comfortable with end-tidal

control, we’ve seen decreased anesthetic gas use anecdotally.

xiv. Ben Stam (Corewell West &UM West): Yes, I totally agree. I’ve started

using end-tidal control too and it’s almost too good. On a standard

machine without end-tidal control, my workflow is: intubate → flows to 0.5

→ Sevo at 8% → then slowly titrate down as the propofol wears off. With

end-tidal control, it achieves maintenance Sevo instantly. I sometimes

find it causes hypotension faster. But still — it’s an amazing tool if people

adapt their workflows. So yes — capturing minute-to-minute flow and

consumption variations is important. It nails down how we’re utilizing and

wasting anesthetic gas.

VII) Next Steps:

a. Schedule the next workgroup meeting to review SUS-03, SUS-07, and SUS-06-

Peds

b. Dr. Stam will present SUS-01 and SUS-04, and Lu-Boettcher will present SUS-

02 at the Quality Committee on May 19th at 10am EST

c. Peds measures will be reviewed and presented at the Pediatric Subcommittee

meeting at the end of June

Meeting Adjourned: 1104