Environmental
Sustainability QI Toolkit
OVERVIEW AND RECOMMENDATIONS
Acknowledgements
Armaan Patel, BS - University of Michigan
Alexander T. Abess, MD - Dartmouth Health
Megan G. Anders, MD, MS - University of Maryland Medical System
Eva Lu-Boettcher, MD - University of Wisconsin Health
Karen B. Domino, MD - University of Washington Health
Patrick Henson, DO - Vanderbilt University Medical Center
Deirdre Clare Kelleher, MD - Weill Cornell Medicine
Patricia Fogarty Mack, MD - Weill Cornell Medicine
Benjamin Stam, MD - Anesthesia Practice Consultants
Objectives
Overview environmental sustainability in anesthesia
Discuss selection of anesthetic agent
Discuss management of fresh gas flow
Review ASPIRE sustainability measures
Section I:
Overview of Environmental
Sustainability in Anesthesia
(Watts, 2018)
Climate Crisis and Impact on Health
● The climate change crisis is the largest and most profound threat to
global health ever described (Watts, 2018).
● 2022 IPCC (Intergovernmental Panel on Climate Change) Report indicates
high confidence that climate change is adversely impacting multiple facets
of human health, including (IPCC, 2022):
○ The spread of infectious disease
○ Malnutrition
○ Mental health
○ Displacement of peoples/communities
Urgency of Climate Change
● Global surface temperature has increased by 0.2°C per decade over the last 30 years
(Hansen, 2006).
● The U.N. Climate Report notes that we are on a pathway to more than double the
1.5°C limit set by climate scientists.
“It’s now or never, if we want to limit global warming to 1.5°C; without immediate and
deep emissions reductions across all sectors, it will be impossible”
Jim Skea, Co-Chair of IPCC Working Group III (Rich, 2022)
Environmental Impact of Healthcare
● The U.S. health care sector contributes
nearly 10% of GHG emissions per year
(Pichler, 2019).
● If the U.S. health care sector were a
country, it would rank 13th in GHG
emissions (Eckelman, 2016).
● If global healthcare were a country, it
would be the fifth largest carbon emitter
on the planet (Budd, 2019).
Healthcare emissions are a
drop in the bucket, right?
Environmental Impact of U.S. Healthcare System
From a 2007 JAMA Study, the U.S. Healthcare Sector
annually contributes approximately (Chung, 2009)
● 8% of all greenhouse gas emissions
● 7% of all carbon dioxide emissions
Within the U.S. Healthcare Sector
● Hospitals make up the largest contributor of
greenhouse gases, followed by prescription
drugs, physician and dental services, structures
and equipment, and nursing home care.
Environmental Impact of U.S. Healthcare System (cont.)
The U.S. healthcare sector is also responsible for significant fractions of national air
pollution emissions and impacts, including:
● Acid rain (12%), greenhouse gas emissions (10%), smog formation (10%) criteria air
pollutants (9%), stratospheric ozone depletion (1%), and carcinogenic and non-
carcinogenic air toxics (1–2%) (Eckelman, 2016).
This is attributable to approximately 123,000 to 381,000 DALYs (Disability-Adjusted Life
Years) in future health damages (Eckelman, 2018).
Environmental Impact of Anesthesia
● Anesthetic gases play a significant role in this contribution.
● From the American Society of Anesthesiologists (Devlin-Hegedus, 2022).
○ Inhaled anesthetics account for 5% of acute hospital CO
2
-equivalent emissions and
50% of perioperative department emissions in high-income countries.
○ Overall, inhaled anesthetic agents are estimated to be responsible for approximately
0.01% to 0.1% of the total global carbon dioxide equivalent emissions per year.
○ Based on recent research and atmospheric sampling of volatile anesthetics, this
accumulation has been and is still currently increasing.
GHGs and the Greenhouse Effect
● Greenhouse gases, or
GHGs, warm our planet by
absorbing/re-radiating the
infrared radiation emitted
from Earth’s surface (US
EPA, 2016).
● Common GHGs include:
○ CO
2
○ Methane
○ Nitrous Oxide
○ Fluorinated Gases
Summary of the Greenhouse Effect
(Ishizawa, 2011)
Image adapted from U.S. Environmental
Protection Agency Website (EPA, 2022)
Global Warming Potential
● Global Warming Potential (GWP): A measure of how much energy the
emissions of 1 ton of a given greenhouse gas will absorb (over a given period
of time) relative to the emissions of 1 ton of carbon dioxide (US EPA, 2016).
○ The larger the GWP, the more that a given greenhouse gas warms the Earth compared
to CO
2.
● GWP is constituted of two primary factors (McGain, 2020):
○ Radiative Efficiency: Ability to absorb energy
○ Atmospheric Lifetime: Estimate of molecular stability in the atmosphere
GWP for Select Greenhouse Gases
Name MW
(g/mol)
Chemical
Formula
Atm Lifetime
(years)
GWP 20 GWP 100
Carbon Dioxide 44.01 CO
2
5-200 1 1
Common Inhaled Anesthetics
Sevoflurane 200.5 C
4
H
3
F
7
O 1.4 349 130, 144, 210
Isoflurane 184.5 C
3
H
2
ClF
5
O 3.2 1401 510, 565
Desflurane 168.0 C
3
H
2
F
6
O 14 3714 1620, 2540, 2720
Nitrous Oxide 44.0 N₂O 114 289 265, 273, 282, 298, 300
GWP 20 and GWP 100: Global warming potential over a 20-year period and 100-year period, respectively
Multiple sources were used, as GWP 100 values are estimates
and thus show variability in published literature
Bolded values represent those used by the
MPOG SUS-02 measure
References: (Budd, 2019; Chung, 2009; US EPA, 2016; Ishizawa, 2011; EPA, 2022;
McGain, 2020; Yasny, 2012)
Reducing Environmental Impact of Anesthesia
● Based on GWP values, all common inhaled anesthetics have a global
warming potential significantly greater than that of carbon dioxide.
○ These gases are thus potent contributors to global warming, even in small
concentrations.
● We can reduce this impact in two primary ways:
○ Selecting environmentally-safer anesthetic agents
○ Managing fresh gas flow
Section II:
Managing Selection of
Inhaled Anesthetic Agent
(Watts, 2018)
Environmental Impact of Inhaled Anesthetics
● Halogenated anesthetics (sevoflurane, isoflurane, and desflurane)
and nitrous oxide are all recognized greenhouse gases (Yasny,
2012).
● Nitrous oxide presents additional environmental concerns:
○ In addition to being a greenhouse gas, it is also classified as an ozone-
depleting agent (Yasny, 2012).
○ When nitrous oxide is used as a carrier gas along with a halogenated
anesthetic, the impact of each gas on the environment is compounded
(McGain, 2020; Axelrod, 2022).
Carbon Dioxide Equivalents
● The environmental impact of a specific inhaled anesthetic over a given
time period can be standardized by converting the amount of the gas
used to carbon dioxide equivalents, or “CO
2
(equiv)(Axelrod, 2022)”
● Calculating CO
2
equivalents can be done by multiplying the mass of the
anesthetic agent used by its global warming potential (GWP).
○ Mass used is dependent on both the concentration of gas used and the fresh
gas flow rate (see calculation on next slide).
Calculating CO
2
Equivalents
Comparing CO
2
Equivalents for Common Anesthetics
Anesthetic FGF (L/min) GWP(100) CO
2
equiv
(x100,000)
Equivalent auto miles
driven per hour use of
anesthetic (Axelrod, 2022)
Sevoflurane 2% 2 144 2.9 8
Isoflurane 1.2% 2 565 6.2 18
Isoflurane 1.2% 1 565 3.1 9
Desflurane 6% 2 2720 137 400
Desflurane 6% 1 2720 68.5 200
Nitrous Oxide 60% 1 282 18.6 61
Recommendation 1: Eliminate Desflurane
Under comparable conditions, desflurane has a significantly greater carbon
footprint
and thus larger impact on global warming than other halogenated
anesthetics such as sevoflurane and isoflurane (McGain, 2020; Axelrod, 2022;
Sherman, 2012; Ryan, 2010).
When looking at the full lifecycle of the drug (i.e. from resource extraction to
disposal), it’s estimated that desflurane accounts for the largest GHG emissions
both in terms of anesthetic gas wasted during a procedure and other life cycle
stages (Axelrod, 2022).
Comparing the Environmental Impact of Common Inhaled
Anesthetics
Atm Lifetime
(years)
CO
2
Equivalents
(at 2 L/min)
Global Warming
Potential (100)
Equivalent MPH
Driven in a Car
Eliminating Desflurane (cont.)
Research suggests negligible clinical differences
between desflurane, sevoflurane, and isoflurane.
● There appears to be no significant difference in
the quality of overall recovery between the 3
agents (see next slide) (White, 2009; Lopez,
2009).
● Home readiness, PONV, and airway irritation
seem to be comparable between the 3 agents as
well (Kurhekar, 2017; Gupta, 2004).
Desflurane is significantly more expensive than
sevoflurane and isoflurane (Moody, 2020).
● Total cost at 1 L/min:
○ Sevo: $2.14
○ Iso: $0.32
○ Des: $10.32
● Total cost at 2 L/min
○ Sevo: $4.28
○ Iso: $0.64
○ Des: $20.64
Clinical Considerations
Economic Considerations
Eliminating Desflurane (cont.)
In comparison to sevoflurane and isoflurane, desflurane appears to show no significant
clinical advantage in terms of the quality of overall recovery, home readiness, PONV,
and post-op airway irritation.
● A study from the University of Texas Southwestern (n = 130) suggests that
although desflurane may lead to a faster initial recovery, the difference in the
quality of overall recovery between the 3 agents is negligible (White, 2009).
○ Other, more recent studies appear to support this finding (Lopez, 2009; Boggett, 2019).
● Studies from John Hopkins University (Kurhekar, 2017) and the Shri Sathya Sai
Medical College (Gupta, 2004) suggest that home readiness and incidences of
post-op nausea, vomiting, and airway irritation are comparable as well.
Eliminating Desflurane (cont.)
● Desflurane has been eliminated at multiple institutions across the country, generating
savings on the order of $100,000 to millions of dollars per year (Silva, 2021).
○ Some hospital systems that have significantly reduced or completely eliminated desflurane
include Michigan Medicine, Stanford Medicine, UCSF Health, Cleveland Clinic, Boston Medical
Center, Kaiser Permanente, Seattle Children’s Hospital, and many more (Schowtzer, 2020;
Zoghbi,
2022).
● The EU has formulated a proposal to ban, or at least severely restrict, the use of
desflurane starting in January of 2026 (Hendrickx, 2022).
● The ASA Environmental Task Force formally recommends the avoidance of desflurane
based on the ecological and economic benefits as well as the negligible clinical
differences between halogenated anesthetics (Devlin-Hegedus, 2022; Axelrod, 2022).
Recommendation 2: Reduce Nitrous Oxide
Estimated Atmospheric Lifetime of Nitrous Oxide (N₂O): 114 years
● This value is approximately 8x that of desflurane, 35x that of isoflurane, and more than 100x that of
sevoflurane.
Although nitrous oxide has a relatively lower global warming potential, it is used in a much
higher concentration in comparison to halogenated anesthetics (Aranake, 2013).
Anesthetic Sevoflurane Isoflurane Desflurane Nitrous Oxide
MAC 2 1.15 6 105
MAC-awake 0.62 0.49 2.5 68
Values expressed as a percentage of 1 atmosphere
Reducing Nitrous Oxide (cont.)
In addition to being a potent greenhouse gas, nitrous oxide is also an ozone-depleting agent.
29, 49
● Ozone Depleting Potential (or ODP): The ratio
of the estimated impact on the ozone layer
relative to CFC-11 (ODP = 1) (Velders, 2014).
● A study into the ozone-depleting effects of
nitrous oxide by Dr. Ravi Ravishankara of
Colorado State University poses nitrous oxide
as “the single most important ozone depleting
emission of the 21st century (Ravishankara,
2009).”
Anesthetic Agent
ODP
(Bosenberg, 2011;
Kleeman, 1994)
Sevoflurane 0
Desflurane 0
Isoflurane 0.01*
Nitrous Oxide 0.017
* Although isoflurane has an ODP of 0.01, the tropospheric lifetime is
short and its ozone-depleting effect is thus minimal (Branche, 2017)
Reducing Nitrous Oxide (cont.)
Nitrous oxide can also increase the carbon footprint of both sevoflurane and isoflurane
when nitrous is used as a carrier gas (relative to using medical air).
From a 2010 study from the Journal of Anesthesia and Analgesia (Ryan, 2010):
“CDEx”: Carbon
dioxide equivalents
emitted over an x
year period
Carrier Used:
Carrier Used:
Reducing Nitrous Oxide (cont.)
The American Society for Anesthesiologists recommends two primary methods of
reducing nitrous oxide emissions in the operating room (Axelrod, 2022):
1. Reserve nitrous oxide for cases in which it is clearly preferred for clinical reasons.
2. Decommission or avoid installing centralized nitrous oxide and substitute portable
tanks that can remain closed between uses.
If logistically feasible, a switch to portable tanks has the potential to dramatically
reduce nitrous leakage (Axelrod, 2022; Devlin-Hegedus, 2022).
Reducing Nitrous Oxide (cont.)
Study from the Providence Portland Medical Center (2016): Compared the
nitrous oxide leak from both central and portable systems (Chesebro, 2022)
● Central Systems: Cryogenic containers (filled with liquid N₂O) and
compressed gas cylinders (filled with gaseous N₂O)
● Portable Systems: Open or closed e-cylinders
Results show a significant decrease in nitrous oxide leak (in comparison to
clinical usage) in using either type of portable system vs. either type of central
system.
Reducing Nitrous Oxide (cont.)
Central Systems Portable Systems
Cryogenic Compressed
Reducing Nitrous Oxide in Pediatric Anesthesia
For pediatric inhalational inductions, limit nitrous oxide use to only medically necessary
cases.
Studies show a difference of < 10 seconds to loss of lash reflex when sevoflurane was
used without N
2
O during single-breath vital capacity inductions (Lee, 2013).
For acceptance of mask induction and sevoflurane, distraction techniques such as
conversation, electronic media, and premedication are effective (Gordon, 2020).
Incorporate IV anesthetics, regional, and local techniques to reduce N
2
O use during
maintenance or emergence.
Reducing Nitrous Oxide in Pediatric Anesthesia (cont.)
Summary
● Commonly used inhaled anesthetic agents such as halogenated gases and
nitrous oxide are greenhouse gases, with nitrous also being an ozone-
depleting agent.
● The environmental impact of anesthetic gases can be compared by converting
to CO
2
equivalents, which both factors in both the amount used in a given
time and the global warming potential (or GWP).
● We can significantly decrease our carbon footprint in the O.R. by both
eliminating desflurane and reducing nitrous oxide usage.
Recommendations
1. Eliminating Desflurane
Problem: In comparison to other halogenated anesthetics, desflurane has a
significantly greater impact on the environment in terms of atmospheric lifetime, GWP 20, GWP
100, and CO
2
equivalents produced.
Recommendation: Completely eliminate desflurane from the operating room and
elect for environmentally-safer alternatives such as sevoflurane or isoflurane.
1. Reducing Nitrous Oxide
Problem: Nitrous oxide adversely affects the environment on its own both as a greenhouse
gas and ozone-depleting agent as well as in conjunction with other anesthetics as a carrier.
Recommendation: Only use nitrous oxide when clinical advantages are transparent and, if
feasible, opt for portable cylinders over centralized nitrous oxide piping.
Section III:
Managing Fresh Gas Flow
(Watts, 2018)
Fresh Gas Flow and Waste
● When fresh gas flow exceeds a patient’s
needs in a circular anesthesia system,
gases and vapors will enter the scavenging
system and be vented into the
atmosphere.
● Thus, the fresh gas flow rate is correlated
to the amount of gas that enters the
scavenging system and ultimately
contaminates the ambient environment.
Image adapted from Pulse Physiology (Pulse Physiology, 2022)
Fresh Gas Flow and Waste (cont.)
● Since all anesthetic gases are greenhouse gases, high fresh gas flows of any
inhaled anesthetic can lead to significant environmental contamination.
○ At high FGFs, it’s estimated that more than 80% of delivered anesthetic is wasted
(Kapoor, 2019).
● Although the impact of a single case is minimal, the effects are cumulative.
○ With an estimated worldwide volume of 200 to 300 million surgeries per year, the
potential to decrease GHG emissions in the O.R. is considerable (Miller, 2022).
Managing Fresh Gas Flow
● Regardless of the inhaled anesthetic agent used, managing fresh gas flow
can reduce waste from circular anesthesia and decrease the overall
carbon footprint of a surgical case.
● There are three primary ways to reduce fresh gas flow that minimize
ecological impact without compromising patient care:
1. Minimizing fresh gas flow during induction in pediatric patients
2. Minimizing fresh gas flow during maintenance
3. Turning the vaporizer up (and the FGF down) during intubation
Minimizing FGF during Pediatric Inductions
The Society for Pediatric Anesthesia published guidelines for weight-based FGF during inhalation induction
(Glensky, 2022):
Set FGF based on patient weight to exceed minute ventilation (VE) in order to prevent rebreathing
Minimizing FGF during Pediatric Inductions (cont.)
Setting induction FGF to exceed minute ventilation during induction prevents rebreathing
and dilution of volatile concentration.
Simulation courtesy of “Low Flow Anesthesia”
from the University of Florida Center for Safety,
Simulation & Advanced Learning Technologies:
● Top diagram: FGF >/= VE with no evidence
of rebreathing.
● Bottom diagram: FGF<VE with evidence of
rebreathing.
Recommendation 1: Reducing FGF During Maintenance
● During induction or emergence, it may be necessary to use high fresh gas flow
when a rapid change in the concentration of anesthetic gas is required.
● However, the maintenance generally relies on a steady concentration of gas.
● Thus, the maintenance phase is an opportunity to lower the fresh gas flow to
meet the patients needs, allowing for fewer GHG emissions without
compromising clinical care.
Literature-Defined Flow Rates (Hönemann, 2013)
Metabolic Fresh Gas Flow
0.35 L/min
Minimal Fresh Gas Flow
0.5 L/min
Low Fresh Gas Flow
1 L/min
High Fresh Gas Flow
2-6 L/min
Minimizing Fresh Gas Flow During Maintenance
● The minimum safe fresh gas flow supplies both enough oxygen and anesthetic to
satisfy patient consumption plus additional gas to compensate for leaks in the
circuit and/or via a sidestream gas analyzer (Axelrod, 2022).
● The patient oxygen uptake is correlated with body mass (Feldman, 2012) and is
conventionally calculated via two different formulas:
Key:
● “VO2”: Volume of oxygen consumed
by the patient per min
● “m”: Patient mass (in kg)
Brody’s Formula
(Hönemann, 2023)
Linear Formula
(Feldman, 2012)
Minimizing Fresh Gas Flow During Maintenance (cont.)
● This graph depicts the correlation
between weight and oxygen
consumption using Brody’s
formula (blue) and the linear
formula (red).
● Although Brody’s formula typically
yields a more accurate estimate
(Pulse Physiology Engine, 2022),
the linear formula is both more
simple to calculate and
overestimates the oxygen
consumption, creating a margin of
safety.
Benefits of Minimizing FGF During Maintenance: Ecological
Minimizing fresh gas flow during maintenance is a
safe and effective way to thwart waste anesthetic
gases, or “WAGs.”
● WAGs are gases that escape from a circular anesthesia
system into the outdoor atmosphere, virtually
unmetabolized and unregulated (McGain, 2020).
● Lower Fresh Gas Flow → Larger Re-Breathed Volume →
Smaller WAG Volume Emitted into the Atmosphere
Benefits of Minimizing FGF During Maintenance (cont.)
● Prior research indicates that minimizing FGF
during the maintenance phase can also…
● Increase heat and moisture content in the
lungs (Kleemann, 1994; Nunn, 2008)
● Increase mucociliary clearance and help
maintain a steady body temperature
(Aldrete, 1981)
● Help providers detect small leaks in the
circuit and adjust accordingly (CSSALT,
2022)
● Reduction of anesthetic gas consumption results
in significant institutional savings (Watts, 2018).
● “Low-flow anesthesia is a simple but highly
effective method of cost minimisation that can be
applied to a large number of patients without any
compromise in patient care or safety (Suttner,
2000)”
Clinical Considerations
Economic Considerations
Concerns of Minimizing FGF During Maintenance
● Inadequate Oxygen Delivery
○ As the fresh gas flow is lowered, the amount of exhaled gas (with a higher carbon dioxide
concentration) returned to the patient increases (Feldman, 2022).
○ This can lead to inadvertent low inspired concentration and hypoxemia.
● Inadequate Anesthetic Agent Delivery
○ A decrease FGF risks an inadequate anesthetic concentration, especially during early procedural
stages in which there is significant uptake of anesthetic from the lungs (Axelrod, 2022; Feldman,
2022.
● Wasted Emissions
○ Lowering FGF still results in significant WAG emission (unlike a true closed circuit in which fresh gas
flow directly equates what is consumed by the patient) (Sherman, 2012).
● Toxicity Associated with CO
2
Absorbents
○ As FGF decreases, a higher concentration of CO
2
absorbent is required.
○ Depending on the absorbent used, the risk of toxicity from Compound A and/or carbon monoxide
production may increase as well (Feldman, 2021; Branche, 2017).
Safely Minimizing FGF: Setting a Buffer
Once minimum FGF is calculated, the utilized FGF can be set slightly above this value to
reduce the risk of inadequate oxygen/anesthetic delivery.
Even a small reduction in FGF can make a significant ecological difference.
● Assuming 500 cases over 35 years, reducing the maintenance flow of isoflurane from 2
liters/min to 1 liter/min prevents an estimated 18,900 liters
from entering the atmosphere
(Feldman, 2012).
The ASA recommends total oxygen flow to be 20% greater than oxygen consumption.
Courses such as the University of Florida’s “Low Flow Anesthesia” can educate on how
to set a flow buffer and balance ecological impact with clinical safety(CSSALT, 2022).
Safely Minimizing FGF: Setting a Buffer
“Low Flow Anesthesia” from the University of Florida Center for Safety, Simulation &
Advanced Learning Technologies
https://simulation.health.ufl.edu/education-training/apsf-technology-education-initiative/low-flow-anesthesia/
Safely Minimizing FGF: Monitoring
Monitoring gas and anesthetic concentrations by the provider throughout the
maintenance phase is essential for reducing the risks of hypercapnia/hypoxia and
inadequate anesthetic delivery (Axelrod, 2022; Honemann, 2013; Feldman, 2012;
Feldman 2022; Garg, 2012).
Inspired/expired carbon dioxide, oxygen, and anesthetic agent concentration
should be consistently observed and fresh gas flow should be adjusted accordingly.
● Note: Managing inspired anesthetic concentration may be more challenging
since uptake of anesthetic falls exponentially over time (Feldman, 2022).
Safely Minimizing FGF: CO
2
Absorbent Choice
● Although some CO
2
absorbents present the possibility of toxicity when mixed with
anesthetic gas, it’s suggested that choosing absorbents containing
no potassium
chloride
and less than 2% sodium chloride would eliminate this risk (Feldman, 2022).
○ In absorbents containing KOH and NaOH, the strong base can react with sevoflurane or desflurane
to produce Compound A or carbon monoxide, respectively.
○ Without these bases present, however, Compound A and carbon monoxide production are no
longer a concern, eliminating the risk of toxicity.
● Thus, these CO
2
absorbent formulations can be used safely to minimize anesthetic
waste by allowing the reduction of fresh gas flow during the maintenance phase
without the risk of toxic gas production.
Intubation: Vaporizer vs. FGF
Common Misconception: Turning off the vaporizer while turning on fresh gas flow
during intubation prevents pollution of the operating room by the anesthetic
agent.
Rather, the anesthetic vapor that has accumulated in the circuit during mask
ventilation is washed into the room by fresh gas flow (Axelrod, 2022; Feldman,
2012; Scott, 2005).
Thus, room contamination is not avoided and vapor in the circuit is wasted.
Recommendation 2: Vaporizer On/FGF Off During Intubation
Alternate Strategy: Leave the vaporizer on and turn the fresh gas flow off during
the intubation process.
● This could mean temporarily switching FGF off or using the 60-second “pause
flow” feature on your anesthesia machine during intubation
● This practice would completely eliminate the discharge of the anesthetic gas
mixture into the O.R. environment during intubation (Scott, 2005).
● In the absence of fresh gas flow, none of the anesthetic vapor is washed into
the room and the reservoir that has built up in the circuit is preserved
(Axelrod, 2022).
Vaporizer On/FGF Off During Intubation: Benefits
Ecological Economic Clinical
●
No environmental
contamination during
intubation (Feldman, 2012)
● A lower FGF can be used to
maintain the circuit
concentration subsequent to
intubation (Feldman, 1999)
● Higher alveolar concentration
can be achieved at the same
vapor cost (Feldman, 1999)
● Additional cost savings when
FGF is kept paused or off
immediately after intubation
● A greater alveolar
concentration speeds up
induction (Feldman, 1999)
● Would also prevent a fall in
concentration within the
circuit, thus reducing the
likelihood of awareness post-
intubation (Scott, 2005)
Vaporizer On/FGF Off During Intubation: Other Considerations
● Note: Pausing or turning off the fresh gas flow during intubation may not be
appropriate for all cases.
○ In the event of difficult airway, fresh gas flow may need to be turned back
on to continue mask ventilation (Axelrod, 2022; Feldman, 2012).
● Each practitioner should make a decision about their own comfort level with
airway management and fresh gas flow changes.
Summary
● Circular anesthetic systems allow leaks of anesthetic vapor into the
ambient environment through the scavenging system.
● Managing fresh gas by both reducing FGF during maintenance and turning
FGF off during intubation when clinically appropriate can help minimize
this waste while also providing both economic and clinical benefits.
Recommendations
1. Minimizing Fresh Gas Flow During Maintenance
● Using minimum fresh gas flow that still satisfies the patient’s anesthetic and oxygen needs provides
ecological, economical, and clinical benefits.
● To ensure adequate anesthetic and oxygen concentrations, a buffer should be set that
overestimates minimum FGF and both gas and anesthetic concentrations should be monitored
throughout the case.
1. Turning Off Fresh Gas Flow During Intubation
● Keeping the vaporizer on and turning the FGF off during mask intubation does not contaminate the
operating room but actually provides numerous ecological and non-ecological advantages.
● However, this technique may not be appropriate for all procedures and should ultimately be a
provider-led decision.
Promoting Environmentally
Sustainable Anesthesia:
Recommendations
Management of Fresh
Gas Flow
Turn off fresh gas flow
during intubation
Selection of Anesthetic
Agent
Minimize fresh gas flow
during maintenance
Reduce usage of
nitrous oxide
Eliminate usage of
desflurane
Section IV:
MPOG QI Measures
(Watts, 2018)
MPOG: Sustainability Dashboard (sample)
SUS-01: Mean Fresh Gas Flow ≤ 3L/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.
Inclusion Criteria:
● Cases with an ETT or LMA as determined by Anesthesia Technique: General
value_codes 1,2,3,6 (Feldman, 2022)
● Patients administered halogenated hydrocarbons and/or nitrous oxide, for greater than
or equal to 30 minutes from placement of the airway device to removal of the airway
device.
Success: Mean FGF equal to, or less than 3L/minute when inspired halogenated
hydrocarbons is > 0.2%, or nitrous oxide FGF > 0.2 L/min, during the maintenance period of
anesthesia.
SUS-01: Percentage Passed Across MPOG Sites
SUS-02: Global Warming Footprint (Maintenance)
Description: Percentage of cases where carbon dioxide equivalents (CO
2
eq) normalized
by hour for cases receiving halogenated agents and/or nitrous oxide is less than CO
2
eq
of 2% sevoflurane at 2L FGF = 2.83 kg CO
2
/hr during the maintenance period of
anesthesia.
Inclusion Criteria:
● Cases with an ETT or LMA as determined by MPOG phenotype Anesthesia
Technique: General (value codes 1,2,3,6) (Feldman, 2022).
● Cases where halogenated hydrocarbons and/or nitrous oxide were administered
during the maintenance phase of anesthesia.
Success: Mean efficiency less than or equal to carbon dioxide equivalents of 2%
sevoflurane at 2L FGF = 2.83 kg CO
2
/hr.
SUS-02: Percentage Passed Across MPOG Sites
SUS-03: Global Warming Footprint (Induction)
Description: Total carbon dioxide equivalents per induction for cases where halogenated
agents and/or nitrous oxide was administered during the induction period of anesthesia
Inclusion Criteria:
● Cases with an ETT or LMA (Feldman, 2022)
● Cases where halogenated hydrocarbons and/or nitrous oxide were administered during
the maintenance phase of anesthesia.
Success: Not applicable - informational measure.
Carbon dioxide equivalents reported as kilograms of carbon dioxide equivalents per case
Emissions data are also converted to other meaningful equivalencies & reported as:
Miles driven by an average gasoline-powered passenger vehicle
Gallons of gasoline consumed
SUS-03: Average CO2 eq (Induction) Across MPOG Sites
SUS-04: Fresh Gas Flow ≤ 2L/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.
Inclusion Criteria:
● Cases with an ETT or LMA as determined by Anesthesia Technique: General
value_codes 1,2,3,6 (Feldman, 2022).
● Patients administered halogenated hydrocarbons and/or nitrous oxide, for greater than
or equal to 30 minutes from placement of the airway device to removal of the airway
device.
Success: Mean FGF equal to, or less than 2L/minute when inspired halogenated
hydrocarbons is >0.2%, or nitrous oxide FGF >0.2L/min, during the maintenance period of
anesthesia.
SUS-04: Percentage Passed Across MPOG Sites
SUS-05-Peds: Nitrous Avoided During Induction
(Pediatrics)
Description: Percentage of pediatric cases where nitrous oxide gas
was avoided during induction of anesthesia.
Inclusion Criteria:
● Patients < 18yo who undergo general anesthesia as defined by
Anesthesia Technique: General
(Feldman, 2022).
Success: Nitrous oxide was not administered during the induction
period of anesthesia.
SUS-05: Percentage Passed Across MPOG Sites
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