Low flow anesthesia can help reduce the amount of anesthesia gas used while still providing safe and effective patient care that is better for the environment. The proper administration of anesthetics is essential to ensure patient safety and comfort during surgical procedures. General anesthesia is used to put patients in a sleep-like state and is commonly administered through a combination of intravenous medicines and inhaled gases. 

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However, patients only metabolize about 5% of administered anesthetic agents, with the remaining 95% vented to the outdoor atmosphere as waste.ⁱ  

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Low flow anesthesia can help reduce the amount of anesthesia gas used while still providing safe and effective patient care that is better for the environment. The proper administration of anesthetics is essential to ensure patient safety and comfort during surgical procedures. General anesthesia is used to put patients in a sleep-like state and is commonly administered through a combination of intravenous medicines and inhaled gases. 

However, patients only metabolize about 5% of administered anesthetic agents, with the remaining 95% vented to the outdoor atmosphere as waste.ⁱ  

Low-flow anesthetic delivery became possible in the early 1900s with the introduction of carbon dioxide absorption.ⁱⁱ In fact, it could be suggested that 2024 serves as the 100-year anniversary of low flow anesthesia based on the publication of Ralph Waters’ paper, “Clinical scope and utility of carbon dioxide filtration in inhalation anesthesia,” in Anesthesia and Analgesia in February 1924. ^{iii iv}

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The benefits of low-flow anesthesia are well established and include reduced inhaled anesthetic waste, decreased cost, and lower greenhouse gas emissions from inhaled anesthetics. With economic, environmental and patient safety benefits, low flow anesthesia is growing in utilization.

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Financial Benefits

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Inhaled anesthetics are estimated to account for 20-25% of all anesthetic drug costs. Patients generally only metabolize about 5% of administered anesthesia, with the remaining 95% exhaled as waste anesthetic gas and vented to the outdoor atmosphere through scavenging systems.^v Cutting fresh gas flow has been shown to have the potential to lower costs by reducing the number of inhalational agents used per patient. Some hospitals have been projected to save $20,000-$30,000 per month – by reducing fresh gas flow rates during appropriate procedures.^vi

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Environmental Benefits

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Anesthesia is integral to the delivery of healthcare but contributes significantly to environmental pollution. Overall, the U.S. health industry is responsible for an estimated 8.5% of national carbon emissions.^vii Volatile anesthetics and nitrous oxide (N₂O) are potent greenhouse gases that contribute to global warming when released into the atmosphere. Desflurane is the inhaled anesthetic that is the most potent greenhouse gas, with a global warming potential (GWP) of 2540 compared to CO₂, which has a GWP of 1.^viii Due to this climate impact and questions about patient benefits, the use of Desflurane has decreased in recent years.^ix

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According to the ASA Task Force on the Environment, greenhouse gas emissions from anesthetic agents can be reduced by using low flow anesthesia techniques and choosing inhalational agents with lower global warming impacts when clinically appropriate. 

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Most modern anesthesia machines are equipped with a circle rebreathing system, which considerably reduces FGF rates. By enabling exhaled anesthetics to be rebreathed, circle anesthesia circuits are intended to lower the amount of inhaled anesthetic waste. 

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In 2021, the World Federation of Societies of Anesthesiologists (WFSA) developed a global consensus statement on the principles of environmentally sustainable anesthesia, which includes minimizing waste and overuse of resources and addressing environmental sustainability in anesthesiologists’ education.^x

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Safety Benefits

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The use of a circle rebreathing system in low flow methods also delivers patient care benefits, as the CO₂ absorption process increases the warmth and humidity of the recirculated gases. Breathing warm and humid gases during anesthesia benefits patients for several reasons, including preventing heat loss and post-operative hypothermia. Increased humidification also helps to reduce airway and bronchial drying during intubation.

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Low-flow anesthetic delivery became possible in the early 1900s with the introduction of carbon dioxide absorption.ⁱⁱ In fact, it could be suggested that 2024 serves as the 100-year anniversary of low flow anesthesia based on the publication of Ralph Waters’ paper, “Clinical scope and utility of carbon dioxide filtration in inhalation anesthesia,” in Anesthesia and Analgesia in February 1924. ^{iii iv}

The benefits of low-flow anesthesia are well established and include reduced inhaled anesthetic waste, decreased cost, and lower greenhouse gas emissions from inhaled anesthetics. With economic, environmental and patient safety benefits, low flow anesthesia is growing in utilization.

Financial Benefits

Inhaled anesthetics are estimated to account for 20-25% of all anesthetic drug costs. Patients generally only metabolize about 5% of administered anesthesia, with the remaining 95% exhaled as waste anesthetic gas and vented to the outdoor atmosphere through scavenging systems.^v Cutting fresh gas flow has been shown to have the potential to lower costs by reducing the number of inhalational agents used per patient. Some hospitals have been projected to save $20,000-$30,000 per month – by reducing fresh gas flow rates during appropriate procedures.^vi

Environmental Benefits

Anesthesia is integral to the delivery of healthcare but contributes significantly to environmental pollution. Overall, the U.S. health industry is responsible for an estimated 8.5% of national carbon emissions.^vii Volatile anesthetics and nitrous oxide (N₂O) are potent greenhouse gases that contribute to global warming when released into the atmosphere. Desflurane is the inhaled anesthetic that is the most potent greenhouse gas, with a global warming potential (GWP) of 2540 compared to CO₂, which has a GWP of 1.^viii Due to this climate impact and questions about patient benefits, the use of Desflurane has decreased in recent years.^ix

According to the ASA Task Force on the Environment, greenhouse gas emissions from anesthetic agents can be reduced by using low flow anesthesia techniques and choosing inhalational agents with lower global warming impacts when clinically appropriate. 

Most modern anesthesia machines are equipped with a circle rebreathing system, which considerably reduces FGF rates. By enabling exhaled anesthetics to be rebreathed, circle anesthesia circuits are intended to lower the amount of inhaled anesthetic waste. 

In 2021, the World Federation of Societies of Anesthesiologists (WFSA) developed a global consensus statement on the principles of environmentally sustainable anesthesia, which includes minimizing waste and overuse of resources and addressing environmental sustainability in anesthesiologists’ education.^x

Safety Benefits

The use of a circle rebreathing system in low flow methods also delivers patient care benefits, as the CO₂ absorption process increases the warmth and humidity of the recirculated gases. Breathing warm and humid gases during anesthesia benefits patients for several reasons, including preventing heat loss and post-operative hypothermia. Increased humidification also helps to reduce airway and bronchial drying during intubation.

The administration of low flow anesthesia is generally performed in three phases: induction, maintenance and recovery. A high FGF is common during the induction phase, after which FGF is decreased to the appropriate level (1 L/min or less) during the maintenance phase where the re-breathing rate increases. When the flow is reduced, continuous monitoring of the patient’s oxygen levels and anesthetic agent concentration is essential to safely and effectively deliver low flow anesthesia. During the recovery phase, the patient may be switched to high flow oxygen to enable faster wash out of residual anesthetic gas as the patient is transferred to recovery.

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Recently, the APSF, in collaboration with ASA, launched an online education course on low flow anesthesia using guided simulation to help anesthesiologists learn and practice proper low flow procedures.

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The administration of low flow anesthesia is generally performed in three phases: induction, maintenance and recovery. A high FGF is common during the induction phase, after which FGF is decreased to the appropriate level (1 L/min or less) during the maintenance phase where the re-breathing rate increases. When the flow is reduced, continuous monitoring of the patient’s oxygen levels and anesthetic agent concentration is essential to safely and effectively deliver low flow anesthesia. During the recovery phase, the patient may be switched to high flow oxygen to enable faster wash out of residual anesthetic gas as the patient is transferred to recovery.

Recently, the APSF, in collaboration with ASA, launched an online education course on low flow anesthesia using guided simulation to help anesthesiologists learn and practice proper low flow procedures.

 

With growing support from industry and professional societies like the World Federation of Societies of Anesthesiologists, American Society of Anesthesiologists, and the Anesthesia Patient Safety Foundation, the adoption of low flow anesthesia continues to increase. A growing body of evidence demonstrates that low flow anesthesia techniques not only provide considerable economic and ecological benefits, but may also improve the quality of patient care. The ability to safely and efficiently reduce inhalation agent usage enables clinicians to practice cost containment while improving their environmental footprint.

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With growing support from industry and professional societies like the World Federation of Societies of Anesthesiologists, American Society of Anesthesiologists, and the Anesthesia Patient Safety Foundation, the adoption of low flow anesthesia continues to increase. A growing body of evidence demonstrates that low flow anesthesia techniques not only provide considerable economic and ecological benefits, but may also improve the quality of patient care. The ability to safely and efficiently reduce inhalation agent usage enables clinicians to practice cost containment while improving their environmental footprint.

The Mindray Difference \r\n

At Mindray, we believe in a better future for our clinicians and patients. Our anesthesia platform embodies this philosophy by retaining traditional features while introducing disruptive technology to maximize patient safety, help improve patient outcomes, complement the way clinicians work best, and increase efficiency in the perioperative environment.

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The Mindray Difference 

At Mindray, we believe in a better future for our clinicians and patients. Our anesthesia platform embodies this philosophy by retaining traditional features while introducing disruptive technology to maximize patient safety, help improve patient outcomes, complement the way clinicians work best, and increase efficiency in the perioperative environment.

 

References:
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ⁱ Hospital anesthetic gas discharges and the environment: prevent the vent. Canadian Centre for Pollution Prevention Web site. Accessed November 10, 2010.

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ⁱⁱ Technology and Low-Flow Anesthesia Practice, APSF

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ⁱⁱⁱ WATERSRM. Clinical scope and utility of carbon dioxidefiltration in inhalation anesthesia. Anesthesia and Analgesia1924; 3: 2&2

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^iv BAUM, J.A. and AITKENHEAD, A.R. (1995), Low-flow anaesthesia. Anaesthesia, 50: 37-44. http://doi.org/10.1111/j.1365-2044.1995.tb06189.x

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^v  Hospital anesthetic gas discharges and the environment: prevent the vent. Canadian Centre for Pollution Prevention Web site. Accessed November 10, 2010.

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^vi Sustainable Anesthesiology, http://anesthesia.wisc.edu/sustainable-anesthesiology/

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^vii Dzau, V.J.; Levine, R.; Barrett, G.; Witty, A. Decarbonizing the U.S. Health Sector—A Call to Action. N. Engl. J. Med. 2021, 385, 2117–2119.

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^viii McGain F, Muret J, Lawson C, Sherman JD. Environmental sustainability in anaesthesia and critical care. Br J Anaesth. 2020 Nov;125(5):680-692. doi: 10.1016/j.bja.2020.06.055. Epub 2020 Aug 12. PMID: 32798068; PMCID: PMC7421303.

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^ix Shelton CL, Sutton R, White SM. Desflurane in modern anaesthetic practice: walking on thin ice(caps)? Br J Anaesth. 2020 Dec;125(6):852-856. doi: 10.1016/j.bja.2020.09.013. Epub 2020 Oct 7. PMID: 33039121.

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^x White SM, Shelton CL, Gelb AW, et al. Principles of environmentally-sustainable anaesthesia: a global consensus statement from the World Federation of Societies of Anaesthesiologists. Anaesthesia. Published online November 1, 2021. doi:10.1111/anae.15598. PMID: 34724710
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References:

ⁱ Hospital anesthetic gas discharges and the environment: prevent the vent. Canadian Centre for Pollution Prevention Web site. Accessed November 10, 2010.

ⁱⁱ Technology and Low-Flow Anesthesia Practice, APSF

ⁱⁱⁱ WATERSRM. Clinical scope and utility of carbon dioxidefiltration in inhalation anesthesia. Anesthesia and Analgesia1924; 3: 2&2

^iv BAUM, J.A. and AITKENHEAD, A.R. (1995), Low-flow anaesthesia. Anaesthesia, 50: 37-44. http://doi.org/10.1111/j.1365-2044.1995.tb06189.x

^v  Hospital anesthetic gas discharges and the environment: prevent the vent. Canadian Centre for Pollution Prevention Web site. Accessed November 10, 2010.

^vi Sustainable Anesthesiology, http://anesthesia.wisc.edu/sustainable-anesthesiology/

^vii Dzau, V.J.; Levine, R.; Barrett, G.; Witty, A. Decarbonizing the U.S. Health Sector—A Call to Action. N. Engl. J. Med. 2021, 385, 2117–2119.

^viii McGain F, Muret J, Lawson C, Sherman JD. Environmental sustainability in anaesthesia and critical care. Br J Anaesth. 2020 Nov;125(5):680-692. doi: 10.1016/j.bja.2020.06.055. Epub 2020 Aug 12. PMID: 32798068; PMCID: PMC7421303.

^ix Shelton CL, Sutton R, White SM. Desflurane in modern anaesthetic practice: walking on thin ice(caps)? Br J Anaesth. 2020 Dec;125(6):852-856. doi: 10.1016/j.bja.2020.09.013. Epub 2020 Oct 7. PMID: 33039121.

^x White SM, Shelton CL, Gelb AW, et al. Principles of environmentally-sustainable anaesthesia: a global consensus statement from the World Federation of Societies of Anaesthesiologists. Anaesthesia. Published online November 1, 2021. doi:10.1111/anae.15598. PMID: 34724710