Anesthetics and the Environment: Comparing CO₂ Absorbers

Still, hospitals can limit these emissions voluntarily by using CO₂ absorbers, which are beneficial in three ways:

• Reducing anesthesia’s environmental impact
• Saving on the cost of anesthetic gases
• Contributing to patient safety

Soda lime has been the most common CO₂ absorber, but AMSORB^® Plus from GE HealthCare has been shown to be a safe and eco-friendly alternative. Here is a look at the environmental and human sides of CO₂ absorbers.

Anesthesia: A Significant Source of Greenhouse Gases

The United States is the world’s second-largest greenhouse gas emitter, and Anesthesiology Clinics reports that 10% of those emissions come from the healthcare sector¹. In the United Kingdom, the Association of Anaesthetists estimates that anesthetic gases account for 5% of National Health Service CO₂ emissions, and that each operating theater exhausts some 5,070 pounds of such gases every year².

The most common anesthetic gases—isoflurane, sevoflurane, and desflurane—change very little while inside the body. When exhaled, they remain as potent greenhouse cases. For example, The Lancet Planetary Health reports that the use of desflurane for one hour is equivalent to driving a modern car 230 miles³.

CO₂ Absorbers: Why They Help, How They Work

CO₂ absorbers have been widely used in anesthesia since the 1920s. CO₂ and anesthesia gas exhaled into a patient’s breathing tube travels to a CO₂ absorber canister. Then, when the patient inhales, the gas passes through the absorber, which removes the CO₂.

This process allows anesthetic agents exhaled by the patient to be rebreathed, minimizing waste, according to the journal Anesthesia Analgesia⁴. This limits both the amount of anesthetic used in the surgery and the amount vented to the air outside. In addition, patients are protected against inhaling CO₂ and other harmful gases. In sum, for decades CO₂ absorbers have helped keep surgeries effective, efficient, and safe.

Which absorber should you choose?

The two best-known absorbers, AMSORB^® Plus and soda lime, have their respective advantages. Both can be assessed in terms of their impact within the hospital and in the larger environment.

Soda Lime

Soda lime is often favored for its relatively low cost. However, according to Current Opinion in Anaesthesiology, it degrades sevoflurane and desflurane, creating compound A and carbon monoxide in its canisters⁵. Patients can then easily inhale these gases, starving their bodies of oxygen.

Soda lime also has potential to introduce more carbon dioxide—not less—to a patient's system. The reaction of CO₂ with soda lime releases heat and water and changes the soda lime pH. For this reason, a pH-activated color indicator called ethyl violet is commonly added to the soda lime canister; a change from white to violet means the soda lime’s absorptive capacity has been exhausted and the material needs replacing.

But sometimes the color change does not happen quickly enough; high levels of CO₂ then remain in a canister and put patient safety at risk⁶.

AMSORB^® Plus Absorbent

AMSORB^® Plus is an eco-friendly material that builds on the basics of CO₂ absorption to improve patient care during anesthesia. AMSORB^® Plus:

• Contains no strong alkali and cannot degrade anesthetic agents such as desflurane.
• Produces no carbon monoxide, formaldehyde, or compound A, removing the risk of patients inhaling those harmful byproducts.
• Is nonhazardous and so can be disposed of with uncontaminated clinical waste according to local policies.
• Breaks down into harmless organic compounds, enabling safe handling and disposal.

Most important AMSORB^® Plus Absorbent is optimized for low-flow anesthesia, which uses less anesthetic agent and emits less gas to the atmosphere. This has both environmental and cost benefits: Reducing fresh gas flow from 3.0 L/min (high) to 1.0 L/min (low) reduces volatile agent consumption by about 50%⁷.

Protecting Patients and the Environment

CO₂ absorbers are a crucial part of anesthesia, and healthcare leaders should not overlook their advantages. Replacing soda lime with AMSORB^® Plus Absorbent enables teams to take better care of patients and communities alike.

References

1. https://www.anesthesiology.theclinics.com/article/S1932-2275%2820%2930046-X/fulltext
2. https://anaesthetists.org/Home/Resources-publications/Environment/Our-environmental-work/Why-it-matters-facts-figures
3. https://anaesthetists.org/Home/Resources-publications/Environment/Our-environmental-work/Why-it-matters-facts-figures
4. https://journals.lww.com/anesthesia-analgesia/Fulltext/2021/04000/Carbon_Dioxide_Absorption_During_Inhalation.10.aspx
5. https://journals.lww.com/co-anesthesiology/Abstract/2001/08000/Inhalational_anaesthesia.2.aspx
6. https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2044.1994.tb03551.x
7. https://www.gehealthcare.com/insights/article/what-and-why-on-low-flow

© 2022 General Electric Company–All rights reserved.GE and the GE Monogram are trademarks of GE. Amsorb is a registered trademark of Armstrong Medical Limited. Reproduction in any form is forbidden without prior written permission from GE HealthCare. Nothing in this material should be used to diagnose or treat any disease or condition. Readers must consult a healthcare professional.

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