Research Suggests Optimal Fresh Gas Flow Depends on Environmental Context

According to researchers, the ideal fresh gas flow (FGF) during TIVA is not universal and varies according to a country’s electricity grid emissions and carbon dioxide absorbent disposal practices. Using these factors, the calculator offers evidence-based FGF recommendations that balance both economic efficiency and environmental sustainability worldwide.

Climate change and healthcare are tightly intertwined, with hospitals and surgeries accounting for a significant portion of greenhouse gas emissions. Anesthesia, in particular, is a notable contributor—estimates suggest anesthetic gases are responsible for about 3% of healthcare’s carbon footprint. While the impact of a single surgery may seem small, the cumulative effect of over 300 million annual operations worldwide is immense.

Rethinking Gas Flow in Total Intravenous Anesthesia

Total intravenous anesthesia (TIVA) is often considered more environmentally friendly than volatile-based anesthesia. Unlike inhalational agents, TIVA allows flexibility in choosing the fresh gas flow (FGF) rate, which can potentially cut both costs and environmental impact. But does simply increasing FGF to save on carbon dioxide absorber usage always make sense ecologically?

A new study published in Anesthesiology takes a closer look, using a detailed life-cycle assessment and real-world data from a hospital in Singapore.

The Study: One Size Does Not Fit All

Researchers developed a web-based calculator (fgfcalculator.com) to help anesthetists identify the optimal FGF for their unique local settings. They compared the costs and environmental impact—measured as 100-year global warming potential (GWP100)—of different FGF rates across various grid emission scenarios and waste disposal methods.

Their findings reveal:

Higher FGF rates can reduce costs by lowering the use of carbon dioxide absorbers, but at the expense of higher oxygen and air usage, which increases the carbon footprint.

The environmental impact of FGF depends heavily on the country’s electricity grid emissions and local waste management practices.

In Singapore, increasing FGF from 1 to 10 L/min cut annual costs from S12,948toS1,572 but nearly tripled the GWP100 from 1,939 to 5,910 kgCO₂e.

Why Local Factors Matter

The study demonstrates that in places with cleaner electricity grids (e.g., Norway, Bhutan), higher FGF may actually lower the environmental impact. Conversely, in regions with carbon-heavy energy sources (like Singapore), higher gas flow rates rapidly increase emissions.

Additionally, waste disposal methods—whether incineration or landfill—significantly influence both cost and carbon footprint.

Empowering Sustainable Choices

This research arms clinicians with a flexible, evidence-based tool that adapts to local realities. By entering context-specific data into the calculator, hospitals can balance cost savings with environmental stewardship, rather than relying on blanket recommendations.

5 Key Takeaways

No universal FGF rate: Optimal fresh gas flow for TIVA depends on local grid emissions and waste management.

Cost vs. carbon trade-off: Higher FGF often cuts costs but can increase environmental impact, especially in carbon-intensive regions.

Singapore example: Best balance found at 2–4 L/min FGF, with steepest cost decline and moderate emissions rise.

Calculator tool: The study offers a free online calculator to tailor FGF decisions to your specific context.

Global relevance: Hospitals worldwide can use this approach to make more sustainable, cost-effective anesthesia decisions.

Citation:

Wong, C. S. W., Ho, K. H. Y., Ee, A. W. L., Ting, P. L. M., Ang, K. S., Tan, J. J., & Poh, P. K. (2026). Optimal Fresh Gas Flow when Employing Total Intravenous Anesthesia. Anesthesiology, 144(6), 1309–1315. https://doi.org/10.1097/ALN.0000000000006025