49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

Environmental Impact of Medical Ultrasound Use

Connor Singrey, MD1, E.B. Fouts-Palmer, MD1, Vivian Ip, MBChB2, Deirdre C. Kelleher, MD1

1 Department of Anesthesiology, Weill Cornell Medicine, New York-Presbyterian Hospital, New York, NY

2 Department of Anesthesiology and Pain Medicine, Cumming School of Medicine, University of Calgary, Calgary, Canada

Introduction

We aim to investigate scope 2 and 3 emissions related to ultrasound use in our department and identify ways to reduce our environmental impact

•Scope 1 (Direct)

•Fuel used on-site

•Volatile anesthetics

•Scope 2 (Purchased electricity)

•Emissions at power plant

•Scope 3 (Everything else)

•Manufacturing

•Use

•Disposal

Methods

•Measured electrical output, battery characteristics, and screen power settings for our ultrasound machines

•Computed theoretical electricity use and carbon emissions1.

•Battery degradation, and its downstream environmental impact, was also evaluated in theoretical use scenarios.

•IRB/IND approval not required for quality improvement project.

Results: Scope 2

•10.8V & 5200-5800 mAh Li-ion batteries

•Maximum power use: 75 watts

•Use AC power when connected to a wall source

•Use pattern

•Brief active periods & prolonged standby time

•Sleep mode (decreased power use) & auto-off engage automatically after adjustable periods

•Default set to maximum intervals

•Two hours of downtime per day calculate to lead to:

•54 kWh wasted

• >21kg CO2e1 per year

Results: Scope 3

•Battery lifespan: 300-700 cycles depending on use pattern & Li-ion composition

•Li-ion degradation is due to increased cycle counts, abnormal state of charge, and abnormal temperature3-2

•Non-productive ultrasound battery time contributes significantly to cycle counts

2h non-productive time = one wasted battery cycle

•Battery degradation is compounded by draining to near-minimal state of charge

•Wasted battery cycles à premature battery replacement

Financial impact: several hundred dollars per battery

Discussion

•Waste can be limited by:

•Limiting non-productive “on” time: turn on right before use, turn off at end of use

•Adjusting sleep & auto-off intervals to minimum settings

•Early battery replacement leads to unnecessary scope 3 emissions.

•Beyond carbon emissions: landfill waste, heavy metals leeching into groundwater2-3

•Calculated electricity emissions are a minor contributor

Abbreviations: CO2e, carbon emissions

References

1: United States, Energy Information Administration. State Electricity Profiles. U.S. Energy Information Administration, 2022, https://www.eia.gov/electricity/state/unitedstates/state_tables.php. Accessed December 7th, 2023.

2: Barcellona, S., and L. Piegari. "Effect of current on cycle aging of lithium-ion batteries." Journal of Energy Storage 29 (2020): 101310.

3: Winslow, Kevin M., Steven J. Laux, and Timothy G. Townsend. "A review on the growing concern and potential management strategies of waste lithium-ion batteries." Resources, Conservation and Recycling.129 (2018): 263-277

49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

ENVIRONMENTAL IMPACT OF MEDICAL ULTRASOUND USE

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