CO₂ absorbent canister life

Estimate canister hours given capacity, fresh-gas flow, and patient CO₂ production. Lower FGF (closed circuit) drives more CO₂ to the absorbent → shorter canister life.

Canister capacity (L CO₂)

Sodalime 500g ≈ 130 L; Amsorb 350g ≈ 80 L

Fresh gas flow (L/min)

Closed circuit ≈ 0.5; low-flow 1; standard 2; high 5+

Patient CO₂ production (mL/min)

Adult ~150–250 mL/min under GA

Estimated duration

13.5 hours

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CO₂ absorbent capacity: 130 L
Patient CO₂ production: 200 mL/min
Fresh-gas factor at FGF 1 L/min: 80% reaches absorbent
CO₂ to absorbent: 160 mL/min
Duration: 130 ÷ 0.160 = 13.5 hours

Clinical note: First sign of canister exhaustion is rising inspired CO₂ (capnogram baseline above 0). Color indicators (white → purple) lag and aren't reliable. Avoid desiccated absorbent + sevoflurane (Compound A risk).