Which signal indicates the need to change soda lime in anesthesia circuits?

Which signal indicates the need to change soda lime in anesthesia circuits?

• A. Granules change colors
• B. Ventilator pressure increases
• C. Oxygen flow decreases
• D. CO2 absorber becomes hot

Answer: (A)

Color change in the granules signals when the soda lime needs replacing. The absorbent is dyed with an indicator that shifts color as CO2 reacts with the lime. When the canister is fresh, the granules show the original color; as CO2 absorption proceeds and the material becomes exhausted, the indicator shifts to the exhausted color. This provides a direct, visible cue that the absorber’s capacity is depleted and rebreathing of CO2 may occur if it isn’t changed. Other signs like a rise in ventilator pressure, a drop in oxygen flow, or the canister feeling hot can happen for reasons other than exhaustion of the CO2 absorber, so they’re less reliable as sole indicators.

Color change in the granules signals when the soda lime needs replacing. The absorbent is dyed with an indicator that shifts color as CO2 reacts with the lime. When the canister is fresh, the granules show the original color; as CO2 absorption proceeds and the material becomes exhausted, the indicator shifts to the exhausted color. This provides a direct, visible cue that the absorber’s capacity is depleted and rebreathing of CO2 may occur if it isn’t changed. Other signs like a rise in ventilator pressure, a drop in oxygen flow, or the canister feeling hot can happen for reasons other than exhaustion of the CO2 absorber, so they’re less reliable as sole indicators.