Water Accumulation in Amsorb Canister May Cause Inspiratory Flow Obstruction: A Case Report

Area of Science:

• Anesthesiology
• Medical Engineering

Background:

• Closed-circuit anesthesia delivery systems are widely used in modern surgical procedures.
• Anesthesia machines, such as the GE Healthcare Avance S/5, incorporate safety features like negative airway pressure alarms.
• The carbon dioxide (CO2) absorber is a critical component in rebreathing anesthesia circuits, responsible for removing exhaled CO2.

Observation:

• A negative airway pressure alarm sounded during a robotic abdominal procedure upon return of spontaneous ventilation.
• The alarm indicated a negative airway pressure of 10-15 cm H2O with each breath.
• Condensation was observed within the CO2 absorber canister, with a wet sponge at the bottom.

Findings:

• The problem was resolved by replacing the CO2 absorber.
• Experimentation demonstrated that as little as 30 mL of water in the sponge could replicate the observed negative airway pressure.
• This suggests that moisture saturation of the CO2 absorber is the cause of the malfunction.

Implications:

• Clinicians should be aware of potential CO2 absorber malfunction due to moisture accumulation.
• Regular maintenance and timely replacement of CO2 absorbers are crucial for preventing anesthesia-related complications.
• This finding highlights the importance of monitoring anesthesia equipment for subtle signs of failure, particularly in complex surgical settings.