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

A patient received closed-circuit anesthesia from a General Electric Avance S/5 (GE Healthcare, Madison, WI) anesthesia machine during a robotic abdominal procedure. With return of spontaneous ventilation at the end of the procedure, the negative airway pressure alarm began to sound, and a negative airway pressure of 10-15 cm H2O was observed with each breath. Replacing the CO2 absorber resolved the problem. There was considerable condensation on the walls of the Amsorb canister, and on disassembly, the sponge at the bottom was wet. Experimentation with an empty canister revealed that as little as 30 mL of water in the sponge can reproduce our observations.