A survey of the anesthesia scavenging systems in a teaching hospital

Pollution by anesthetic gases can be a problem in operating theaters. More than 90 per cent of this pollution can be reduced by using a scavenging system. Such systems increase the complexity, and thus the hazards of administering anesthesia. A case of pneumothorax prompted an investigation of the active scavenging systems currently used in a teaching hospital by using a pre-use check up protocol. Thirty-eight closed-reservoir active scavenging systems were included. Ten systems (26.3%) were assembled incorrectly. All systems passed a negative pressure relief valve test. Seventeen systems (44.7%) failed to pass a positive pressure relief valve test because high pressure (over 10 cmH2O) developed during an O2 flush, but direct measurement of the pressure at the scavenging interface revealed that these defects were caused by a problem with the adjustable pressure limiting (APL) valves, not with the positive pressure relief valves of the system. We suggest that routine pre-use check up together with regular maintenance of equipment should be emphasized and all personnel should be encouraged to learn more about safety precautions.