Decontamination of anaesthetic equipment

The risk of cross infection due to contaminated anaesthetic equipment is currently causing concern. It is accepted that masks, endotracheal tubes, catheters and Y pieces are an infection hazardl-3, but the importance of corrugated anaesthetic tubing and rebreathmg bags has been in dispute4. In this hospital tests carried out at the end of morning operating sessions upon corrugated tubing which had been sterilised by autoclaving before use show that this tubing can be, at least potentially, dangerous. Five of twenty-five lengths of tubes examined were contaminated with pathogenic bacteria; three with Ps. aerugiitosa, one with Escli. coli and one with Staph. pq’ogenes. None of the lengths of tubing examined proved to be sterile. In view of these findings and similar reports from elsewhere 1-39 5 it was felt that this reservoir of infection could not be ignored and that it was especially menacing when a closed circuit or partial rebreathing system was employed. Ideally all anaesthetic equipment should be decontaminated after every case, but if this proves impracticable it should be processed after every patient known to have a respiratory infection or after every operating session. All the reported methods for decontaminating this equipment have serious practical drawbacks. Autoctaving is economically prohibitive due to the rapid deterioration in the rubber of the corrugated tubes and bags. Ethylene oxide requires expensive special apparatuss, skilled management and prolonged sterilization and airing time. Formaldehyde is relatively inefficient unless used in combination with subatmospheric steam, but in these conditions specialised and expensive apparatus is required7. Germicidal soaks with chlorhexidine or glutaraldehyde require suitable soaking facilities, rinsing must be scrupulous and draining and drying is a problem. Pasteurisation is beset with problems of floating loops of corrugated tubing and masks, with resultant inadequate decontamination. Lastly, the efficiency of all these methods depends for success upon separate and adequate initial washing to remove organic material, such as sputum or blood, which could protect the bacteria from the sterilising agent.