Sterilization versus disinfection of anesthesia breathing circuits: safety and economic considerations.

Previous studies In 1977, du Moulin and Saubermann compared the bacterial contamination of the anesthesia machine to two groups of patients: one group had upper respiratory tracts colonized with gram negative bacilli and another group had normal upper respiratory tract flora. 4 They found no significant difference between the organisms cultured from the inspiratory and expiratory tubing used by these two groups of patients. Their study suggests that patients rarely contaminate the anesthesia machine with significant levels of bacteria regardless of the duration of anesthesia. The authors concluded that the use of extra measures such as bacterial filters or disposable circle systems were unwarranted, as routine cleaning and sterilization procedures are sufficient to minimize the risk of cross-contamination. In 1981, Feeley and associates approached the problem in a different fashion. Randomly chosen patients (n=293) similar in age, sex and type of surgical procedure were arbitrarily anesthetized with either sterile breathing circuits and bacterial filters (sterile group), or reused breathing circuits cleaned with soap and water (non-sterile group). Five patients (3.6%) in the sterile group (n=138) and four patients (2.6%) in the non-sterile group (n = 155) developed postoperative pulmonary infections. As there was no significant difference in postoperative infections between the two groups, the authors concluded that the need to use a sterile breathing circuit remains unproven.6 On the other hand, in 1974, Albrecht and Dryden, alarmed by a high (unspecified) incidence of postoperative pneumonia in their open heart surgical patients, instituted a gradual change from reused breathing circuits to totally disposable breathing circuits.1 Subsequently, they reviewed the charts of 220 patients who underwent noncontaminated abdominal surgery. They found that the incidence of postoperative pulmonary infections decreased over a five-year period from 20%