Using breathing systems in anaesthesia for up to 7 days instead of 24 hours: a comparative microbial safety study

SummaryThe replacement frequency of mechanical ventilators breathing systems used in operating rooms (ORs) currently varies between hospitals. In light of evidence-based decision-making and sustainability efforts, we aim to determine whether 7-day use of breathing systems instead of 24 hours is microbial safe. In this prospective single-centre explorative study, 30mm UniflowTM breathing systems used in eight ORs were included. In four ORs, breathing systems were replaced daily following standard practice. In the remaining four ORs, they were intended for a 7-day use. Breathing systems were sampled daily on three locations of the exterior surface and cultured for the presence of microorganisms. A total of 128 breathing systems were included, 99 from an OR with daily replacement and 29 from an OR with weekly replacement. A total of 604 samples were cultured, of which the majority, 549 (90.9%) cultures were negative. From the 55 (9.1%) positive cultures, the majority (n=49, 70%) were coagulase-negative staphylococci. None of the identified microorganisms were found in consecutive cultures. Cultures from day 2 to 7 did not show a statistically significant increased positivity rate compared to cultures from day 1, respectively 22.9% vs. 24.1%. The weekly replacement regimen, furthermore, decreased the number of breathing systems used with 71%. Our data indicates that use of breathing systems up to seven days remains microbial safe. Additionally, only a minimal number of pathogenic microorganisms were detected, and these were not persistent on the breathing systems. Transitioning from 24-hours to intended 7-day use could significantly reduce costs and CO2 emissions.