Can clothing systems and human activity in operating rooms with mixed flow ventilation systems help achieve the ultraclean air requirement (≤10 CFU/m3) during orthopaedic surgeries?

OBJECTIVES: The level of airborne microbial contamination in operating rooms (ORs) is an important indicator of indoor air quality and ensures a clean surgical environment. The main objective of this study was to clarify the possibility of achieving the requirement for an ultraclean operating room (≤ 10 CFU/m3) with mixed flow ventilation based on clothing and human activity. METHODS: Experimental measurements during mock surgeries were conducted in an actual OR with mixed flow ventilation in the Emergency, Heart and Lung Centre at St. Olavs Hospital in Trondheim. The bacterial concentration close to the surgical site was measured during five mock-up surgeries. All five mock-up surgeries followed real surgical procedures which could represent similar conditions in the OR. RESULTS: The experiment results verified that the average CFU/m3 of three of the five mock-up surgeries was 8.5, which was below or equal to the ultraclean requirement, while the other two mock-up surgeries did not meet the ultraclean requirement. Surgical activity together with the type of clothing worn by surgical staff in ORs seem to be the most significant reason for the high CFU level during surgery. CONCLUSIONS: It is possible to achieve the ultraclean air requirement (≤ 10 CFU/m3) during a surgical process with proper clothing and low surgical activity in ORs. This study clarifies the effect of clothing and human activity on the CFU level in the surgical micro-environment in ORs, and contributes to developing new products for the surgical team.

Comparison of UV C light and chemicals for disinfection of surfaces in hospital isolation units.

OBJECTIVE: To determine the bactericidal effect on surfaces of ceiling- and wall-mounted UV C (UVC) light (wavelength, 254 nm) in isolation units, compared with standard hospital environmental cleaning and chemical disinfection during final disinfection after patients are treated for infections. DESIGN: Microbial samples were obtained from surfaces in isolation units (patient room, anteroom, and bathroom) before and after irradiation with UVC, chloramine disinfection, and standard hospital environmental cleaning. Samples were tested using standard contact plates. SETTING: Four identical, negative air-pressure isolation units (patient room, anteroom, and bathroom) with a defined number of ceiling- and wall-mounted UVC light units. The UVC distribution was monitored in one isolation unit after irradiation for approximately 40 minutes, corresponding to doses ranging from 160 J/m2 in a shadowed area to 19,230 J/m2 at the mostly highly exposed site (which is high enough to inactivate most bacterial organisms, including spores). RESULTS: UVC disinfection significantly reduced the number of bacteria on surfaces directly or indirectly exposed to UVC to a very low number, as did 5% chloramine disinfection alone (P<.001 for both). Completely shadowed areas in the isolation unit (eg, the bed rail, lockers, and mattresses) still required disinfection by chemicals. CONCLUSION: Disinfection with UVC light may significantly reduce environmental bacterial contamination and thereby protect the next patient housed in an isolation room. UVC disinfection may not be used alone but is a good addition to chemical disinfection.