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Environmental controls in operating theatres
1Infection Control Programme, Department of Internal Medicine, University of Geneva Hospitals, Switzerland.
Abstract:
Surgical-site infection is the leading complication of surgery. Normal skin flora of patients or healthcare workers causes more than half all infections following clean surgery, but the importance of airborne bacteria in this setting remains controversial. Modern operating theatres have conventional plenum ventilation with filtered air where particles >/=5 microm are removed. For orthopaedic and other implant surgery, laminar-flow systems are used with high-efficiency particulate air (HEPA) filters where particles >/=0.3 microm are removed. The use of ultra-clean air has been shown to reduce infection rates significantly in orthopaedic implant surgery. Few countries have set bacterial threshold limits for conventionally ventilated operating rooms, although most recommend 20 air changes per hour to obtain 50-150 colony forming units/m(3) of air. There are no standardized methods for bacterial air sampling or its frequency. With the use of HEPA filters in operating theatre ventilation, there is a tendency to apply cleanroom technology standards used in industry for hospitals. These are based on measuring the presence of particles of varying sizes and numbers, and are better suited than bacterial sampling. Environmental bacterial sampling in operating theatres should be limited to investigation of epidemics, validation of protocols, or changes made in materials which could influence the microbial content.
Insights
Airborne bacteria in operating rooms are a concern for surgical-site infections. Ultra-clean air systems with HEPA filters significantly reduce infection rates in implant surgery.
Area of Science:
- Infection control in surgical environments.
- Environmental microbiology and hospital hygiene.
Background:
- Surgical-site infection (SSI) is a major surgical complication, often caused by normal skin flora.
- The role of airborne bacteria in SSIs, particularly in conventionally ventilated operating rooms, remains debated.
- Modern operating theatres utilize filtered air (removing particles ≥5 µm) or laminar-flow systems with HEPA filters (removing particles ≥0.3 µm) for implant surgery.
Purpose of the Study:
- To evaluate the significance of airborne bacteria in surgical environments.
- To discuss current ventilation standards and their effectiveness in controlling microbial contamination.
- To assess the suitability of cleanroom technology standards for operating theatres.
Main Methods:
- Review of existing literature on operating theatre ventilation and bacterial contamination.
- Comparison of conventional plenum ventilation with laminar-flow systems using HEPA filters.
- Discussion of particle measurement standards versus bacterial air sampling.
Main Results:
- Ultra-clean air systems with HEPA filtration have demonstrated significant reductions in infection rates for orthopaedic implant surgery.
- Bacterial threshold limits and standardized sampling methods for operating rooms are not widely established.
- Cleanroom technology standards, focusing on particle measurement, are increasingly being considered for hospital environments.
Conclusions:
- Environmental bacterial sampling in operating theatres should be reserved for specific situations like epidemic investigations or protocol validation.
- HEPA-filtered ventilation systems offer superior control of airborne particles relevant to surgical site infections.
- Particle-based cleanroom standards may be more appropriate than bacterial sampling for assessing operating theatre air quality.