Author(s): *Richard P. Evans, MD, University of Arkansas for Medical Sciences, Little Rock, AR
Title: Laminar air flow in the operating room - How effective is it in reducing infection?
Purpose: Developed in conjunction with the AAOS Patient Safety Committee this presentation provides a summary of the literature reviewed and the current state of understanding of the effect of laminar air flow in the operating room environment.
Methods: Laminar air flow in the orthopedic operating room remains a controversial subject. This presentation originated as an AAOS Infection Committee literature review and evaluation designed to provide an educated response to frequent inquiries from the academy fellowship and others. These inquiries have ranged from requests for an AAOS Advisory, a determination of effectiveness, recommendations of which systems were proven best to how to retrofit an existing operating room. With ¡¥Pay for Performance Standards¡¦ looming, all potential infection control measures available need to be considered. Both airborne bacteria and other sources of bacterial contamination must be reduced to a minimum to achieve optimal surgical site infection rates Decades of laminar flow operating room ventilation in combination with other infection control measures have improved infection rates; however no uniform opinion about laminar flow efficacy has developed. This current concepts review of laminar flow technology effectiveness was developed after evaluation of the Center for Disease Control, National Institutes of Health, orthopedic and affiliated literature. The latest information, technology and opinion are evaluated.
Results: Uncontrolled variables in the evaluation of laminar air flow include improved air turnover in traditional operating rooms, standardization of prophylactic antibiotics, behavioral change in personnel and awareness and elimination of other vectors of wound contamination. Laminar flow technology itself has evolved through the years. Improvement of laminar flow technology has presented its own evaluation challenge. This technology has evolved from fiberglass wall packs to High Efficiency Particulate Air (HEPA) filter filtration. HEPA-filtered laminar air flow can be provided by unidirectional horizontal flow from wall mounted units with and without curtains or sliding walls and by vertical air-flow systems. Each has its own associated problems of airflow disruption. To overcome these problems newer ¡§exponential laminar flow¡¨ systems have been developed in which air flow has the form of an upside down trumpet. However studies that document the merits of any one system do not include system design data. This makes it difficult to establish specific system comparisons and recommendations.
Discussion: The literature regarding laminar air flow remains compelling. The preference of many total joint surgeons is to use laminar flow and body exhaust suits when available. The analysis of surgical laminar air systems worldwide has resulted in specific standards. Examples are the UK Health Technical Memorandum (HTM 2025) in the United Kingdom and territories, and the German VDI Standards, both of which are being amended to comply with the International Standards Organization (ISO) 14644. The Centers for Disease Control (CDC) suggest that both ultra clean air and antimicrobial prophylaxis can reduce the incidence of surgical site infections in orthopaedic implant operations. Current CDC recommendations include the recommendation to consider performing orthopaedic implant operations in clean air and body exhaust suits. Additionally, the National Institutes of Health (NIH) Office of Research Services, Division of Engineering Services recently concluded that systems that provide laminar flow regimes represent the best option for contamination control in the operating room.
