Laminar airflow systems. Issues surrounding their effectiveness

Infection Control Practices to Reduce Airborne Bacteria During Total Knee Replacement: A Hospital Survey in Four States

Objective:

To describe the use of laminar airflow, body exhaust, and ultraviolet lights during total knee replacement (TKR) in four U.S. states.

Design:

Survey of healthcare facilities.

Setting:

Hospitals in Illinois, North Carolina, Ohio, and Tennessee that performed TKR during 2000 as identified by Medicare claims data.

Participants:

Hospitals responding to a mailed questionnaire.

Results:

Two hundred ninety-five (73%) of 405 eligible hospitals that performed 18,374 primary and revision TKR procedures responded to the questionnaire. Among responding hospitals, 30% reported regular use (for > 75% of procedures) of laminar airflow, 42% reported regular use of body exhaust, and 5% reported regular use of ultraviolet lights. Among hospitals providing complete data, 150 (58%) performing 66% of procedures reported regular use of at least one of these techniques. On regression analyses, laminar airflow was used more often by hospitals with a TKR volume greater than 25 procedures per year (odds ratio [OR], 2.0; 95% confidence interval [CI95], 1.1-3.7) and orthopedic residency programs (OR,2.8;CI95,1.3-6.3), but its use was not significantly related to hospital setting or ownership status.

Conclusions:

Although these clean air practices are not recommended by any U.S. governmental or professional organization, they are used in nearly two-thirds of TKR procedures. Better information about their impact on current practice and more explicit guidelines may aid decisions about the use of these resource-intensive infection control practices.

Deep Infection After Total Knee Replacement: Impact of Laminar Airflow Systems and Body Exhaust Suits in the Modern Operating Room

We investigated the relationship between the risk of deep infection and intraoperative use of laminar airflow systems and body exhaust suits during 8,288 total knee replacements performed in 256 hospitals. The overall 90-day cumulative incidence of deep infection requiring subsequent operation was 0.34% (28 procedures). In all combinations of laminar airflow systems and body exhaust suits, the 90-day cumulative incidence of infection requiring subsequent operation was 0.27%-0.43%. The risk ratio was 1.57 (95% confidence interval, 0.75-3.31) for laminar airflow systems and 0.75 (95% confidence interval, 0.34-1.62) for body exhaust suits suits. The risk was not statistically associated with use of either method, but infections were rare.

Ultraclean laminar airflow ORs

To minimize postoperative infections, ultraclean laminar airflow (LAF) units equipped with high-efficiency particulate air filters developed for electronic and aerospace technology have been adapted for ORs. Traditionally, the airflow was either vertical or horizontal and, to function properly, encompassed extra side walls inside the OR. Recently, new airstream technology has provided zoned down-flow units that provide an exponential airflow (i.e., resembling an upside-down trumpet mouth). The exponential airflow allows for omission of extra side walls, making them more versatile in clinical use. Each different type of LAF requires knowledge of airstream patterns and how OR team members need to dress and work to prevent contamination of the sterile air and the aseptic areas. This article discusses different LAF systems and related demands on OR clothing and behavior.

Zoned exponential, vertical and horizontal ultra-clean laminar airflows. No differences in bacteriological efficiency

We compared the novel zoned exponential ultra-clean operating room ventilation, needing no extra side-walls with the traditionally used ultra-clean air systems having vertical or horizontal laminar airflow, but requiring extra side-walls. The three units were evaluated with regard to elimination of particles with focus on airborne and sedimenting bacteria-carrying particles (colony forming units, cfu) during rigidly standardized sham operations. Although minor differences were recorded inside the ultra-clean airflows, the three systems were comparable with regard to bacteriological efficiency and ensured a low air and surface contamination (0.05-4 cfu/m3 and 7-72 cfu/m2/h, depending on the site of sampling). We conclude that all three systems fulfilled well the criteria for ultra-clean air (< 10 cfu/m3), but that exponential airflow is the most versatile alternative, as additional side-walls around the operating area can be omitted.