INTEGRATED HORIZONTAL LAMINAR AIRFLOW WITH CONTRALATERAL OUTFLOW: THE MOST FAVOURABLE SYSTEM FOR ORTHOPAEDIC SURGERY

Abstract

Purpose: Although few theatres have been equipped in France, integrated horizontal laminar airflow with air flowing in from the entire surface of one wall and flowing out through the contralateral wall is the most favourable installation for orthopaedic surgery. We had the opportunity to work in two theatres installed in 1980 with the construction of a new hospital. The objectives were to: 1) resolve the problem of airborne biocontamination of our aseptic rooms (excepting the complete isolation unit for septic patients), 2) allow intensive use of both horizontal airflow operative theatres considering the authorized budget was 2.5 aseptic rooms for 90 beds and approximately 400000 K annually (K=surgery cost-unit reimbursed by the national health insurance fund), 3) enable more favourable personnel movement and material handling than vertical flow systems where the operative surface is limited and the risk of dust accumulation is high, for indications we considered particularly important (targeted orthopaedic procedures: hip surgery for example). In addition, it appeared advisable to have repairs performed outside the operative unit, a possibility proposed with the Luwa system (Zurich, Switzerland).

Material and methods: The floor surface area of each of the theatres is 34 m2 for a 99 m3 volume. One entire wall (the wall opposite the entrance for patients and surgeons) emits the horizontal laminar airflow. Air flows out through captors on the opposite wall next to the doors and is recycled. Airflow rate is greater than 0.25 m/s maintaining laminar flow throughout the theatre (anemometric measurements). The hygrometry can be controlled. Filtration removes all particles measuring 0.2 mm or larger. The temperature is maintained at 20° maximum. The entire air volume is renewed 600 times per hour. Overpressure is maintained permanently (manometric measurements) and can be controlled manually every day (first approximation).

Results: 1. Aeraulic quality controls were performed by a non-specialized nurse. Intensive use was maintained for more than 15 years. Parameters were controlled after installation then every six months (during non-active periods). Essential material included a particle counter (graduated in cubic feet) which showed we were situated at a level below class 100 (Fed US 209 D). Anomalies observed several times (localised particle ascension) were related to filter dysfunctions. The ‘holes’ were eliminated by changing filters. Other parameters were maintained with no problem. The only change occurred in one of the theatres where airflow was considered to be insufficient at the end of the theatre and a defective outflow was removed; because of these changes, inflow had to be readjusted and the door occlusions had to be changed; later quality controls were favourable. Activity level was not monitored with sufficient precision to take into consideration. 2. The rate of clinical infections associated with these theatres was maintained very low but antibiotic prophylaxy was continued.

Discussion: The objectives we set for these theatres have been achieved. This type of installation is very superior to vertical flow suggesting we should equip future theatres with this type of system.