[Comparison of perforated metal ceiling systems (supported airflow ceilings) with laminar airflow ceilings in type A (DIN 1946 T.4) operating rooms under surgical conditions].

In eleven centrally ventilated operating theatres the concentration of particles and airborne germs in wound vicinity was measured on three workdays. Five theatres were equipped with air supply ceilings with supporting flow outlets (supporting flow ceilings), five with laminar air flow ceilings and one with an air supply ceiling, a body exhaust system and a partition wall between the anesthetic and operating areas. Under routine conditions the air supply of the laminar air flow ceiling with its lower turbulence shielded the operating field from the largely staff-related air contamination in the rest of the theatre better than in the case of the supporting flow ceilings. Particles and airborne germs were removed from the endangered wound area faster. A spatial separation between the anesthetic and the operating areas as well as a body exhaust system lead to a considerable reduction of the contamination. Two theatres were conspicuous by reason of their considerably raised values due to defective control engineering and the wrongly positioning of the operating table. From the point of view of ventilation technique the laminar air flow ceilings with lower turbulence are superior to air supply ceilings with supporting flow outlets in the working day of an operating theatre. In order to minimize the influence of the staff, which up till now has been neglected in testing specifications, constructional possibilities such as the size of ceiling, the partitioning off of operating and anaesthetic areas and the positioning of the operating table in relation to the incoming air should be coordinated rationally. Taking measurements regularly during operations can provide the impulse for considerable improvements in both operational and planning phases.