Mobile zoned/exponential LAF screen: a new concept in ultra-clean air technology for additional operating room ventilation.

A mobile screen (0.5 x 0.4 m) producing ultra-clean exponential LAF (air-flow central zone 0.6 m/s and peripheral zone 0.4 m/s) was investigated as an addition to conventional turbulent/mixing operating room ventilation. The evaluation was performed during strictly standardized sham operations reflecting conditions during major surgery. The study consisted of a pilot experiment designed to give high counts of sedimenting aerobic colony forming units (cfu). In a second main study, recording dust particles, air-borne and sedimenting aerobic cfu, the screen was associated with optimal operating room clothing. In the pilot experiment the use of the screen resulted in a substantial reduction of sedimenting bacteria from 3835-4940 to 0-390 cfu/m(2)/h. In the main study, the use of the additional LAF reduced the surface contamination from 416-329 to 7-78 cfu/m(2)/h up to 1.6 m from the screen (P=0.001-0.0001). Measured in the wound area the screen reduced the air counts of bacteria from 9-14 to 0.2-0.4 cfu/m(3) (P=0.008-0.0001) and a marked reduction of air-borne dust particles was recorded (P=0.007-0.009). In conclusion, the additional mobile LAF screen reduced the counts of aerobic air-borne and sedimenting bacteria-carrying particles as well as dust particles to the levels gained with complete ultra-clean LAF room ventilation. Thus, the screen might prove a valuable addition to operating room ventilation as well as in other areas where asepsis is essential. Copyright 2002 The Hospital Infection Society.