The conventionally ventilated operating theatre and air contamination control during cardiac surgery--bacteriological...

The purpose of the study was to compare the usefulness of a conventional bacteriological technique with that of particle counting under lower air contamination and better aseptic conditions achieved with special staff garments and covering for the patient. Contamination levels were estimated with continuous on line air particle counting measurement, volumetric intermittent short period aerobic bacteriological cultures and wound surface contact cultures.

In a series of 66 consecutive coronary artery bypass operations performed by the same team and in the same theatre using different types of patient and staff clothing, the impact of a reduced bacteriological and particulate contamination were assessed. The volumetric air contamination of particles > or =5 microm and bacteria-carrying particles were monitored 30 cm above the sternal wound. The bacterial contamination and bacterial wound infections in the sternal and leg wounds were assessed as well.

With the alternative garment and textile system, the air counts fell from 25 colony-forming units (CFU)/m3 to 7 CFU/m3 (P < 0.0038). The contamination of the sternal wound was reduced by 46% and that of the leg wound by >90%. In order to give continuous contamination feedback during the whole operation to the theatre staff, particle counts > or =5 microm were monitored and visualized. Air particle counts decreased rapidly from 850 particles/m3 and stabilized to approximately 50 particles/m3 when the alternative clothing system was used (P < 0.001). Low particle counts > or =5 microm should offer the possibility to indirectly estimate air bacteria carrying particle counts during the entire operation. Less than 20% of the total count in this size group carries bacteria. The low air contamination was achieved even in an ordinary ventilated theatre when individual team members used clean air suits in combination with impermeable patient drapes. When air particle level < or =50 particles/m3 is reached, the bacterial air contamination is in the order of that of orthopaedic hip operations. The staff must during the entire operation adjust their activity to air asepsis.

The use of clean air suits and impermeable patient clothing results in a low exogenous contamination of air and wound. Continuous air particle monitoring is a good intraoperative method to monitor the air contamination longitudinally in an operating theatre.