Influence of drape permeability on wound contamination during mastectomy

Sixty-one patients undergoing mastectomy at three hospitals were randomly allocated to receive one of three types of drape: permeable linen sealed to the skin with self-adhesive nonwoven tape, and impermeable nonwoven with self-adhesive edges. Bacteriological contamination was assessed both in the wound and in the wound surroundings. The air counts at the centres differed but were generally low, mean approximately 10(1) colony-forming units (CFU)/m3 but higher at the beginning of the operation. Patients whose skin counts were high before disinfection had the highest skin counts after disinfection and operation and gave the highest counts on the gloves of the surgeon. The use of impermeable drapes instead of permeable linen drapes resulted in significantly fewer bacteria in the operative field (393 CFU/50 cm2 compared with 664, p less than 0.002) and also in the wound itself (12 compared with 164 CFU/sample, p less than 0.01). As a result of correlations between counts, we are also able to show how bacteria transfer from the patient's skin to the surgical wound.