Surgical face masks for patients during regional anaesthesia. Hygenic necessity or dispensable ritual?

Objective. The use of surgical face masks (SFM) is believed to minimize the transmission of oro-and nasopharyngeal bacteria to wounds and surgical ins truments. However, there are disadvantages for patients undergoing regional anaesthesia and wearing masks: deficient assessment of lip cyanosis, anxie ty, retention of CO2, costs. Up to now no studies have been published inves tigating whether or not SFMs, worn by patients during regional anaesthesia, will reduce bacterial convection. Methods. We investigated 72 patients during aseptic operations: 24 individu als with regional anaesthesia and SFMs, 22 individuals with regional anaest hesia without SFMs and 26 patients undergoing general anaesthesia. Using an air sampler (volumetric impaction method) 100 L air were collected on bloo d agar over 2 min.After incubation at 37 degreesC over 60 h the colony form ing units (CFU) were counted and differentiated. Airborne culturable bacter ia were sampled over the operation field,on the anaesthetic side of the sur gical curtain,as well as 10 cm before and to the side of the patients mouth . Results. At all 4 locations there were no significant differences in the nu mber of CFUs between patients wearing a SFM or not (e.g. over the operation field: patient with SFM 5.5 +/-1.1; no SFM 4.8 +/-1.2;X +/- SEM). Signific antly more CFUs were detected in patients undergoing general anaesthesia (p less than or equal to0.05). The extent of the operation did not correlate with the number of CFUs; however, we observed a trend that more CFUs were d etected with an increasing number of persons working in the operating room. Conclusion. Surgical face masks worn by patients during regional anaesthesi a, did not reduce the concentration of airborne bacteria over the operation field in our study.Thus they are dispensable. A higher airborne germ conce ntration has been detected in patients during general anaesthesia,The reaso ns for this finding are unknown, but it may be discussed as being a result of a higher activity and number of staff involved during general anaesthesi a causing more air turbulence.