An Assessment of the Benefit of Surgical Face Masks in Preventing Aerosol Droplet Spread during a Simulated Spinal Anaesthetic-a Blinded in vitro Study

Aims: The purpose of this study was to assess the benefit of wearing a surgical face mask in reducing aerosol contamination of agar plates in a simulated spinal anaesthetic. The contamination of plates with virulent organisms, association of growth with recent upper respiratory tract infection and food intake were also studied.

Methods: A poster containing written text was fixed to a wall, with a standard agar plate suspended at its midpoint. Each volunteer (n=30) then read the text from the wall chart to simulate verbal interaction with a patient during a spinal anaesthetic, initially wearing a surgical mask and then once again without a mask.

Results: This study revealed an increased risk (p =0.006) of bacterial growth on agar plates when not wearing a surgical face mask. Results also suggest that eating prior to surgical procedures may increase the risk of contamination of the surgical field in the absence of a barrier mask.