The influence of surgical hoods and togas on airborne particle concentration at the surgical site: an experimental study.

BACKGROUND: Arthroplasty surgeons are increasingly using personal protection systems with helmets. It is theoretically possible for the fans in these helmets to blow squames, sweat droplets and orobronchial fomites onto the surgical site. A controlled experiment was set up to investigate the effect of different surgical gowns on counts of airborne particles measuring ≥0.3 µm, using a hand-held particle counter. METHODS: The clothing that was sequentially tested included the following: 1. Barrier(®) surgical gown (single use) made from nonwoven polypropylene (Mölnlycke Health Care Ltd, Dunstable, UK) 2. Stryker(®) T5 Helmet (reusable) covered with a disposable Stryker(®) T4/T5 urethane hood worn separate to and enclosed by the Barrier(®) surgical gown both at the front and back 3. Stryker(®) T5 Helmet (reusable) worn within a disposable Stryker(®) T4/T5 urethane zippered toga (Stryker Corporation, Kalamazoo, MI, USA) Six readings were taken for each of the following three setups in a randomised order: 1. Gown: surgeon with surgical gown and face mask 2. Hood: surgeon with surgical gown and hood, maximum fan speed 3. Toga: surgeon with toga, maximum fan speed Wilcoxon rank sum tests were applied to assess equality of means between the three occlusive measures (gown, hood, toga). P values were computed based upon one-sided tests and adjusted for multiple comparisons using the Bonferroni correction. RESULTS: The mean particle counts (over more than 5 L of air) for the three set-ups were: gown: 1178 (least protective), hood: 328, toga: 42 (most protective). There was a significant reduction in particle counts for the toga versus gown (p = 0.007) and toga versus hood (p = 0.037); differences in particle counts were not significant between the hood and gown (p = 0.140). CONCLUSIONS: The fans in the helmets do not increase contaminants by blowing particles from the head area. A significant reduction in surgeon-originated contaminants was seen with the toga compared to both the hood/gown separate ensemble and gowns alone.