A preliminary evaluation of surgical field contamination risk from surgeon's oro-nasopharyngeal commensal organisms while using reusable FFP3 respirator masks and power hoods with relevance to the COVID 19 pandemic – A pilot study

In early 2019 in the UK, concern about the risk of COVID-19 transmission to surgeons who operate near to the airway led to wide scale adoption of different masks, including valved types used in industry. It was noted early on that although these masks protect clinicians, they may represent a risk to the patient due to unfiltered air being directed towards them during close contact(1) and the National Health Service circulated guidance to that effect(2). Subsequently, an increased incidence of surgical site infection (SSI) was noticed, postulated to be due to contamination of the surgical field by microbial particles from valved masks or hoods leading to a National Patient Safety Alert(3). A study recommended that a surgical mask be placed over the exhaust valves of these mask types(4). We reviewed the literature using the key words surgical masks, power hoods, FFP3 masks and surgical site infection. Most studies showed no reduction in the incidence of SSI with surgical masks(5), but some showed an increase(6). There were no studies comparing bacterial contamination of the surgical site with different types of masks. A pilot study was designed to evaluate if FFP3 respirators and powerhoods allowed bacterial contamination of the surgical field in comparison with standard surgical masks and no masks. The results appeared to confirm our methodology and suggested that reusable valved FFP3 masks are associated with bacterial dissemination. Subsequent examination of these masks identified a potential mechanism for this bacterial contamination. A larger scale study is needed.