Discussion
This workplace study, involving practicing ENT surgeons, supports our concern that use of PPE reduces the view of the operating microscopic field available to the surgeon. Data analysis shows an inverse correlation between eye-microscope distance and target view.
The use of FFP-3 masks with the surgeon’s own prescription glasses or slimline polycarbonate safety glasses (PPE level C) or over-glasses (PPE level D) produced a highly variable effect on view. This depended on fit of the PPE to the surgeon’s face and resultant increase in eye-microscope distance. It should be noted that neither of these PPE levels provides the droplet protection recommended by current UK COVID-19 PPE guidelines4.
The use of a full-face visor satisfies the level of PPE recommended for AGPs such as mastoid drilling. However, the reduction in surgical view is severe, with less than 10% of the microscope view visible in most cases. This makes recommended AGP PPE incompatible with the use of the operating microscope at this time.
This study highlights the challenges facing otological surgeons in the era of COVID-19. Urgent action is needed to address this challenge, with the aim of providing a safe operating environment for otological surgeons whilst preserving the ability to deliver effective, safe surgical care. Variations in surgical technique may obviate the need for simultaneous use of high-speed mastoid drilling and the operating microscope (such as the use of endoscopic ear surgery, surgical loupes or 3-D exoscopes). A number of alternative approaches, such as use of the “double-drape” system have also been suggested2,6,7. Bespoke surgical shields that attach to the microscope may afford some protection to the surgeon. Any modification or devices, designed to shield the otological surgeon’s eyes and face from the aerosol generated by mastoid drilling, must fulfil strict PPE requirements (preventing droplet contact with the surgeon’s eyes) whilst also allowing relatively unhindered access to the microscope eyepieces.
Based on the data obtained in this study, a working distance of around 20mm is likely to preserve at least a 70% view of the microscopic field, with an ideal working distance of 15mm or less preserving almost complete view of the surgical field (90% or more). Individual surgeons may need to judge their level of confidence in performing safe otological surgery with even minor reductions in view. Data obtained in this study may be specific to the microscope and PPE used in our institute and should be interpreted with this in mind.