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.