Technical Description
The device is composed of an anaesthetic “closed” facemask, anaesthetic filter, DAR™ (Covidien) connector (or similar), which is L shaped with a closable hole for instruments (alternatively a T-piece connector 22mm) and a harness attachment for continuous positive airway pressure (CPAP) (VYGON) (Figure 1 ). Local cost for all disposable pieces (all save the CPAP harness) totals £1.86. The filter and DAR/T-piece are attached to the closed facemask as seen inFigure 1 with the filter facing inferiorly. If using a T-piece, a seal is made with “finger” of glove attached and a small hole is made with a thick needle for passing of endoscope. The mask is inverted to align the hole with the nostrils instead of the mouth and it is secured in place with the CPAP harness (Figure 2 ).
The “closed” anaesthetic masks come in many sizes. Sizes 3-4 are generally suitable for women and 5-6 for men. The correct size is best ascertained by measuring the distance between the nasal bridge and a point below the lower lip where it is fully covered by the sides of the mask. For edentulous patients, dentures are left in place. Applying a thick coat of gel lubrication to patients with facial hair can encourage a seal for these patients.
The device was tested for comfort by the authors and barrier seal was verified by manually covering the anaesthetic filter. This can be replicated with every patient to test an appropriate fit (Figure 2 ). It should be impossible for the patient to breath in when the filter is covered. Nasoendoscopy is performed as demonstrated on patients (Figure 2 ).
Full PPE as described above should still be used as well as a camera and monitor where able. Local anaesthetic on a cotton patty (not spray) should be used before attaching the mask to reduce sneeze or cough. The scope could be withdrawn whilst holding a cleaning wipe to reduce the chance of droplets failing and contaminating the air. After the procedure, remove the scope and send for cleaning as per local protocols. The mask and attachments should be discarded apart from the harness which can be reused after cleaning with appropriate wipes for 60 seconds (or as per local policy).