MATERIALS AND METHODS
All patients who underwent surgery for head and neck cancer in the
Division of Head and Neck Surgery of the Department of Surgery, The
University of Hong Kong at Queen Mary Hospital and Gleneagles Hong Kong
Hospital between 01 March 2020 and 09 April 2020 were included.
All patients underwent comprehensive work-up for tumour staging
including clinical and endoscopic examination of the upper aerodigestive
tract, and ultrasonography of the neck +/- fine needle aspiration for
cytology of suspected neck nodal metastasis with full barrier
protection. Magnetic resonance imaging +/- whole-body positron emission
tomography scans were also performed for tumour staging.
Admission to head and neck surgical ward was only allowed (1) on
declaring absence of travel history 14 days prior to surgery, (2)
absence of close contact with confirmed cases, and (3) tympanic body
temperature <37.5 degrees Celsius taken at ward entrance. On
admission, routine bloods including white cell count and chest X-ray
were checked. As recommended by Centre for Health Protection in Hong
Kong (CHP) and Queen Mary Hospital Infection Control Unit, PCR would
only be tested for febrile and symptomatic patients +/- radiological
changes on chest X-ray.
All operations were performed by a consultant surgeon and two assistants
who have completed their fellowship in head and neck surgery. Skin
incisions and tracheotomies were performed using scalpel knife.
Reciprocating and oscillating saws were used for maxillary swing and
manubrial resection respectively. Monopolar and bipolar diathermy was
used for tissue dissection and haemostasis.
Full barrier protection was adopted by all three surgeons and one scrub
nurse. The face shield used was a piece of optically clear, latex free
plastic film imported from China measuring 32cm in length and 22cm in
width with foam forehead cushion and elastic strap. It covered a full
face length from forehead to neck, with outer edges of the face shield
reaching bilateral ears. It had anti-fog and anti-glare properties with
no hearing restrictions.
The face shield of each surgeon and scrub nurse was removed after each
procedure. Each face shield was put against a white background with 12
grids measuring 7cm x 7cm each to facilitate counting at maximal
magnification (Figure 1). The number and size of droplets splashed was
counted for each face shield using the surgical microscope Leica M720
0H5 (Leica Microsystems GmbH, Germany) (Figure 2). Droplet distribution
per face shield was plot on a separate sheet with the same grid as that
used in Figure 1 (Figure 3). Each of the 12 grids were labelled 1 to 12
(Figure 4). Counting and plotting of droplets splashed were performed by
a surgeon who did not participate in the operation. The face shields
were discarded once counting was complete.
Operative diagnosis and procedure; size, average number and distribution
of droplets on face shield for each party were documented.