DISUCSSION
The current global stockpile of PPE is insufficient due to the rapidly
increasing number of infected patients world-wide. In view of global PPE
shortage, strategies have been formulated to optimise PPE availability
include minimising the need for PPE in health care settings, and
ensuring rational and appropriate use of PPE [9].
In Queen Mary Hospital, attempts at minimising PPE need include reducing
the volume of head and neck patients undergoing outpatient clinic and
endoscopy service by 60%, and operations by 50%; and the number of
healthcare providers within endoscopy suites and operating theatre.
Based on current evidence, SARS-CoV-2 is transmitted between people
through close contact and droplets. Airborne transmission may occur
during AGP and support treatments including tracheal intubation,
non-invasive ventilation, tracheotomy, cardiopulmonary resuscitation,
manual ventilation before intubation, and bronchoscopy. Despite concerns
of aerosolisation of blood through the use of energy device,
manipulation of upper aerodigestive tract mucosa and resection of
tumours in the upper aerodigestive tract are not classified as AGP
[9-12]. According to World Health Organisation (WHO), droplet and
contact precautions with the use of medical masks, eye protection, cap,
gown and gloves are sufficient for regular care of COVID-19 patients.
Respirators such as N95 or PAPR are advocated for AGP [9,13].
There is currently no universal standard for face and/or eye protection
from biohazards. Face shield is usually in the form of an optically
clear plastic film which covers the forehead to neck and both sides of
the face up to the ears. Due to the lack of a good facial seal
peripherally, face shields are usually used as an adjunctive PPE which
acts to provide additional physical barrier against splashes, sprays,
and spatter of body fluids [14]. However, the use of face shield
hinders the use of a head-light when performing head and neck surgery.
Prolonged use can give rise to fogging, carbon dioxide retention
especially when combined with respirator, and impaired communication.
Centres for Disease Control and Prevention (CDC) Standard Precautions
guidelines for prevention of transmission of infectious agents includes
the use of face shields (with a medical/surgical face mask) when sprays,
splashes, or splatter are anticipated [15]. The effectiveness of
face shields in preventing the transmission of viral respiratory
diseases is unknown [16]. With the use of goggles and appropriate
respiratory protection device, we re-evaluate the need for face shield
in performing head and neck cancer surgical procedures.
In an attempt to conserve face shield and other PPE consumption, we
minimised the number of health care providers during operation: all
tracheostomy (n=8) was performed by the operating surgeon alone.
Furthermore, second assistant was not involved in TORS and free flap
harvest procedures. Only the operating surgeon and scrub nurse was
involved in all 45 surgical procedures.
From our study, the percentage of procedures with droplet contamination
was 57.8% for the operating surgeon , 59.5% for the first assistant
and 8.0% for the second assistant. No droplets were noted on all face
shields of the scrub nurse. In view of 0% contamination rate, face
shield is not necessary for the scrub nurse for all non-AGP.
Droplet count was highest and most widespread with procedures involving
osteotomies such as maxillectomy, maxillary swing and manubrial
resection. Other than blood, irrigation fluid also contributed to the
number of droplets. Vibrations of saw blade caused droplets to be
dispersed over a large area during osteotomy, as reflected by the
distribution on the surgeon and 2 assistants’ face shields (Figure 3,
Table 1). This can be minimised by controlled irrigation and vigilant
suction to minimise the amount of irrigation fluid and blood
accumulating around the saw blade. Operation by an experienced surgeon
would also help to reduce blood loss and shorten procedure time. Face
shield should be provided for the operating, first and second assistant
surgeons during osteotomy related procedures.
Non-osteotomy surgical procedures involving mucosa of the upper
aerodigestive tract yielded minimal droplet count on face shields of the
operating surgeon and first assistant, affecting zones 6-11 which were
centred over the lower half of the face. There was one droplet splash at
zone 2 of the first assistant during nasopharyngectomy, corresponding to
the first assistant’s eye-level. No droplet splash was noted on the
second assistant’s face shield. Abiding by CDC, WHO and CHP guidelines,
face shield should be used by all surgeon(s) for AGP including
tracheostomy and laryngectomy. For non-AGP, face shield for second
assistant may not be warranted. Given the low droplet count on face
shields of the operating surgeon and first assistant, one could argue
against the need for face shield as an adjunctive PPE to goggles and
adequate respiratory device for the aforementioned procedures which are
non-aerosol-generating.
For TORS, docking was performed by the operating surgeon prior to
commencement of surgery. In order to prevent droplet splash the
following steps have been taken: (1) ensure that the cuff of the
endotracheal tube was inflated with no evidence of air leak (2) Fr 16
Nelaton suction catheter was placed through the remaining nostril down
to the level of the oropharynx for suctioning of saliva prior to docking
and also of blood and diathermy smoke and aerosols during the operation.
There were no droplets noted on the operating surgeon’s face shield
during docking and none noted on the first assistant’s face shield after
the operation. Hence face shield is not necessary for the operating and
assistant surgeons when performing TORS.
Average droplet count from non-mucosal, non-osteotomy related surgical
procedures such as neck dissection and free flap harvest was minimal on
both the operating surgeon’s and first assistant’s face shields, mainly
affecting the lower half of the face. One drop was noted in the lower
half of the second assistant’s face shield during modified radical neck
dissection. Given the low droplet count and low risk of aerosol
generation of such procedures, one could argue against the routine use
of a face shield as an adjunctive PPE for all surgeons when resources
are low during the COVID-19 pandemic.
Given proper eye protection and adequate respiratory device, results
from our preliminary study suggested that face shield as an adjunctive
PPE was not mandatory for all head and neck surgical procedures. The
following recommendations can be made when performing head and neck
cancer surgery in an attempt to conserve PPE during the COVID-19
pandemic: (1) All operations are to be performed by an experienced
surgeon assisted by specialists in the field of head and neck surgery in
order to minimise operation time and droplet contamination. (2) Number
of surgeons should be kept at a minimum for all procedures not limiting
to AGP. (3) Face shield is advocated for operating and assistant
surgeons for procedures involving osteotomies. (4) Conforming to CDC,
WHO and CHP guidelines, face shield should be worn by surgeon(s)
performing AGP in unknown, suspected and confirmed cases. (5) For
non-AGP involving mucosa of the upper aerodigestive tract, face shield
can be provided to the operating and first assistant surgeon if
resources allow. (6) Routine use of a face shield as adjunctive PPE is
not necessary for all parties when performing TORS and all non-AGP,
non-mucosal and non-osteotomy related procedures. (7) Scrub nurse could
be spared of using a face shield for all non-AGP. (8) If resources
allow, all patients to be operated on can be quarantined in hospital 14
days prior to surgery, followed by 2 sets of PCR tests performed 24
hours apart. This would further ensure that patients are COVID-19 free
prior to operation whereby we can revert to standard droplet
precautions. Larger scale studies with more patients, procedures and
operating surgeons is warranted to justify such recommendations. Other
means to conserve PPE for instance the role and efficacy of N95
respirator versus medical masks in preventing viral transmission is
beyond the scope of this study.