4. Discussion
We describe a safe and rapid hybrid MPDT technique that reduces the risk
of COVID aerosol transmission associated with tracheostomy or
percutaneous dilatational tracheostomy (PDT). When performing procedures
on critically ill COVID-19 patients, it is essential to minimize
infection risk to medical staff. Several studies have devised various
modified PDT techniques aimed at reducing the risk of occupational
exposure. Takhar et al. suggested a modified PDT technique involving
clamping of ETT and stopping the ventilator during the
procedure.5 However, during the ventilation pause,
lack of tissue oxygenation is dangerous, especially in patients with
diminished lung capacity, and preoxygenation extends procedural times.
Our hybrid MPDT technique does not require preoxygenation, because the
tracheal membrane incision does not take much time and the incision is
too small to allow aerosol transmission. On the other hand, Vargas et
al. proposed a modified PDT procedure for COVID-19 patients that
included the use of a smaller ETT cuffed at the carina and a
bronchoscope inserted between the ETT and the inner surface of the
trachea.6 However, replacing the ETT introduces the
risk of aerosol formation and is time-consuming. In addition, because
the ETT and bronchoscope are both present in the trachea, the procedure
it is difficult to perform when the trachea is small and the field of
view is obscured by sputum. The described hybrid MPDT technique is
similar to that described by Paran et al. as it does not require a
bronchoscope7. However, the point of Paran’s
technique, which was dependent on the touch sense of tracheal palpation,
is not applicable when tracheal cartilages are calcified. Furthermore,
blunt dissection of subcutaneous and pretracheal tissues with surgeon’s
finger can lead the unnecessary risk of wound infection.
In terms of operation time, the hybrid MPDT procedure seems to take less
than conventional tracheostomy. Nishio et al. reported an average time
for surgical tracheostomy of 27 min (range, 17 - 39
min).8 In our patients, the average operation time was
6.71±1.92 min, presumably because tracheal cartilage resection and
unnecessary dissection were not performed.
Hybrid MPDT allows visually checking of ETT position and enables the
position of the incision hole to be determined, which are not during
conventional PDT, and does not require manpower to operate the
bronchoscope. An experienced, small number of tracheostomy team is
essential to perform safe tracheostomy in patients with COVID-19 and to
minimize the risk of occupational infection.
In conclusion, hybrid MPDT comprised of conventional surgical
tracheostomy and MPDT and involving the use of only four instruments and
no bronchoscope was found to enable rapid and safe airway management in
critically ill COVID-19 patients and to minimize the risk of
occupational infections.