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.