Pausing ventilation during insertion of the tracheostomy
tube minimises aerosol spread. Adjunctive manoeuvres
such as placing the inflated cuff of the endotracheal tube
well below the tracheostomy site in surgical tracheostomy
can minimise the duration of apnoea. Because apnoea
can cause rapid and substantial hypoxia in patients who
are critically ill and dependent on a ventilator, we suggest
preoxygenation, followed by a trial of apnoea in the ICU, with an FiO2 of 1·0 and positive end expiratory pressure
of 5 cm H2O, in a patient in a supine position before
tracheostomy. Rapid desaturation during these trials
predicts a similar response during tracheostomy, indicating risks to the patient (and also to staff who might be
required to do unplanned or additional airway interventions) and tracheostomy should be deferred.