Ventilator settings for fibreoptic bronchoscopy during mechanical ventilation: a study protocol for a pragmatic...

Fibreoptic bronchoscopy (FOB) is a challenging procedure during mechanical ventilation (MV) as it considerably reduces the endotracheal tube's internal diameter, causing a drastic increase in respiratory resistance, which may compromise the delivery of ventilatory assistance. According to respiratory physiology principles applied to MV, the reduction of inspiratory flow and tidal volume is likely to reduce airway pressure during the inspiratory phase when respiratory resistances increase. Based on this assumption, we propose new ventilator settings aimed at reducing airway pressure during FOB. This study represents the first investigation to test special ventilator settings in order to facilitate FOB during MV.

This is a single-centre randomised double-blind controlled trial, in which intubated patients undergoing an FOB will be assigned (1/1) either to receive the new ventilatory strategy or to stay on the ventilator settings previously selected by the attending physician. The intervention group will be applied the specific ventilator settings (inspiratory flow ≤25 L/min, tidal volume=5 mL/Kg, 1 s≤inspiratory time≤1.3 s, respiratory frequency=16 c/min, positive end-expiratory pressure=5 cm H₂O). The primary endpoint will be the reduction of the occurrence of a serious adverse event (inability to deliver ventilatory support, significant arterial desaturation or haemodynamics instability) during FOB, prompting the interruption of the procedure. The primary endpoint will be validated a posteriori by an external adjudication committee. The sample size was estimated at a minimum of 42 patients to demonstrate a 50% reduction in the occurrence of such a serious adverse event with a power of 90% and an alpha risk of 0.05 (χ² test). Considering the possibility of technical problems in 10% of cases, 46 patients will be included.

The study has been approved by the national ethics committee for the protection of the individuals (ID number: 2024-A00747-40). Written informed consent will be obtained from all patients. The results will be submitted for publication in peer-reviewed journals.

NCT06562725.