Pressure support ventilation during fibreoptic intubation under propofol anaesthesia

Goal of the study. To assess the benefit of pressure support ventilation during fibreoptic intubation performed under propofol anaesthesia in patients having an anticipated difficult intubation. Procedures. Thirty-two patients with ENT cancer, and having at least two criteria for anticipated difficult intubation were prospectively included. All patients received topical lidocaine 2% and propofol by plasma target control infusion (initial target concentration 3 μg ml^-1, then adjusted to maintain loss of consciousness without apnoea). They were randomly assigned between two groups: spontaneous breathing (SB) or pressure support ventilation (with a support level set at 10 cm H₂O) both using Fi_o2=1. Conditions for fibreoptic intubation, respiratory parameters (pulse oxymetry, ventilatory frequency, tidal volume and Pet_CO2 after intubation) and haemodynamic parameters were recorded. Results. Patient characteristic data and intubation conditions were similar between both groups. All patients had a successful fibreoptic intubation and none needed a rescue procedure because of desaturation. In spite of a longer duration of intubation, PE′_CO2 after intubation was lower and tidal volume during intubation was higher with pressure support ventilation than in SB patients [38.1 (4.2) vs 42.3 (4.7) mm Hg and 371 (139) vs 165 (98) ml, respectively]. Desaturation episodes were observed in two SB patients conversely to no episode during pressure support ventilation, probably because of the higher minute ventilation. Conclusion. Pressure support represents a useful method to improve ventilation during fibreoptic intubation under propofol anaesthesia in patients with an anticipated difficult intubation.