Contribution of the nasal passage to face mask ventilation: a prospective blinded randomized crossover trial

Abstract

Background: Previous studies have shown that the nasal passage plays an important role in manual face mask ventilation, but this has yet to be quantitatively assessed. We conducted a prospective randomized crossover clinical trial to compare the change in pressure-controlled face mask tidal volume with and without nasal airway occlusion. Method: Female patients undergoing elective surgery under general anesthesia served as study subjects. Patients were randomly assigned to face mask ventilation beginning either with or without nasal passage occlusion (achieved with a swimmer’s nose clip), followed by removal or application of the nose clip, respectively. After standardized induction of general anesthesia and muscle paralysis, a tight-fitting face mask was applied to each patient, and tidal volume was measured by the anesthesia machine during pressure-controlled ventilation (10, 15, 20 cm H2O; 8 breaths·min−1; inspiratory:expiratory ratio 1:2). Results: The median [interquartile range] tidal volume was lower with vs without nasal passage occlusion at 10 cm H2O inspiratory pressure (100 [55-134] mL vs 300 [230-328] mL, respectively; median difference (MD), 200 mL; 95% confidence interval (CI), 157 to 229; P < 0.001), 15 cm H2O inspiratory pressure (190 [120-230] mL vs 520 [420-593] mL, respectively; MD, 340 mL; 95% CI, 257 to 395; P < 0.001), and 20 cm H2O inspiratory pressure (270 [215-390] mL vs 790 [713-823] mL, respectively; MD, 520 mL; 95% CI, 390 to 582; P < 0.001). Conclusion: Nasal passage obstruction considerably reduces tidal volume achieved during face mask ventilation. In some patients, it may be advantageous to relieve nasal airway obstruction for effective face mask ventilation. Trial registration: UMIN Clinical Trials Registry, number UMIN000022184. Registered 2 May 2016.