Detection of upper airway obstruction by diaphragm ultrasound combined with inspired volume measurement

Background Upper airway stenosis may remain undiagnosed for extended periods. Ultrasound allows for the evaluation of the impact of respiratory diseases on diaphragmatic function. Methods Three patients presenting with symptoms suggestive of upper airway obstruction were assessed using diaphragmatic ultrasound. Simultaneously, inspired volumes were measured on a breath‐by‐breath basis. Inspiratory flow was calculated during both quiet and deep breathing by dividing inspired volume by excursion duration. Results Diaphragmatic function, studied by the measurement of excursion and thickening fraction, was preserved in all cases. However, the temporal profile of diaphragmatic excursion differed from that observed in healthy individuals. A reduction in inspiratory flow was observed and appeared to be related to the severity of obstruction, as determined by clinical presentation and flow‐volume loop analysis. Conclusion Based on these preliminary findings, the combination of diaphragmatic ultrasound and inspired volume measurement should be able to provide valuable information in the assessment of upper airway stenosis. Further prospective studies are warranted to confirm its clinical utility.