Ultrasound Analysis of Diaphragm Kinetics and the Diagnosis of Airway Obstruction: The Role of the M-Mode Index of Obstruction

• Published in: Ultrasound in medicine & biology Vol. 40; no. 6; pp. 1065 - 1071
• Main Authors: Zanforlin, Alessandro, Smargiassi, Andrea, Inchingolo, Riccardo, di Marco Berardino, Alessandro, Valente, Salvatore, Ramazzina, Emilio
• Format: Journal Article
• Language: English
• Published: England 01.06.2014
• Subjects: Aged; Airway Obstruction - diagnostic imaging; Airway Obstruction - physiopathology; Diaphragm - diagnostic imaging; Diaphragm - physiopathology; Female; Forced Expiratory Volume; Humans; Image Interpretation, Computer-Assisted; Kinetics; Male; Middle Aged; Pulmonary Disease, Chronic Obstructive - diagnostic imaging; Pulmonary Disease, Chronic Obstructive - physiopathology; Radiology; Spirometry; Ultrasonography; Vital Capacity; Spirometry; Chronic obstructive pulmonary disease; Diaphragm; Airway obstruction; Ultrasound
• ISSN: 0301-5629; 1879-291X; 1879-291X
• DOI: 10.1016/j.ultrasmedbio.2013.12.009

AbstractDiaphragm motion in forced expiration can be analyzed using M-mode ultrasound in an anterior subcostal approach. Maximum expiratory diaphragmatic excursion (EDE Max) and forced expiratory diaphragmatic excursion in the first second (FEDE 1) are considered the physiopathological analogues of vital capacity (VC) and forced expiratory volume in the first second (FEV 1). As the FEV 1/VC % ratio is used as a marker of obstruction, our aim was to determine if the ratio FEDE 1/EDE Max (M-mode index of obstruction [MIO]) differs between healthy subjects and patients with airway obstruction. One hundred twenty-four outpatients were examined by diaphragm ultrasound after spirometry. The MIO, expressed as the mean ± standard deviation (range), was 87.08 ± 6.64 (72.84–100) in the healthy group (N = 61) and 67.09 ± 12.49 (33.33–91.30) in the group with obstructed airways (N = 63). The difference between the two groups was significant ( p < 0.0001), and MIO was significantly correlated with FEV 1/VC ( p < 0.0001). A MIO <77 was identified as a possibile cutoff for suspecting an obstructive spirometric pattern with a 95.5% positive predictive value. The MIO can be interpreted as a speed index of diaphragmatic relaxation that seems to be slower in obstructed patients and could be used to screen for obstructed airway diseases.