Identifying decreased diaphragmatic mobility and diaphragm thickening in interstitial lung disease: the utility of ultrasound imaging

Abstract

Objective: To investigate the applicability of ultrasound imaging of the diaphragm in interstitial lung disease (ILD). Methods: Using ultrasound, we compared ILD patients and healthy volunteers (controls) in terms of diaphragmatic mobility during quiet and deep breathing; diaphragm thickness at functional residual capacity (FRC) and at total lung capacity (TLC); and the thickening fraction (TF, proportional diaphragm thickening from FRC to TLC). We also evaluated correlations between diaphragmatic dysfunction and lung function variables. Results: Between the ILD patients (n = 40) and the controls (n = 16), mean diaphragmatic mobility was comparable during quiet breathing, although it was significantly lower in the patients during deep breathing (4.5 ± 1.7 cm vs. 7.6 ± 1.4 cm; p < 0.01). The patients showed greater diaphragm thickness at FRC (p = 0.05), although, due to lower diaphragm thickness at TLC, they also showed a lower TF (p < 0.01). The FVC as a percentage of the predicted value (FVC%) correlated with diaphragmatic mobility (r = 0.73; p < 0.01), and an FVC% cut-off value of < 60% presented high sensitivity (92%) and specificity (81%) for indentifying decreased diaphragmatic mobility. Conclusions: Using ultrasound, we were able to show that diaphragmatic mobility and the TF were lower in ILD patients than in healthy controls, despite the greater diaphragm thickness at FRC in the former. Diaphragmatic mobility correlated with ILD functional severity, and an FVC% cut-off value of < 60% was found to be highly accurate for indentifying diaphragmatic dysfunction on ultrasound.

Inspiratory muscle strength, diaphragmatic mobility, and body composition in chronic obstructive pulmonary disease

“…In addition to affecting the peripheral musculature, muscle fatigue caused by the deleterious effects of COPD may compromise respiratory muscle function (Barreiro & Jaitovich, 2018). Among the respiratory muscles involved, the diaphragm is mechanically disadvantaged due to airway obstruction and lung hyperinsulflation, which leads to chronic reduction in the diaphragmatic apposition zone with abnormal lowering and shorter excursion during inspiration (Rocha et al, 2017), leading to a reduction in respiratory capacity (Santana, Prina, Albuquerque, Carvalho, & Caruso, 2016).…”

Ultrasound to assess diaphragmatic function in the critically ill—a critical perspective

“…Cut-off values for predicting successful extubation presented in earlier studies ranged from 30-36% (3)(4)(5). For healthy individuals thickening has an extremely large range with values ranging from 24.5% to 53.2% during normal breathing (6), up to 131% during forceful inspiration (7). As one might have already guessed, this means that changes considerably less than 0.5 millimetre have to be accurately assessed, while some probes have a smallest measurable distance of 0.1 mm (given that the speed of sound waves averages 1,540 m/s in human tissue, the range of high frequency probes lies around 3-15 MHz and that λ= v/f = 1,540/15×10 6 =0.1×10 −3 m =0.1 mm) which equals 5-7% of the total thickness.…”

Translation and cultural adaptation of the King’s Brief Interstitial Lung Disease health status questionnaire for use in Brazil

“…The condition also reduces patient quality of life and survival. (6)(7)(8)(9) ILDs are often diagnosed late, (10) mainly because of the limited knowledge of health care professionals and the lack of local resources. Different ILDs have different prognoses and treatments, and it is difficult to establish accurate prognoses for patients with newly diagnosed ILD, because the natural history of the disease can vary.…”