Diaphragm Ultrasound is an Imaging Biomarker that Distinguishes Exacerbation Status from Stable Chronic Obstructive Pulmonary Disease
Tai Joon An, Yeun Jie Yoo, Jeong Uk Lim, Wan Seo, Chan Kwon Park, Chin Kook Rhee, Hyoung Kyu Yoon
Abstract
Background: Evaluating the diaphragm muscle in chronic obstructive pulmonary disease (COPD) is important. However, the role of diaphragm ultrasound (DUS) in distinguishing the exacerbation status of COPD (AECOPD) is not fully understood. We set this study to evaluate the role of DUS as a biomarker for distinguishing the AECOPD. Methods: COPD patients who underwent DUS were enrolled between March 2020 and November 2020. The diaphragm thickening fraction (TF max ) and diaphragm excursion (DE max ) during maximal deep breathing were measured. Patients were divided into exacerbation and stable groups. Demographics, lung function, and DUS findings were compared between the two groups. Receiver operating characteristic curve and univariate/multivariate logistic regression analyses were performed. Results: Fifty-five patients were enrolled. The exacerbation group had a lower body mass index (BMI) (20.9 vs 24.2, p = 0.003), lower TF max (94.8 ± 8.2% vs 158.4 ± 83.5%, p = 0.010), and lower DE max (30.8 ± 11.1 mm vs 40.5 ± 12.5 mm, p = 0.007) compared to stable group. The areas under the TF max (0.745) and DE max (0.721) curves indicated fair results for distinguishing AECOPD. The patients were divided into low and high TF max and DE max groups based on calculated cut-off values. Low TF max (odds ratio [OR] 8.40; 95% confidence interval [CI] 1.55– 45.56) and low DE max (OR 11.51; 95% CI 1.15– 115.56) were associated with AECOPD after adjusting for age, sex, BMI, and lung functions. Conclusion: DUS showed the possibility of an imaging biomarker distinguishing AECOPD from stable status. Keywords: COPD, exacerbation, diaphragm, ultrasound, biomarker