Diaphragmatic Movement at Rest and After Exertion: A Non-Invasive and Easy to Obtain Prognostic Marker in COPD

Abstract

Introduction

Diaphragmatic dysfunction is common in patients with chronic obstructive pulmonary disease (COPD). This study aimed to assess the prognostic significance of impaired diaphragmatic movement at rest and after exercise.

Methods

This was a prospective study of patients with stable COPD. Diaphragmatic movements were examined at rest and after a 6-minute walking test (6MWT) with a convex transducer with a frequency of 3.5-5-7.5 MHz. Maximal movement of the diaphragm was measured in both right and left diaphragm, and the side with higher amplitude was selected for further analysis. Measurements obtained were evaluated for their prognostic value for a composite endpoint of moderate and severe COPD exacerbations and death in 1 year time period was assessed. In addition, postbronchodilator spirometry, symptoms, quality of life, and demographic and clinical information were collected.

Results

A total of 96 patients were analyzed (62.5% male, mean age 65.1 years (standard deviation (SD): 8.1), mean FEV1 (% predicted): 55.8%, SD: 18.3%, mean CAT: 15.6 units, SD: 9.2). Sixty-four patients (67%) presented the composite endpoint. In the multivariate Cox analysis, FVC (HR = 0.944, p = 0.005), CAT score (HR = 1.133, p = 0.011), previous severe exacerbations (HR = 5.446, p = 0.004) and diaphragmatic movement at rest (HR = 0.932, p = 0.033) were found to be predictors of the composite endpoint. This model correctly classified 86.5% (83/96) of the patients.

Conclusion

Non-invasive assessment of diaphragmatic movement by ultrasound measurement both at rest and after exercise could contribute to the assessment of disease severity and prognosis of COPD.

Keywords:

• COPD
• diaphragmatic dysfunction
• comorbidities
• thoracic ultrasound
• exacerbations

Abbreviations

AUC, Area under the curve; CAT, COPD Assessment Test; COPD, Chronic obstructive pulmonary disease; DM, Diaphragmatic movement; FEV1, Forced expiratory volume in one second; FVC, Forced vital capacity; GOLD, Global Initiative for Obstructive Lung Disease; HR, Hazard ratio; MHz, Megahertz; IQR, Interquartile range; mMRC, Modified Medical Research Council; Q, Quartile; ROC, Receiver-operating characteristics; SD, Standard deviation; US, Ultrasound; 6MWT, Six-minute walking test.

Disclosure

Evgeni Mekov has received grants and personal fees from Chiesi, and speaker or consulting fees from Astra Zeneca and Chiesi. Nikolay Yanev has received speaker or consulting fees from Astra Zeneca, Boehringer Ingelheim, Berlin Chemie and Chiesi. Nedelina Kurtelova has received speaker or consulting fees from Astra Zeneca, Boehringer Ingelheim, and Chiesi. Marc Miravitlles has received speaker or consulting fees from AstraZeneca, Atriva Therapeutics, Bial, Boehringer Ingelheim, Chiesi, Cipla, CSL Behring, Laboratorios Esteve, Ferrer, Gebro Pharma, GlaxoSmithKline, Grifols, Kamada, Menarini, Mereo Biopharma, Novartis, ONO Pharma, Palobiofarma SL, pH Pharma, Rovi, Sanofi, Sandoz, Spin Therapeutics, Takeda, TEVA, Verona Pharma and Zambon, and research grants from Grifols. Rosen Petkov has received speaker or consulting fees from Astra Zeneca and Boehringer Ingelheim. The authors report no other conflicts of interest in this work.

Additional information

Funding

There is no funding to report.