Ultrasound as diagnostic tool in diaphragm dysfunction: a prospective construct validity study.

INTRODUCTION

Diaphragm dysfunction is a frequently overlooked cause of dyspnea. Diagnosis typically relies on a combination of history, symptoms, and imaging. Diaphragm ultrasound is a promising alternative for fluoroscopy. This study evaluated the construct validity of ultrasound compared to traditional diagnostic methods in diaphragm dysfunction.

METHODS

A prospective, operator-blinded study was conducted at two centers in the Netherlands. Thirty-six adults with suspected diaphragm dysfunction underwent fluoroscopy, pulmonary function tests, and ultrasound examination. The primary outcome was the agreement between predefined ultrasound diagnostic criteria and traditional diagnostic criteria (fluoroscopy, pulmonary function tests). Secondary outcomes included concordance of diagnostic criteria with the treating physician's final diagnosis, agreement of individual test parameters, and inter-rater reliability.

RESULTS

The diagnostic criteria for ultrasound and traditional tests were concordant in 55.6 % (95 %CI: 0.381-0.721) of cases. Ultrasound criteria showed higher concordance with the treating physician's final diagnosis (75.0 %, 95 %CI: 0.578-0.879) compared to traditional test criteria (63.9 %, 95 %CI: 0.462-0.792). Individual parameters; visual ultrasound assessment, Thickening Fraction (TF), Diaphragm Excursion (DE), and fluoroscopy, had high concordance with the final diagnosis at 91.4 %, 90.3 %, 88.3 %, and 91.7 %, respectively. Inter-rater reliability was good for fluoroscopy, visual ultrasound assessment, and DE, but poor for TF.

CONCLUSION

This study demonstrates that ultrasound is a reliable tool for diagnosing diaphragm dysfunction, showing high concordance with the treating physician's final diagnosis and strong performance of individual parameters. The robust inter-rater reliability for visual assessment and DE supports its use as alternative to traditional methods like fluoroscopy in clinical practice. (ClinicalTrials.gov number: NCT05682027).