Supplementary Material for: Ultrasonography in Assessment of Respiratory Muscles Function: A Systematic Review

Introduction: The purpose of this study was to evaluate the potential utility of respiratory muscles ultrasound (US) imaging for assessing respiratory function and identify US variables that best correlate with pulmonary parameters. Materials and Methods: A search of 5 databases was conducted. Initially, there was no language, study design, or time frame restrictions. All studies assessing the relationship between pulmonary and US parameters were included. Two reviewers independently extracted and documented data regarding to examined population, age, gender, health condition, methodology, US, and pulmonary function measurements. All studies were qualitative synthesis. Results: A total of 1,272 participants from 31 studies were included. Diaphragm thickness, diaphragm thickening ratio, and diaphragm excursion amplitude were mainly used as US parameters. Forced vital capacity, forced expiratory volume1sec, and maximal inspiratory pressure were mainly used as pulmonary parameters. The relationships between pulmonary and US parameters varied from negligible to strong (depend on examined population and methodology used). Data were not quantitatively synthesis due to high heterogeneity in terms of study design, population examined, and various pulmonary and US parameters. Conclusion: A strong relationship between US measurements and pulmonary parameters was demonstrated in some studies but not others. This review confirmed that US measurements can complement spirometry, but the exact role of the US remains to be confirmed. Further studies using standardized methodology are needed to obtain more conclusive evidence on the usefulness of US for assessing respiratory function.