Sonography indicators of diaphragm and their correlation with spirometry data in healthy individuals
OBJECTIVES: Revealing the correlation between sonography indicators of diaphragm performance and spirometry data of healthy persons in a reclining position. MATERIAL AND METHODS: The study included in total 50 healthy volunteers (female – 30). The structural and functional indicators of diaphragm (thickness, thickening fraction, excursion, rates during calm and deep inhalation/exhalation) were assessed with the Philips CX50 ultrasound machine (produced by Philips Ultrasound, Inc, USA). The spirometry characteristics were assessed by means of parallel measurement of the tidal volumes during calm and deep breathing with the Bellavista 950e ventilator (Russia, registry number RZN 2021/13644, registration date 31.03 2022) using a mask in the ventilation mode with the constant positive pressure set to 0 cm H2O and the fraction of inspired oxygen set to 21%. The following indicators were assessed: tidal volumes, length of inhalation and exhalation, strength of respiratory muscles. Mathematical analysis by STATISTICA 10 (StatSoft Inc, USA). The type of data distribution: Kolmogorov-Smirnov test and Shapiro-Wilk test. Spearman correlation analysis with assessment by the Chaddock scale. The descriptive part is presented as the mean and standard deviation (M±SD). The validity of relations was accepted with р ≤0,05. RESULTS: It was possible to assess the thickness of diaphragm on both sides in all subjects; the diaphragm excursion on the left – only in 20% of subjects. Spirometry has been performed in all subjects. The obtained data are consistent with the literature. In particular, sonography and spirometry indicators of the healthy individuals are within reference values. Inspiratory muscles strength has also proved to be consistent with the literature data. Correlation analysis has revealed no statistically significant relationship between the examined sonography and spirometry parameters. In addition, no relation between age and sonography indicators of diaphragm has been found. There are weak statistically significant relations revealed between the structural and functional state of diaphragm and such anthropometric characteristics of the subjects as body mass and body mass index. CONCLUSION: Sonography structural and functional indicators of diaphragm performance do not correlate or correlate poorly with spirometry data, i.e. with tidal volumes. There is no reason to use sonography of diaphragm in healthy individuals since it does not practically provide any additional information about the state of external respiratory apparatus. The discrepancy between the sonography indicators of diaphragm function and spirometry data is due to many reasons including the methodological features of the conducted research as well as the apparently unknown contribution of the additional respiratory muscles work and a breathing type.