Correlation of diaphragm mobility and thickness with anthropometric variables in mucopolysaccharidosis VI

Abstract

Background: Mucopolysaccharidosis type VI (MPS VI) is a metabolic rare disease with impact on the respiratory system. Ultrasound is a method used to evaluate the mobility and thickness of the diaphragm muscle. However, no previous studies have been performed on MPS VI. Objectives: To correlate the diaphragm mobility (DM) and thickness (DT) with antropometric variables in MPS VI. Method: Cross-sectional study with 12 MPS VI carriers. DM and DT was acquired with portable ultrassound. DM was measured from total lung capacity (TLC) on M mode at supine position (45°); and DT from TLC and functional residual capacity (FRC) at lateral position. Ultrasound variables (DM and DT) were correlated with the anthropometric variables, using Pearson’s correlation. Normality was calculated with Shapiro Wilk test (parametric distribution of all outcomes), considering p>0.05. Results: From 12 pacients with MPS VI, 58% were male and aged 10±3,86 years old. There was positive correlation of anthropometric variables [height (p=0.003, r=0.766), weight (p=0.004,r=0.757), muscle mass (p=0.007;r=0.785), fat free mass (p=0.002;r=0.805), waist circumference (p=0.006;r=0.736)] and DM. The DT in the FRC maneuver presented moderate positive correlation (p=0.047;r=0.583) with the height of the patients, whereas the DT in the TLC maneuver showed good correlation with all variables (except free fat mass), with muscle mass being the highest positive correlation (p=0.016;r=0.677). Conclusion: In this group evaluated, DM and DT in the TLC presented strong positive correlations with the anthropometric variables, the fat free mass being a stronger correlation in DM, and muscle mass stronger in DT in the TLC.