Diaphragmatic dysfunction associates with dyspnoea, fatigue, and hiccup in haemodialysis patients: a cross-sectional study

Muscle wasting is associated with increased mortality and morbidity in chronic kidney disease (CKD) patients, especially in the haemodialysis (HD) population. Nevertheless, little is known regarding diaphragm dysfunction in HD patients. We conducted a cross-sectional study at the Institute of Nephrology, Southeast University, involving 103 HD patients and 103 healthy volunteers as normal control. Ultrasonography was used to evaluate diaphragmatic function, including diaphragm thickness and excursion during quiet and deep breathing. HD patients showed lower end-inspiration thickness of the diaphragm at total lung capacity (0.386 ± 0.144 cm vs. 0.439 ± 0.134 cm, p < 0.01) and thickening fraction (TF) (0.838 ± 0.618 vs. 1.127 ± 0.757; p < 0.01) compared to controls. The velocity and excursion of the diaphragm were significantly lower in the HD patients during deep breathing (3.686 ± 1.567 cm/s vs. 4.410 ± 1.720 cm/s, p < 0.01; 5.290 ± 2.048 cm vs. 7.232 ± 2.365 cm; p < 0.05). Changes in diaphragm displacement from quiet breathing to deep breathing (△m) were lower in HD patients than in controls (2.608 ± 1.630 vs. 4.628 ± 2.110 cm; p < 0.01). After multivariate adjustment, diaphragmatic excursion during deep breathing was associated with haemoglobin level (regression coefficient = 0.022; p < 0.01). We also found that the incidence of dyspnoea and hiccup and the fatigue scores, all of which were related to diaphragmatic dysfunction, were significantly higher in HD patients than in controls (all p < 0.01). Improving diaphragm function through targeted therapies may positively impact clinical outcomes in HD patients.