Altered diaphragm position and function in patients with chronic heart failure

Background: Breathlessness is a common symptom experienced by patients with chronic heart failure (CHF) but its etiology remains controversial. Various molecular and histological adaptations have been reported for the diaphragm in CHF but their functional consequences are poorly described. Aims: This study aims to determine the position and function of the diaphragm in CHF patients. Methods: The diaphragm position was measured, relative to the renal pelvis, by ultrasound in 20 CHF patients and ninety controls matched for age and body mass. The extent and velocity of diaphragm movement was also measured during quiet breathing and sniffing. Results: At the end of expiration, the diaphragm was significantly nearer to the renal pelvis in CHF patients (89.3 ± 16.8 vs. 96.3 ± 19.2 mm, P < 0.05) and also moved further during quiet breathing (18.2 ± 4.4 vs. 12.7 ± 4.6 mm, P < 0.001) and sniffing (23.9 ± 7.4 vs. 18.2 ± 5.7 mm, P < 0.005). Velocity of diaphragm movement was also increased in CHF patients during quiet breathing (26.5 ± 8.2 vs. 15.9 ± 6.1 mm s−1, P < 0.001). Conclusions: These data demonstrate that the position and function of the diaphragm is altered in CHF