Abstract 14799: Differing Relationship between Nocturnal Rostral Fluid Shift and Obstructive Sleep Apnea in Men and Women with Heart Failure
Background: Obstructive sleep apnea (OSA) is common in patients with heart failure (HF), in whom it is associated with increased mortality. We recently reported that nocturnal rostral fluid displacement from the legs was associated with an increase in the neck circumference (NC) and the severity of OSA in men with HF. However, it is not known whether nocturnal rostral fluid shift relates to the OSA in women with HF. Because the prevalence of OSA is higher in men than in women, and because we demonstrated that for the same rostral fluid displacement by application of positive pressure to the legs of healthy subjects, upper airway collapsibility increased more in men than in women, we hypothesized that in women with HF, overnight rostral fluid shift from the legs would not be related to the degree of overnight change in NC or severity of OSA.
Methods: In 17 men and 19 women with medically stable HF (ejection fraction ≤45%, NYHA class I-III), we measured change in NC and leg fluid volume (LFV) by bioelectrical impedance before and after overnight sleep study. The severity of OSA was assessed by the number of apneas and hypopneas/hr of sleep (i.e. apnea-hypopnea index: AHI).
Results: Although the mean overnight change in LFV was similar in men and women (133±110 vs 151±93 ml, p = n.s.), in women, the overnight change in NC was smaller (1.0±1.0 vs 0.2±0.5 cm, p = 0.003), and the AHI was lower (32±21 vs 11±10, p < 0.001). Furthermore, although change in LFV correlated inversely with the change in NC and AHI in men, this was not the case in women (Figure).
Conclusions: Our findings indicate differing relationships between overnight rostral fluid shift from the legs and severity of OSA in men and women. This may be due to greater redistribution of fluid into the neck in men, and greater sequestration of fluid below the neck, possibly in pelvic and abdominal capacitance vessels, in women. These novel findings shed light on a potential mechanism contributing to the lower prevalence of OSA in women than in men with HF.
- © 2010 by American Heart Association, Inc.