Chest
Volume 123, Issue 4, April 2003, Pages 1119-1126
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Clinical Investigations
SLEEP AND BREATHING
Impact of Sleep Apnea on Sympathetic Nervous System Activity in Heart Failure

https://doi.org/10.1378/chest.123.4.1119Get rights and content

Objectives:

To compare and establish the relevance of the relative degree of sympathetic nervous system activity (SNSA) in groups of patients with congestive heart failure (CHF) and obstructive sleep apnea (OSA), and in a control group.

Background:

Elevated SNSA is a characteristic feature of CHF, as well as of OSA and nonhypercapnic central sleep apnea (CSA). OSA and CSA commonly occur with CHF; however, the relative contribution of apnea-related hypoxemia and sleep fragmentation to the SNSA of patients with CHF is not known.

Methods:

This was a prospective, controlled, observational trial in which the overnight urinary norepinephrine (UNE) level, which is a measure of integrated overnight SNSA while asleep, was measured in 15 healthy male volunteers, 15 male OSA patients who did not have CHF, and 90 CHF patients (77 men). CHF patients also had right heart pressure measurements and then were grouped by the presence of sleep apnea.

Results:

Compared with healthy individuals, the mean (± SD) UNE level was significantly elevated in the OSA group and was even further elevated in the CHF group (13.4 ± 5.6 vs 19.7 ± 12.3 vs 32.2 ± 20.2 nmol/mmol creatinine, respectively; p < 0.001 [by analysis of variance]). Within the CHF group, the mean UNE levels were greatest in the CHF-CSA group compared with the CHF-OSA group and the CHF nonapnea group (43.9 ± 24.1 vs 24.0 ± 10.8 vs 22.4 ± 8.9 nmol/mmol creatinine, respectively; p < 0.001). Using a multivariate regression model, the variance of the UNE level in the CHF group was predicted, in descending order, by pulmonary capillary wedge pressure (14% variance), rapid eye movement sleep (8%), and the mean sleep pulse oximetry level (7%).

Conclusions:

Overnight SNSA is significantly greater in CHF patients than in OSA patients. Moreover, the hemodynamic severity of CHF contributes to the elevation of SNSA in CHF patients to a greater degree than apnea-related hypoxemia.

Section snippets

Subjects

Patients being assessed by the Alfred Hospital Heart Failure Service and healthy volunteers were invited to take part in this study. Consecutive patients with CHF of either gender who were aged 18 to 75 years were enrolled if they met the following criteria: (1) clinical evidence of symptomatic CHF of at least 6 months duration and receiving medical therapy; (2) a left ventricular ejection fraction (LVEF) of ≤ 55% and New York Heart Association class II to IV; and (3) stable condition, which

Comparison Among the Normal, OSA, and CHF Groups

The demographic characteristics of the normal group (n = 15), the OSA group (n = 15), and the CHF group (n = 90; unselected for apnea) were similar, apart from the subjects in the normal group being 8 years younger than those in the CHF group (Table 1). The OSA and CHF groups had similar AHI values, movement arousal index values, and mean and minimum Spo2 values. The CHF group had lower amounts of total and REM sleep than did the normal group. Furthermore, the CHF group had a greater mean sleep

Discussion

Although CHF, OSA, and CSA are known to be associated with elevated SNSA, their relative contributions have not been previously investigated. In this study, the overnight UNE level was used as an integrated marker of SNSA when patients were asleep, and awake invasive hemodynamic pressures were measured in a large population of, mainly male, CHF patients and then was compared with that of healthy male volunteers without sleep apnea and male OSA subjects who were free of heart disease. Two

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  • Cited by (0)

    This research was supported by the Australian National Health and Medical Research Council, the Australian Lung Foundation, the Viertal Foundation, and an Alfred Research Grant.

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