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Trent A Hargens, Guill SG, Aron A, Zedalis D, Gregg JM, Nickols-Richardson SM, Herbert WG. . Altered ventilatory responses to exercise testing in young adult men with obstructive sleep apnea. Respiratory Medicine (accepted for publication), 2009.

Abstract: Background: Obstructive sleep apnea (OSA) is a disorder characterized by repetitive obstructions of the upper airway. Individuals with OSA experience intermittent hypoxia, hypercapnia, and arousals during sleep, resulting in increased sympathetic activation. Chemoreflex activation, arising from the resultant oscillatory disturbances in blood gases from OSA, exerts control over ventilation, and may induce increases in sympathetic vasoconstriction, contributing to increased long-term risks for hypertension (HTN) and cardiovascular disease (CVD).
Methods: To evaluate whether OSA elicits exaggerated ventilatory responses to exercise in young
men, 14 overweight men with OSA and 16 overweight men without OSA performed maximal ramping cycle ergometer exercise tests. Oxygen consumption (VO2), ventilation, (VE), ventilatory
equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), and VE/VCO2 slope were measured. Results: The VO2 response to exercise did not differ between groups. The VE, VE/VCO2, VE/VO2 were higher (p < 0.05, 0.002, and p < 0.02, respectively) in the OSA group across all workloads. The VE/VCO2 slope was greater in the OSA group (p < 0.05). The VE/VCO2 slope and AHI were significantly correlated (r = 0.56, p < 0.03). Thus, young, overweight men with OSA exhibit increased ventilatory responses to exercise when compared to overweight controls. This may reflect alterations in chemoreflex sensitivity, and contribute to increased sympathetic drive and HTN risk.

Keywords: obstructive sleep apnea, exercise test; chemoreceptors

Posted by Adrian Aron


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