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Pulmonary Arterial Hypertension

The high prevalence of pulmonary arterial hypertension (PAH) in patients with obstructive sleep apnea (OSA) and the putative pathophysiologic connections have been extensively documented. Conversely, patients with established PAH are at risk for sleep-related ventilatory instability, including OSA, central sleep apnea, and nocturnal desaturations. This chapter reviews the prevalence and pathophysiologic interactions of these conditions, the interplay with associated disorders, and the effects of continuous positive airway pressure therapy on pulmonary hemodynamics. In patients with OSA, chronic effects of repetitive hypoxia as well as comorbidities, including chronic obstructive pulmonary disease and left-sided heart dysfunction, play a role in promoting pulmonary hypertension. Sleep disordered breathing, representing a spectrum of sleep-related breathing disorders inclusive of OSA, is highly prevalent among patients with established pulmonary hypertension. Obstructive events, central sleep apnea, and nocturnal hypoxia are within the spectrum of sleep-related breathing disorders in pulmonary hypertension. The mechanisms for these associations remain speculative.