Hypoxemia during sleep and overnight rostral fluid shift in pulmonary arterial hypertension: a pilot study

Abstract

Introduction. Sleep-related breathing disorders, including sleep apnea and hypoxemia during sleep, are common in pulmonary arterial hypertension (PAH), but the underlying mechanisms remain unknown. Overnight fluid shift from the legs to the upper airway and to the lungs promotes obstructive and central sleep apnea, respectively, in fluid retaining states. The main objective was to evaluate if overnight rostral fluid shift from the legs to the upper part of the body is associated with sleep-related breathing disorders in PAH. Methods. In a prospective study, a group of stable patients with idiopathic, heritable, related to drugs, toxins, or treated congenital heart disease PAH underwent a polysomnography and overnight fluid shift measurement by bioelectrical impedance in the month preceding or following a one-day hospitalization according to regular PAH follow-up schedule with a right heart catheterization. Results. Among 15 patients with PAH (women: 87%; median [25th;75th percentiles] age: 40 [32;61] years; mean pulmonary arterial pressure 56 [46;68] mmHg; pulmonary vascular resistance 8.8 [6.4;10.1] Wood units), 2 patients had sleep apnea and 8 (53%) had hypoxemia during sleep without apnea. The overnight rostral fluid shift was 168 [118;263] mL per leg. Patients with hypoxemia during sleep had a greater fluid shift (221 [141; 361] mL) than those without hypoxemia (118 [44; 178] mL, p = 0.045). Conclusion. This pilot study suggests that hypoxemia during sleep is associated with overnight rostral fluid shift in PAH.

Development and Validation of a Nomogram for Predicting Obstructive Sleep Apnea in Patients with Pulmonary Arterial Hypertension

“…First, the rostral shift of fluid from the legs to the neck at night could contribute to the upper airway obstruction. 17 , 18 Second, the skeletal and respiratory muscle weakness observed in PAH may also affect the upper airway. 19 Third, the tolerance of ventilatory perturbations during sleep is likely to be impaired in patients with PAH.…”