Overnight rostral fluid shift in group 1 pulmonary arterial hypertension

Abstract

Background: High prevalence of both obstructive and central sleep apnea has been reported in group 1 pulmonary arterial hypertension (PAH). Central and obstructive sleep apnea can be promoted by overnight fluid shift from the legs to the lungs and the upper airway, respectively, in fluid retaining states. PAH is characterized by fluid retention but fluid shift in PAH has not been previously evaluated. Objective: To detect the occurrence of fluid shift in PAH. Methods: We developed a questionnaire to test the frequency (0=never; 1=rarely; 2=often; 3=always) of signs/symptoms caused by fluid accumulation in lower body at the end of the day (heavy legs, socks markers and tight shoes) and in the upper body during night (orthopnea, sleep with 2 pillows or more, sleep sitting and paroxysmal nocturnal dyspnea) and in the morning (swollen hands, face, throat and obstructed nose). Sleep quality was evaluated by Pittsburgh Sleep Quality Index (PSQI), daytime sleepiness by Epworth Sleepiness Scale (ESS), fatigue by Pichot's Fatigue Scale (PFS). Results: A total of 73 stable PAH patients and 55 control subjects matched for gender, sex and body mass index were included in this study. The total score of fluid shift was higher in PAH than in control group, in particular orthopnea (0.6±0.9 vs 0.2±0.6, p=0.002), sleep with 2 pillows or more (0.6±1.1 vs 0.2±0.6, p=0.005) and obstructed nose (1.2±1.1 vs 0.6±0.8, p<0.001) were more frequent in PAH than in control group. PFS was higher in PAH than in control group (p<0.001). There was no difference in the PSQI and ESS between the two groups. Conclusions: A clinically detectable overnight fluid shift is present in PAH which could explain the high prevalence of sleep apnea in PAH.