摘要：

Background: Exercise-induced hypoxemia and exercise intolerance are common in patients with pulmonary arterial hypertension (PAH). Reduced cerebral oxygenation has been associated with exercise intolerance and development of fatigue. Up-to-date, the effects of O2 supplementation on cerebral oxygenation and exercise tolerance in PAH patients have not been examined.Aim: To investigate the acute effects of O2 supplementation on: a) exercise duration, b) dyspnea and perceived exertion, and c) cerebral oxygenation in PAH patients without resting hypoxemia.Methods: This is a prospective, single-blind, placebo-controlled trial. Stable outpatients with PAH (category 1) underwent a maximum cardiopulmonary exercise testing, followed by two submximal exercise trials during which patients randomly received supplementary O2 or medical air in a cross-over design. Near-infrared spectroscopy continuously monitored the relative changes from baseline in oxygenated (O2Hb), deoxygenated (HHb) and total hemoglobin (tHb) in the microvasculature of the cerebral pre-frontal lobe. Modified Borg dyspnea scale (mBDS), rate of perceived exertion scale (RPE) and continuous pulse oximetry were also recorded.Results: Preliminary results of 8 patients (51±3.4 years, 7 women) are presented. With O2 supplementation patients exercised for longer (p=0.016), had lower mBDS (p=0.022), higher O2 saturation (p<0.001), a greater increase in O2Hb (p=0.03), and a lower increase in HHb (p=0.04), vs. medical air, without differences in tHb (an index of microvascular blood volume).Conclusion: Oxygen supplementation during exercise improves dyspnea severity, cerebral oxygenation and exercise capacity in PAH patients.

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