Effects of acute oxygen supplementation on functional capacity and heart rate recovery in Eisenmenger syndrome.

Background: Eisenmenger syndrome (ES) precipitates the extreme manifestation of pulmonary hypertension, which leads to severe functional limitation and poor quality of life. The propose of the current study was: 1) examined the acute effects of 40% oxygen supplementation during the 6-minute walk test (6MWT); and 2) evaluate the relation between exercise capacity and clinical cardiac parameters in patients with ES.
Methods: Thirty subjects were prospectively included; all were submitted to a 6MWT with compressed air and with 40% of oxygen. Heart rate recovery at the first minute (HRR ₁ ) and perceived effort Borg scale for dyspnea and lower limb fatigue were recorded in both tests scenarios.
Results: The 6MWT distance was modestly, negatively associated with pulmonary vascular resistance (PVR) [r=0.46, p=0.02]. Patients improved 6MWT distance (p<0.001) and exhibited a faster HRR ₁ (p<0.001) with 40% supplemental oxygen compared to compressed air. With 40% supplemental oxygen, subjects revealed lower dyspnea and lower limb fatigue compared to 6MWT without oxygen supplementation (p<0.001). The amount of change in the 6MWT distance from air to oxygen was moderate, positively associated with tricuspid annular plane systolic excursion (TAPSE) and right ventricular fractional area change (RV _FAC ) [r=0.50, p=0.03; r=0.64, p<0.001, respectively].
Conclusion: Acute 40% oxygen supplementation in patients with Eisenmenger syndrome led to an improvement in 6MWT distance, faster HRR ₁ and lower dyspnea and lower limb fatigue perception. Moreover, functional capacity was positively associated with right ventricular parameters.
(Copyright © 2017. Published by Elsevier B.V.)