Obstructive sleep apnea does not impair cardiorespiratory responses to progressive exercise performed until exhaustion in hypertensive elderly

Abstract

Background: Elderly people have a high prevalence to systemic arterial hypertension (SAH) and obstructive sleep apnea (OSA). Both comorbidities are closely associated and inflict damage on cardiorespiratory capacity.

Methods: In order to assess cardiorespiratory responses to the cardiopulmonary exercise test (CPET) among hypertensive elderly with OSA, we enrolled 28 subjects into two different groups: without OSA (No-OSA: apnea/hypopnea index (AHI) < 5 events/h; n = 15) and with OSA (OSA: AHI ≥ 15 events/h; n = 13). All subjects underwent CPET and polysomnographic assessments. After normality and homogeneity evaluations, independent t test and Pearson's correlation were performed. The significance level employed was p ≤ 0.05.

Results: Hypertensive elderly with OSA presented lower heart rate recovery (HRR) in the second minute (HRR₂) in relation to the No-OSA group. A negative correlation between AHI and ventilation (VE) (r = -0.63, p = 0.02) was found in polysomnography and CPET data comparisons, and oxygen saturation (O₂S) levels significantly correlated with VE/VCO_2slope (r = 0.66, p = 0.01); in addition, OSA group presented a positive correlation between oxygen consumption and O₂S (r = 0.60, p = 0.02), unlike the no-OSA group.

Conclusions: OSA does not affect the CPET variables in hypertensive elderly, but it attenuates the HRR₂. The association between O₂S during sleep with ventilatory responses probably occurs due to the adaptations in the oxygen transport system unleashed via mechanical respiratory feedback; thus, it has been identified that OSA compromises the oxygen supply in hypertensive elderly.

Keywords: Aged; Exercise; Hypertension; Obstructive sleep apnea syndrome; Oxygen consumption.