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, No-OSA group presented a positive correlation between oxygen consumption and O₂S (r = 0.66, p = 0.01), unlike the 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.

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