No Decrease in Blood Pressure After an Acute Bout of Intermittent Hyperpnea and Hypoxia in Prehypertensive Elderly.

Jan Stutz,Ruben Oliveras,Remo Eiholzer,Christina M Spengler

doi:10.3389/fphys.2020.556220

Abstract

Prevalence of hypertension, subjective sleep complaints and snoring increases with age. Worse sleep and snoring, in turn, are independent risk factors to develop hypertension. Both respiratory muscle training (RMT) and intermittent hypoxia (IH) are suggested to have positive effects on these physiological and behavioral variables. This study therefore aimed to test the acute effects of a single bout of RMT, with and without IH, on resting blood pressure (BP) and sleep. Fourteen prehypertensive elderly performed a 60-min session of (a) intermittent voluntary normocapnic hyperpnea (HYP) alone, (b) HYP in combination with IH (HYP&IH) and (c) a sham intervention in randomized order. BP, hemodynamics, heart rate variability (HRV), cardiac baroreflex sensitivity (BRS) and pulse wave velocity (PWV) were assessed before and 15, 30 and 45 min after each intervention. Variables of sleep were assessed with actigraphy, pulse oximetry and with questionnaires during and after the night following each intervention. Neither HYP nor HYP&IH resulted in a decrease in BP. Repeated measures ANOVA revealed no significant interaction effect for systolic BP (p = 0.090), diastolic BP (p = 0.151), HRV parameters, BRS and PWV (all p > 0.095). Fragmentation index was lower after both HYP (−6.5 units) and HYP&IH (−8.4 units) compared to sham, p(ANOVA) = 0.046, although pairwise comparisons reveal no significant differences. There were no other significant effects for the remaining sleep variables. We conclude that one bout of intermittent hyperpnea, alone or in combination with IH, is not effective in lowering blood pressure or improving sleep in prehypertensive elderly.

Highlights

Hypertension is a global public health issue, with aging being a major risk factor for the development of high blood pressure (World Health Organization, 2013)
While physical exercise leads to significant drops in blood pressure in the minutes to hours following activity – a phenomenon called post-exercise hypotension (PEH) (Thompson et al, 2001) – it might not be suitable for individuals who are unwilling or physically unable to engage in traditional activities such as resistance training, walking or cycling
intermittent hypoxia (IH), on the other hand, has long been considered a factor contributing to increases in blood pressure (BP), a view that stems from the findings in patients with obstructive sleep apnea, where severe hypoxia increases sympathetic discharge (Mateika et al, 2015)

Summary

Introduction

Hypertension is a global public health issue, with aging being a major risk factor for the development of high blood pressure (World Health Organization, 2013). While aerobic exercise typically results in a large increase in cardiac output, shear stress and consequent adaptations in vascular function (Schmidt et al, 2011), HYP is more likely to affect BP via the central baroreflex pathway and autonomic adaptations given the large BP swings seen during HYP (unpublished data). This is probably the result of the missing vasodilatory effect of the large muscles and the intrathoracic pressure swings directly affecting arterial pressure. It has been suggested that systematic bouts of low/moderate hypoxia might contribute to lowering BP (Serebrovskaya et al, 2008), possibly via higher parasympathetic activation and/or hypoxic stimulation of endothelial nitric oxide production, with resulting vasodilation

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