Effect of Short Systemic Intermittent Hypoxia on Systemic Hemodynamics Blunted in Cutaneous Microcirculation

Background: Hypoxic stimulus induces a homeostatic disruption to enhance physiological adaptation. Blood flow in the microcirculation plays an important role in maintaining healthy tissues by delivering oxygen. The cutaneous microcirculations responses to short systemic hypoxia and especially its duration are poorly understood; however the mechanisms of this phenomenon are at the microcirculatory level. The aim of our study was to determine the short systemic intermittent hypoxia's influence on blood flow in skin, local regulatory mechanism fluctuations and changes of systemic hemodynamic parameters in humans.

Place and Duration of Study: Research was performed in University of Latvia, Institute of Cardiology and Regenerative Medicine, Ojāra Vacieša Street 4, Riga, Latvia, between May 2016 and December 2016.

Methodology: Twelve healthy subjects (n=12, 25.1±2.9 years old) participated in this study. After 20min of acclimatization 10 min of basal resting period in normoxia (FiO2=21%) was recorded. Intermittent hypoxic air breathing was made, corresponding 5 min of acute systemic hypoxic (FiO2=12%) period followed by 5 min of normoxic period, were repeated four times, after hypoxia, 10min of recovery period followed in normoxia. Heart rate variability and systemic hemodynamic parameters and regional blood flow were evaluated. To register skin blood flow laser-Doppler flowmetry was used and evaluation of local factor influences to cutaneous circulation was made by wavelet analysis; fluctuations in the frequency intervals of 0.0095–0.021, 0.021–0.052, and 0.052–0.145 Hz correspondingly represented endothelial, sympathetic, and myogenic activities.

Results: Intermittent acute hypoxia increased systemic hemodynamic parameters, but it didn't significantly change skin blood flow and local regulatory factor activities.

Conclusions: The main findings of study are that intermittent acute hypoxia increase systemic hemodynamic parameters, but didn't change skin blood flow and local endothelial, sympathetic, and myogenic activities.