title: Relationship between heart rate variability, blood pressure and arterial wall properties during air and oxygen breathing in healthy subjects.
abstract: Previous studies reported that normobaric hyperoxia influences heart rate, arterial pressure, cardiac output and systemic vascular resistance, but the mechanisms underlying these changes are still not fully understood. Several factors are considered including degeneration of endothelium-derived nitric oxide by reactive oxygen species, the impact of oxygen-free radicals on tissues and alterations of autonomic nervous system function. Recently, new devices for the detailed non-invasive assessment of large and small arteries have been developed. Therefore, the aim of our study was to assess heart rate variability (HRV) as a potential indicator of autonomic balance and its relation to blood pressure and vascular properties during medical air (MAB) and 100% oxygen breathing (OXB) in healthy volunteers. In 12 healthy subjects we assessed heart rate and blood pressure variability, baroreflex sensitivity, respiratory frequency, common carotid artery diameter and its wall distensibility, as well as changes in the digital artery pulse waveform, stroke index and systemic vascular resistance during MAB and OXB. Mean and systolic blood pressure have increased significantly while digital pulse amplitude and carotid artery diameter were significantly lower during hyperoxia. Heart rate variability measures did not differ during MAB and OXB. However, the correlations between spectral HRV components and those hemodynamic parameters which have changed due to hyperoxia varied substantially during MAB (correlated significantly) and OXB (no significant correlations were noted). Our findings suggest that autonomic nervous system might not be the main mediator of the cardiovascular changes during 100% oxygen breathing in healthy subjects. It seems that the direct vascular responses are initial consequences of hyperoxia and other cardiovascular parameter alterations are secondary to them.
authors.affiliation: Hypertension Unit, Dept. of Hypertension and Diabetology, Medical University of Gdańsk, Poland. Electronic address: bgraff@gumed.edu.pl.
authors.forename: Beata
authors.initials: B
authors.lastname: Graff
authors.forename: Anna
authors.initials: A
authors.lastname: Szyndler
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Czechowicz
authors.forename: Wiesława
authors.initials: W
authors.lastname: Kucharska
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Graff
authors.forename: Pierre
authors.initials: P
authors.lastname: Boutouyrie
authors.forename: Stephane
authors.initials: S
authors.lastname: Laurent
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Narkiewicz
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002307:Cardiography, Impedance; D002339:Carotid Arteries / Q000033:anatomy & histology* / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000494:pharmacology*; D012044:Regression Analysis; D012119:Respiration; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D010100:Oxygen
keywords: Autonomic nervous system; Heart rate variability; Hyperoxia