Open AccessAcute hypoxia diminishes the relationship between blood pressure and subarachnoid space width oscillations at the human cardiac frequency
Author(s) -
Magdalena Wszędybył-Winklewska,
Jacek Wolf,
Ewa Świerblewska,
Katarzyna Kunicka,
Agnieszka Gruszecka,
Marcin Gruszecki,
W. Kucharska,
Paweł J. Winklewski,
Joanna Zabulewicz,
Wojciech Gumiński,
Michal Pietrewicz,
Andrzej F. Frydrychowski,
Leszek Bieniaszewski
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0172842
Subject(s) - heart rate , medicine , blood pressure , cardiology , transcranial doppler , diastole , anesthesia , cerebral blood flow , hypoxia (environmental) , hemodynamics , pulsatile flow , chemistry , oxygen , organic chemistry
Background Acute hypoxia exerts strong effects on the cardiovascular system. Heart-generated pulsatile cerebrospinal fluid motion is recognised as a key factor ensuring brain homeostasis. We aimed to assess changes in heart-generated coupling between blood pressure (BP) and subarachnoid space width (SAS) oscillations during hypoxic exposure. Methods Twenty participants were subjected to a controlled decrease in oxygen saturation (SaO 2 = 80%) for five minutes. BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography, oxyhaemoglobin saturation with an ear-clip sensor, end-tidal CO 2 with a gas analyser, and cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a recently-developed method called near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the relationship between BP and SAS oscillations. Results Gradual increases in systolic, diastolic BP and HR were observed immediately after the initiation of hypoxic challenge (at fifth minute +20.1%, +10.2%, +16.5% vs. baseline, respectively; all P<0.01), whereas SAS remained intact (P = NS). Concurrently, the CBFV was stable throughout the procedure, with the only increase observed in the last two minutes of deoxygenation (at the fifth minute +6.8% vs. baseline, P<0.05). The cardiac contribution to the relationship between BP and SAS oscillations diminished immediately after exposure to hypoxia (at the fifth minute, right hemisphere -27.7% and left hemisphere -26.3% vs. baseline; both P<0.05). Wavelet phase coherence did not change throughout the experiment (P = NS). Conclusions Cerebral haemodynamics seem to be relatively stable during short exposure to normobaric hypoxia. Hypoxia attenuates heart-generated BP SAS coupling.