Muscle oxygen saturation increases during head-up tilt-induced (pre)syncope.

Autor: Lund A; Department of Neuroanaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark., Sørensen H; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark., Jensen TW; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark., Niemann MJ; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark., Olesen ND; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.; Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark., Nielsen HB; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark., Olsen NV; Department of Neuroanaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.; Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark., Secher NH; The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
Jazyk: angličtina
Zdroj: Acta physiologica (Oxford, England) [Acta Physiol (Oxf)] 2017 Sep; Vol. 221 (1), pp. 74-80. Date of Electronic Publication: 2017 Mar 22.
DOI: 10.1111/apha.12863
Abstrakt: Aim: To evaluate whether muscle vasodilatation plays a role for hypotension developed during central hypovolaemia, muscle oxygenation (S m O 2 ) was examined during (pre)syncope induced by head-up tilt (HUT). Skin blood flow (SkBF) and oxygenation (S skin O 2 ) were determined because evaluation of S m O 2 may be affected by superficial tissue oxygenation. Furthermore, we evaluated cerebral oxygenation (S c O 2 ) and middle cerebral artery mean blood flow velocity (MCAv mean ).
Methods: Twenty healthy male volunteers (median age 24 years; range 19-38) were subjected to passive 50° HUT for 1 h or until (pre)syncope. S c O 2 and S m O 2 (near-infrared spectroscopy), MCAv mean (transcranial Doppler) along with mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) (Modelflow ® ) were determined.
Results: (Pre)syncopal symptoms appeared in 17 subjects after 11 min (median; range 2-34) accompanied by a decrease in MAP, SV, CO and TPR, while HR remained elevated. During (pre)syncope, S c O 2 decreased [73% (71-76; mean and 95% CI) to 68% (65-71), P < 0.0001] along with MCAv mean [40 (37-43) to 32 (29-35) cm s -1 , P < 0.0001]. In contrast, S m O 2 increased [63 (56-69)% to 71% (65-78), P < 0.0001], while S skin O 2 [64% (58-69) to 53% (47-58), P < 0.0001] and SkBF [71 (44-98) compared to a baseline of 99 (72-125) units, P = 0.020] were reduced.
Conclusion: We confirm that the decrease in MAP during HUT is associated with a reduction in indices of cerebral perfusion. (Pre)syncope was associated with an increase in S m O 2 despite reduced S skin O 2 and SkBF, supporting that muscle vasodilation plays an important role in the circulatory events leading to hypotension during HUT.
(© 2017 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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