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Cerebral blood velocity dynamics during inspiratory resistance breathing
Author(s) -
Rickards Caroline Alice,
Ryan Kathy L,
HinojosaLaborde Carmen,
Convertino Victor A,
Lurie Keith G
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1024.2
We tested the hypothesis that the observed delay in presyncopal symptoms with inspiratory resistance breathing during exposure to central hypovolemia would be associated with characteristics of cerebral blood velocity (CBV) oscillations that may improve cerebral perfusion. Nine healthy human subjects were exposed to lower body negative pressure (LBNP) while breathing through either a sham (0 cm.H 2 O) or active (7 cm.H 2 O) inspiratory threshold device (ITD). CBV was measured via transcranial Doppler. Time domain characteristics of each oscillation were calculated for each condition for the same 3‐min period of LBNP. Active ITD breathing increased the amplitude (P=0.01), duration (P=0.02) and slope of upstroke (P=0.09) of CBV oscillations compared with sham ITD breathing (Table); minimum and maximum velocities were statistically indistinguishable (P≥0.10). These CBV characteristics, in the presence of delayed presyncopal symptoms, may reflect improved cerebral perfusion by 1) increasing sheer stress on cerebral vessels, promoting vasodilation and flow, and 2) increasing time for delivery of blood and oxygen to cerebral tissues.