Linked Life Data

14574578

Source:http://linkedlifedata.com/resource/pubmed/id/14574578

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2-3
pubmed:dateCreated
2004-3-1
pubmed:abstractText
Gravity places considerable stress on the cardiovascular system but cerebral autoregulation usually protects the cerebral blood vessels from fluctuations in blood pressure. However, in conditions such as those encountered on board a high-performance aircraft, the gravitational stress is constantly changing and might compromise cerebral autoregulation. In this study we assessed the effect of oscillating orthostatic stress on cerebral autoregulation. Sixteen (eight male) healthy subjects [aged 27 (1) years] were exposed to steady-state lower body negative pressure (LBNP) at -15 and -40 mmHg and then to oscillating LBNP at the same pressures. The oscillatory LBNP was applied at 0.1 and 0.2 Hz. We made continuous recordings of RR-interval, blood pressure, cerebral blood flow velocity (CBFV), respiratory frequency and end-tidal CO(2). Oscillations in mean arterial pressure (MAP) and CBFV were assessed by autoregressive spectral analysis. Respiration was paced at 0.25 Hz to avoid interference from breathing. Steady-state LBNP at -40 mmHg significantly increased low-frequency (LF, 0.03-0.14 Hz) powers of MAP ( P<0.01) but not of CBFV. Oscillatory 0.1 Hz LBNP (0 to -40 mmHg) significantly increased the LF power of MAP to a similar level as steady-state LBNP but also resulted in a significant increase in the LF power of CBFV ( P<0.01). Oscillatory LBNP at 0.2 Hz induced oscillations in MAP and CBFV at 0.2 Hz. Cross-spectral analysis showed that the transfer of LBNP-induced oscillations in MAP onto the CBFV was significantly greater at 0.2 Hz than at 0.1 Hz ( P<0.01). These results show that the ability of the cerebral vessels to modulate fluctuations in blood pressure is compromised during oscillatory compared with constant gravitational stress. Furthermore, this effect seems to be more pronounced at higher frequencies of oscillatory stress.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1439-6319
pubmed:author
pubmed:issnType
Print
pubmed:volume
91
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
279-86
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Cerebral autoregulation is compromised during simulated fluctuations in gravitational stress.
pubmed:affiliation
Autonomic Laboratory, Dept. of Neurology, University of Erlangen-Nuremberg, Germany. CliveBrown750@hotmail.com
pubmed:publicationType
Journal Article, Clinical Trial