Linked Life Data

16306163

Source:http://linkedlifedata.com/resource/pubmed/id/16306163

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2006-3-15
pubmed:abstractText
Reductions in end-tidal Pco(2) (Pet(CO(2))) during upright posture have been suggested to be the result of hyperventilation and the cause of decreases in cerebral blood flow (CBF). The goal of this study was to determine whether decreases in Pet(CO(2)) reflected decreases in arterial Pco(2) (Pa(CO(2))) and their relation to increases in alveolar ventilation (Va) and decreases in CBF. Fifteen healthy subjects (10 women and 5 men) were subjected to a 10-min head-up tilt (HUT) protocol. Pa(CO(2)), Va, and cerebral flow velocity (CFV) in the middle and anterior cerebral arteries were examined. In 12 subjects who completed the protocol, reductions in Pet(CO(2)) and Pa(CO(2)) (-1.7 +/- 0.5 and -1.1 +/- 0.4 mmHg, P < 0.05) during minute 1 of HUT were associated with a significant increase in Va (+0.7 +/- 0.3 l/min, P < 0.05). However, further decreases in Pa(CO(2)) (-0.5 +/- 0.5 mmHg, P < 0.05), from minute 1 to the last minute of HUT, occurred even though Va did not change significantly (-0.2 +/- 0.3 l/min, P = not significant). Similarly, CFV in the middle and anterior cerebral arteries decreased (-7 +/- 2 and -8 +/- 2%, P < 0.05) from minute 1 to the last minute of HUT, despite minimal changes in Pa(CO(2)). These data suggest that decreases in Pet(CO(2)) and Pa(CO(2)) during upright posture are not solely due to increased Va but could be due to ventilation-perfusion mismatch or a redistribution of CO(2) stores. Furthermore, the reduction in Pa(CO(2)) did not fully explain the decrease in CFV throughout HUT. These data suggest that factors in addition to a reduction in Pa(CO(2)) play a role in the CBF response to orthostatic stress.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0363-6119
pubmed:author
pubmed:issnType
Print
pubmed:volume
290
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
R1087-93
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Cerebral blood flow during orthostasis: role of arterial CO2.
pubmed:affiliation
Division on Aging, Harvard Medical School, Beth Israel Deaconess Medical Center, One Deaconess Rd., Palmer 117, Boston, MA 02215, USA. serrador@hms.harvard.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't