TY - JOUR
T1 - Effect of ventilation on cerebral oxygenation during exercise
T2 - Insights from canonical correlation
AU - Heine, Martin
AU - Subudhi, Andrew W.
AU - Roach, Robert C.
N1 - Funding Information:
The authors express their gratitude to Brittany Miramon and Matthew Granger for their managerial and technical assistance during data collection. This project was funded in part by National Heart, Lung and Blood Institute Grant HL-070362.
PY - 2009/4/30
Y1 - 2009/4/30
N2 - We tested hypothesis that cerebral deoxygenation near maximal exercise intensity is mediated by hyperventilation, via hypocapnia-induced reductions in cerebral blood flow, by utilizing canonical correlation analysis (CCA) to determine the relative influence of cardiopulmonary changes on cerebral oxygenation, as assessed by near infrared spectroscopy (NIRS). Twenty-three subjects performed incremental exercise tests under normoxic and hypoxic conditions. Changes in ventilation (over(V, ̇)E) were strongly correlated with end-tidal CO2 (PE TC O2) and NIRS after the respiratory compensation point (RCP) (r2 > 0.97). However, in contrast to our expectations, CBF velocity (CBFv) shared the least amount of variance with NIRS measurements (r2 < 0.56) and the reduction in CBFv was not accompanied by a reduction in cerebral blood volume. These results demonstrate that while cerebral deoxygenation was associated with hyperventilation, it was not solely explained by hypocapnia-induced reductions in CBFv. CCA revealed that a relative increase in the venous contribution to NIRS explained a larger amount of variation in cerebral oxygenation than reductions CBFv.
AB - We tested hypothesis that cerebral deoxygenation near maximal exercise intensity is mediated by hyperventilation, via hypocapnia-induced reductions in cerebral blood flow, by utilizing canonical correlation analysis (CCA) to determine the relative influence of cardiopulmonary changes on cerebral oxygenation, as assessed by near infrared spectroscopy (NIRS). Twenty-three subjects performed incremental exercise tests under normoxic and hypoxic conditions. Changes in ventilation (over(V, ̇)E) were strongly correlated with end-tidal CO2 (PE TC O2) and NIRS after the respiratory compensation point (RCP) (r2 > 0.97). However, in contrast to our expectations, CBF velocity (CBFv) shared the least amount of variance with NIRS measurements (r2 < 0.56) and the reduction in CBFv was not accompanied by a reduction in cerebral blood volume. These results demonstrate that while cerebral deoxygenation was associated with hyperventilation, it was not solely explained by hypocapnia-induced reductions in CBFv. CCA revealed that a relative increase in the venous contribution to NIRS explained a larger amount of variation in cerebral oxygenation than reductions CBFv.
KW - Cerebral blood flow
KW - Hypoxia
KW - Near infrared spectroscopy
KW - Transcranial Doppler
UR - http://www.scopus.com/inward/record.url?scp=63449137167&partnerID=8YFLogxK
U2 - 10.1016/j.resp.2009.02.013
DO - 10.1016/j.resp.2009.02.013
M3 - Article
C2 - 19429529
AN - SCOPUS:63449137167
SN - 1569-9048
VL - 166
SP - 125
EP - 128
JO - Respiratory Physiology and Neurobiology
JF - Respiratory Physiology and Neurobiology
IS - 2
ER -