TY - JOUR
T1 - Comparing the effect of hypercapnia and hypoxia on the electroencephalogram during wakefulness
AU - Wang, David
AU - Yee, Brendon J.
AU - Wong, Keith K.
AU - Kim, Jong Won
AU - Dijk, Derk Jan
AU - Duffin, James
AU - Grunstein, Ronald R.
PY - 2015/1/1
Y1 - 2015/1/1
N2 - Objective: Hypoxia has been postulated as a key mechanism for neurocognitive impairment in sleep-disordered breathing. However, the effect of hypoxia on the electroencephalogram (EEG) is not clear. Methods: We examined quantitative EEG recordings from 20 normal volunteers under three 5-min ventilatory control protocols: progressive hypercapnia with iso-hyperoxia (pO2=150mmHg) (Protocol 1), progressive hypercapnia with iso-hypoxia (pO2=50mmHg) (Protocol 2), and progressive hypoxia with a CO2 scrubber in the circuit (Protocol 3). Each protocol started with a 5-min session of breathing room air as baseline. Results: In Protocol 1, compared to its baseline, iso-hyperoxia hypercapnia led to a lower Alpha% and higher Delta/Alpha (D/A) ratio. Similarly, in Protocol 2, the iso-hypoxia hypercapnia induced a higher Delta%, a lower Alpha% and higher D/A ratio. No difference was found in any EEG spectral band including the D/A ratio when Protocols 1 & 2 were compared. In Protocol 3, the Delta%, Alpha% and D/A ratio recorded during hypoxia were not significantly different from baseline. Conclusions: We found that hypercapnia, but not hypoxia, may play a key role in slowing of the EEG in healthy humans. Significance: Hypercapnia may be a greater influence than hypoxia on brain neuroelectrical activities.
AB - Objective: Hypoxia has been postulated as a key mechanism for neurocognitive impairment in sleep-disordered breathing. However, the effect of hypoxia on the electroencephalogram (EEG) is not clear. Methods: We examined quantitative EEG recordings from 20 normal volunteers under three 5-min ventilatory control protocols: progressive hypercapnia with iso-hyperoxia (pO2=150mmHg) (Protocol 1), progressive hypercapnia with iso-hypoxia (pO2=50mmHg) (Protocol 2), and progressive hypoxia with a CO2 scrubber in the circuit (Protocol 3). Each protocol started with a 5-min session of breathing room air as baseline. Results: In Protocol 1, compared to its baseline, iso-hyperoxia hypercapnia led to a lower Alpha% and higher Delta/Alpha (D/A) ratio. Similarly, in Protocol 2, the iso-hypoxia hypercapnia induced a higher Delta%, a lower Alpha% and higher D/A ratio. No difference was found in any EEG spectral band including the D/A ratio when Protocols 1 & 2 were compared. In Protocol 3, the Delta%, Alpha% and D/A ratio recorded during hypoxia were not significantly different from baseline. Conclusions: We found that hypercapnia, but not hypoxia, may play a key role in slowing of the EEG in healthy humans. Significance: Hypercapnia may be a greater influence than hypoxia on brain neuroelectrical activities.
KW - Brain waves
KW - CO
KW - Cortical depression
KW - Daytime sleepiness
KW - EEG spectra
KW - O
UR - http://www.scopus.com/inward/record.url?scp=84917698423&partnerID=8YFLogxK
U2 - 10.1016/j.clinph.2014.04.012
DO - 10.1016/j.clinph.2014.04.012
M3 - Article
C2 - 24875233
AN - SCOPUS:84917698423
SN - 1388-2457
VL - 126
SP - 103
EP - 109
JO - Clinical Neurophysiology
JF - Clinical Neurophysiology
IS - 1
ER -