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Early detection of diving-related cognitive impairment of different nitrogen-oxygen gas mixtures using critical flicker fusion frequency.
- Source :
- Diving & Hyperbaric Medicine: Journal of the South Pacific Underwater Medicine Society; Jun2019, Vol. 49 Issue 2, p119-126, 8p
- Publication Year :
- 2019
-
Abstract
- Introduction: Cognitive impairment related to inert gas narcosis (IGN) is a threat to diving safety and operations at depth that might be reduced by using enriched air nitrox (EANx) mixtures. Using critical flicker fusion frequency (CFFF), a possible early detection of cognitive abilities/cerebral arousal impairment when breathing different oxygen (O2) fractions was investigated. Methods: Eight male volunteers performed, in random order, two dry chamber dives breathing either air or EANx40 (40% O2-60% nitrogen) for 20 minutes (min) at 0.4 MPa. Cognition and arousal were assessed before the dive; upon arrival at 0.4 MPa; after 15 min exposure at 0.4 MPa; on surfacing and 30 min post-dive using behavioural computer-based testing psychology experiment building language (PEBL) and by CFFF while continuously recording brain oxygenation with near-infrared spectroscopy. Results: In both breathing conditions, CFFF and PEBL demonstrated a significant inverse correlation (Pearson r of -0.90, P < 0.0001), improved cognitive abilities/cerebral arousal occurred upon arrival at 0.4 MPa followed by a progressive deterioration. Initial brain activation was associated with a significant increase in oxyhaemoglobin (HbO2) and a simultaneous decrease of deoxyhaemoglobin (HHb). The magnitude of the changes was significantly greater under EANx (P = 0.038). Conclusions: Since changes were not related to haemodynamic variables, HbO2 and HHb values indicate a significant, O2-dependent activation in the prefrontal cortex. Owing to the correlation with some tests from the PEBL, CFFF could be a convenient measure of cognitive performance/ability in extreme environments, likely under the direct influence of oxygen partial pressure, a potent modulator of IGN symptoms. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 18333516
- Volume :
- 49
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Diving & Hyperbaric Medicine: Journal of the South Pacific Underwater Medicine Society
- Publication Type :
- Academic Journal
- Accession number :
- 137837037
- Full Text :
- https://doi.org/10.28920/dhm49.2.119-126.PMID:31177518