Pierre Lafère1,2,3,4, Walter Hemelryck1,3, Peter Germonpré1,5, Lyubisa Matity6, François Guerrero1,2, Costantino Balestra1,3,7,8,9. 1. DAN Europe Research Division, Roseto, Italy. 2. Laboratoire ORPHY, EA 4324, UFR sciences et techniques, Université de Bretagne Occidentale, Brest, France. 3. Environmental, Occupational, Ageing (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), Brussels, Belgium. 4. Corresponding author: Pierre Lafère, Laboratoire ORPHY, EA 4324, UFR sciences et techniques, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu - CS 93837, 29238 Brest Cedex 3, France, doc.lafere@sfr.fr. 5. Centre for Hyperbaric Oxygen Therapy, Military Hospital 'Queen Astrid', Brussels. 6. Hyperbaric Unit, Mater Dei Hospital, Msida, Malta. 7. Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel (V.U.B.), Brussels. 8. Anatomical Research Training and Education (ARTE), Vrije Universiteit Brussel (V.U.B.). 9. Motor Sciences, Université Libre De Bruxelles (U.L.B.), Brussels.
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. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.
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. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.
Authors: Walter Hemelryck; Miroslav Rozloznik; Peter Germonpré; Costantino Balestra; Pierre Lafère Journal: Diving Hyperb Med Date: 2013-09 Impact factor: 0.887
Authors: Xavier Ce Vrijdag; Hanna van Waart; Jamie W Sleigh; Costantino Balestra; Simon J Mitchell Journal: Diving Hyperb Med Date: 2020-12-20 Impact factor: 0.887