Effects of voluntary neck extension on cerebral blood flow, in breath-hold divers ending an apnoea of two minutes or more
Par : Cariou, Simon
Document archivé le : 04/01/2018
Diving in apnoea, some blackouts have been described when divers realised neck extension. The main objective of this study is to search a potential implication of the neck extension into the decrease of cerebral blood perfusion, by showing a significant difference of this perfusion between pre and post neck-extension, at apnoea breaking on free divers. Methods : healthy male free divers, who regularly practice apnoea or spearfishing, were included in this study. They all had to perform an apnoea of two minutes or more, out of water, with cooled wet strips on the face. It was measuring by Doppler ultrasonography the variation in the pulsatility index of the right internal carotid artery (RICPI), by the intra-individual comparison of post neck-extension values versus pre neck-extension values. The main decision criterion was a pulsatility index of the right internal carotid artery increased by a factor of two. Results : fifteen trained free divers were included. The minimal apnoea duration observed was 2 minutes 20 seconds. Variations of pulsatility index averages were analysed by a matched Wilcoxon test. Post neck-extension RICPI average was increased by a factor 1,61 (p<0,0001), compared with pre-extension average, and still increases after ventilatory recovery. During an apnoea, a neck extension can produce a decrease of cerebral blood perfusion. Conclusion : breath-hold blackout during free dive seems to be plurifactorial, and a gesture as simple as neck extension should be considered as dangerous during apnoea breaking.
17NANT200M
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