NCT03210857

Effects of Voluntary Neck Extension on Cerebral Blood Flow, in Breath-hold Divers Ending an Apnoea of Two Minutes or More.

Effect of Voluntary Neck Extension in the Occurrence of an Increase in the Pulsatility Index of Right Internal Carotid Artery in the Amateur Diver, Performing an Apnoea of Two Minutes or More: a Prospective, Monocentric, Open Interventional Study

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 15 (actual)
• Sponsor: Nantes University Hospital · Academic / Other
• Sex: Male
• Age: 18 Years – 51 Years
• Healthy volunteers: Accepted

Summary

The aim of this study is to demonstrate the effect of the voluntary neck extension in the occurrence of an increase in the pulsatility index of the right internal carotid artery in the amateur diver, realizing an apnea of two minutes or more.

Detailed description

In literature concerning apnoea, accidents have been described during neck extension. Accidental drowning are frequent on the French coast every year and many of them concern apneists victims of apnoeic blackout. Neck extension is thus suspected to possibly produce an apnoeic blackout at the end of the dive since 1965, when Sir Sciarli (diving medicine pioneer) suspected this hypothesis. Physiologically, during a dive in apnea, the human cardiovascular system is subjected to a parasympathetic dominance, via the apnea reflex and the diving reflex. This parasympathetic dominant could be reinforced during a neck extension at the end of snorkeling during the ascent. Hypothesis: the neck extension at the end of apnea contributes to increase the pulsatility index of the right internal carotid artery by vagal component and thus causes a decrease in cerebral blood flow and may lead to the initiation of syncope in the healthy amateur free diver or underwater fisherman.

Conditions

• Healthy Amateur Divers

Interventions

Type	Name	Description
OTHER	apnea performing	The included subjects will make an apnea of two minutes or more, sitting on a chair with cold strips on the face, initially with the head in neutral position. Then, when they feel the end of their apnea, they will have to raise their left hand to signal it to the Doppler manipulator, who will then realize the apnea reference measurement. As soon as this is done, the subjects will be asked to perform an extension of the neck, so as to look at the ceiling. A final measurement will then be made in apnea, the head always in extension. Subjects then resume their breathing in this same position. A final measurement will then be made.

Timeline

• Start date: 2017-07-10
• Primary completion: 2017-07-24
• Completion: 2017-07-24
• First posted: 2017-07-07
• Last updated: 2017-08-15

Locations

1 site across 1 country: France