Clinical trial NCT03210857: Effects of Voluntary Neck Extension on Cerebral Blood Flow, in Breath-hold Divers Ending an Apnoea of Two Minutes or More.
Official title: 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
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Healthy Amateur Divers
Keywords: apnea
neck extension
syncope
diving blackout
right internal carotid arteria
pulsatility index
healthy trained apnoea divers
doppler ultrasonography
Lead sponsor: Nantes University Hospital
Sponsor class: OTHER
First posted: 2017-07-07
Enrollment: 15
Sex: MALE
Minimum age (years): 18
Maximum age (years): 51
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Intervention model description: Subject will realize an apnea of 2 minutes or more, depending on his abilities, and some parameters will be measured.
Primary purpose: BASIC_SCIENCE

Brief 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.

Eligibility criteria: Inclusion Criteria:

* Major (≥18 years), under the age of 51
* Male
* Can hold an apnea of 2 minutes or more
* Practicing for less than 2 years the apnea at the rate of at least 10 sessions of apnea in the year
* Not having a known cardiovascular history : any form of heart rhythm disorder, Ischemic heart disease, angina, arteriopathy, any valvular pathology, high blood pressure ...
* No known respiratory history (asthma, Chronic Obstructive Pulmonary Disease, bronchiectasis, pulmonary emphysema, pneumothorax, pleurisy, pulmonary infection, lobectomy ...)
* No neurological history of type: epilepsy, deficit syndrome, iterative loss of knowledge, recent head trauma with loss of consciousness

Exclusion Criteria:

* - Minors and persons over 51 years of age
* Person under curators or trusteeship
* Person with a history of cardiovascular, respiratory or epilepsy as cited by the French Federation of Study and Submarine Sports, which poses as a contra-indication to the practice of apnea: Cardiac insufficiency, Obstructive Cardiomyopathy, syncopal risk pathology (valvulopathies type aorting narrowing or mitral narrowing), paroxysmal tachycardia, non-paired auriculo ventricular block 2/3, stroke, uncontrolled hypertension after stress test, recent infarction, angina, pericarditis. Asthma stage 3, severe Chronic Obstructive Pulmonary Disease, bronchiectasis, pulmonary emphysema, pneumothorax, pleurisy, pulmonary infection, lobectomy ...) Epilepsy, deficit syndrome, iterative loss of knowledge, recent head trauma with loss of consciousness in difficulty, symptomatic cervical or lumbar disc herniation
* Patient with medical treatment affecting the cardiovascular or respiratory system (for example: ventolin, betablocker ...)

Primary outcomes:
measure: 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
timeFrame: 2 minutes or more: at the breaking point of apnea.
Secondary outcomes:
Other outcomes:
Locations:
city: Nantes
country: France
facility: Nantes hospital
Study officials:
affiliation: Nantes University Hospital
name: Antoine ANDRE, Doctor
role: PRINCIPAL_INVESTIGATOR
References: