Effect of Maximal Apnoea Easy-Going and Struggle Phases on Subarachnoid Width and Pial Artery Pulsation in Elite Breath-Hold Divers

PLoS One. 2015 Aug 18;10(8):e0135429. doi: 10.1371/journal.pone.0135429. eCollection 2015.

Abstract

Purpose: The aim of the study was to assess changes in subarachnoid space width (sas-TQ), the marker of intracranial pressure (ICP), pial artery pulsation (cc-TQ) and cardiac contribution to blood pressure (BP), cerebral blood flow velocity (CBFV) and cc-TQ oscillations throughout the maximal breath hold in elite apnoea divers. Non-invasive assessment of sas-TQ and cc-TQ became possible due to recently developed method based on infrared radiation, called near-infrared transillumination/backscattering sounding (NIR-T/BSS).

Methods: The experimental group consisted of seven breath-hold divers (six men). During testing, each participant performed a single maximal end-inspiratory breath hold. Apnoea consisted of the easy-going and struggle phases (characterised by involuntary breathing movements (IBMs)). Heart rate (HR) was determined using a standard ECG. BP was assessed using the photoplethysmography method. SaO2 was monitored continuously with pulse oximetry. A pneumatic chest belt was used to register thoracic and abdominal movements. Cerebral blood flow velocity (CBFV) was estimated by a 2-MHz transcranial Doppler ultrasonic probe. sas-TQ and cc-TQ were measured using NIR-T/BSS. Wavelet transform analysis was performed to assess cardiac contribution to BP, CBFV and cc-TQ oscillations.

Results: Mean BP and CBFV increased compared to baseline at the end of the easy phase and were further augmented by IBMs. cc-TQ increased compared to baseline at the end of the easy phase and remained stable during the IBMs. HR did not change significantly throughout the apnoea, although a trend toward a decrease during the easy phase and recovery during the IBMs was visible. Amplitudes of BP, CBFV and cc-TQ were augmented. sas-TQ and SaO2 decreased at the easy phase of apnoea and further decreased during the IBMs.

Conclusions: Apnoea increases intracranial pressure and pial artery pulsation. Pial artery pulsation seems to be stabilised by the IBMs. Cardiac contribution to BP, CBFV and cc-TQ oscillations does not change throughout the apnoea.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Apnea*
  • Blood Flow Velocity / physiology*
  • Blood Pressure
  • Breath Holding
  • Case-Control Studies
  • Cerebral Arteries / physiology*
  • Cerebrovascular Circulation / physiology*
  • Female
  • Healthy Volunteers
  • Heart Rate
  • Humans
  • Male
  • Subarachnoid Space / physiology*
  • Wavelet Analysis

Grant support

The study was conducted as a part of the PHYPODE Marie Curie Initial Training Networks (FP7-PEOPLE-2010-ITN) and received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FRP/2007-2013/ under the Research Executive Agency grant agreement [grant number 264816]. Funding came also from the University of Split, Medical University of Gdansk and NIRT sp. z o. o., Wierzbice, Poland. The Croatian Science Foundation supported Zeljko Dujic, Otto Barak and Ivan Drvis. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.