title: Effects of acute hypercapnia on the amplitude of cerebrovascular pulsation in humans registered with a non-invasive method.
abstract: OBJECTIVE
  The aim of the study was to assess non-invasively the effects of acute hypercapnia on the amplitude of cerebrovascular pulsation (CVP) in humans.
  
  
  METHODS
  Experiments were carried out in four male volunteers aged 25, 26, 31 and 49. Changes in blood flow through the pial arteries were induced using two interventions: (A) breathing a gas mixture containing 5% CO(2) for 2 minutes and (B) intravenous administration of 1g acetazolamide. The amplitude of CVP and width of subarachnoid space (SAS) were measured non-invasively using near-infrared transillumination/backscattering sounding (NIR-T/BSS), while cerebral blood flow was assessed by single photon emission computed tomography (SPECT) and mean blood flow velocity in the left anterior cerebral artery by transcranial Doppler.
  
  
  RESULTS
  Inhalation of a gas mixture containing 5% CO(2) evoked an increase in the amplitude of CVP (202.5% ± SE 10.1), normalized number of counts (22.6% ± SE 3.5%) and mean blood flow velocity in the left cerebral anterior artery (37.6%± SE 11.7%), while resistive index decreased (-8.7% ± SE 2.3%) and the width of SAS decreased (-8.0 ± SE 0.45). Acetazolamide also produced an increase in the amplitude of CVP (23.7% ± SE 5.4%), normalized number of counts (7.9% ± SE 1.1%), and mean blood flow velocity in the left cerebral anterior artery (62.8% ± SE 13.7%), while resistive index decreased (-7.9% ± SE 1.7%), and the width of SAS decreased (-13.4% ± SE 3.4%).
  
  
  CONCLUSIONS
  Acute hypercapnia causes an increase in the amplitude of CVP pulsation in humans. NIR-T/BSS allows for non-invasive bedside monitoring of the amplitude of CVP. NIR-T/BSS is consistent with transcranial Doppler and SPECT.
authors.affiliation: Institute of Human Physiology, Faculty of Health Sciences, Medical University of Gdansk, Tuwima Str. 15, 80-210 Gdansk, Poland.
authors.forename: Andrzej F
authors.initials: AF
authors.lastname: Frydrychowski
authors.forename: Magdalena
authors.initials: M
authors.lastname: Wszedybyl-Winklewska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Guminski
authors.forename: Piotr
authors.initials: P
authors.lastname: Lass
authors.forename: Tomasz
authors.initials: T
authors.lastname: Bandurski
authors.forename: Pawel J
authors.initials: PJ
authors.lastname: Winklewski
mesh_terms: D000086:Acetazolamide / Q000008:administration & dosage; D000208:Acute Disease; D000328:Adult; D001783:Blood Flow Velocity; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D006801:Humans; D006935:Hypercapnia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods; D010841:Pia Mater / Q000098:blood supply*; D011044:Poland; D011237:Predictive Value of Tests; D011673:Pulsatile Flow / Q000187:drug effects; D012039:Regional Blood Flow; D012542:Scattering, Radiation; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014172:Transillumination / Q000379:methods*; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D000086:Acetazolamide