Transcranial Doppler Study of the Cerebral Hemodynamic Changes During Breath-Holding and Hyperventilation Tests

Abstract

The authors concluded that breath-holding and hyperventilation tests seem to be a practical alternative to acetazolamide and the CO2 inhalation method in the assessment of cerebral hemodynamics.

Assessment: Transcranial Doppler ultrasonography: [RETIRED]

“…VMR testing techniques of static (i.e., at rest) or dynamic (i.e., after provocative stimuli) cerebral autoregulation include measuring changes in flow velocities following 1) hemodynamic stimuli (rapid leg cuff deflation, Valsalva maneuver, deep breathing, ergometric exercise, head-down tilting, orthostasis and lower body negative pressure, beat-tobeat spontaneous transient pressor and depressor changes in mean arterial pressure), 2) CO 2 inhalation (hypercapnia/hyperventilation hypocapnia), 3) the breath-holding index (BHI), 4) acetazolamide injection, and 5) the transient hyperemia response and its variants. [38][39][40][41][42][43][44][45][46] VMR testing techniques with TCD have been used to evaluate patients with symptomatic or asymptomatic extracranial ICA stenosis or occlusion, [38][39][40][41][42][43][44][45] cerebral small-artery disease, head injury, and aneurysmal subarachnoid hemorrhage (SAH). 46 Although TCD may detect abnormalities of cerebral hemodynamics (increased or decreased pulsatility) in patients with risk factors for or symptoms of cerebrovascular disease, 39 the value of TCD evaluation of cerebral hemodynamic impairment and stroke risk has recently been questioned.…”

Cigarette smoking and cerebral microvasculature in patients with type 1 diabetes: a pilot study

“…Velocity measurements were performed simultaneously in both MCA by one well-trained ultrasonographer (GK) using a two-channel monitoring kit: two probes at 2 MHz PW, a fixation band and a monitoring programme (MF version 8.27 L, DWL). The physiological technique of provoking cerebrovascular reactivity by changes in pCO 2 was applied according to the published standards [18][19]. During the CO 2 reactivity test, the CO 2 content in expired air (end-tidal CO 2 concentration) was monitored continuously (capnograph Datex Normocap, Helsinki, Finland).…”

“…Before and after the tests, the systemic blood pressure was measured. The vasomotor reactivity reserve expressed as a percent change from baseline was calculated according to a standard protocol published previously [18][19].…”

Holotropic Breathwork: The Potential Role of a Prolonged, Voluntary Hyperventilation Procedure as an Adjunct to Psychotherapy

“…[8][9][10][11] Hypocapnia caused by hyperventilation has been demonstrated to induce changes in a range of neurophysiologic measures, including resting 12 and evoked 13,14 electroencephalographic (EEG) as well as magnetoencephelographic (MEG) 13,15 potentials, along with functional neuroimaging 16 and cerebral hemodynamics. 17 Briefly, resting EEG in hyperventilation has demonstrated slowing of brain activation rhythms across the brain, with substantial increases in lower frequency, ␦-(up to 4 Hz) and -(4-8 Hz) activity. 12 Visually evoked potentials have been shown to be altered by voluntary hyperventilation, with increases in ␥-band (30-45 Hz) responses to visual stimuli.…”

“…16 Cerebral hemodynamic measurement has shown that within 20-30 seconds of voluntary hyperventilation, blood flow velocity decreases in cerebral arteries, along with increases in capillary pH, PO 2 , and oxygen saturation. 17 Unsurprisingly, given the extent of the neurophysiologic changes just summarized, hyperventilation also has been shown to cause cognitive changes, 18 and when prolonged, to induce subjectively altered consciousness that corresponds temporally with the neurophysiologic changes. 19,20 Manifestations of altered consciousness emerging after approximately 8 minutes of hyperventilation have included ringing/roaring in the ears, clouded vision, and feelings of lightness, astonishment, and/or euphoria.…”