CO2 / VMR tests

The amount of blood supplied to the brain is regulated by changing the resistance in the arterioles of the brain. The remarkable vasomotor reaction of the blood circulation to changes of the arterial CO2 value has been known for many years due to examinations with indicator methods. The first examination virtually delivered the same results as previous CBF (cerebral blood flow velocity) examinations. To this examination, the TCD method was applied to determine the vasomotor reactivity in a normal state of health. Since then, Doppler has established itself as an instrument to determine the vasomotor reactivity and reserve. The most common vasomotor reactivity tests are included in this software.


The non-invasive determination of cerebral autoregulation is useful in developing strategies for its improvement. In addition, it can help control the intracranial pressure (ICP) and maintain optimum cerebral blood circulation.

The applications of the CO2/VMR test include:

  • Assessment of the haemodynamic relevance of stenoses of the carotid artery
  • Asymptomatic extracranial stenoses
  • Pre-operative and post-operative carotid endarterectomy
  • Symptomatic regulation problems
  • Determination of the cerebral reserve capacity