METHOD FOR ASSESSING CEREBROVASCULAR RESPONSIVENESS Russian patent published in 2014 - IPC A61B8/06 

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to neurology, cardiology, neurosurgery and angiosurgery, and may be used if it is required to assess the cerebrovascular responsiveness. That is ensured by a transcranial Doppler sonography with the insonated segment M₁ of medial cerebral arteries (MCA) and assessment of a hypercapnic gain of a time-average maximum blood velocity (TAMX) in the MCA per a unit of a partial carbon dioxide in alveolar air (PetCO₂). A recording procedure uses a capnograph. A maximum TAMX is recorded for first 30 seconds of the hypercapnic test within the PetCO₂ gain by no more than 11 mmHg. A systemic blood pressure (BP) remains constant. A BP-independent cerebrovascular hypercapnia responsiveness index (BPI RI_CO2) is calculated by formula: $$BPI{\text{ RI}}_{\text{CO2}}=\frac{(TAM{X}_{hyper}-TAM{X}_{norm})/TAM{X}_{norm}}{PetC{O}_{2hyper}-PetC{O}_{2norm}}\ast 100\%,$$ wherein TAMX_norm is a time-average maximum blood velocity in normocapnia; TAMX_hyper is a time-average maximum blood velocity in hypercapnia at the moment of PetCO_2hyper measurement; PetCO_2norm is a partial CO₂ pressure in alveolar air in normocapnia; PetCO_2hyper is a partial CO₂ pressure in alveolar air in hypercapnia, but not exceeding PetCO_2norm by no more than 11 mmHg. If the value BPI RI_CO2 falls within the range of 1.1-3.2% by 1 mmHg, then PetCO₂ cerebrovascular responsiveness is considered to be normal.

EFFECT: method provides high information value and accuracy ensured by prevented misinterpretation of the hypercapnic test considering the effect of the systemic BP gain on the cerebral blood flow, and respectively enables assessing the actual cerebrovascular responsiveness independent from the systemic blood pressure and reflecting the intensification of the cerebral blood flow in hypercapnia as a manifestation of the vasodilating effect of CO₂.

2 dwg, 1 ex