Clinical Physiology of Circulation

Chief Editor

Leo A. Bockeria, MD, PhD, DSc, Professor, Academician of Russian Academy of Sciences, President of Bakoulev National Medical Research Center for Cardiovascular Surgery


Influence of hypercapnia on system and cerebral hemodynamics in healthy patients

Authors: Shumilina M.V., Strelkova T.V.

Company:
A.N. Bakoulev Scientific Center for Cardiovascular Surgery, Rublevskoe shosse, 135, Moscow, 121552, Russian Federation

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Link: Clinical Physiology of Blood Circulaiton. 2014; (): -

Quote as: Shumilina M.V., Strelkova T.V. Influence of hyper- capnia on system and cerebral hemodynamics in healthy patients. Klinicheskaya Fiziologiya Krovoobrashcheniya. 2014; 4: 33-39.

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Abstract

Objective – to examine the influence of hypercapnia on system and cerebral hemodynamics in healthy patients.
Material and methods. Structure of the study included 30 healthy volunteers. Complex ultrasound research of brachio- cephalic vessels was made all patients. Device “Carbonic” provided the level of 6% CO2 in the alveolar air. Transcranial Doppler was used to assess the blood flow velocity in the MCA in rest and at the peak of hypercapnia. Arterial and venous blood pressure (ABP, VBP), heart rate (HR) were assessed noninvasively in rest and at peak of hypercapnia. Reactivity coefficient ABP, VBP, HR per 1 mm Hg increase in CO2, reactivity index for peak systolic, averaged on time and end-dias- tolic blood flow velocity (BFV) per 1 mm Hg increase in CO2, vasodilation reserve index per 1% increase in CO2 for pul- satility, systolic-diastolic indexes and index resistance were calculated by the corresponding formulas.
Results. Reactivity coefficient ABP was from -0,32 to 0,61, HR – from -0,60 to 1,40, BBP – from -0,65 to 0,32 per 1 mm Hg increase in CO2. Changes in ABP, HR, VBP during CO2 reactivity testing are statistic non-significantly (p > 0,05). Reactivity index for peak systolic, time averaged mean velocity and end-diastolic BFV in healthy patients was ≥1,4, ≥1,6 and ≥2,1 per 1 mm Hg respectively. Vasodilation reserve index for resistance index, systolic-diastolic index and pulsatility index on 1% increase in CO2 was ≤ -2,4, ≤ -3,2, ≤ -5,3 respectively. Changes in systolic, time averaged mean and diastolic BFV and peripheral resistance indexes in healthy patients during CO2 reactivity testing increased statistically significant (p < 0,01).
Conclusion. Negative subjective feelings and significant changes of objective indicators of system haemodynamics (AD, VD, HR) at healthy patients in during CO2 reactivity testing don't occur. Increase end-diastolic velocity is the most sensitive because of not less than 1.5 times more growth peak systolic velocity and, therefore, diagnostically more valuable when determining the true CVR. The most significant changes affected pulsatility (index Gosling), systolic-diastolic indexes, less pronounced – the index of the circulatory resistance (index of Pourcelot).

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