CO2 cerebrovascular reactivity as a function of perfusion pressure--a modelling study

Area of Science:

• Neuroscience
• Biomedical Engineering
• Physiology

Background:

• Cerebral autoregulation is crucial for maintaining stable cerebral blood flow (CBF) despite fluctuations in cerebral perfusion pressure (CPP).
• Understanding the dynamic properties of cerebrovascular resistance and compliance is essential for diagnosing and managing neurological conditions.

Purpose of the Study:

• To develop a mathematical model characterizing cerebral vascular resistance and compliance as functions of CPP and PaCO2.
• To utilize the model for differentiating normal and impaired cerebral autoregulation.
• To analyze dynamic cerebrovascular properties and CBF reactivity to CO2.

Main Methods:

• Development of a mathematical model integrating CPP, PaCO2, cerebral vascular resistance, and compliance.
• Analysis of dynamic properties of cerebrovascular circulation using CBF waveform and CPP relationships.
• Application of the model to interpret interhemispheric asymmetry of CBF reactivity in patients with carotid artery stenosis.

Main Results:

• The model demonstrated hypercapnia-induced shifts in the lower limit of autoregulation, aiding in distinguishing normal from impaired autoregulation.
• Dynamic cerebrovascular properties, such as pulsatility index dependence on autoregulatory reserve, were analyzed at varying PaCO2 levels.
• The model successfully interpreted interhemispheric CBF reactivity asymmetry in patients with carotid artery stenosis.

Conclusions:

• The developed mathematical model provides a valuable tool for assessing cerebral autoregulation and cerebrovascular dynamics.
• The model's ability to differentiate autoregulation states and interpret CO2 reactivity has significant clinical and research implications.
• Further application of this model can enhance understanding of cerebrovascular pathophysiology in various neurological conditions.