Table 1.
Summary of relevant physiological values for many cerebrovascular reactivity imaging protocols. Cerebral hemo-metabolic (Derdeyn et al., 2002; Donahue et al., 2017a; Leenders et al., 1990) and gas exchange values (Guyton, 1977) are based on approximate literature ranges.
| Parameter | Units | Typical range |
|---|---|---|
| Hemodynamic and metabolic parameters | ||
| Cerebral blood flow | ml blood / 100g tissue / min | 35 – 60 (gray matter) 17 – 28 (white matter) |
| Cerebral blood volume | ml blood/100g tissue | 3.5 – 6.6 (gray matter) 2.1 – 3.0 (white matter) |
| Cerebral metabolic rate of oxygen | ml O2 / 100g tissue / min | 2.8 – 5.0 (gray matter) 1.2 – 1.7 (white matter) |
| Oxygen extraction fraction | (O2 consumed/ O2 delivered; unitless) | 0.35 – 0.44 (gray matter) 0.31 – 0.42 (white matter) |
| Parameters relevant to gas tension experiments | ||
| Partial pressure of carbon dioxide in arterial blood (PaCO2) | mmHg | 35 – 45 |
| Partial pressure of oxygen in arterial blood PaO2 | mmHg | 75–100 |
| Partial pressure of carbon dioxide in venous blood (PvCO2) | mmHg | 40–50 |
| Partial pressure of oxygen in venous blood (PvCO2) | mmHg | 30 – 40 |
| End-tidal CO2 (EtCO2) | mmHg | 35 – 45 |
| Blood pH | −log[H+] (unitless) | 7.34 – 7.44 |
| Tissue pH | −log[H+] (unitless) | 7.0 – 7.1 |
| Partial pressures of respiratory gases as they enter and leave the lungs (total pressure 760 mmHg) | ||
| Atmospheric air: N2/O2/CO2/H2O | mmHg | 597.0 / 159.0 / 0.3 / 3.7 |
| Humidified air: N2/O2/CO2/H2O | mmHg | 563.4 / 149.3 / 0.3 / 47.0 |
| Alveolar air: N2/O2/CO2/H2O | mmHg | 569.0 / 104.0 / 40.0 / 47.0 |
| Expired air: N2/O2/CO2/H2O | mmHg | 566.0 / 120.0 / 27.0 / 47.0 |
| Other parameters relevant to reactivity experiments | ||
| Pressure at sea level | mmHg | 760 |
| Room air composition | Percent by volume | 78.1 (Nitrogen) / 20.9 (Oxygen). CO2 = 0.03 |
| Hematocrit | Percent | 40 – 52% (male); 37 – 46% (female) |
| Hemoglobin | g/dL | 13.2 – 6.2 (male) 12.0 – 15.2 g/dL (female) |