Volumetric Carotid Flow Characteristics in Doppler Ultrasonography in Healthy Population Over 65 Years Old

Background: Carotid flow velocity criteria are well established, with age being a factor influencing measurements. However, there are no volumetric standards for the flow in extracranial arteries. The aim of the study was related to volumetric flow assessment of extracranial arteries in a healthy population >65 years old. Methods: Doppler volumetric measurements of internal carotid (ICA), external carotid (ECA) and vertebral arteries (VA) were performed in 123 healthy volunteers >65 years old and compared with 56 healthy volunteers <65 years old. Results: The continuous decline in cerebral blood flow (CBF) volume was observed (p < 0.00001). Volumetric reference values were established in study groups: 1., 65–69 years: 898.5 ± 119.1; 2., 70–74 years: 838.5 ± 148.9; 3., 75–79 years: 805.1 ± 99.3; 4., >80 years: 685.7 ± 112.3 (mL/min). Significant differences were observed between groups: 1 and 3.4, as well as 3 and 4 (p = 0.0295, < 0.000001, 0.00446 respectively). CBF volume decreases gradually with age: 28–64 years—6.2 mL/year (p = 0.0019), 65–75 years—11.4 mL/year (p = 0.0121) and >75 years—14.3 mL/year (p = 0.0074). This is a consequence of flow volume decline in ICA (p = 0.00001) and to lesser extent ECA (p = 0.0011). The decrease of peak systolic (p = 0.002) and end diastolic (p = < 0.00001) velocities in ICA and peak systolic velocity in ECA (p = 0.0017) were observed. Conclusions: CBF decreases with ageing. Volumetric assessment of CBF may play an important additional role in diagnostics of patients with carotid stenosis. Doppler assessment of cerebral flow volume may create an interesting tool for identifying patients with diminished cerebrovascular reserve and higher risk of ischemic symptoms occurrence.