Interindividual relationships between blood pressure and cerebral blood flow variability (1184.11)

Abstract

The relationships between blood pressure variability (BPV) and cerebral blood flow variability (CFV) are poorly understood. This study sought to characterize the interindividual characteristics between spontaneous BPV and CFV across individuals with intact cerebrovascular control. We analyzed blood pressure and flow velocity data from 105 healthy subjects. Spontaneously occurring fluctuations in mean arterial blood pressure (MAP) and middle cerebral artery flow velocity (MCAvmean; Transcranial Doppler ultrasound) were characterized using power spectral and transfer function analysis in the very low‐ (0.02‐0.07 Hz), low‐ (0.07‐0.20 Hz), and high‐frequency (0.20‐0.40 Hz) ranges. Across our study sample, MAP was a positive predictor of MCAvmean to varying degrees in all three frequency ranges (Very Low Frequency (R2= 0.088, P< 0.01) Low Frequency (R2= 0.47, P< 0.01), High Frequency (R2 = 0.55, P< 0.01)). The increased predictive power of MAP for MCAvmean in higher frequencies demonstrates that BPV is a determinant of CFV. However, factors other than BPV are influential, especially in the very low frequencies. These results demonstrate that intermittent blood pressure, a clinical measurement predominantly representative of very low frequency BPV content, is an inadequate surrogate of cerebral perfusion variability.