Synchronization between arterial blood pressure and cerebral oxyhaemoglobin concentration investigated by wavelet cross-correlation

• Published in: Physiological measurement Vol. 28; no. 2; pp. 161 - 173
• Main Authors: Rowley, A B, Payne, S J, Tachtsidis, I, Ebden, M J, Whiteley, J P, Gavaghan, D J, Tarassenko, L, Smith, M, Elwell, C E, Delpy, D T
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 01.02.2007
• Subjects: Adult; Aged; Algorithms; Autonomic Nervous System Diseases - metabolism; Autonomic Nervous System Diseases - physiopathology; Blood Pressure - physiology; Brain Chemistry - physiology; Data Interpretation, Statistical; Female; Homeostasis - physiology; Humans; Male; Middle Aged; Oxyhemoglobins - analysis; Plethysmography; Spectroscopy, Near-Infrared; Supine Position - physiology; Tilt-Table Test
• ISSN: 0967-3334; 1361-6579
• DOI: 10.1088/0967-3334/28/2/005

Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O(2)Hb) and mean arterial blood pressure (MAP) in patients suffering from autonomic failure and age-matched controls. Statistically significant differences are found in the wavelet scale of maximum cross-correlation upon posture change in patients, but not in controls. We propose that WCC analysis of the relationship between O(2)Hb and MAP provides a useful method of investigating the dynamics of cerebral autoregulation using the spontaneous low-frequency oscillations that are typically observed in both variables without having to make the assumption of stationarity of the time series. It is suggested that for a short-duration clinical test previous transfer-function-based approaches to analyse this relationship may suffer due to the inherent nonstationarity of low-frequency oscillations that are observed in the resting brain.