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Rate of change in cerebral oxygenation and blood pressure in response to passive changes in posture: a comparison between pure autonomic failure patients and controls.
- Source :
-
Advances in experimental medicine and biology [Adv Exp Med Biol] 2005; Vol. 566, pp. 187-93. - Publication Year :
- 2005
-
Abstract
- The cardiovascular and cerebrovascular responses to head-up postural change are compromised in pure autonomic failure (PAF) patients because of sympathetic denervation. The aim of this study was to characterize the rate of change of systemic mean blood pressure (MBP) and cerebral haemodynamics in response to passive posture changes. Nine PAF patients and 9 age-matched controls took part in this study. MBP and oxy- (O2Hb), deoxy-haemoglobin (HHb), and tissue oxygenation index (TOI) on the forehead were continuously monitored non-invasively using the Portapres and near-infrared spectroscopy (NIRS), respectively. From visual inspection of the haemoglobin difference signal (Hb(diff) = O2Hb-HHb), seven distinct phases were marked (1: supine, 2: start passive tilt, 3: head up to 60 degrees degrees, 4: end of tilt, 5: tilt reversal, 6: return to supine, 7: rest); the same time points were used for all of the other signals. For each phase, the slope was calculated using a linear regression algorithm. Significant differences were found between PAF patients and controls in the Hb(diff) slope magnitudes for phases 3 (P < .05) and 5 (P = .01), and the duration of phase 2 (P < .05). MBP slope magnitudes showed significant differences for phases 2 (P < .01) and 5 (P < .01). These differences in the rate of change suggest differences in blood vessel resistance related to sympathetic activation.
- Subjects :
- Aged
Case-Control Studies
Hemoglobins metabolism
Humans
Middle Aged
Oxyhemoglobins metabolism
Spectroscopy, Near-Infrared
Autonomic Nervous System Diseases metabolism
Autonomic Nervous System Diseases physiopathology
Blood Pressure physiology
Brain metabolism
Oxygen metabolism
Posture physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0065-2598
- Volume :
- 566
- Database :
- MEDLINE
- Journal :
- Advances in experimental medicine and biology
- Publication Type :
- Academic Journal
- Accession number :
- 16594152
- Full Text :
- https://doi.org/10.1007/0-387-26206-7_26