Changes in cerebral oxygenation and haemodynamics during postural blood pressure changes in patients with autonomic failure.
Patients with autonomic failure suffer severe postural hypotension that may be associated with symptoms of cerebral hypoperfusion. This study utilized near-infrared spectroscopy (NIRS) to measure changes in cerebral oxygenation and haemodynamics during the head-up tilt table test in 18 patients with autonomic failure and 10 healthy age-matched volunteers. Heart rate, blood pressure (MAP), oxygen saturation, cerebral tissue oxygen index (TOI) and total cerebral haemoglobin concentration [HbT] were measured continuously. In patients with autonomic failure there was a mean (SD) reduction in MAP of 46.7 (26.5) mmHg (p < 0.005) associated with a reduction in TOI of 8.6 (6.2)% (p < 0.005) during the head-up tilt table test. In healthy volunteers mean (SD) MAP rose by 12.3 (8.0) mmHg (p < 0.005) and TOI fell by 2.6 (3.2)% (p < 0.05). There was a mean (SD) reduction in [HbT] of 3.09 (2.82) micromol l(-1) (p < 0.005) in patients, equivalent to a decrease in cerebral blood volume of 0.2 (0.18) ml/100 g. There were no changes in [HbT] in the healthy volunteers. Postural hypotension in patients with autonomic failure is associated with a substantial decrease in absolute cerebral oxygenation measured by NIRS and this might reflect a critical reduction in cerebral oxygen delivery.
Hunt
Katharine
K
Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery and Institute of Neurology, Queen Square, London WC1N 3BG, UK. Centre for Anaesthesia, University College London, UK.
Tachtsidis
Ilias
I
Bleasdale-Barr
Katharine
K
Elwell
Clare
C
Mathias
Christopher
C
Smith
Martin
M
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology*; D002545:Brain Ischemia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000378:metabolism*; D011187:Posture; D012791:Shy-Drager Syndrome / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D018667:Tilt-Table Test / Q000379:methods
D010100:Oxygen