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The Sit-to-Stand Technique for the Measurement of Dynamic Cerebral Autoregulation

2008; Elsevier BV; Volume: 35; Issue: 1 Linguagem: Inglês

10.1016/j.ultrasmedbio.2008.08.001

1879-291X

Farzaneh A. Sorond, Jorge M. Serrador, Richard N. Jones, Michele L. Shaffer, Lewis A. Lipsitz,

Optical Imaging and Spectroscopy Techniques

Measurement of cerebral autoregulation is important for the evaluation and management of a number of clinical disorders that affect cerebral blood flow.We currently lack simple bedside measures that mimic common physiologic stresses.Therefore, we evaluated a new sit-to-stand technique as an alternative method to the frequently used thigh-cuff technique in healthy volunteers.Continuous middle cerebral artery (MCA) blood flow velocities (BFV) and arterial blood pressure (ABP) were measured in response to standing from a sitting position, or rapid thigh-cuff deflation in 24 healthy subjects (50 ± 22 years).Autoregulatory Index (ARI) was calculated as the BFV response for step changes in ABP using a second-order differential equation with a set of parameters that can be used to grade the performance of autoregulation.Of these 24 subjects, 30% could tolerate only two thighcuffs and refused to proceed with the third cuff, while none of our subjects had any difficulty with performing the three sit-to-stand trials.The two techniques produced similar changes in mean arterial blood pressure (ABP), but the times to nadir of the blood pressure and BFV were significantly faster for the thigh-cuff.The mean group ARIs were similar between the two techniques.While between subjects variability was higher for sit-to-stand ARIs, the within subject sit-to stand ARI variability was small.Thus, for the assessment of cerebral autoregulation, the sit-to-stand procedure is well tolerated and produces ARI values that have low within subject variability.The sit-to-stand technique appears to be a suitable measure of individual ARI values for inferring dynamic cerebral autoregulation.