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Forehead Laser Doppler And Transcranial Doppler During Simulated Hypovolemia, Kathleen Samuels

Yale Medicine Thesis Digital Library

The present study employed lower body negative pressure (LBNP), a rapidly titratable, safe and reversible means of inducing simulated hypovolemia, for a comparison of transcranial Doppler (TCD) ultrasound of the middle cerebral artery and laser Doppler (LD) flowmetry of the forehead microvasculature. With IRB approval, 9 healthy volunteers (26.3±2.7 years) were monitored continuously with EKG, noninvasive finger arterial blood pressure (BP), and TCD positioned at the transtemporal window. After a baseline (Base) period, subjects underwent rapid onset of LBNP to -70 mmHg over the course of 1 minute, followed by progressive declines of ~10 mmHg until lightheadedness or had a …