PURPOSE: Multiple biologic effects of ultrasound on the human body have been described. Our aim was to monitor changes in blood flow velocities in the radial artery during continuous pulsed wave Doppler monitoring (DM). METHODS: Fifteen healthy volunteers (8 males; mean age 55 ± 17 years) underwent two 1-hour sessions of left radial artery DM using a diagnostic transcranial 2-MHz pulsed-wave transducer. Blood flow velocities were recorded twice at 2-minute intervals, for the measurement of peak systolic velocity, end-diastolic velocity, and mean flow velocity, and the calculation of pulsatility index, and resistance index. Insonation was either intermittent (by periods <10 seconds) or continuous during the first session, and conversely during the second session 2 weeks later. RESULTS: Blood flow velocities and indices fluctuated during both sessions. These changes were symmetrical during the intermittent DM session. In contrast, end-diastolic velocity increased while pulsatility index and resistance index decreased significantly during the continuous DM session (p < 0.05 for all three parameters). The changes in peak systolic velocity and mean flow velocity did not differ between sessions. CONCLUSIONS: One-hour sonographic Doppler monitoring using a 2-MHz diagnostic transcranial PW Doppler probe may induce peripheral vasorelaxation in humans.

Department of Neurology Hospital Třinec Sosna Třinec Czech Republic

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