Forearm blood flow by Doppler ultrasound during rest and exercise: tests of day-to-day repeatability

Abstract

The between-day repeatability of simultaneous measures of brachial artery diameter (D) (echo Doppler) and mean blood velocity (MBV) (pulsed Doppler) was tested during rest and exercise. On 3 separate days, six volunteers performed one trial of 1-min rest followed by a step increase in dynamic handgrip exercise for 4 min which required the lifting and lowering of a 4.4-kg weight (approximately 8-12% MVC) in a 1s/2s (work/rest) cadence. Measures for MBV and D were collected continuously on a beat-by-beat basis during the transition from rest to end exercise. The mean rest values over one min, and single data points at 30, 60, 120, and 240 s of exercise were extracted from the time series data. At all exercise time points, MBV was greater than rest (P < 0.05), but these levels were not different across test days. Arterial D at all exercise time points ranged from 3.8 +/- 0.1 mm to 4.1 +/- 0.1 mm (mean +/- SEM) and did not differ from rest (3.9 +/- 0.1 mm) (P > 0.05), nor did D differ between days. The mean between-day coefficient of variation for D was 4.08 +/- 0.7% at rest and ranged from 2.90 +/- 0.4% to 3.96 +/- 0.5% during exercise. The coefficient of variation for MBV was 13.2 +/- 2.6% at rest and reached 20.2 +/- 3.1% during the final min of exercise; the exercise variability was reduced to 14.9 +/- 2.4% by averaging MBV over 3 s (the duration of a contraction/relaxation duty cycle) (P < 0.05) with no further advantage of averaging over ten 60-s sample periods. The data indicate that, for the six subjects tested, Doppler ultrasound measures of arterial MBV and diameter during both rest and exercise were reproducible across different test days and can be used as a reliable, noninvasive means of testing hypotheses pertaining to blood flow control.

Flow-mediated dilation in human brachial artery after different circulatory occlusion conditions

“…The signal was directed 45°relative to the skin, and the ultrasound gate was adjusted to the total width of the artery. Arterial diameter was obtained from frozen screen images during the same phase of the cardiac cycle (diastole) by placing three pairs of markers on the trailing edge of the anterior wall to the leading edge of the posterior wall (25,26). Shear rate was calculated as 8 ϫ MBV/D (21), where MBV is the mean blood velocity over each cardiac cycle and D is the corresponding diameter for that cycle estimated as described in Blood flow analysis.…”

“…Signals from an electrocardiograph (model VS4, Cambridge Instruments; Cambridge, UK), finger-cuff photoplethysmograph (Finapres 2300, Ohmeda), and pulsed Doppler ultrasound (model 500V, Multigon Industries) were recorded at 100 Hz on a computer to allow measurement of heart rate, mean arterial pressure, and mean blood velocity, respectively. Forearm blood flow was calculated beat by beat (25,26) from the product of the mean blood velocity and the cross-sectional area of the brachial artery obtained by echo Doppler imaging using a 7.5-MHz probe in B-mode (model SSH-140A, Toshiba; Toshigi-Ken, Japan). Placement of the echo Doppler probe was just proximal to the pulsed Doppler probe to avoid accoustic interference.…”

Effect of acute sympathetic nervous system activation on flow-mediated dilation of brachial artery

“…The pulsed Doppler 4-MHz probe was secured above the brachial artery proximal to the cubital fossa with strips of tape. The signal was directed 45°relative to the skin, and the ultrasound gate was adjusted to encompass the total width of the artery (34). The brachial artery was continuously imaged with the use of high-resolution ultrasound with a 7.5-MHz probe in B-mode (model SSH-140A, Toshiba, Tochigi-Ken, Japan) and recorded to s-VHS tape for later analysis (1,34).…”

“…The signal was directed 45°relative to the skin, and the ultrasound gate was adjusted to encompass the total width of the artery (34). The brachial artery was continuously imaged with the use of high-resolution ultrasound with a 7.5-MHz probe in B-mode (model SSH-140A, Toshiba, Tochigi-Ken, Japan) and recorded to s-VHS tape for later analysis (1,34). Brachial artery blood flow was arrested by rapid inflation (E-20 Rapid Cuff Inflator, D. E. Hokanson, Issaquah, WA) of a standard blood pressure cuff to 300 mmHg.…”

The effects of body-weight supported treadmill training on cardiovascular regulation in individuals with motor-complete SCI

“…The blood flow velocity of our system was calibrated against a corn-starch solution pumped through tubing. 37 Arterial blood flow volume (BF) was calculated as: BF (ml/min) ¼ MBV (cm/s) Â mean vessel cross-sectional area (CSA; cm 2 ) Â 60; where CSA ¼ p(mean diameter/2) 2 . Arterial resistance (mmHg min/ml) was calculated as: Resistance (mmHg min/ml) ¼ mean arterial pressure (MAP)/BF.…”