Cohen Jeremy N, Jasiak Jessica N, Nahas Hassan, Yu Alfred C H, Au Jason S
Department of Kinesiology and Health Sciences, University of Waterloo, Ontario, Canada.
Schlegel-University of Waterloo Research Institute for Aging, University of Waterloo, Ontario, Canada.
Am J Physiol Heart Circ Physiol. 2024 Dec 1;327(6):H1467-H1473. doi: 10.1152/ajpheart.00690.2024. Epub 2024 Nov 1.
The accuracy of femoral artery blood flow measurements via Doppler ultrasound hinges on assumptions of laminar flow upstream of the femoral bifurcation. Existing scanning guidelines recommend a minimum proximity to the flow divider of 2-3 cm for avoiding multidirectional blood flow yet lack experimental evidence to support this recommendation. This study aimed to determine the minimum distance required to avoid multidirectional flow contamination near the femoral bifurcation and to assess the reliability of vector flow imaging (VFI) in these measurements. Twenty healthy adults (10 females, 25 ± 4 yr) participated in this study. Ultrasound VFI was used to visualize blood flow patterns and quantify flow uniformity via vector concentration coefficient (VCC), and multidirectional flow length was quantified at rest in triplicate ( = 20), postisometric contraction ( = 20), and during thigh cuffing ( = 10). At rest, the mean multidirectional flow length was 3.12 ± 0.59 cm, which decreased to 2.80 ± 0.66 cm postcontraction ( = 0.02). Thigh cuffing (80 mmHg) resulted in a multidirectional flow length of 2.75 ± 0.64 cm, not significantly different from rest ( = 0.69). Males exhibited a shorter multidirectional flow length compared with females (mean difference: 0.31 ± 0.71 cm, = 0.05). The VCC increased from 0.39 ± 0.08 at rest to 0.57 ± 0.15 postcontraction ( < 0.01), indicating increased flow uniformity. Reliability metrics demonstrated good-to-excellent reproducibility at rest, with intraclass correlation coefficient [ICC(3,1)] = 0.85 and 0.84 and coefficient of variation (CV)% = 7.1 ± 6.2% and 7.5 ± 4.5% for multidirectional flow length and VCC, respectively. Our data suggest a minimum scanning proximity of 3.5 cm to the femoral bifurcation to ensure that blood flow assessments are free of multidirectional flow and invite further study in different body positions and arteries of interest to increase rigor in this area. Current ultrasound scanning guidelines to avoid multidirectional flow contamination in the femoral artery of 2-3 cm lack supporting evidence. We used vector flow imaging to report the multidirectional flow length during rest and manipulation of downstream vessel resistance in males and females. We suggest measurements at least 3.5 cm upstream from the femoral bifurcation to minimize multidirectional flows. This study also supports reliability of vector flow imaging for femoral artery assessments, with good-to-excellent reproducibility of results.
通过多普勒超声测量股动脉血流的准确性取决于股动脉分叉上游层流的假设。现有的扫描指南建议与分流器保持至少2 - 3厘米的距离以避免多向血流，但缺乏实验证据支持这一建议。本研究旨在确定避免股动脉分叉附近多向血流污染所需的最小距离，并评估矢量血流成像（VFI）在这些测量中的可靠性。20名健康成年人（10名女性，25±4岁）参与了本研究。超声VFI用于可视化血流模式，并通过矢量浓度系数（VCC）量化血流均匀性，多向血流长度在静息状态下进行三次重复测量（n = 20），等长收缩后（n = 20）以及大腿袖带加压期间（n = 10）进行量化。静息时，平均多向血流长度为3.12±0.59厘米，收缩后降至2.80±0.66厘米（P = 0.02）。大腿袖带加压（80 mmHg）导致多向血流长度为2.75±0.64厘米，与静息时无显著差异（P = 0.69）。男性的多向血流长度比女性短（平均差异：0.31±0.71厘米，P = 0.05）。VCC从静息时的0.39±0.08增加到收缩后的0.57±0.15（P < 0.01），表明血流均匀性增加。可靠性指标显示静息时具有良好至优秀的可重复性，多向血流长度和VCC的组内相关系数[ICC(3,1)]分别为0.85和0.84，变异系数（CV）%分别为7.1±6.2%和7.5±4.5%。我们的数据表明，与股动脉分叉的最小扫描距离为3.5厘米，以确保血流评估不受多向血流影响，并呼吁在不同体位和感兴趣的动脉中进行进一步研究，以提高该领域的严谨性。目前关于避免股动脉多向血流污染的超声扫描指南中2 - 3厘米的建议缺乏支持证据。我们使用矢量血流成像报告了男性和女性静息状态以及下游血管阻力操作期间的多向血流长度。我们建议在股动脉分叉上游至少3.5厘米处进行测量，以尽量减少多向血流。本研究还支持矢量血流成像在股动脉评估中的可靠性，结果具有良好至优秀的可重复性。
