Norwegian Air Ambulance Foundation, Department of Research and Development, Oslo, Norway.
Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
PLoS One. 2024 May 7;19(5):e0302159. doi: 10.1371/journal.pone.0302159. eCollection 2024.
Stroke volume can be estimated beat-to-beat and non-invasively by pulse wave analysis (PWA). However, its reliability has been questioned during marked alterations in systemic vascular resistance (SVR). We studied the effect of SVR on the agreement between stroke volume by PWA and Doppler ultrasound during reductions in stroke volume in healthy volunteers.
In a previous study we simultaneously measured stroke volume by PWA (SVPWA) and suprasternal Doppler ultrasound (SVUS). We exposed 16 healthy volunteers to lower body negative pressure (LBNP) to reduce stroke volume in combination with isometric hand grip to elevate SVR. LBNP was increased by 20 mmHg every 6 minutes from 0 to 80 mmHg, or until hemodynamic decompensation. The agreement between SVPWA and SVUS was examined using Bland-Altman analysis with mixed regression. Within-subject limits of agreement (LOA) was calculated from the residual standard deviation. SVRUS was calculated from SVUS. We allowed for a sloped bias line by introducing the mean of the methods and SVRUS as explanatory variables to examine whether the agreement was dependent on the magnitude of stroke volume and SVRUS.
Bias ± limits of agreement (LOA) was 27.0 ± 30.1 mL. The within-subject LOA was ±11.1 mL. The within-subject percentage error was 14.6%. The difference between methods decreased with higher means of the methods (-0.15 mL/mL, confidence interval (CI): -0.19 to -0.11, P<0.001). The difference between methods increased with higher SVRUS (0.60 mL/mmHg × min × L-1, 95% CI: 0.48 to 0.72, P<0.001).
PWA overestimated stroke volume compared to Doppler ultrasound during reductions in stroke volume and elevated SVR in healthy volunteers. The agreement between SVPWA and SVUS decreased during increases in SVR. This is relevant in settings where a high level of reliability is required.
通过脉搏波分析（PWA）可以逐搏、无创地估计心搏量。然而，其在全身性血管阻力（SVR）明显改变时的可靠性受到质疑。我们研究了 SVR 对健康志愿者心搏量降低时 PWA 和超声心动图测量心搏量之间一致性的影响。
在之前的一项研究中，我们同时通过 PWA（SVPWA）和胸骨上多普勒超声（SVUS）测量心搏量。我们让 16 名健康志愿者进行下肢负压（LBNP），以降低心搏量，同时进行等长手握以升高 SVR。LBNP 每 6 分钟增加 20mmHg，从 0mmHg 增加到 80mmHg，或直至出现血流动力学失代偿。使用混合回归的 Bland-Altman 分析检查 SVPWA 和 SVUS 之间的一致性。从残差标准差计算组内一致性界限（LOA）。从 SVUS 计算 SVRUS。我们引入方法的平均值和 SVRUS 作为解释变量，以检查一致性是否依赖于心搏量和 SVRUS 的大小，从而允许出现斜率偏倚线。
偏倚±一致性界限（LOA）为 27.0±30.1mL。组内 LOA 为±11.1mL。组内百分比误差为 14.6%。方法之间的差异随方法均值的升高而减小（-0.15mL/mL，95%CI：-0.19 至-0.11，P<0.001）。方法之间的差异随 SVRUS 的升高而增加（0.60mL/mmHg×min×L-1，95%CI：0.48 至 0.72，P<0.001）。
与多普勒超声相比，在健康志愿者心搏量降低和 SVR 升高时，PWA 高估了心搏量。在 SVR 升高时，SVPWA 和 SVUS 之间的一致性降低。在需要高可靠性的情况下，这一点很重要。
