Error introduced into velocity measurements by inappropriate Doppler angle assignment

Yamamoto, M.; Carrillo, J.; Insunza, A.; Mari, Giancarlo; Ville, Y.

doi:10.1002/uog.3847

Cited by 18 publications

(11 citation statements)

References 4 publications

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“…This uncertainty has been estimated by asking the operator to recursively assess the correct Doppler angle so as to evaluate the standard deviation of the mean. The variability of such technical aspect may potentially lead to an overestimation of the TAV, finally affecting the Q up to 20% [16]. …”

Section: Discussionmentioning

confidence: 99%

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An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

et al. 2013

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BackgroundThe quantification of the flow returning from the head through the cervical veins and the collaterals of the internal jugular vein (IJV), is becoming of prominent interest in clinical practice. We developed a novel model to calculate the cerebral venous return, normalized to the arterial inflow, in the different segments of the IJV.MethodsWe assessed, by established Echo Colour Doppler (ECD) methodology, the head inflow (HBinF) defined as the sum of common carotids and vertebral arteries, as well as the cerebral flow (CBF) defined as the sum of internal carotid and vertebral arteries. We also assessed the head outflow (HBoutF) defined as the sum of the measurements at the junction of the IJV and the vertebral veins. In addition, we also calculated the collateral flow index (CFI) by estimating the flow which re-enters directly into the superior vena cava as the amount of blood extrapolated by the difference between the HBinF and the HBoutF. We preliminarily tested the model by comparing ten healthy controls (HC) with ten patients affected by chronic cerebral spinal venous insufficiency (CCSVI), a condition characterized by some blockages in the IJV which are bypassed by collateral circulation.ResultsIn HC the HBinF was 956+-105ml/min, whereas the HBoutF was > 90% of the HBinF, leading to a final CFI value of 1%. The last result shows that a very small amount of blood is drained by the collaterals. In upright we confirmed a reduction of the outflow through the IJV which increased CFI to 9%. When we applied the model to CCSVI, the HBinF was not significantly different from controls. In supine, the flow of CCSVI patients in the IJV junction was significantly lower (p < 0.001) while the correspondent CFI value significantly increased (61%, p < 0.0002).ConclusionsOur preliminary application of the novel model in the clinical setting suggests the pivotal role of the collateral network in draining the blood into the superior vena cava under CCSVI condition.

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Section: Discussionmentioning

confidence: 99%

“…Such parameter and the uncertainty of the operator in placing it usually affect the TAV assessment. In our off-line processing we managed to estimate the uncertainty of TAV measurements as described in [16]:…”

Section: Methodsmentioning

confidence: 99%

An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

et al. 2013

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“…The operator of a handheld probe may introduce an error into the angle of insonation during velocity recordings. A deviation of 5°yields an error of 10% in ICA blood velocity (Yamamoto et al 2006). ETCO 2 was necessarily calculated once per respiratory cycle (end-expiration).…”

Section: Methodological Considerations and Limitationsmentioning

confidence: 99%

Dynamic cerebral autoregulation is preserved during isometric handgrip and head-down tilt in healthy volunteers

2018

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In healthy humans, cerebral blood flow (CBF) is autoregulated against changes in arterial blood pressure. Spontaneous fluctuations in mean arterial pressure (MAP) and CBF can be used to assess cerebral autoregulation. We hypothesized that dynamic cerebral autoregulation is affected by changes in autonomic activity, MAP, and cardiac output (CO) induced by handgrip (HG), head‐down tilt (HDT), and their combination. In thirteen healthy volunteers, we recorded blood velocity by ultrasound in the internal carotid artery (ICA), HR, MAP and CO‐estimates from continuous finger blood pressure, and end‐tidal CO 2. Instantaneous ICA beat volume (ICABV, mL) and ICA blood flow (ICABF, mL/min) were calculated. Wavelet synchronization index γ (0–1) was calculated for the pairs: MAP–ICABF, CO–ICABF and HR–ICABV in the low (0.05–0.15 Hz; LF) and high (0.15–0.4 Hz; HF) frequency bands. ICABF did not change between experimental states. MAP and CO were increased during HG (+16% and +15%, respectively, P < 0.001) and during HDT + HG (+12% and +23%, respectively, P < 0.001). In the LF interval, median γ for the MAP–ICABF pair (baseline: 0.23 [0.12–0.28]) and the CO–ICABF pair (baseline: 0.22 [0.15–0.28]) did not change with HG, HDT, or their combination. High γ was observed for the HR–ICABV pair at the respiratory frequency, the oscillations in these variables being in inverse phase. The unaltered ICABF and the low synchronization between MAP and ICABF in the LF interval suggest intact dynamic cerebral autoregulation during HG, HDT, and their combination.

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“…The effect of visual error, introduced inevitably by the operator when angle assignment is used, is minimized when the vessel is closer to the vertical on‐screen. It has been demonstrated mathematically39 that at insonation angles of less than 30°, small angle errors (< 5°) have little impact on velocity estimation; beyond 30°, the impact increases exponentially. The Doppler sample gate can only be increased in length by increasing the electronic gating of the received signals32, and cannot be increased in width.…”

Section: Accuracymentioning

confidence: 99%

Umbilical venous blood flow measurement: accuracy and reproducibility

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Fernández

Hernández‐Andrade

et al. 2008

Ultrasound in Obstet & Gyne

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Error introduced into velocity measurements by inappropriate Doppler angle assignment

Cited by 18 publications

References 4 publications

An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

Dynamic cerebral autoregulation is preserved during isometric handgrip and head-down tilt in healthy volunteers

Umbilical venous blood flow measurement: accuracy and reproducibility

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