Determination of the minimum number of cardiac cycles necessary to ensure representative blood flow velocity measurements

Kurmanavichius, Juozas; Baumann, Hans; Huch, R.; Huch, A.

doi:10.1515/jpme.1989.17.1.33

Cited by 9 publications

(10 citation statements)

References 10 publications

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“…In similar studies, the SD was used to find the minimum number of cardiac cycles required to calculate a stable mean pulsatility index from Doppler recordings 17 . The minimum number of observations that gave an SD of the individual mean not significantly different from the SD of the final mean established by ten observations was considered the ideal practical method.…”

Section: Discussionmentioning

confidence: 99%

How repeat measurements affect the mean diameter of the umbilical vein and the ductus venosus

Kiserud

Rasmussen

1998

Ultrasound in Obstet & Gyne

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Blood flow measurement in the fetus is susceptible to substantial error. Increased numbers of measurements can improve the precision. To quantify this, we assessed how the number of ultrasound measurements affected the calculation of individual mean diameters of fetal veins. A study of the umbilical vein (UV) and ductus venosus (DV) was carried out in 167 pregnancies in a clinical setting. The UV diameter was measured 2-13 times in 163 participants and the DV for the same number of times in 158. A one-way analysis of variance gave mean within-subject SD of 0.23 mm for the UV (diameter 2.0-8.0 mm) and 0.17 mm for the DV (diameter 0.3-2.3 mm). The 95% limit for the within-subject mean diameter calculated from two, four, six and ten measurements of the UV were 0.31, 0.22, 0.18 and 0.14 mm, respectively. For the DV the corresponding results were 0.23, 0.16, 0.13 and 0.10 mm. The study shows how increasing the number of measurements to calculate a mean diameter substantially improves the precision of vascular cross-section assessment. The limitation of the method is expressed in the exponential increase in numbers needed to achieve further improvement.

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Section: Discussionmentioning

confidence: 99%

How repeat measurements affect the mean diameter of the umbilical vein and the ductus venosus

Kiserud

Rasmussen

1998

Ultrasound in Obstet & Gyne

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“…The tip of the 7.5 MHz ultrasound probe was placed directly on the uterine surface next to the fetus and a B-mode image was recorded to the hard disc of the ultrasound scanner equipment (EUB-6500, Hitachi Medical, Tokyo, Japan) for subsequent measurement of fetal size. Umbilical arteries (UmA) in a midcord site of the free-floating umbilical cord were visualized by color Doppler, and then pulsed wave Doppler was applied to record the waveforms with at least three consecutive cardiac cycles [25]. Thereafter, the measurement was continued with the laterally located fetus.…”

Section: Laparoscopic Procedures and Doppler Ultrasound Measurementsmentioning

confidence: 99%

Laparoscopy Guided Doppler Ultrasound Measurement of Fetal Blood Flow Indices During Early to Mid-Gestation in Pigs

Brüssow

Kurth

Vernunft

et al. 2012

Journal of Reproduction and Development

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Abstract. The objectives of this study were to obtain relevant blood flow indices of umbilical arteries (UmA) of porcine fetuses using a laparoscopic ultrasound probe and to relate these data with fetal size at early to mid gestation. Fetal parameters and flow indices, i.e., fetal length and area, fetal heart rate (FHR), systolic pulse duration (T1), interpulse duration (T2), T2/T1 ratio, peak systolic velocity (PSV), time averaged velocity (TAV), resistance index (RI) and pulsatility index (PI), were measured in 182 fetuses of 26 pregnant Landrace gilts on pregnancy day (PD) 36 (122 fetuses from 17 gilts), PD42 (19 fetuses from 3 gilts) and PD51 (42 fetuses from 6 gilts). Fetal heart rate was higher on PD36 than on PD42 (P<0.05). No differences (P>0.05) were obtained concerning systolic pulse duration, flow velocities and RI. On PD42, the PI was lower (P<0.05), while the interpulse duration (P=0.06) and T2/T1 ratio tended (P=0.08) to be higher on PD42 compared with PD36 and to PD51. To find differences in UmA blood flow parameters concerning fetal size, i.e., fetal length, fetuses were retrospectively grouped as follows: small (lower 25%), medium (mean 50%) and large (upper 25%), respectively. Although, fetuses differed in size (P<0.001) within and between days of pregnancy, FHR, PSV, TAV, RI and PI did not differ (P>0.05) among the size classes. Only systolic pulse duration tended to be longer (P=0.05) in large compared with small fetuses on PD36, and interpulse duration was lower in large fetuses on PD36 in comparison with PD51 (P<0.05). Though there was no link between fetal blood flow indices and fetal intrauterine growth retardation (IUGR), with further studies based on these flow indices, it might be possible to evaluate nutrient-or stress-related influences on fetal growth and development, particularly in the case of IUGR. Key words: Female pig, Fetal blood flow, Laparoscopy, Pregnancy, Ultrasonography (J. Reprod. Dev. 58: [243][244][245][246][247] 2012) T he profitability of pig production considerably depends on the number of live born and fostered piglets. Breeding efforts result nowadays in a greater than before number of piglets. However, pre-and postnatal losses are concomitantly increasing (up to 30%) [1]. Furthermore, intrauterine growth retardation (IUGR), resulting in lighter body weight at birth, is a significant problem in pig production [2]. Lighter birth weight piglets show reduced survival rate, compromised postnatal development [3] as well as decreased carcass and meat quality [4]. Uterine and umbilical blood flows maintain the placental transport and exchange of respiratory gases, nutrients and wastes, and thereby support fetal growth and metabolism [5]. As previously demonstrated in the pig, the blood flow to the fetus was reduced with increasing number of fetuses [6]. Experimental vascular occlusion of the uterine arteries of pigs markedly reduced conceptus development [7]. In utero growth retardation, beside other factors such as uterine capacity and number and position of fetuses ...

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“…The duplex ultrasound measurements of diameter and velocity at the ICAs and VAs over three cardiac cycles 20 were converted to time varying volume flow rate and waveform averaged and processed as described previously 41 . This resulted in spline fitted and peak aligned data.…”

Section: Methodsmentioning

confidence: 99%

Comparison of Transcranial Doppler Ultrasound with Computational Fluid Dynamics: Responses to Physiological Stimuli

Caddy

Thomas

Kelsey

et al. 2022

Preprint

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Few studies have compared transcranial Doppler (TCD) ultrasound with independent techniques such as computational fluid dynamics (CFD) simulations, particularly in response to stimuli. We compared TCD cerebral blood flow velocity in healthy participants with subject-specific CFD simulations to determine differences in techniques. Twelve participants underwent head and neck imaging with 3 Tesla magnetic resonance angiography. Velocity waveforms in the middle cerebral artery (MCA) were measured with TCD while velocity and diameter in the neck arteries were measured with duplex ultrasound at rest, hypercapnia and exercise. Subject-specific CFD simulations were developed for each condition, with velocity waveforms extracted in the same region as TCD. We found that absolute TCD velocities were significantly higher than CFD data, and non-significantly correlated across all conditions (r range 0.030-0.377, all P>0.05). However, relative changes from rest to hypercapnia and exercise generally exhibited significant positive correlations (r range 0.448-0.770), with the strongest correlation being average velocity change from rest to exercise (r=0.770, P<0.01). We have found that although absolute MCA velocity measurements from different sources vary, relative velocity changes yield stronger correlations regardless of source. Our findings indicate relative responses to physiological stimuli, along with absolute data, should be considered for analyzing cerebral blood flow velocity.

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Determination of the minimum number of cardiac cycles necessary to ensure representative blood flow velocity measurements

Cited by 9 publications

References 10 publications

How repeat measurements affect the mean diameter of the umbilical vein and the ductus venosus

How repeat measurements affect the mean diameter of the umbilical vein and the ductus venosus

Laparoscopy Guided Doppler Ultrasound Measurement of Fetal Blood Flow Indices During Early to Mid-Gestation in Pigs

Comparison of Transcranial Doppler Ultrasound with Computational Fluid Dynamics: Responses to Physiological Stimuli

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