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Fetal growth restriction
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Daniel L. Jackson, M. Y. Divon, Hung N. Winn
Normal fetal growth is determined by multiple maternal–fetal variables. Continuous blood flow on either side of the placenta and adequate fetal perfusion are obviously an absolute necessity. Indeed, FGR is associated with various abnormalities of the uteroplacental, umbilical, and fetal circulations (60,61). Doppler devices allow for a noninvasive evaluation of blood flow by displaying Doppler-shifted frequencies that are proportional to the velocity of red blood cells. Qualitative assessment of these waveforms is provided by angle-independent indices that are based on various ratios between the systolic and diastolic components of the waveform. Most studies concur that the simplest index (i.e., the systolic: diastolic ratio, S:D) is clinically as useful as any of the more complicated indices such as the resistance index (RI) [(Peak systolic velocity − end-diastolic velocity)/peak systolic velocity] or the pulsatility index (PI) [(peak systolic velocity − end-diastolic velocity)/average frequency shift].
Implantation and In Utero Growth
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
Kugajeevan Vigneswaran, Ippokratis Sarris
Uterine artery blood flow can be expressed using either the pulsatility index (PI) or the resistance index (RI). Both markers of impedance can be used to assess and quantify impaired uterine artery blood flow. An early study in 1988 demonstrated poor uterine artery blood flow, reflecting a suboptimal response to exogenous estradiol that resulted in a lower pregnancy rate in IVF cycles. The same study also demonstrated improved uterine perfusion following hormone therapy and a resultant increase in pregnancy rates [9]. Steer et al. followed on from this work and looked at the role of uterine artery blood flow as a marker for uterine receptivity in ART cycles; they found higher implantation rates in the women with low impedance uterine blood flow before embryo transfer [10].
Prediction of pre-eclampsia
Published in Pankaj Desai, Pre-eclampsia, 2020
Two forms of changes in the uterine artery are studied: one, changes in Doppler indices pulsatility, resistance and systolic-to-diastolic ratio and second, the diastolic notch in the waveform of the uterine artery for prediction of pre-eclampsia. It was interesting to study the diastolic notch and the behaviour of indices at around 12 weeks and then again at or around mid-trimester. Basically, pulsatility index, resistance index and systolic-to-diastolic ratio help us in identifying the quantum of diastolic flow in the uterine vascular system. This can be better understood if correlated with the pathophysiology occurring at or around this time. The process of the second wave of trophoblastic invasion is expected to get competently completed at or around mid-trimester. With this moulding, the maternal vascular bed becomes a low-resistance, high-flow pool of blood. It becomes nearly shielded off from the other changes that are taking place in the maternal systems. It also gets shielded off from the pressor substances that may be in circulation in the maternal system at some time or the other. The sum total effect of all these changes is an increase in blood flow to the pregnant uterus. That apart, this increase in blood flow is continuous and guarded by blunting the effects of sympathetic and parasympathetic systems on spiral arterioles.
Staphylococcus-induced proliferative glomerulonephritis and cerebral hemorrhage – fatal complications in a young female with postpartum cardiomyopathy and an implanted left ventricular assist device: a case report and review of the literature
Published in Acta Chirurgica Belgica, 2022
Carmen Elena Opris, Horatiu Suciu, Laura Banias, Cosmin Marian Banceu, Cosmin Opris, Marius Harpa, Mihaela Ispas, Simona Gurzu
Measuring the LVAD pulsatility index (PI) and the aortic valve opening (assessed by echocardiography), Wever-Pizon et al. suggested that low pulsatility had an important role in bleeding [20]. The bleeding risk is also correlated with the angiogenesis rate, which can be stimulated by shear stress and increased intraluminal pressure [23]. A study conducted by Yoshioka reported an increased incidence of cerebral microbleeds (CMBs) involving 35 out of the 36 examined patients [24]. CMBs are defined as parenchymatous hematomas which are less than 10 mm in diameter and can appear in patients with increased fragility of their small vessels [24]. Diapedesis hemorrhage and brain edema were also found in our patient, likely resulting from bacteria-induced capillary fragility [24–29]. Inflammatory damage to endothelial cells induces a loss of nitrogen oxide (NO) endothelial synthase and increases the risk of a hemorrhagic stroke 20 times [23–27]. In our patient, bacteremia with MRSA was present, but MBP values of 70–80 mmHg and therapeutic INR values were consistently recorded.
The influence of intracranial hypertension on static cerebral autoregulation
Published in Brain Injury, 2020
Marcelo de-Lima-Oliveira, Almir Andrade Ferreira, Alessandro Rodrigo Belon, Angela Macedo Salinet, Ricardo Carvalho Nogueira, Brasil Chian Ping, Wellingson Silva Paiva, Manoel Jacobsen Teixeira, Edson Bor-Seng-Shu
CA was evaluated through cerebral blood flow velocities (CBFv) that were obtained by ultrasound examination (4–8 MHz transducer, MicroMax® model, Sonosite®, Bothel, WA). A specific artery of the skull base, after a “rete mirabile” complex, which was our anatomical vascular reference, was identified by ultrasound color flow, and the CBFv were acquired from this same arterial segment via the Doppler technique during all steps of the study. The static autoregulation (sCA) index was calculated before and after balloon inflation. For each evaluation, the mean arterial blood pressure (MABP) was increased using noradrenaline by 20 mmHg to a value less than 120 mmHg, which is supposed to be the upper limit of CA under physiologic conditions. CBFv and MABP were obtained before and after noradrenaline infusion in the pre and post balloon inflation. The initial (basal) and final (after noradrenaline infusion) MABP and CBFv values were recorded to calculate the cerebral vascular resistance (CVR) as follows: CVR = MABP/CBF. It is important to consider that for constant diameter of the basal encephalic arteries (macrovasculature), CBFv can be used to estimate CBF. Thus, CBF was replaced by CBFV to calculate CVR. The static rate of regulation (sROR) was calculated as follows: sROR (sCA%) = 100(%ΔCVR/%ΔMABP), in which ΔCVR = the change in CVR, and ΔMABP = the change in MABP (5). Moreover, pulsatility index (PI) was calculated by dividing the difference between the peak systolic and diastolic velocity by the mean velocity (PI = (S-D)/M).
Comparative study of umbilical cord cross-sectional area in foetuses with isolated single umbilical artery and normal umbilical artery
Published in Journal of Obstetrics and Gynaecology, 2022
Tian-Gang Li, Chong-Li Guan, Jian Wang, Mei-Juan Peng
The GE Healthcare E10 ultrasound system with preset obstetric functions was used in this study, and foetal biological parameters were measured at each scan. To obtain the UA blood flow spectrum, we initiated colour Doppler ultrasonography with the Doppler sampling line placed in the free segment umbilical cord to parallel the Doppler sampling line and UA blood flow (angle ≤30°). We performed continuous measurements of more than three cycles and then acquired the blood flow spectrum parameter–pulsatility index (PI). We obtained a 2 D image of an umbilical cord cross section depicting the cross-sectional area of the UV and UA (Figure 2). Thereafter, we calculated the UV area/UA area ratio by averaging the results of two or three measurements.