Pulsed Doppler Ultrasonography Research Articles

Eye microcirculation in glaucoma. Part 1. Diagnostic methods

Glaucoma is a socially significant disease, which is a wide group of polyetiological diseases. In the etiology of primary glaucoma, in addition to the mechanical theory, a vascular mechanism is also distinguished, and therefore, the search and development of the most informative and accurate method for studying ocular blood flow continues. Existing methods are divided into invasive and non-invasive. Invasive methods include angiography with intravenous fluorescein and indocyanine. Non-invasive methods include ultrasound Doppler mapping and pulsed Doppler modes, optical coherence tomography with angiography and laser speckle flowography. The review presents data on modern methods for ocular hemodynamics in glaucoma and ocular hypertension with technologies for studying retrobulbar blood flow and intraocular hemocirculation.

Ultrasonographic Assessment of Testicular Biometry and Arterial Blood Flow in Pre- and Postpubertal Miranda Donkeys: Correlations With Semen Quality Parameters.

The main goals of this study were to document and compare the normal ranges of testicular haemodynamic parameters in pre- (aged 8-12 months; n = 4) and postpubertal (aged 24-259 months; n = 16) Miranda donkeys in the breeding season, and to correlate animal biometric data and testicular Doppler indices with basic semen quality parameters of sexually mature jacks. Colour and pulsed-Doppler ultrasonography were employed to assess blood flow in the left and right distal supratesticular artery (DsTA) and their marginal branches (marginal arteries-MA). Peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI) and resistive index (RI) were evaluated in both blood vessels, and TAMV (time-averaged mean velocity), TABF (total arterial blood flow) and TABF rate (TABF-R) were calculated for MA. The mean diameter of MA was greater (p < 0.05; 0.24 ± 0.05 vs. 0.19 ± 0.05 cm; mean ± SD) but TABF-R was less (p < 0.05; 0.004 ± 0.004 vs. 0.02 ± 0.01 mL/s/cm3) in sexually mature donkeys compared with prepubertal animals. Apart from RI values for the right testicle of prepubertal donkeys, PI and RI were consistently greater (p < 0.05) in DsTA compared with MA. Significant correlations were found among select biometric and haemodynamic attributes of the testes (height, width and length, TV, TTV and PSV-ST) and ejaculate characteristics (volume, sperm defects-total, head and midpiece) in sexually mature donkeys (n = 8). The present results highlight the importance of scrotal ultrasonography for the reproductive assessment of jacks and provide reference values, based on the available subpopulation of Miranda donkeys that can be used in their clinical and reproductive management and research, or conservation programmes.

Assessment of Thermal and Mechanical Indices as Acoustic Output Parameters Used in Obstetric Ultrasound in Saudi Arabia.

Patient safety is paramount in ultrasound procedures, particularly in obstetric ultrasounds involving both the mother and fetus. The thermal and mechanical indices (TI and MI) serve as crucial indicators of the acoustic output during ultrasound. Clinicians and specialists must know these indices and ensure they are within safe ranges. This study aimed to assess the parameters of acoustic output power employed in obstetric ultrasound (thermal and mechanical index). A cross-sectional observational study conducted at Maternity and Children's Hospital in Al-Madina Al-Munawwarah, the data was collected from obstetric scanning of 411 pregnant females using a data collection sheet including gravida and women's age, gestational age, scan mode, scan time, and thermal and mechanical index (TI and MI) values. The study found that there were significant differences in safety indices measurement between different modes; in Pulsed Doppler, mean Thermal Index Bone (TIb) had the highest value (1.60±0.40), and the Mechanical Index (MI) was the lowest (0.68±0.33). There were insignificant differences in safety indices values in different modes in different trimesters. The thermal indices of soft tissue and bony structure (TIs and TIb) of brightness mode (B-mode) were constant in all trimesters, but the MI in the first trimester was lower than in the other trimesters. This study found significant differences in TIs, TIb, and MI in different modes of obstetric ultrasound. Pulsed Doppler ultrasonography had the highest TIb value and a lower MI value. The ultrasound acoustic exposure output parameters were within the standard's recommended limit.

Tissue displacement assessment by ultrasound predicts peri-laryngeal leak after supraglottic device insertion (I-gel)

Background and aims Supraglottic airway devices (SADs) have revolutionized airway management during general anesthesia, and they fill the niche between the face mask and endotracheal tube in terms of both airway anatomy and degree of invasion. The aim of this study was assessment of peri-laryngeal leak after insertion of I- gel using ultrasound (US) pulse Doppler mode. Methods Hundred patients scheduled for elective surgery after I-gel placement were recruited. Airway leak pressure was detected by using closed circuit in anesthesia workstation and increasing the pressure to 20 mm Hg. Parameters were noted include, leak as observed in the monitor, leak as assessed using the US machine, fiberoptic visualization of the SAD and grading and end tidal CO2 (ETCO2). Results In ultrasound we have detected peri-laryngeal tissue displacement in 18 patients (18%) out of which 10 patients have grade 3 or 4 on fiberoptic examination (Fig. 2). Among these ten patients, eight patients have inadequate ventilation required reinsertion of I-gel. Conclusion Tissue displacement assessment by ultrasound can be used as a noninvasive alternative to predict leak following supraglottic device insertion (I-gel) placement with the added advantage of no interruption of ventilation.

Changes in blood flow in the dorsal scapular artery and relationship to shoulder joint function in rotator cuff tears

One of the pain-related factors in rotator cuff tears (RCTs) is abnormal scapular motion, which is thought to be related to the levator scapulae muscle activation. Additionally, attention has recently focused on the peak systolic velocity (PSV) as one of the causes of pain, but blood flow outside of the vessels supplying the rotator cuff has not been clarified. This study aimed to determine the difference in PSV in the dorsal scapular artery (DSA), which is the vessel that supplies the levator scapulae muscles, and the association between PSV and pain and shoulder function in patients with RCTs between the tear and nontear sides. This study included 31 patients with RCTs with tear and nontear sides. Magnetic resonance imaging and radiographic examinations included Cofield classification, Goutallier classification, thickening of the coracohumeral ligament, and measurement of the acromiohumeral interval. Clinical evaluation included an automatic range of motion (ROM) for flexion, abduction, and external rotation (ER), a visual analog scale, and the Shoulder36. PSV was evaluated using ultrasound pulsed Doppler mode to assess PSV of DSA. The PSV of DSA on the first rib was drawn in the medial aspect of the suprascapular angle in the long axis, and the maximum PSV waveform was measured three times. The average value was used for further analysis. The PSV in the DSA was significantly higher (P=.04, 95% confidence interval: 0.2-7.6) on the tear (22.6±7.4 cm/s) than the nontear sides (18.9±6.9 cm/s). In addition, a significant negative correlation (r=-0.46, P=.0087) was found between PSV in DSA and ER on the tear side. This study revealed a significantly increased PSV in the DSA on the tear side in RCTs and negatively correlated with ER ROM. The results suggest that increased PSV in the DSA may contribute to ER ROM limitation in the glenohumeral joint.

Fundamental validation of flow volume measurement by ultrasound pulse Doppler method using simulated circuit

Fundamental validation of flow volume measurement by ultrasound pulse Doppler method using simulated circuit

Predictive Model for the Type of Active Retinopathy of Prematurity Based on Data from Angiological Studies

The purpose — to develop a prognostic model of the type of active retinopathy of prematurity (ROP) based on informative prognostic parameters of optical coherence tomography of the retina in angio-mode (OCT-A) and color duplex scanning (CDS) for a reliable choice of patient management tactics.Patients and methods. 30 premature infants (30 eyes) with favorable and unfavorable types of 1–3 stages of active ROP were performed with optical coherence tomography of the retina in angio-mode. Children were born at a gestational age of 25–34 weeks. The birth weight of children was 680–2030 g. 55 premature infants (55 eyes) with active ROP were performed with CDS in modes of color Doppler mapping and pulsed Doppler sonography. Children were born at a gestational age of 25–32 weeks. The birth weight of children was 680–1760 g. ROC analysis was used to estimate the prognostic information content of the quantitative indicators of OCT-A and CDS in relation to the type of active ROP. The discriminant analysis was used to estimate the contribution of the studied quantitative indicators to the intergroup differences in the type of active ROP. A regression model was built to obtain a prediction of a favorable or unfavorable type of disease. The assessment of the acceptability of the model as a whole was carried out according to the index of determination and the level of significance of the resulting model (p &lt; 0.05).Results. The most informative prognostic indicators of the type of active ROP were determined, according to OCT in angio-mode: the area of the foveal avascular zone — and, according to CDS: maximum systolic and end diastolic blood flow velocity in the ophthalmic artery, maximum systolic blood flow velocity in the posterior short ciliary arteries, minimum velocity blood flow in the central retinal vein. On the basis of informative indicators, a reliable prognostic model of the type of active ROP was built, which has two independent variables: the area of the foveal avascular zone and the end diastolic blood flow velocity in the ophthalmic artery. The dependent variable can take values close to 0, which determine the favorable type of the disease, or close to 1, which determines the unfavorable type of the disease.Conclusion. The introduction of the obtained model into clinical practice will allow to objectively determine the unfavorable course of the pathological process at the earliest stages, as well as to carry out early treatment of active ROP.

The state of ocular arterial blood flow in active retinopathy of prematurity

Purpose: to study the state of blood flow in the ocular arteries of patients with various forms, stages and course types of active retinopathy of prematurity (ROP). Material and methods. Colour duplex scanning was performed by colour Doppler mapping and pulsed Doppler sonography for 55 premature babies (55 eyes) with active ROP and 8 premature babies (8 eyes) without ROP signs. The children’s gestation age was 25 to 32 weeks, and the body weight at birth was 680 to1760 g. Blood flow was examined in the ophthalmic artery (OA), the central retinal artery (CRA) and the medial and lateral posterior short ciliary arteries (PSCA). Results. The ophthalmic artery revealed no significant differences between the children with ROP and without ROP, except for a significant increase in the peak systolic velocity (Vsyst) in an unfavorable course of stage III of ROP. The development of aggressive posterior ROP is accompanied by a statistically insignificant decrease in blood flow velocity of OA. Hemodynamic parameters of CRA indicate an increase in peripheral vascular resistance in children with an unfavorable course of ROP. A significant increase of Vsyst in the posterior short ciliary arteries was revealed in children with an unfavorable course of stages I–III of ROP and Vsyst, and Vdiast (diastolic blood flow velocity) in children with aggressive posterior ROP as compared with children without ROP. A pronounced impact of the ROP course (favorable or unfavorable) on the Vsyst, Vdiast, and PI indicators in the posterior short ciliary arteries was revealed. The most informative hemodynamic parameters in predicting the course of active ROP are Vsyst and Vdiast values in the ophthalmic artery and Vsyst in the posterior short ciliary arteries. The least informative were the hemodynamic parameters of the central retinal artery. Conclusion. The assessment of hemodynamic changes in eye arteries may be used as an additional diagnostic criterion in the early diagnosis of ROP.

Is there a Correlation between Hepatic Venous Indices and Main Pulmonary Artery Diameter?

To search whether there is a correlation between middle hepatic venous indices (HVIs) obtained by pulsed waved doppler ultrasonography (PW-DUS) and the main pulmonary artery (mPA) diameter, calculated by computed tomography (CT). A descriptive cross-sectional study. Department of Radiology, Balikesir University School of Medicine, Turkey, from February to December 2020. After excluding the cases with suspected COVID-19 from the cases sent to the Radiology Department for chest CT exams with the mPA included in the cross-sections, the volunteers were evaluated with PW-DUS. The study group consisted of 66 cases. Two radiologists measured the velocity values of the A, S, and D waves in the recorded PW Doppler spectra. HVIs (A/S, A/S+D, A/A+S+D) were calculated. The mPA diameter was calculated in the axial plane from the pulmonary trunk, 1cm proximally to the bifurcation manually on the workstation. The correlation between the HIVs and mPA diameter was evaluated. Interoperator reliability was also analysed. Thirty-nine males (59%) and 27 (41%) females were included in the study group. The mean HVI values were 0.50 ±0.20, 0.28 ±0.12, and 0.21 ±0.07 for A/S, A/A+S, and A/A+S+D, respectively. The mean mPA diameter was 24.0 ±3.3 mm. Correlation analysis determined that the HVIs were positively correlated with mPA diameter (r=0.730-0.765-0.751, p<0.001). Inter-observer correlation coefficients were found to be compatible between two radiologists. A significant and strong correlation was found between HVIs and mPA diameter. The mPA diameter that reflects the pulmonary artery systolic pressure (PAP) increased as the HVIs increased. Therefore, PW-DUS may be helpful to evaluate PAP as a quantitative method that is cost-effective, easily accessible and radiation-free. Hepatic veins, Pulmonary artery, Multidetector computed tomography, Pulmonary hypertension, Pulsed doppler ultrasonography.

Behaviors of sliding bubbles in an inclinable turbulent channel flow investigated by optoacoustic measurement

Bubbles sliding in the vicinity of inclined walls are experimentally investigated to understand their fundamental behavior inside a turbulent boundary layer. A qualitative visualization confirms that the bubble shape varies with changes in channel inclination. An optoacoustic measurement technique is adopted to investigate the sliding motion of the bubbles. The diameters and advection velocities of individual bubbles are obtained from particle-tracking-type image processing, while the liquid velocity profiles in the bubbly flow and the maximum distance between the wall and bottom of the bubble are obtained using an ultrasound pulsed Doppler method. The combined measurement confirms that the effect of buoyancy on the slip velocity of the bubble is enhanced by an increase in inclination. Moreover, the drag and buoyancy determine the bubble shape in the inclined condition. The drag coefficient is derived from the measured variables using a force balance equation between drag and buoyancy, and we reveal that the drag coefficient increases with the inclination angle up to 35°. Finally, we propose a modeling equation for the drag coefficient in terms of the Weber number, inclination angle, and ellipticity of the bubble. This equation is applicable to bubbles inside turbulent boundary layers.

Effects of a single dose of long-acting FSH on testicular blood flow, testicular echotexture, and circulating testosterone, estradiol, and nitric oxide in rams during the non-breeding season

The present study investigated the effect of a single administration of long-acting follicle simulation hormone (FSH) on testicular blood perfusion as measured by pulsed-wave Doppler ultrasonography, testicular echotexture, and circulating testosterone (T), estradiol (E2), and nitric oxide (NO) in the plasma of rams in the non-breeding season. Twelve Ossimi rams were subjected to either a single administration of long-acting FSH subcutaneously (FSH group; n=6) or the vehicle (control group; n=6). Assessment of testicular hemodynamics at the level of the supratesticular artery was performed just before administration (0 h), and at 4, 24, 48, 72, 96, and 168 h after FSH or the vehicle administrations. Testicular volume (TV), and echotexture of testicular parenchyma including pixel intensity and heterogeneity were derived by the computer analysis software. Concentrations of T, E2, and NO were measured using commercial kits. Results revealed significant decreases (P ˂ 0.05) in the values of Doppler indices (resistive index: RI and pulsatility index: PI), especially at 48 h after administration of FSH (RI: 0.42 ± 0.02, PI: 0.56 ± 0.04) compared to their values in the control group (RI: 0.54 ± 0.03, PI: 0.77 ± 0.04). FSH administration induced significant decreases (P ˂ 0.05) in the pixel intensity of testicular parenchyma. Testicular volume and T concentrations were not significantly changed (P ˃ 0.05). Concentrations of E2 increased significantly (P ˂ 0.05) at 48 h and 72 h after FSH administration. (30.07 ± 5.23 pg/ml, 29.93 ± 1.44 pg/ml, respectively) compared to their values before FSH administration (14.63 ± 1.37 pg/ml). Concentrations of NO increased significantly (P ˂ 0.05) in the FSH group between 4 h to 48 h compared to the values in the control one. In conclusion, a single administration of long-acting FSH enhanced testicular blood perfusion as measured by pulsed Doppler ultrasonography in rams during the non-breeding season. Concurrently, significant increases in the concentrations of E2 and NO were found.

An exploratory study to identify neonatal arterial ischemic stroke: A single-center study

BackgroundNeonatal arterial ischemic stroke (NAIS) presents as seizures, including convulsions, subtle seizures, and apnea, and most patients experience neurological sequelae. Diagnosis is often delayed owing to low test sensitivity. The present study aimed to identify the early clinical diagnostic factors for NAIS in neonates with seizures. MethodsThe present study included 54 patients born at ≥36 weeks of gestation during the last 15 years who presented to the neonatal intensive care unit with neonatal seizures and underwent brain magnetic resonance imaging (MRI), 6 of whom were diagnosed with NAIS. Maternal background, clinical characteristics, and transcranial pulsed Doppler sonography results were retrospectively reviewed. ResultsOf the 24 patients who presented with convulsions or subtle seizures, 3 (13%) were diagnosed with NAIS and 3 of 30 patients (10%) presented with apnea. Maternal premature ventricular contraction complications were higher in the NAIS group than in the non-NAIS group (p = 0.01). NAIS group showed lower mean middle cerebral artery (MCA) resistance index (RI) was lower the non-NAIS group (p = 0.009), while the left–right RI difference (p = 0.019), mean MCA blood velocity (MnV; p = 0.04), and left–right MnV difference (p < 0.001) in cerebral blood flow velocities (CBFVs) were higher in the NAIS group. ConclusionsOur results revealed that maternal arrhythmia may be a diagnostic factor for NAIS in neonates with seizures. Early brain MRI is essential in neonates with seizures and findings of low MCA-RI, high MCA-MnV, or high left–right difference in CBFVs to distinguish between NAIS and non-NAIS.

Comparing The Resting Cardiovascular Response To Commonly Used Blood Flow Restriction Devices

Alone, blood flow restriction is used to decrease muscle atrophy or recovery time. However, it is unknown whetherdevices used in clinical or research settings elicit a similar stimulus when using similar protocols. PURPOSE: To compare cardiovascular responses between a commonly used research device (RES) and clinical device (CLIN). METHODS: Over one visit, 24 individuals’ cardiovascular response to blood flow restriction using CLIN and RES devices were measured on the right arm in a randomized and counterbalanced order. After 5 min of supine rest, arterial occlusion pressure (AOP) was measured, then during a second 5 min rest, a near-infrared spectroscopy device was placed at the muscle belly of the forearm to measure tissue deoxygenation (HHb, μm) and tissue saturation index (TSI, %). A pulse oximeter on the index finger measured heart rate (bpm) and % oxygen saturation. 0-10 scale ratings of perceived discomfort (RPE-D, AU) were also assessed. Blood flow (ml/min) was measured using pulsed wave Doppler ultrasonography at the brachial artery proximal to the antecubital space. All variables were assessed twice at 0% AOP and once at 50% AOP. Measures were spaced 1 min apart. Change scores (50% AOP - 0% AOP) and AOP presented as mean ± SD, were compared using Bayesian paired samples t-tests (JASP). RESULTS: AOP differed between RES (157.13 ± 19.54) and CLIN (143.17 ± 16.92; BF10 = 156.75). However, weak to moderate evidence suggested that changes in blood flow volume (RES: -33.13 ± 30.64; CLIN: -28.71 ± 28.75; BF10 = .41), TSI (RES: -4.68 ± 5.17; CLIN: -4.92 ± 5.50; BF10 = 0.23), heart rate (RES: 0 ± 3; CLIN: 0 ± 7; BF10 = 0.22), and oxygen saturation (RES: -1 ± 1; CLIN: -1 ± 1; BF10 = 0.25) did not differ between the devices. Moderate evidence suggested HHb for channel 1 (RES: 16.48 ± 5.50; CLIN: 16.41 ± 6.69; BF10 = 0.22), channel 2 (RES: 16.12 ± 4.84; CLIN: 15.89 ± 6.21; BF10 = 0.22), and channel 3 did not differ (RES: 15.44 ± 4.53; CLIN: 15.13 ± 5.78; BF10 = 0.23) between devices. Moderate evidence also suggested RPE-D did not differ (RES: 1.06 ± 1.29; CLIN: 1.10 ± 1.30; BF10 = 0.22). CONCLUSION: AOP measurements differed between devices, possibly due to cuff width, material, and/or assessment method. However, this did not lead to a difference in cardiovascular responses when applying a relative pressure of 50% AOP for each device.

Diagnostic Performance of Pulsed Doppler Ultrasound of the Common Femoral Vein to Detect Elevated Right Atrial Pressure in Pulmonary Hypertension.

Right atrial pressure (RAP) is an important prognostic criterion in pulmonary hypertension (PH). The main goals were to evaluate the following: (i) the accuracy of Doppler assessment of common femoral vein flow waveform to detect elevated RAP and (ii) the diagnostic accuracy of RAP assessed by echocardiography (eRAP). Fifty-seven patients, addressed for right heart catheterization, were included in a retrospective cross-sectional study during a 6-month period. Forty-five patients (78.9%) had PH confirmed by RHC. Elevated RAP was defined by RAP ≥ 10mmHg. Femoral venous stasis index (FVSI) was highly correlated to RAP on both univariate (p < 0.001) and multivariate analysis (p = 0.003), and showed good diagnostic performances to detect elevated RAP (specificity: 92.3% [80.0-99.3], diagnosis accuracy: 90.4 [77.4-97.3], positive likelihood ratio: 12.5 [3.01-51.97]). Diagnosis accuracy of eRAP was only 51.2% (36.2-66.1). FVSI is independently correlated to RAP and a useful tool to predict elevated RAP in PH patients.

Evaluation of Renal Blood Flow in Dogs during Short-Term Human-Dose Epoprostenol Administration Using Pulsed Doppler and Contrast-Enhanced Ultrasonography.

Simple SummarySince there is a lack of information regarding how epoprostenol, a prostacyclin, affects canine renal blood flow (RBF), we investigated the effects of short-term administration of epoprostenol at human doses of 2, 5, and 10 ng/kg/min intravenously for 20 min on RBF in six healthy dogs under anesthesia. The effects of short-term administration were investigated. As the dose of epoprostenol increased, peak systolic and end diastolic velocities of the renal arteries, maximum and minimum venous flow velocities of the interlobular and renal veins, and heart rate all tended to increase. However, these increases were not significant. These results indicate that the administration of human doses of epoprostenol to dogs does not produce significant changes in renal or systemic circulation.Prostacyclin is an in vivo bioactive substance that regulates renal blood flow (RBF). Information regarding how epoprostenol, a prostacyclin preparation, affects RBF in dogs is lacking. We investigated the effects of short-term epoprostenol administration on RBF in six healthy dogs under anesthesia by administering it intravenously at human doses—2, 5, and 10 ng/kg/min for 20 min. RBF was evaluated before and during epoprostenol administration using pulsed Doppler ultrasonography, and renal perfusion was evaluated using contrast-enhanced ultrasonography. Effects on renal and systemic circulation were evaluated by measuring systolic arterial, mean arterial, diastolic arterial, pulmonary arterial, mean right atrial, and pulmonary capillary wedge pressures; heart rate; and cardiac output. Kruskal–Wallis and Bonferroni multiple comparison tests and Spearman’s rank correlation coefficient were used for statistical analyses. As epoprostenol dosage increased, the peak systolic and end diastolic velocity of the renal artery, maximum and minimum venous flow velocities of the interlobular and renal veins, and heart rate all tended to increase, although not significantly. Our results indicate that human-dose epoprostenol administration in dogs does not cause significant changes in renal or systemic circulation. However, the human doses used may have been too low to produce a clinical effect in dogs.

Lift coefficient of bubble sliding inside turbulent boundary layers in an inclinable channel flow

The behavior of bubbles traveling in the proximity of a tilted wall is studied experimentally to understand the fundamental sliding motion of bubbles inside turbulent boundary layers along an inclined wall. The qualitative visualization of sliding bubbles confirms the contribution of bubble buoyancy on the sliding motion for negative and positive inclinations of the channel. An opto-acoustic combined measurement technique is adopted to explore the sliding motion. Liquid velocity profiles in the bubbly flow and the distance between the wall and bottom of the bubble are obtained using the ultrasound pulsed Doppler method, while the bubble diameters and velocities are obtained from particle-tracking type image processing. The combined measurements reveal that the velocity of bubbles decreases under the negative slope condition and increases under the positive slope condition due to opposite buoyancy effects. In addition, the distance between the wall and bottom of the bubble increases with an increase in negative inclination. The lift coefficient is derived from the measured variables using a force–balance equation among the buoyancy, lift, and surface tension. Finally, we propose modeling equations for the lift coefficient expressed in terms of the Reynolds, Weber, and Bond numbers, which apply to the bubbles inside boundary layers.

Exogenous L-carnitine Administration Ameliorates the Adverse Effects of Heat Stress on Testicular Hemodynamics, Echotexture, and Total Antioxidant Capacity in Rams.

Heat stress (HS) diminishes the testicular antioxidant defense systems, which adversely affect the testicular blood perfusion. Improving the testicular hemodynamics during HS conditions is of a great impact on the whole reproductive performance in rams. This study aimed to evaluate the ameliorative effects of L-carnitine (LC) on the testicular blood flow and echotextures and also on the total antioxidants (TAC) and nitric oxide (NO) concentrations in the serum during HS conditions in rams. Testicular blood flow was evaluated through scanning of the supra-testicular artery (STA) spectral patterns through pulsed Doppler ultrasonography [peak systolic velocity (PSV), end-diastolic velocity (EDV), time average maximum velocity (TAMAX), resistive index (RI), and pulsatility index (PI)], while the echotexture assessment of testicular parenchyma was performed by a computerized software program. Moreover, TAC and NO concentrations were assayed colorimetrically using the spectrophotometer. There were significant decreases (P < 0.05) in values of PSV at 48 and 168 h (23.45 ± 0.39 and 23.37 ± 1.41 cm/s, respectively), and TAMAX at 1, 48, and 168 h (17.65 ± 0.95, 17.5 ± 0.13, and 16.9 ± 1.05 cm/s, respectively) after LC administration compared to just before administration (31.92 ± 1.13 and 21.58 ± 0.92 cm/s, respectively). Values of RI and PI of the examined STA significantly decreased, especially at 1 h for RI (0.45 ± 0.02) and 1 and 48 h for PI (0.66 ± 0.06 and 0.65 ± 0.05, respectively) after LC treatment to 0 h (0.55 ± 0.03 and 0.84 ± 0.06, respectively). The EDV values did not show any significant (P < 0.05) changes in all the experimental time points. There were significant (P < 0.05) increases in the values of pixel intensity of the testicular parenchyma, especially at 1 and 168 h (78.71 ± 2.50 and 88.56 ± 4.10, respectively) after LC administration, compared to just before administration (69.40 ± 4.75). Serum NO levels tend to increase after LC administration (P = 0.07) concerning just before administration. While TAC values showed significant gradual increase and reached the highest values at 168 h (2.75 ± 0.58 mM/l) after LC administration, compared to 0 h (1.12 ± 0.05 mM/l). In conclusion, exogenous LC administration ameliorates testicular hemodynamic disruptions, as measured by spectral Doppler ultrasonography, via augmentation of the rams' total antioxidant capacity under HS conditions.

Development of an instantaneous velocity-vector-profile method using conventional ultrasonic transducers

A velocity vector profile technique based on an ultrasound pulsed Doppler method can enrich the information on the flow field. However, it has shown low availability because a new design of special transducers is required for each measurement case. This study proposes a new method of profiling the velocity vectors using conventional ultrasound transducers that are widely supplied to ultrasound velocity profile users. We constructed a configuration of transducers to minimize the uncertainty of the detection points at the receivers, and a measurable distance was theoretically determined by the configuration. Two feasibility tests were carried out. One was a test for the assessment of the measurable distance, which agreed well with the theoretical distance. The other was the evaluation of the measurement of 2D velocity vectors by the new method, and it was performed in a towing tank facility without the velocity fluctuation. From the evaluation, it was confirmed that the measured vectors showed good agreement with the reference values, and their accuracy and precision were competitive compared to previous studies. In order to demonstrate this, the developed method was applied to two unsteady flows. The results clarified that the proposed method guarantees high availability and accuracy for the velocity vector profiles.

Fetal pulmonary hemodynamics: Doppler reference values in low risk pregnancies

Objective To investigate fetal pulmonary hemodynamics in normal pregnancy using pulsed and color Doppler ultrasonography and to define Doppler reference ranges values in the whole fetal pulmonary circulation during different gestational ages. Materials and methods A prospective observational study was conducted to evaluate 190 healthy singleton pregnancies between 20 and 38 weeks of gestation, including 10 cases for each gestational age. The main pulmonary artery, right pulmonary artery, left pulmonary artery, ductus arteriosus and pulmonary veins waveforms were evaluated. The waveform profile was studied for each pulmonary vessel investigated. We calculated the normal distribution of data of 12 Doppler parameters, their values were expressed as 5th, 25th, 50th, 75th and 95th centile. Results We report several pulmonary hemodynamic changes with the progression of pregnancy. We focused on the hemodynamic values of the parameters most useful in clinical practice and that would better describe the hemodynamic events of this vascular district. Conclusion This study reports a complete description of the fetal pulmonary hemodynamics at different gestational ages. Many hemodynamic parameters show a typical change during gestation. The reference ranges described in this study may help in situations where is indicated to evaluate the pulmonary hemodynamics and to identify healthy fetuses from those affected by pathological conditions related mainly to fetal cardiovascular anomalies and/or feto-maternal pathologic conditions.

Peripheral chemoreflex activation and cardiac function during hypoxemia in near-term fetal sheep without placental compromise.

A drop in arterial oxygen content activates fetal chemoreflex including an increase in sympathetic activity leading to peripheral vasoconstriction and redistribution of blood flow to protect the brain, myocardium, and adrenal glands. By using a chronically instrumented fetal sheep model with intact placental circulation at near-term gestation, we investigated the relationship between peripheral chemoreflex activation induced by hypoxemia and central hemodynamics. A total of 17 Åland landrace sheep fetuses at 115-128/145 gestational days were instrumented. Carotid artery was catheterized in 10 fetuses and descending aorta in 7 fetuses. After a 4-day recovery, baseline measurements of fetal arterial blood pressures, blood gas values, and fetal cardiovascular hemodynamics by pulsed Doppler ultrasonography were obtained under isoflurane anesthesia. Comparable data to baseline were collected 10 min (acute hypoxemia) and 60 min (prolonged hypoxemia) after maternal hypo-oxygenation to saturation level of 70%-80% was achieved. During prolonged hypoxemia, pH and base excess (BE) were lower and lactate levels were higher in the descending aorta than in the carotid artery. During hypoxemia mean arterial blood pressure (MAP) in the descending aorta increased, whereas in the carotid artery, MAP decreased. In addition, right pulmonary artery pulsatility index values increased, and the diastolic component in the aortic isthmus blood flow velocity waveform became more retrograde, thus decreasing the aortic isthmus antegrade/retrograde blood flow (AoI Net Flow) ratio. Both fetal ventricular cardiac outputs were maintained even during prolonged hypoxemia when significant fetal metabolic acidemia developed. Fetal chemoreflex activation induced by hypoxemia decreased the perfusion pressure in the cerebral circulation. Fetal weight-indexed left ventricular cardiac output (LVCO) or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.NEW & NOTEWORTHY During fetal hypoxemia with intact placental circulation, peripheral chemoreflex was activated, as demonstrated by an increase in the descending aorta blood pressure, pulmonary vasoconstriction, and an increase in retrograde diastolic AoI blood flow, while both ventricular cardiac outputs remained stable. However, perfusion pressure in the cerebral circulation decreased. These changes were seen even during prolonged hypoxemia when significant metabolic acidosis developed. Weight-indexed LVCO or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.