Time-averaged Peak Velocity Research Articles

Cerebrovascular pulsatility indicates preoperative subcortical cognitive impairment and an increased risk for postoperative delirium in elderly patients undergoing elective spine surgery.

Advances in spine surgery enable safe interventions in elderly patients, but perioperative neurocognitive disorders (pNCD), such as post-operative delirium (POD) and cognitive dysfunction (POCD), remain a serious concern. Pre-operative cognitive impairment is a major risk factor for pNCD. Comprehensive pre-operative cognitive assessments are not feasible in clinical practice, making effective screening methods desirable. This study investigates whether pre-operative cerebrovascular duplex sonography can assess subcortical (vascular) cognitive impairment and the risk for POD. This prospective single-center study recruited patients aged ≥60 years scheduled for elective spine surgery at a German university hospital. Patients underwent pre-operative assessments including cognitive abilities (CERAD test battery), structural MRI, and cerebrovascular duplex sonography. POD screening was conducted three times daily for at least 3 days. The primary hypothesis, that the mean pulsatility index (PI) of both internal carotid arteries (ICA) predicts POD risk, was tested using logistic regression. Secondary analyses examined the association between POD risk and ICA flow (time-averaged peak velocities, TAPV) and correlations with cognitive profiles and MRI characteristics. POD occurred in 22% of patients (n = 22/99) within three postoperative days. Patients with POD were significantly older (75.9 ± 5.4 vs. 70.0 ± 6.9 years, p < 0.01) but did not differ by gender (p = 0.51). ICA PI significantly predicted POD risk (OR = 5.46 [95%CI: 1.81-16.49], p = 0.003), which remained significant after adjustment for age and duration of surgery (ORadj = 6.38 [95% CI: 1.77-23.03], p = 0.005). TAPV did not inform the POD risk (p = 0.68). ICA PI Pre-operative cognitive scores were significantly associated with ICA PI (mean CERAD score: r = -0.32, p < 0.001). ICA PI was also significantly associated with total white matter lesion volume (τ = 0.19, p = 0.012) and periventricular white matter lesion volume (τ = 0.21, p = 0.007). This is the first study to demonstrate that cerebrovascular duplex sonography can assess the risk for POD in elderly spine surgery patients. Increased ICA PI may indicate subcortical impairment, larger white matter lesion load, and lower white matter volume, predisposing factors for POD. Pre-operative cerebrovascular duplex sonography of the ICA is widely available, easy-to-use, and efficient, offering a promising screening method for POD risk. Increased ICA PI could supplement established predictors like age to adjust surgical and peri-operative procedures to individual risk profiles.

Exploring Cerebral Perfusion Transcranial Doppler Parameters in Patients Admitted to Combined Medical Surgical Intensive Care Unit

Introduction: Encephalopathy, a common complication in Intensive Care Unit (ICU) patients, is often linked to poor outcomes. Transcranial Doppler (TCD), a non-invasive tool assesses cerebral perfusion via the Pulsatility Index (PI), Resistivity Index (RI), and Time-Averaged Peak (TAP) or Mean Flow Velocity (MFV). These parameters may offer insights into cerebral perfusion and outcomes in encephalopathic patients. Aim: To describe the PI, RI of the Middle Cerebral Artery (MCA), and MFV or TAP measured by TCD in patients admitted to the ICU, comparing those with and without encephalopathy at the time of admission. Materials And Methods: This cross-sectional observational study was conducted from January 2019 to November 2020, in a combined medical-surgical ICU of a tertiary care hospital, involving 45 enrolled patients. Patients were evaluated within 24 hours of admission and subsequently every 24 hours until ICU discharge, death, or discharge against medical advice. Bilateral Middle cerebral artery TCD studies were conducted using a 1-5 MHz phased array probe or TCD mode through the transtemporal window. The PI, RI, and MFV were measured on both sides, with the higher value used for analysis, and all statistical analyses were performed using Statistics and Data 13 software. Results: In the present study, 88% (n=40) of patients had encephalopathy (GCS&lt;15 and RAAS less than or more than 0). The mean APACHE II score was 19 (14-25), indicating severe illness with a predicted mortality of 30-40%. Patients with encephalopathy had significantly higher APACHE II scores compared to those without (19.5 (16-25) vs 10 (4-19)). Although there was a trend towards a higher Pulsatility Index in encephalopathic patients at admission (1.11±0.378 vs 1.07±0.12, p=0.81), PI, RI, and TAP values did not significantly differ in non-survivors (1.12±0.49 vs 1.11±0.33, p=0.750). Persistent encephalopathy was associated with a trend towards higher PI at admission (1.05±0.24 vs 1.16±0.46; p=0.756), and a moderate correlation was found between decreasing PI and improvement in GCS (rho=-0.489, p=0.001). Conclusions: PI, RI, and TAP at the time of admission were not found to be associated with occurrence and recovery of encephalopathy as well as mortality. The trend of change in PI moderately correlated with improvement in GCS suggesting the importance of trends rather than absolute values.

Transcranial Color-Coded Sonography With Angle Correction As a Screening Tool for Raised Intracranial Pressure.

Transcranial Doppler (TCD) has been evaluated as a noninvasive intracranial pressure (ICP) assessment tool. Correction for insonation angle, a potential source of error, with transcranial color-coded sonography (TCCS) has not previously been reported while evaluating ICP with TCD. Our objective was to study the accuracy of TCCS for detection of ICP elevation, with and without the use of angle correction. Prospective study of diagnostic accuracy. Academic neurocritical care unit. Consecutive adults with invasive ICP monitors. Ultrasound assessment with TCCS. End-diastolic velocity (EDV), time-averaged peak velocity (TAPV), and pulsatility index (PI) were measured in the bilateral middle cerebral arteries with and without angle correction. Concomitant mean arterial pressure (MAP) and ICP were recorded. Estimated cerebral perfusion pressure (CPP) was calculated as estimated CPP (CPPe) = MAP × (EDV/TAPV) + 14, and estimated ICP (ICPe) = MAP-CPPe. Sixty patients were enrolled and 55 underwent TCCS. Receiver operating characteristic curve analysis of ICPe for detection of invasive ICP greater than 22 mm Hg revealed area under the curve (AUC) 0.51 (0.37-0.64) without angle correction and 0.73 (0.58-0.84) with angle correction. The optimal threshold without angle correction was ICPe greater than 18 mm Hg with sensitivity 71% (29-96%) and specificity 28% (16-43%). With angle correction, the optimal threshold was ICPe greater than 21 mm Hg with sensitivity 100% (54-100%) and specificity 30% (17-46%). The AUC for PI was 0.61 (0.47-0.74) without angle correction and 0.70 (0.55-0.92) with angle correction. Angle correction improved the accuracy of TCCS for detection of elevated ICP. Sensitivity was high, as appropriate for a screening tool, but specificity remained low.

Doppler indices of uterine arteries and mRNA transcripts of hormone receptors in cervix vis-à-vis dilatation therapy in buffaloes affected with incomplete cervical dilatation associated with uterine torsion

The present study aimed to investigate the Doppler indices and mRNA transcripts of hormone receptors in relation to the response of dilatation therapy in incomplete cervical dilatation (ICD) associated with uterine torsion in buffaloes. Out of 36 successfully detorted uterine torsion cases, eight buffaloes revealed a fully dilated cervix, while the remaining 28 had ICD, and subjected to dilatation therapy (500 μg cloprostenol + 2 mg estradiol benzoate + 80 mg valethamate bromide + 50 IU oxytocin + 250 mL calcium borogluconate). The responses of dilatation therapy were assessed in 26 buffaloes as one died, and one could not follow up. Doppler indices of middle uterine arteries on trans-rectal ultrasound were evaluated pre- and 30–60 min post-detorsion. Cervical tissue biopsies were collected from 16 buffaloes to study mRNA transcripts of hormone receptors. The duration, degree, location of uterine torsion, fetal viability, consistency of the cervix, relaxation of pelvic ligaments, udder engorgement, and gestation length were also recorded to evaluate the response of dilatation therapy. The 73.08% (19/26) buffaloes responded to the therapy with a duration ranging from 2 to 56 hrs (18.41 ± 4.11). The significantly increased blood flow volume (BFV) and time-average peak velocity (TAP) while the significantly reduced resistive index (RI) and pulsatility index (PI) in an ipsilateral middle uterine artery (MUA) at post-detorsion were observed in dilation therapy responded than the not-responded group. The mRNA transcripts of estradiol receptors-α (ESR1), prostaglandin receptors (PTGFR), and oxytocin receptors (OXTR) were upregulated by 7.47, 6.63, and 8.72-fold in the ICD group, respectively. The Doppler indices along with duration of illness, location of uterine torsion, consistency of the cervix, and udder engorgement can be used to predict the response of dilatation therapy in ICD associated with uterine torsion. The upregulated mRNA expression of ESR1, PTGFR and OXTR is mandatory for success of dilatation therapy.

Doppler parameters of ophthalmic artery in women with preeclampsia: A meta-analysis.

Preeclampsia is a progressive and severe cardiovascular disorder in pregnant women. To determine the potential significance of ophthalmic Doppler parameters in preeclamptic women and to provide evidence-based hints for clinical practice and scientific investigation. We searched PubMed, Embase, Web of Science, and the Cochrane Library till July 31, 2022. Pooled standardized mean difference (SMD) with 95% confidence intervals (CIs) were calculated using the random effects model. Heterogeneity across included studies was evaluated utilizing the Q test and I2 statistic. We identified 8 observational studies that met the inclusion criteria. The pooled SMD for peak systolic velocities (PSV) was .12 (95% CI: -.82, 1.06, p=.8071; I2 =94%, p<.0001). The overall SMD for time-averaged mean peak velocities (MV) was 1.79 (95% CI: .87, 2.71, p=.0001; I2 =60%, p=.1152). Regarding the pulsatility index (PI), the pooled SMD was -2.05 (95% CI: -3.12, -.98, p=.0002; I2 =92%, p<.0001). Overall SMD for end-diastolic velocities (EDV) was 1.11 (95% CI: .23, 1.98, p=.0136; I2 =92%, p<.0001). The pooled SMDs for resistance index (RI) and peak ratio (PR) was -.18 (95% CI: -1.90, 1.53, p=.8333; I2 =96%, p<.0001) and 1.46 (95% CI: -1.30, 4.22, p=.2994; I2 =99%, p<.0001), respectively. Publication bias was not identified. MV, PI, and EDV showed significant differences between patients with preeclampsia and non-hypertensive pregnant participants. Studies on the predictive performance of ophthalmic artery Doppler parameters are warranted.

Use of duplex echoencephalography to evaluate brain death in children: A novel approach to the diagnosis.

Brain death is defined as the irreversible cessation of brain function with a known etiology. This study aims to establish the value of duplex echoencephalography (DEG) in children fulfilling clinical brain death diagnostic criteria. DEG must show intracranial brain structures. Power Doppler is used to assess venous flow when feasible. Color Doppler patterns in all major arteries are assessed. Spectral analysis of arterial flow is divided into four grades: grade 1: inverted flow during entire diastole with time average peak velocity (TAPV) less or equal to zero; grade 2: disappearance of the inverted diastolic flow at the end of diastole; grade 3: oscillating pattern in early diastole; and grade 4: no diastolic flow with systolic blip. To fulfill diagnosis of brain death, brain perfusion must be lost for 30 minutes. DEG is performed in 41 pediatric patients. In infants, loss of venous flow occurs regardless of the etiology. Grade 1 is the most common arterial color flow pattern and TAPV is always below zero. A pulsatile color flow is associated with three other types of flow patterns (grades 2-4). TAPV is not calculated, when there is loss of diastolic flow. Diagnosis of brain death is validated using nuclear brain scan in 4patients. Two have a grade 1 flow pattern, while the other two have a grade 4 flow pattern. In children, DEG following a strict protocol can be used to confirm diagnosis of brain death in the appropriate clinical setting.

Transcranial Duplex Ultrasonography Measurements Towards Identification of Blood Vessel Conditions: Artificial Cerebral Blood Flow in Pathologies

Abstract The aim of the study was to investigate how cerebral vasospasm, vasodilation and haemorrhage under artificial circulation conditions during cardiopulmonary bypass affect transcranial duplex ultrasonography measurements. A description of transcranial duplex ultrasonography and phantom development is provided. Measurements were made using a commercially available ultrasound system and cardiopulmonary bypass machine, water phantom and 32% glycerol solution with cornstarch. The experiments showed that the cerebral blood vessel condition in artificial circulation affects transcranial duplex ultrasonography measurement limit values. The most sensitive parameter for blood vessel condition changes is Peak Systolic Velocity (PSV) for which changes were observed in 100% of cases. The most insensitive was Time-Averaged Peak-Velocity (TAPV), and Minimum Diastolic Velocity (MDV) for which changes were observed in 83% of cases.

Study on flow characteristics and diversity index of diamond-type boulder cluster with different spacing ratios.

The placement of boulder or boulder cluster in rivers can increase or repair the complexity of river structure and the diversity of hydraulic conditions, which is very important for the habitat of many aquatic organisms. In this study, the diamond-type boulder cluster was modeled as four hemispheres exposed to a fully developed turbulent open channel flow. Numerical simulation was conducted to investigate the time-averaged flow characteristics, three-dimensional coherent structures, turbulence characteristics, and flow diversity index at different spacing ratios L/D (the ratio of the distance L to the diameter D, 1.0 ≤ L/D ≤ 3.5, where L is the center-to-center distance between two adjacent hemispheres and D is the diameter of the hemisphere). The results show that with the increase of the spacing ratio, the shear layer on the side of the gap flow gradually strengthens, and the single Karman vortex street in the wake region of the hemisphere array is suppressed. The time-averaged peak velocity in the gap flow gradually decreases with the increase of the spacing ratio, and the single of the recirculation zone behind the hemisphere array transforms into the recirculation zone behind each hemisphere, and the length of the each recirculation zone increases to the same. The turbulence intensity of the array first increases with the increase of the spacing ratio and then gradually decreases to a constant, reaching the peak intensity at L/D = 2. Based on the Shannon entropy concept, the flow diversity index in the zone of influence (ZOI) is calculated by considering the velocity and turbulence kinetic energy. The flow diversity index is the largest in the ZOI at the spacing ratio of 1.5.

Pedal Musculovenous Pump Activation Effectively Counteracts Negative Impact of Knee Flexion on Human Popliteal Venous Flow.

Knee scooters are commonly used for mobility instead of other devices. However, passive popliteal venous flow impedance has been observed with knee scooter usage ostensibly as a result of deep knee flexion. This study aimed to characterize the magnitude of impact knee flexion has on popliteal venous flow in relation to the degree of knee flexion when walking boot immobilized. Furthermore, the countervailing effect of standardized pedal musculovenous pump (PMP) activation was observed. Popliteal venous diameter and flow metrics were assessed with venous ultrasonography in 24 healthy individuals. Straight leg, crutch, and knee scooter positioning while wearing a walking boot and non-weight-bearing were compared. Flow was assessed with muscles at rest and with PMP activation. Of 24 participants, 16 (67%) were female. Twelve limbs (50%) were right sided. The mean age was 21.9 (SD = 3.0) years, and the mean body mass index was 21.9 (SD 1.9) kg/m2. Observer consistencies were excellent (intraclass correlation range = 0.93 to 0.99). No significant differences in mean vessel diameter, time-averaged mean velocity, and total volume flow occurred (all P > .01). Corresponding knee flexion effect sizes were small (range = -0.04 to -0.26). A significant decrease (-24%) in active median time-averaged peak velocity occurred between upright and crutch positions (20.89 vs 15.92 cm/s; P < .001) with a medium effect size (-0.51). PMP activation increased all flow parameters (all P < .001), and effect sizes were comparatively larger (>0.6) across all knee flexion positions.Clinical Significance: Knee flexion has a small to medium impact on popliteal venous return in healthy patients. Active toe motion effectively counters the negative effects of gravity and knee flexion when the ankle is immobilized.Levels of Evidence: Therapeutic, Level IV.

Clinical and prognostic value of TAMX index of interlobar arteries of the middle segment in patients after allograph kidney transplantation in the late postoperative period

Introduction. Kidney transplantation has become the best treatment for patients with end-stage of chronic renal failure. The issues of studying the causes and mechanisms of the development of renal transplant dysfunction in the late postoperative period, the search for high-precision minimally invasive methods for early diagnosis of renal transplant dysfunction remain relevant, since this largely determines the further normal functioning of the organ and prognosis for the patient.The aim of the study was to investigate the clinical and prognostic value of the time-averaged peak velocity (TAMX) index of the interlobar arteries of the middle segment in patients after allograft transplantation in the long-term postoperative period.Material and research methods. For the period 2014-2015 ultrasound scan of renal grafts were performed in 26 patients with creatinine levels within the normative values. The average age of recipients in this group was 31.4 ± 1.67 years. Among the recipients there were 15 men (57.7%), 11 women (42.3%). Living related kidney transplantation (LRKT) were performed in 61.54% of patients, in 38.46% – cadaveric kidney transplantation (CKT). In all patients, the plasma creatinine level met the standard value or exceeded them by no more than 25%, fluctuating on average from 94 to 130 μmol / L, averaging 114.5 ± 3.85 μmol / L.The second study is based on the results of ultrasound scan of renal transplants in 26 patients with creatinine levels exceeding the standard values for the period 2015-2016. The average age of recipients in this group was 38.99 ± 2.32 (34.35-43.62) years. There were 14 men (53.84%) among the recipients, and 12 women (46.16%). LRKT were performed in 6 patients, in 20 – CKT. In all patients the plasma creatinine level was above normal values, fluctuating on average from 155 to 629 μmol / L, averaging 259.46 ± 35.33 μmol / L. The groups were comparable in terms of the main clinical and demographic parameters.Results. The method for predicting complications by the level of TAMX of the interlobar arteries of the middle segment of the kidneys during Doppler ultrasonography of the renal blood flow (&lt;15 cm / s) has a fairly high sensitivity (83.87%), specificity (79.31%), positive and negative predictive significance (81.25% and 82.14%, respectively) in the diagnosis of a high risk of developing late nephrodysfunction in recipients after organ transplantation. Recipients with allograft with a TAMX level of interlobar arteries (middle segment) of more than15 cm / s, as a result of our examination, had a serum creatinine level 2.35 times less, and the glomerular filtration rate is almost 2 times higher than similar indicators in patients with a TAMX level less15 cm / s (p &lt;0.01), which confirms the presence of more expressive manifestations of chronic allograft dysfunction.The interdependence between the TAMX of the interlobar arteries of the middle segment and serum creatinine, which is gradually regressing in a parabola, shows that more than half of the entire variance of the creatininemia sign can be associated with a change in the TAMX indicator (as a sign of deterioration in the renal blood flow of the graft), and the largest "failure" of the function were observed in the range from 12 to15 cm/ s TAMX, where in the overwhelming majority of cases (about 80%) there were impaired renal hemodynamics and the available laboratory markers of impaired renal function (creatinine above 200 μmol / l).Conclusions. A reliable prognostic value of TAMX of interlobar arteries (middle segment) was shown in spectral Doppler ultrasonography of renal blood flow in a priori assessment of the risk of developing post-transplant nephropathy, which allows us to consider it as a cumulative predictor of an unfavorable prognosis and a potential factor not only for the formation of graft dysfunction, but also for rejection in the late postoperative period.

The Effect of Knee Flexion on Active and Passive Popliteal Venous Flow When Using Crutches or Knee Scooter While Immobilized

Category:Trauma; OtherIntroduction/Purpose:Knee flexion has been demonstrated to impede popliteal venous return with large effect size among patients lying supine for surgery. Passive popliteal flow impedance has also been suggested to occur with knee scooter usage due to knee flexion. This study compared the effect of knee flexion angles on popliteal venous return between upright, crutch and knee scooter positioning when immobilized. Further, the countervailing effect of standardized hallux musculovenous pump activation was observed.Methods:This was an IRB approved study of young, healthy volunteers. Popliteal venous diameter and flow metrics were assessed with venous ultrasonography and compared between straight leg, crutch, and knee scooter positioning while wearing a walking boot and nonweightbearing. Flow was assessed with muscles at rest and with hallux musculovenous pump activation via active oscillation between hallux metatarsophalangeal joint extension and flexion at one motion per second (0.5 Hz) as paced by a metronome. Observer consistency was assessed. Paired-sample Student’s t-test and the Wilcoxon signed rank tests were used to assess within-subject differences for diameter and venous flow parameters, respectively. Knee flexion and musculovenous pump activation effects sizes were calculated. A priori sample size indicated 24 subjects were needed to achieve 80% power to detect a significant ( p < 0.006 ) difference in medial flow for any of 8 comparisons, assuming large effect sizes.Results:16 of 24 (67%) subjects were female. Twelve limbs (50%) were right sided. The mean age was 21.9 years (SD 3.0 years) and the mean body mass index was 21.9 (SD 1.9). Observer consistencies were excellent (0.93 to 0.99). No significant differences in mean vessel diameter, time-averaged mean velocity, and total volume flow occurred. Corresponding knee flexion effect sizes were small (range -0.04 to -0.26). A significant decrease (-24%) in active median time-averaged peak velocity (TAPV) occurred between upright and crutch position (20.89 cm/s vs. 15.92 cm/s, p < 0.001) with a medium effect size (-0.51). Hallux musculovenous pump increased all flow parameters (all p< 0.001) and effect sizes were comparatively larger (>0.6) across all knee flexion positions.Conclusion:Compared to values reported for supine individuals, upright passive popliteal venous return was observed to be markedly diminished at all knee flexion angles. Knee flexion had minimal effect on diameter, a small effect in further diminishing TAMV and TVF and a medium effect on diminishing TAPV. Hallux musculovenous pump activiation had a large effect on increasing flow at all knee flexion angles. Patients may well be counseled to use toe motion to counter the negative effects of gravity, and to a lesser extent knee flexion, when using crutches and knee scooters while their ankle is immobilized.

Critically Ill COVID-19 Patients With Acute Kidney Injury Have Reduced Renal Blood Flow and Perfusion Despite Preserved Cardiac Function: A Case-Control Study Using Contrast-Enhanced Ultrasound.

Acute kidney injury (AKI) is a common complication of COVID-19 critical illness but the pathophysiology is uncertain. Some evidence has indicated that a vascular aetiology may be implicated. We used contrast-enhanced ultrasound (CEUS) and echocardiography to study renal perfusion and global blood flow and compared our findings with measurements taken in a group of septic shock patients and healthy volunteers. Prospective case-control study. Renal perfusion variables were assessed with CEUS; macrovascular blood flow was assessed using Doppler analysis of large renal vessels; echocardiography was used to assess right and left heart function and cardiac output. CEUS-derived parameters were reduced in COVID-19 associated AKI compared with healthy controls (perfusion index 3,415 vs. 548 a.u., P = 0·001; renal blood volume 7,794 vs. 3,338 a.u., P = 0·04). Renal arterial flow quantified using time averaged peak velocity was also reduced compared with healthy controls (36·6 cm/s vs. 20·9 cm/s, P = 0.004) despite cardiac index being similar between groups (2.8 L/min/m2 vs. 3.7 L/min/m2, P = 0.07). There were no differences in CEUS-derived or cardiac parameters between COVID-19 and septic shock patients but patients with septic shock had more heterogeneous perfusion variables. Both large and small vessel blood flow is reduced in patients with COVID-19 associated AKI compared with healthy controls, which does not appear to be a consequence of right or left heart dysfunction. A reno-vascular pathogenesis of COVID-19 AKI seems likely.

Doppler perfusion index in adolescents with non-alcoholic fatty liver disease

Introduction: Non-alcoholic fatty liver disease (NAFLD) as a multi-factorial disorder is the most common cause of abnormal liver function tests in adolescents. Objectives: The present study aimed to assess Doppler perfusion index (DPI) in adolescents with NAFLD as compared with healthy subjects. Patients and Methods: Thirty-seven adolescents with NAFLD and 25 healthy individuals were enrolled in the study. Hemodynamic indices were measured using a color Doppler ultrasound machine. Severity of fatty liver disease and steatosis grade were assessed using FibroScan. The measured indices were peak systolic velocity (PSV), resistive index (RI), end-diastolic velocity (EDV), time-averaged mean velocity (TAMV), time-averaged peak velocity (TAPV), portal venous blood flow (PVBF) volume, hepatic arterial blood flow (HABF) volume, and DPI. Results: The mean of DPI in the case and control groups was 0.31±0.11 and 0.31±0.09, respectively (P=0.972). HABF volume was significantly lower in the case group as compared with the control group (103.8 versus 153.3 respectively, P=0.015). PSV, TAMV, mean velocity, and PVBF volume were significantly lower in the case group as compared with the control group (P&lt;0.05). Patients with a higher steatosis grade indicated a significantly lower mean of PSV and TAMV portal than controls (P&lt;0.05). Conclusion: DPI was similar in adolescents with NAFLD and healthy subjects and was not associated with severity of fatty liver disease and steatosis grade. In addition, the percentage of steatosis would be increased with increased liver span.

Critically Ill COVID-19 Patients with Acute Kidney Injury Have Reduced Renal Blood Flow and Perfusion Despite&amp;nbsp;Preserved Cardiac Function; A Case-Control Study Using Contrast Enhanced Ultrasound

Background: Acute Kidney Injury (AKI) is a common complication of COVID-19 critical illness but the pathophysiology is uncertain. Some evidence has indicated that a vascular aetiology may be implicated. We used contrast enhanced ultrasound (CEUS) and echocardiography to study renal perfusion and global blood flow and compared our findings with measurements taken in a group of septic shock patients and healthy volunteers. Method: Prospective case-control study. Renal perfusion variables were assessed with contrast enhanced ultrasound (CEUS); macrovascular blood flow was assessed using Doppler analysis of large renal vessels; echocardiography was used to assess right and left heart function and cardiac output. Findings: CEUS derived parameters were reduced in in COVID-19 associated AKI compared to healthy controls (perfusion index 3415 v 548 a.u., p=0·001; renal blood volume 7794 v 3338 a.u., p=0·04). Renal arterial flow quantified using time averaged peak velocity (TAPV) was also reduced compared to healthy controls (36·6 v 20·9 cm/s, p=0.004) despite cardiac index being similar between groups (2.8 v 3.7 L/min/m2, p=0.07). There were no differences in CEUS derived or cardiac parameters between COVID-19 and septic shock patients but patients with septic shock had more heterogeneous perfusion variables. Interpretation:Both large and small vessel blood flow is reduced in patients with COVID-19 associated AKI compared to healthy controls, which does not appear to be a consequence of right or left heart dysfunction. A reno-vascular pathogenesis of COVID-19 AKI seems likely. Funding: Royal Centre for Defence Medicine (UK Ministry of Defence), 2019; European Society of Intensive Care Medicine Point of Care Ultrasound award, 2019 Declaration of Interests: All authors declare that they have no conflicts of interest. Ethics Approval Statement: Yorkshire and Humber (Leeds East) Research Ethics committee (18/YH/0371).

Doppler indices of middle uterine artery as a tool for predicting the fetal status in cattle with uterine torsion and the recovery of uterine blood flow subsequent to detorsion

The aim was assessment of blood flow to uterus in cattle suffering from uterine torsion as a tool for predicting the fetal survivability after detorsion. Dairy cattle (14) with uterine torsion were detorted and fetal delivery was completed within 30 min after detorsion. Doppler sonography of middle uterine artery ipsilateral (IpsiUA) and contralateral (ContUA) to the side of torsion was carried out before uterine detorsion and 30 min after fetal delivery for Doppler indices, viz. blood flow volume (BFV), time-averaged peak velocity (TAP), resistance index (RI) and pulsatility index (PI). Before uterine detorsion, RI-IpsiUA and PI-IpsiUA were high in comparison to their values in ContUA. Although RI-IpsiUA and PI-IpsiUA had difference between their values before uterine detorsion and 30 min after fetal delivery, but in contrast, at the same time point, there was no difference in RI-ContUA and PIContUA. In comparison to RI-IpsiUA and PI-IpsiUA before detorsion, their respective values decreased after fetal delivery subsequent to successful detorsion, and were almost similar to their respective post-fetal delivery RIContUA and PI-ContUA. In cases where fetus after detorsion of uterus was delivered dead, in the middle uterine artery ipsilateral to the side of uterine torsion, BFV-IpsiUA and TAP-IpsiUA were low, whereas PI-IpsiUA were high. In conclusion, depicting the blood flow within middle uterine artery using Doppler sonography could be helpful in predicting the viability of fetus in uterine torsion affected cattle and may confirm the resumption of blood flow to uterus subsequent to detorsion.

Assessment of Hemodynamic Alterations in Cerebral Veins in Patients With Intracerebral Hemorrhage Using Duplex Color-Coded Sonography.

To investigate the contributions of hemodynamic alterations in cerebral veins to the prognosis of patients with primary intracerebral hemorrhage (ICH). Duplex color-coded sonography was performed on 87 ICH patients between July 2016 and October 2017. The time-averaged peak velocity, the time-averaged mean velocity (TAMV), the blood flow volume (BFV) of bilateral internal jugular veins (IJVs) and vertebral veins (VVs), and the mean velocities of bilateral basal veins of Rosenthal, straight sinus, and bilateral transverse sinuses were calculated to understand the relationship of hemodynamic data with prognosis in patients with ICH. The study revealed that the time-averaged peak velocities, TAMVs and BFVs of both right IJV and VV in ICH patients with good clinical outcomes were higher than those of the left IJV and VV, whereas statistically significant differences were not found in the mean velocity of bilateral veins of Rosenthal. The perihematomal edema volume, time-averaged peak velocities, TAMVs, and BFVs of the bilateral IJVs and right VV and the TAMV of the left VV were associated with the prognosis of ICH patients in the univariate analysis. However, the TAMV of the right IJV and BFV of the left IJV were the independent factors that predicted prognosis in multivariate analysis. Partial correlation showed that there was a linear dependence between the differences in TAMV and BFV between bilateral IJVs. The presence of hemodynamic changes in cerebral veins in patients with ICH has an impact on prognosis.

Impact of Flow Differentials According to Cardiac and Respiratory Cycles on Three Types of Fontan Operation.

Few hemodynamic comparison studies on various types of Fontan operation have been reported. The objective of this study was to perform hemodynamic comparisons for flow size and volume in three types of Fontan operation: atriopulmonary connection (APC), lateral tunnel (LT), and extracardiac conduit (ECC). Forty patients with Fontan operation (8 with APC Fontan, 22 with LT Fontan, and 10 with ECC Fontan) were enrolled. Velocity time integral (VTI) and average peak velocity (APV) were assessed according to cardiac and respiratory cycles in SVC, IVC, hepatic vein, conduit, LPA, and RPA using direct intravenous Doppler echocardiography. During each cardiac cycle in APC, VTI and APV between inspiration and expiration did not show significant differences in SVC, IVC, HV, LPA, or RPA. During each cardiac cycle in LT and ECC, VTI and APV between inspiration and expiration showed significant differences in all native vessels. The gap between S and D wave in APC was the highest, followed by that in LT. It was the lowest in ECC regardless of inspiration or expiration. Hepatic reverse VTI and APV in APC showed significant decreases compared to those in VC and PA during inspiration and expiration. Flow size and volume in APC were more influenced by cardiac cycle. Those in LT were moderately influenced by both respiratory cycle and cardiac cycle while those in ECC were more influenced by respiratory cycle. APC Fontan has hemodynamic inefficiency with prominent reverse flow. However, total cavopulmonary connection (TCPC) Fontan has more hemodynamic efficiency without prominent reverse flows.

Correlation Between Fetal Weight Gain and Birth Weight with Blood Flow in the Uterine Arteries Calculated with the PixelFlux Technique.

Introduction The aim was to investigate correlations between fetal weight gain/day and birthweight with blood flow estimates in the uterine arteries calculated with the PixelFlux technique and with measurements from TAmax. We also aimed to examine the agreement between estimates using the two methods. Material and methods We conducted a prospective observational pilot study in pregnancy week 24–25 in women with risk pregnancies referred to the fetal medical centre at St. Olavs Hospital, Trondheim, Norway from March 2016 to June 2016. Blood flow in the uterine arteries was calculated using time-averaged peak velocity (TAmax) and the PixelFlux technique. PixelFlux is a method based on pixelwise calculation of spatially angle-corrected velocities and areas of all pixels inside a vessel during a heart cycle. Results The mean flow calculated from PixelFlux and TAmax was 811 ml/minute and 787 ml/minute, respectively. The intra-class correlation coefficient was 0.83 (95% CI 0.72-0.90) and limits of agreement were −441 ml/minute (95% CI -558 to −324 ml/minute) to 489 ml/minute (95% CI 372 to 606 ml/minute). We observed a significant correlation between mean flow calculated from PixelFlux and birthweight (r=0.41; p<0.01) and between flow calculated from PixelFlux and weight gain/day (r=0.33; p=0.02). Calculation based on TAmax was significant correlated to birthweight (r=0.34; p=0.02), but not to weight-gain/day. Pulsatile index was not correlated to flow, birthweight or fetal weight-gain/day. Conclusions We found significant correlations between estimated blood flow in the uterine arteries using the PixelFlux technique with fetal weight-gain/day and with birthweight. Estimates from two methods showed good agreement.

Abstract 12861: Assessment of Both Coronary Microvascular Damage and Epicardial Flow Velocity Measurement Immediately After Successful Percutaneous Coronary Intervention Predicts In-Hospital Complications and Survival in ST-Segment Elevation Myocardial Infarction

Background: Quantitative measurement of post-reperfusion epicardial flow velocity by a Doppler guidewire can predict clinical cardiac events in ST-segment elevation myocardial infarction (STEMI). It has also been reported that the coronary flow velocity pattern in patients with microvascular obstruction is characterized by the presence of early systolic retrograde flow and a rapid diastolic deceleration time (DDT). The purpose of this study was to examine the role of assessing both epicardial flow velocity and microvascular damage in the prediction of in-hospital complications and survival after percutaneous coronary intervention (PCI). Methods: Two hundred and fifty-one consecutive patients with first anterior STEMI who underwent successful PCI were subjected to coronary flow measurement with a Doppler guidewire. The coronary flow velocity spectrum provided the following parameters: time-averaged peak velocity (cm/s, APV), systolic peak velocity (cm/s) and DDT (ms). We defined the presence of microvascular obstruction as DDT ≤600 ms and the presence of systolic flow reversal, and slow epicardial flow as resting APV ≤10cm/s. We classified the patients into three categories: without microvascular obstruction (group 1, n=140), with microvascular obstruction and normal epicardial flow (group 2, n= 51, with microvascular obstruction and slow epicardial flow (group 3, n=60). The clinical event rate was compared among the 3 groups. Results: The in-hospital event rates for congestive heart failure (15/140 [11%], 15/51 [29%] and 34/60 [57%], respectively; P &lt; 0.01), left ventricular thrombus (3/140 [2%], 9/51 [18%] and 14/60 [23%], respectively; P &lt; 0.01), and cardiac rupture (0/140 [0%], 5/51 [10%], and 16/60 [27%]; P &lt; 0.01) were highest in group 3 and lowest in group 1. Group 3 was at the highest risk of cardiac death, while group 1 was at the lowest (0/140 [0%], 3/51 [6%], and 12/60 [20%]; P &lt; 0.01). Conclusions: Assessment of both coronary microvascular damage and epicardial flow velocity can accurately predict in-hospital complications and survival in STEMI patients who underwent successful reperfusion of the infarct-related coronary artery, identifying a subset of high risk patients.

Predicting the Impact of Degree and Duration of Uterine Torsion on Uterine Blood Supply in Cattle using Doppler Ultrasonography

The aim of study was doppler ultrasonography-aided assessment of uterine blood flow in relation to duration and degree of uterine torsion in cattle. Fourteen dairy cattle with uterine torsion were detorted and fetal delivery was completed after detorsion. Six live and eight dead calves were delivered by cattle having torsion from lesser and prolonged duration, respectively. Whereas the dams of majority of live (n = 4/6) or dead (n = 5/8) fetus had uterine torsion ≤180° or >180°, respectively. Doppler ultrasonography of middle uterine artery ipsilateral (IpsiUA) and contralateral (ContUA) to the side of torsion was carried out before uterine detorsion for doppler indices viz. blood flow volume (BFV), time-average peak velocity (TAP), resistive index (RI) and pulsatility index (PI). With increase in degree and duration of torsion, BFV in both IpsiUA and ContUA reduced significantly (p<0.05) but TAP decreases only with increase in duration of torsion. In ipsilateral uterine artery PI (PI-IpsiUA) increased with an increase in duration of torsion (p<0.05). The presence of Pre-diastolic notch in IpsiUA and ContraUA validates the hindrance in blood flow through the vessel and absence of diastole in higher degree and/or duration of uterine torsion defined the severity of torsion which further relates to fetal viability. In conclusion, assessing the blood flow parameters of middle uterine artery in relation to degree and duration of uterine torsion can serve as useful prognostic indicator. The cattle having lesser degree of uterine torsion could have more chances of fetal survival due to lesser alterations in blood flow.