Doppler Scanning Research Articles

Short-Term Wind Power Forecasting at the Wind Farm Scale Using Long-Range Doppler LiDAR

It remains unclear to what extent remote sensing instruments can effectively improve the accuracy of short-term wind power forecasts. This work seeks to address this issue by developing and testing two novel forecasting methodologies, based on measurements from a state-of-the-art long-range scanning Doppler LiDAR. Both approaches aim to predict the total power generated at the wind farm scale with a five minute lead time and use successive low-elevation sector scans as input. The first approach is physically based and adapts the solar short-term forecasting approach referred to as “smart-persistence” to wind power forecasting. The second approaches the same short-term forecasting problem using convolutional neural networks. The two methods were tested over a 72 day assessment period at a large wind farm site in Victoria, Australia, and a novel adaptive scanning strategy was implemented to retrieve high-resolution LiDAR measurements. Forecast performances during ramp events and under various stability conditions are presented. Results showed that both LiDAR-based forecasts outperformed the persistence and ARIMA benchmarks in terms of mean absolute error and root-mean-squared error. This study is therefore a proof-of-concept demonstrating the potential offered by remote sensing instruments for short-term wind power forecasting applications.

Scanning Doppler lidar measurements of drag force on a solitary tree

Abstract

Offshore wind farm global blockage measured with scanning lidar

Abstract. The objective of this paper was the experimental investigation of the accumulated induction effect of a large offshore wind farm as a whole, i.e. the global-blockage effect, in relation to atmospheric-stability estimates and wind farm operational states. We measured the inflow of a 400 MW offshore wind farm in the German North Sea with a scanning long-range Doppler wind lidar. A methodology to reduce the statistical variability of different lidar scans at comparable measurement conditions was introduced, and an extensive uncertainty assessment of the averaged wind fields was performed to be able to identify the global-blockage effect, which is small compared to e.g. wind turbine wake effects and ambient variations in the inflow. Our results showed a 4 % decrease in wind speed (accuracy range of 2 % to 6 %) at transition piece height (24.6 m) upwind of the wind farm with the turbines operating at high thrust coefficients above 0.8 in a stably stratified atmosphere, which we interpreted as global blockage. In contrast, at unstable stratification and similar operating conditions and for situations with low thrust coefficients (i.e. approx. 0 for not operating turbines and ≤ 0.3 for turbines operating far above rated wind speed) we identified no wind speed deficit. We discussed the significance of our measurements and possible sources of error in long-range scanning lidar campaigns and give recommendations on how to measure small flow effects like global blockage with scanning Doppler lidar. In conclusion, we provide strong evidence for the existence of global blockage in large offshore wind farms in stable stratification and the turbines operating at a high thrust coefficient by planar lidar wind field measurements. We further conclude that global blockage is dependent on atmospheric stratification.

VENOUS HEMODYNAMICS IN ACUTE VARICOTHROMBOPHLEBITIS IN THE GREAT SAPHENOUS VEIN BASIN

Abstract. Objective. To evaluate the influence of venous hemodynamics in acute varicothrombophlebitis in the basin of the great saphenous vein on the spread of the thrombotic process.
 Materials and methods. The analysis of venous hemodynamic disorders in 245 patients with acute varicothrombophlebitis in the basin of the great saphenous vein was performed. The age of patients participating in the study ranged from 19 to 82 years (mean age 52±2,7 years). There were 93 men (38.0%) and 152 women (62.0%). The laboratory and instrumental methods were used for all the patients. They included doppler ultrasound and ultrasound duplex scanning. («ULTIMA PRO–30, zone Ultra», ZONARE Medical Systems Inc., USA).
 Results. When AVTF occurred in the GSV basin, all patients showed reflux in the superficial veins of the lower extremities. The ultrasound scanning was performed at the initial examination and immediately before urgent surgery for AVTF. The data of color duplex mapping allowed to reveal certain regularities of venous blood flow disturbance in AVTF and divided patients depending on the state of venous blood flow in the GSV basin into 5 groups. Each of these groups of patients, depending on the prevalence of venous reflux in the GSV pool, was divided into two subgroups: local and widespread reflux. It should be noted, that the conditions for the detection of total reflux in ATVF, with the involvement of GSV in the pathological process, were not due to thrombotic lesions of the latter. When venous reflux was detected, the elasticity and extensibility of the vein wall at the apex of thrombotic masses were evaluated. The ratio of the diameters of the GSV in these positions and the assessment of the "degree of elasticity" by Schwalb PG (2005), which indirectly characterized the state of venous tone were calculated. Venous reflux was assessed on a Valsalva test in vertical and horizontal positions. Venous reflux of blood in the femoral veins was found in 134 (54.7%) patients. At the same time, local reflux was found in 38 (15.5%), and widespread - in 96 (39.2%) patients. It should be noted that the prevalence of venous reflux was directly proportional to its power. Among all groups of patients with acute varicothrombophlebitis, 176 (71.8%) had widespread reflux in the great saphenous vein and 96 (39.2%) in the femoral vein. In 37 (15.1%) patients with acute varicothrombophlebitis revealed a combined nature of reflux, ie the spread of reflux from the superficial venous system not only to the apex of thrombotic masses, but also to the site of horizontal perforation, and reflux from the deep venous system spread through failed perineal veins in the great saphenous vein. Thus, widespread venous reflux was found in 87.3% of patients. In the absence of vertical reflux through the sapheno-femoral cochlea and the presence of an ascending process of thrombosis, it is necessary to identify another source of reflux.
 Conclusions. It is proved that the process of thrombosis in acute varicothrombophlebitis depends on the power of venous reflux, the severity of venous discharge through the communicating veins, the state of collateral venous blood flow in venous shunts and basins of large and small subcutaneous venous blood vessels. Venous reflux in the trunk of the great saphenous vein to some extent determines the embolism of the thrombus and participates in its development. Varicose veins of the great saphenous vein and the discharge of blood through incapable permeable veins reduce the power of reflux through the sapheno-femoral cochlea and reduce the rate of thrombosis in the main trunk.

Isolated reversal of flow in the vertebral artery - A missed entity.

Isolated reversal of flow in the vertebral artery is a rare phenomenon occurring in the general population and is due to intrinsic anatomical defects. The most common cause is subclavian stenosis; however, reversal of flow in the vertebral artery can occur regardless of any detection of anatomic deterioration. In this series, we report three asymptomatic cases where the extracranial Doppler scan preceding off-pump coronary arterial bypass grafting showed isolated reversal of flow in the vertebral artery. No signs of subclavian stenosis or steal syndrome were elicited. However, all patients subsequently suffered from a posterior circulation stroke following off-pump coronary arterial bypass grafting but recovered fully with medical management. We conclude that a detailed pre-operative neurological investigation can mitigate this risk and improve neurological outcomes following off-pump coronary arterial bypass grafting.

Quality control of fetal biometric evaluation and Doppler ultrasound.

In recent years quality control in obstetric ultrasound has become recommended and an essential component of obstetric scanning. This is to minimize the inaccuracy and variability related to fetal measurements, to provide an effective quality assurance system to sonographers to certify their practice and decrease the impact of medical litigations. For a quality control system in obstetric ultrasound to be useful clinically, multiple strategies need to be employed: certified training, practical standardization exercise, image storing, qualitative and quantitative quality control. Qualitative quality control consists of the evaluation of images obtained for fetal biometry and Doppler scans using an objective score against predefined criteria. Quantitative quality control consists of analyzing quantitatively the performance of a sonographer and the impact on measurements values. Quantitative analysis could be performed either using estimates of intraobserver or interobserver reproducibility of plane acquisition and caliper placements.

Sonographic 3-D Power Doppler Imaging Enhances Rapid Assessment of Morphologic and Pathologic Arteriovenous Fistula Variations

Early detection of pathologic variations in an arteriovenous fistula (AVF) is essential for preventing fistula dysfunction in individuals undergoing hemodialysis. This study aimed to evaluate the clinical applicability of 3-D tomographic ultrasound (tUS) for rapid and simple visualization of AVF morphology and pathology. We assessed 53 AVFs in 50 consecutive patients using 3-D tUS including secondary, blinded reading. For all examinations, a high-end ultrasound (US) device was used with linear probe, attached to a tUS system to allow freehand 3-D scanning. Participants were examined by 2-D US and 3-D tUS with different raw data (B-mode, power Doppler, B-flow). Additional angiography was available for 15 participants with scheduled interventions. In all participants, 3-D tUS allowed a 3-D representation of AVFs in angiographic-like images with good image quality. The 2-D US assessment took 7.9 ± 4.0 min. A 3-D power Doppler scan required, on average, 1.4 ± 0.6 min. Diagnostic accuracy of blinded reading for pathologies was high (86.8% for aneurysms and 79.2% for stenoses). Bland–Altman plots showed an excellent correlation of 3-D tUS with 2-D US and angiography. 3-D tUS is an easily and rapidly applicable method for visualizing morphologic and pathologic AVF variations. Color-coded 3-D reconstruction of power Doppler data simplifies detection of perfused aneurysms and stenoses.

LiSBOA (LiDAR Statistical Barnes Objective Analysis) for optimal design of lidar scans and retrieval of wind statistics – Part 1: Theoretical framework

Abstract. A LiDAR Statistical Barnes Objective Analysis (LiSBOA) for the optimal design of lidar scans and retrieval of the velocity statistical moments is proposed. LiSBOA represents an adaptation of the classical Barnes scheme for the statistical analysis of unstructured experimental data in N-dimensional space, and it is a suitable technique for the evaluation over a structured Cartesian grid of the statistics of scalar fields sampled through scanning lidars. LiSBOA is validated and characterized via a Monte Carlo approach applied to a synthetic velocity field. This revisited theoretical framework for the Barnes objective analysis enables the formulation of guidelines for the optimal design of lidar experiments and efficient application of LiSBOA for the postprocessing of lidar measurements. The optimal design of lidar scans is formulated as a two-cost-function optimization problem, including the minimization of the percentage of the measurement volume not sampled with adequate spatial resolution and the minimization of the error on the mean of the velocity field. The optimal design of the lidar scans also guides the selection of the smoothing parameter and the total number of iterations to use for the Barnes scheme. LiSBOA is assessed against a numerical data set generated using the virtual lidar technique applied to the data obtained from a large eddy simulation (LES). The optimal sampling parameters for a scanning Doppler pulsed wind lidar are retrieved through LiSBOA, and then the estimated statistics are compared with those of the original LES data set, showing a maximum error of about 4 % for both mean velocity and turbulence intensity.

Effect of SARS-CoV-2 infection during the second half of pregnancy on fetal growth and hemodynamics: A prospective study.

IntroductionOur objective was to compare the fetal growth velocity and fetal hemodynamics in pregnancies complicated and in those not complicated by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection.Material and methodsProspective case‐control study of consecutive pregnancies complicated by SARS‐CoV‐2 infection during the second half of pregnancy matched with unaffected women. The z scores of head circumference, abdominal circumference, femur length, and estimated fetal weight were compared between the two groups. Fetal growth was assessed by analyzing the growth velocity of head circumference, abdominal circumference, femur length, and estimated fetal weight between the second‐ and third‐trimester scans. Similarly, changes in the pulsatility index of uterine, umbilical, and middle cerebral arteries, and their ratios were compared between the two study groups.ResultsForty‐nine consecutive pregnancies complicated, and 98 not complicated, by SARS‐CoV‐2 infection were included. General baseline and pregnancy characteristics were similar between pregnant women with and those without SARS‐CoV‐2 infection. There was no difference in head circumference, abdominal circumference, femur length, and estimated fetal weight z scores between pregnancies complicated and those not complicated by SARS‐CoV‐2 infection at both the second‐ and third‐trimester scans. Likewise, there was no difference in the growth velocity of all these body parameters between the two study groups. Finally, there was no difference in the pulsatility index of both maternal and fetal Doppler scans throughout gestation between the two groups.ConclusionsPregnancies complicated by SARS‐CoV‐2 infection are not at higher risk of developing fetal growth restriction through impaired placental function. The findings from this study do not support a policy of increased fetal surveillance in these women.

Wound healing: what is the NICE guidance from the UK?

Alteration of wound healing increases the risk of a patient's morbidity and mortality. This can lead to scarring, infection, malignant transformation and a reduction in quality of life. Management of wounds costs the UK an estimated £5.3 billion annually which is paid for by the state, with further financial burden due to health related productivity loss. Wound care is managed by a broad spectrum of different health professionals leading to different standards of care. For example, only 16% of lower leg wounds have either an ankle-brachial pressure index measurement or Doppler scan. Due to this variation in wound care, we have summarised all available NICE guidelines and guidance up to February 2021 on the topic of wound healing listed in the National Institute for Health and Care Excellence (NICE) archives. The goal is to provide an easy to access summary of wound care interventions. Our search provided us with 18 technology appraisals related to wound healing which have been summarised.

A Variational Method for Analyzing Vortex Flows in Radar-Scanned Tornadic Mesocyclones. Part II: Tests with Analytically Formulated Vortices

AbstractThe variational method formulated in Part I for analyzing vortex flow (VF), called VF-Var, is tested with simulated radar radial-velocity observations from idealized and pseudo-operational Doppler scans of analytically formulated benchmark vortices with spiral-band structures to resemble VFs in observed tornadic mesocyclones. The idealized Doppler scans are unidirectional in parallel along horizontal grid lines of a coarse-resolution grid, so they measure only the horizontal components of three-dimensional velocities in the analysis domain. The pseudo-operational Doppler scans mimic a scan mode used by operational WSR-88Ds for severe storms. Paired numerical experiments are designed and performed to test the two-step analysis versus single-step analysis formulated in VF-Var. Both analyses perform very well with dual-Doppler scans and reasonably well with single-Doppler scans. Errors in the analyzed velocities from single-Doppler scans are mainly in the unobserved velocity components and only in fractions of the benchmark velocities. When the vortex is upright or slanted in the direction perpendicular to idealized single-Doppler scans, the two-step analysis slightly outperforms the single-step analysis for idealized Doppler scans and pseudo-operational dual-Doppler scans. When the vortex becomes slanted in the direction largely along or against Doppler scans, both analyses become less (more) accurate in analyzing the horizontal (slantwise vertical) velocity, and the single-step analysis outperforms the two-step analysis especially for single-Doppler scans. By considering the projections of analyzed velocity on radar beams in the original Cartesian coordinates, useful insights are gained for understanding why and how the analysis accuracies are affected by vortex slanting.

Twinkle artefact diagnostic role when having dogs and cats’ digestive system ultrasonography

The article is devoted to the description of the Doppler twinkle artefact recorded during transcutaneous ultrasound examination of dogs and cats’ alimentary canal and characterization of its clinical significance. The object of the study are dogs of different ages and different breeds (45) and cats (53). Ultrasound was performed on SonoAce R7 scanners (Samsung Medison Co., Ltd., Seoul, South Korea) and SIUI Apogee 1100 (Shantou Institute of Ultrasonic Instruments Co., Ltd., Guangdong, China) according to the standard technique using multifrequency convex and linear sensors with frequencies of 3.5-12 MHz. Reproduction of the twinkle artefact in the model was carried out using a plastic container with water in which objects with different densities and interfaces were placed. The characteristic of the “ twinkle artefact ” in Doppler scanning modes which we register only in pathology is given. In 14.7% of cases it was recorded on the surface of foreign bodies of the small intestine. When the artefact was reproduced in the model and it was established that it appeared on objects with a rough surface and high reflectivity. Also “twinkle artefact ” is described with hepatic parenchyma focal area of mineralization.

Establishing Sexual Dimorphism in Diameter of Carotid Arteriesamong Normotensive Adult Nigerians

Background: The Doppler scan serves as an early and non-invasive diagnostic tool for carotid artery disease due to its location, which is significant for cerebrovascular accidents. The carotid diameter has been associated with hypertension just as a sexual variation in hypertensives is documented. However, the difference among healthy individuals with normal pressure and body weight with relation to the diameter of the carotid is not proven among healthy Nigerians. Objective: The objective of the study is to identify a sexual dimorphism in the diameter of the carotid artery and its association with body mass index and blood pressure among normotensive Nigerians. Materials and Methods: A total of 104 were sampled with the average age of 28 years comprising 62 males and 42 females. Doppler ultrasound scans of common, internal, and external carotid arteries were made by an experienced radiologist using a linear transducer with a frequency of 7.0 Mhz. Diameter measurements were taken in end-diastolic alongside blood pressure, pulse, height, weight, and neck and waist circumference. Results: The total diameter measurements of the common carotid artery for male and female were 0.62 ± 0.09 and 0.60 ± 0.07 cm, respectively, internal carotid artery were 0.60 ± 0.08 and 0.61 ± 0.08 cm, respectively, and external carotid artery were 0.48 ± 0.11 and 0.50 ± 0.08 cm, respectively. Although the differences were not statistically significant, their associations with the measured biophysical and clinical parameters showed significant differences in both sexes. Conclusion: we opine that sexual dimorphism should not be ruled out by the mere absence of significant difference in the descriptive analysis but also in the associations with other parameters.

Neutral Wind Dynamics Preceding the STEVE Occurrence and Their Possible Preconditioning Role in STEVE Formation

AbstractStrong Thermal Emission Velocity Enhancement (STEVE) is a nightsky optical phenomenon of great research interest in recent years. Recent findings indicated that STEVE likely represents certain extremely intensified chemiluminescence airglow instead of traditional aurora. In this study, we investigate the patterns and variations of the neutral wind and temperature before the STEVE emergence using joint scanning Doppler imager (SDI 630 nm) and optical all‐sky imager (ASI) observations, and make an initial effort to explore the potential preconditioning role of neutral winds in the STEVE production. Neutral winds enhance in westward and southward directions following substorm auroral intensification, and show an equatorward propagating trend from auroral latitudes. However, in STEVE events the enhanced equatorward winds feature a steep stop/reversal at certain subauroral latitude, and strong wind convergence is developed there. This pattern sustains for ∼15–20 min, and then STEVE arises at about this stop latitude. The strength of the southward wind intensification and wind convergence is in general weaker or absent in nonSTEVE substorm events. We propose that enhanced equatorward winds may transport relevant neutrals species that are key to the STEVE airglow production to subauroral latitudes, and pile up at the stop latitude of the equatorward winds due to the strong convergence there. Such a transport/pileup effect led by the neutral winds may prepare a reservoir of neutral constituent which, when further aided by subauroral ion drift, leads to a dramatic increase of the airglow production and the STEVE occurrence.

Antagonizing αvβ3 Integrin Improves Ischemia-Mediated Vascular Normalization and Blood Perfusion by Altering Macrophages.

Background: αVβ3 integrin has been implicated in the physiological processes and pathophysiology of important angiogenesis-related disorders; however, the preclinical and clinical data on integrin αVβ3 antagonists have not demonstrated improved outcomes. Our goal was to test the hypothesis that inhibition of αVβ3 integrin improves blood flow in a mouse hindlimb ischemia model. Methods: In this study, we examined the effect of cilengitide, an αVβ3/αVβ5 integrin-specific RGD-mimetic cyclic peptide, on blood perfusion and angiogenesis after hindlimb ischemia. Blood flow was measured using Laser Doppler Scanner. Vascular density, and macrophages infiltration were examined by immunofluorescence. Macrophage polarization was measured by quantitative real time PCR. Results: We found that low-dose, not high-dose, cilengitide increased blood flow perfusion, capillary formation, and pericyte coverage, accompanied by an accumulation of macrophages and increased expression of the chemokine (C-C motif) ligand 2 (CCL2) in ischemic muscles. Macrophage depletion using clodronate liposomes resulted in a reduction in low-dose cilengitide-induced blood flow perfusion, macrophage accumulation, pericyte coverage, and CCL2 expression. Finally, in vitro assays showed that low-dose, not high-dose, cilengitide increased macrophage migration. Conclusion: These studies identified a novel role of the inhibition of αVβ3 integrin in modulating ischemia-induced angiogenesis, possibly through effects on macrophage infiltration and polarization, and revealed αVβ3 integrin inhibition to be a promising therapeutic strategy for peripheral artery disease.

Endovascular Balloon Treatment of a Failing Arteriovenous Fistula. A Case Report.

BACKGROUND: Arterio-venous (AV) fistula is created for patients requiring renal replacement therapy (hemodialysis and hemofiltration). A failing A-V fistula requires urgent treatment to keep it patent. Understanding the simple tips and tricks will contribute to the quality of life for the patient with end-stage renal disease and reducing radiation dose to the operator. CASE SUMMARY: A 77 year old male with end-stage renal disease, hypertension and coronary artery disease. He has been on regular haemodialysis after A-V fistula (left forearm) was constructed in 2013. He presented with 2 weeks history of A-V fistula occlusion. Examination was essentially normal. Serum sodium=136mmol/l, potassium=5.5mmol/l urea=100mg/l, creatinine=3.5mg/dl. The Doppler scan showed 50 % stenosis just proximal to the anastomosis with calcification. Percutenous arteriography and venography was done with non-compliance balloon (3x12mm) up to 24 atm . The post procedure venography showed restoration of flow across the fistula. CONCLUSION: Endovascular treatment of a failing A-V fistula can be life saving. The simple tips and tricks of using the groin route, reducing the concentration of contrast and maneuver devices may contribute to safety and reduce radiation to the operator.

Precisão clínica do teste de Barbeau reverso no diagnóstico de oclusão da artéria radial após cateterização transradial

Background Radial artery occlusion is an infrequent complication of transradial catheterization. Assessment of radial artery occlusion is a critical aspect of clinical care, and it should be done with an additional test, commonly by a plethysmographic test (reverse Barbeau test) or ultrasound (Doppler), the last is the gold standard. The objective of this study was to evaluate the accuracy of the reverse Barbeau test in detecting radial artery occlusion after transradial catheterization. Methods A study carried out in two centers encompassing patients submitted to procedures by radial access. All patients received at least 5,000IU of heparin. Sheaths were immediately removed after the procedure, using a patent hemostasis protocol. Patency of the radial artery was verified by reverse Barbeau test and duplex Doppler evaluation within the first 24 hours. Results A total of 350 patients were enrolled, with a mean age of 61.7 (±9.7) years. Radial artery occlusion was verified after the procedure in 19 (5.4%) patients, using duplex Doppler scan. Application of reverse Barbeau test had the following results: 64.0% type A curve, 15.7% type B, 8.3% type C, and 12.0% type D (the last suggesting occlusion). With reverse Barbeau test, patients with confirmed occlusion by ultrasound evaluation, 21.1% would be missed by a false-negative test, and in the ones, without radial artery occlusion, 8.2% would be misdiagnosed as having it (sensibility 78.9%; specificity 91.8%). Conclusion Reverse Barbeau test has good accuracy to detect radial artery occlusion, and it is a good option for clinical day use, although using reverse Barbeau test results in the overestimation of radial artery occlusion.

State of Renal Blood Flow in Premature Children with Hemodynamically Significant Patent Ductus Arteriosus

Abstract: Introduction: Hemodynamically significant patent ductus arteriosus (HSPDA) lowers the renal circulation because of the "ductal stealing phenomenon," which can change the renal blood flow.
 The aim: To study the state of blood flow in the main renal artery and interlobar renal artery in premature infants with HSPDA. 
 Materials and methods: 74 preterm newborns (gestational age 29-36 weeks) were divided into three groups: І - 40 children with HSPDA, ІІ - 17 children with patent ductus arteriosus (PDA) without hemodynamic disorders, ІІІ - 17 children with closed ductus arteriosus. Color ultrasound Doppler scan of the vascular bed of the kidneys was performed using a microconvex sensor with a frequency of 5-8 MHz ("TOSHIBA" Nemso XG model SSA-580A (Japan) from the main renal artery to the interlobar renal arteries of the right kidney. The following parameters of renal blood flow were studied: peak systolic velocity (PSV), end-diastolic velocity (EDV), resistance index (RI). 
 Results: Peak systolic velocity (PSV) in the main renal artery and interlobar renal arteries did not differ significantly between groups. On the first, third, and tenth days of life, there was a significant decrease in the EDV of blood flow and increased RI in the main renal artery. The EDV of blood flow and RI in the interlobar renal artery on the first day of life did not differ depending on PDA's presence and its hemodynamic significance. On the third and tenth days of life and in the interlobar renal artery, a significant decrease in EDV of blood flow and increased RI were noted. These renal blood flow characteristics were closely related to the size of the PDA on the first day of life.
 Conclusion: A feature of renal hemodynamics in HSPDA in premature infants is a decrease in the EDV of blood flow in the main renal artery and interlobar renal artery, as well as an increase in the RI of these vessels, directly correlating with the size of the PDA in the first day of life. During the first ten days of life, dynamic control revealed a slowed process of restoration of renal blood flow in babies with HSPDA, despite the PDA's closure.

Congenital diaphragmatic hernia repair analysis in relation to postoperative abdominal compartment syndrome and delayed abdominal closure.

Limited abdominal space in congenital diaphragmatic hernia (CDH) might result in abdominal compartment syndrome (ACS) and require delayed abdominal closure (DAC). This study reviewed outcomes in pediatric ACS/DAC after CDH repair. Medline/PubMed, Scopus, Web of Science, Ovid and Lilacs databases were reviewed. Data from studies published in English/Spanish/Portuguese between 1990-2020 was collected. Results are presented as descriptive statistics. Sixteen reports offered 118 children, 112 (94.9%) being neonates. There were six ACS (5.1%) and 112 DAC (94.9%). Regarding ACS, the diagnosis was made clinically (n = 4; 66.7%), using Doppler scans (n = 1; 16.7%) or bladder pressure measurement (n = 1; 16.7%). There was one (16.7%) lethal outcome. The rationale to perform DAC was not clearly stated, and measurement of abdominal pressure was not mentioned in all reports. Silo was the preferred approach in 36 children (32.1%), followed by skin closure only (n = 16; 14.3%), vacuum (n = 10; 8.9%), fascia patch and skin closure (n = 5; 4.5%), fascia patch and vacuum dressing (n = 1; 0.9%), fasciotomy (n = 1; 0.9%); with no DAC technique reported in 43 patients (38.4%). Complications after DAC were reported in nine children (8.1%). One DAC using vacuum dressing that was clinically diagnosed with ACS required silo placement. There were 19 (17%) lethal outcomes. ACS/DAC after CDH repair are reported more frequently in neonates (112/118; 94.9%). There is no clear rationale stated behind the decision to perform DAC, with the silo being the preferred approach. Criteria need to be worked for DAC in CDH with large herniated content and small volume abdomen to prevent ACS.

Hepatic vein thrombosis secondary to COVID-19

COVID-19 is known to cause both arterial and venous thromboembolism. Although a lot of attention is being given to those presenting with myocardial infarction and stroke, splanchnic vein thrombosis which includes portal, mesenteric, splenic, and hepatic vein thrombosis is often underreported. A 21-year-old female presented with progressive abdominal distension and obstipation for the past 2 weeks. The patient was diagnosed as a case of moderate COVID-19 illness 2 weeks before the onset of these symptoms and recovered on receiving treatment according to the COVID protocol. Physical examination revealed pallor and bilateral pitting pedal edema up to ankles. Systemic examination revealed uniformly distended abdomen with signs of free fluid and tenderness in the right hypochondrium. Hematological investigations showed moderate-grade microcytic hypochromic anemia. Biochemically, indirect hyperbilirubinemia and transaminitis with moderately elevated D-dimers and Lactate dehydrogenase (LDH) was noted. Radiological imaging of the abdomen (including USG with doppler and CT contrast Scans) revealed gross ascites, nutmeg appearance of liver with completely obscured hepatic veins indicating no flow of blood, multiple intrahepatic portosystemic collaterals and a partially thrombosed inferior vena cava with no evidence of portal hypertension. All other workup to rule out other causes of hepatic vein thrombosis was inconclusive. The patient was treated with low-molecular-weight heparin and then continued with oral warfarin at discharge. On a 4-week follow-up, the patient showed marked clinical improvement with partial resolution of presenting symptoms.