Doppler Ultrasound Variables Research Articles

MO766EARLY ARTERIOVENOUS FISTULA FAILURE PREDICTION WITH ARTIFICIAL INTELLIGENCE: A NEW APPROACH WITH CHALLENGING RESULTS

Abstract Background and Aims The native arteriovenous fistula is considered the vascular access of preference, since it is directly related to major survival, reduced complications, mortality, and costs. Still, its proper maintenance remains a challenge for nephrologists. A previous study from our group, which used the data of 117 arteriovenous fistulas, led to identify in the multivariable analysis age and vein diameters as predictive factors for early failure. On the other hand, Artificial Intelligence has been established as a tool to identify relationships between variables at deep levels, which might be unseen with more conservative methods like classic statistics. Therefore, through a Machine Learning technique known as Random Forest, the aim is to evaluate the same comorbidity, biological and Doppler ultrasound variables data to identify those with a major relation with the early failure of the native arteriovenous fistula. Method Retrospective cohort study, gathering the same data of the previous study (from 2011 to 2015): survival, ultrasound mapping (morphology and hemodynamics), comorbidities (blood pressure, severe arteriopathy, diabetes, Charlson’s Index), and laboratory (haemoglobin, calcium, phosphorus, PTH, ferritin, PCR). Different Artificial Intelligence algorithms were tested, but the most suited one for the study's aim turned out to be Random Forest. A model was trained, dividing the data in two sets, training and validation, with an 80/20 ratio. The algorithm used 100 decision trees, with a maximum individual depth of 3 levels. The training was made with the variables that represented the 100%, 95%, 90% and 85% of impact in the fistula's maturation from a theresold according to Gini’s Index. Results Age 65.7 (32-88) years, male 59.8%. Hypertension 86.7%, diabetes 50.7% and vascular disease 41.3%. The trained model obtained provided the following results in the evaluation: accuracy 0.82, precision 0.86, AUROC 0.85, F1 0.86 (balance between precision and predictive value). The most relevant variables by decision order were age, phosphorous, PTH, ferritin and calcium. Morphologic and hemodynamic variables such as the vessels diameter, Peak Systolic Velocity, Charlson’s Index or PCR, were also found to be relevant, but in a minor level. Conclusion In comparison with classic statistics, Machine Learning techniques might create a change of paradigm in predictive models for the patency of the vascular access for Haemodialysis. Even though the Artificial Intelligence-based model provided the same relevance for age in maturation failure as traditional models, other findings stand out, like the major participation of variables related with mineral metabolism or inflammation, rather than ultrasound based ones.

Doppler Ultrasound of Hepatic Artery and Portal Vein: Relationship with Clinical Severity of Hepatitis C Virus Liver Cirrhosis

AbstractBackground: Doppler ultrasonography is an essential part of evaluating the vascular haemodynamic variation seen within cirrhotic patients. Differences in haemodynamics exhibited in hepatic vasculature has been appeared in previous reports to associate with the clinical severity of cirrhosis. In any case, the degree of changes in Doppler ultrasound flow parameters in foreseeing the clinical severity of liver cirrhosis stays uncertain.Aim of Study: The purpose of this study was to evaluate the contribution of Doppler ultrasound of Hepatic Artery (HA) and Portal Vein (PV) with Child-Pugh (CP) score to assess the advancement of Hepatitis C Virus (HCV)-related liver cirrhosis.Patients and Methods: One hundred patients with HCV-related liver cirrhosis divided according to CP score were included. Doppler ultrasound variables including Portal Vein (PV) diameter, Maximum Portal Vein Velocity (MPVV), and resistance index of the hepatic artery (HARI) were measured.Results: There was significant association between the diameter of PV and the increase in CP score, which was statistically significant (p=0.000). A choice of 12mm as a cutoff point of PV diameter between CP, A and B revealed sensitivity of 96.9%, and specificity of 97.9%. The mean MPVV was statistically significantly higher with Child A (mean 17.1±1.6 cm/sec), compared to Child B and C (p= 0.000), and Child B (mean 14.1±1.9cm/sec) compared to Child C (mean 11.3±1.4cm/sec) (p=0.000). The mean HARI was statistically significantly lower with Child A and B (0.8cm/sec), compared to Child C (0.9cm/sec) (p=0.000). There was a strong negative correlation between HARI and MPVV which was statistically significant (p=0.000). There was a strong positive correlation between HARI and Child class and diameter of PV which was statistically significant (p=0.000).Conclusion: PV diameter is a useful predictor of advance-ment of liver cirrhosis. Doppler measurements of MPVV, and HARI are useful in differentiating patients with CP, A and B from C.

Cerebrovascular Physiology During Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Study Using Transcranial Doppler Ultrasonography*

To explore changes to expected, age-related transcranial Doppler ultrasound variables during pediatric extracorporeal membrane oxygenation. Prospective, observational, multicenter study. Tertiary care PICUs. Children 1 day to 18 years old requiring veno arterial extracorporeal membrane oxygenation. Participants underwent daily transcranial Doppler ultrasound measurement of bilateral middle cerebral artery flow velocities. Acute neurologic injury was diagnosed if seizures, cerebral hemorrhage, or diffuse cerebral ischemia was detected. Fifty-two children were enrolled and analyzed. In the 44 children without acute neurologic injury, there was a significant reduction in systolic flow velocity and mean flow velocity compared with predicted values over time (F [8, 434] = 60.44; p ≤ 0.0001, and F [8, 434] = 17.61; p ≤ 0.0001). Middle cerebral artery systolic flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-5, and mean flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-3. In the six infants less than 90 days old suffering diffuse cerebral ischemia, middle cerebral artery systolic flow velocity, mean flow velocity, and diastolic flow velocity from extracorporeal membrane oxygenation days 1-9 were not significantly different when compared with children of similar age in the cohort that did not suffer acute neurologic injury (systolic flow velocity F [8, 52] = 0.6659; p = 0.07 and diastolic flow velocity F [8, 52] = 1.4; p = 0.21 and mean flow velocity F [8, 52] = 1.93; p = 0.07). Pulsatility index was higher in these infants over time than children of similar age in the cohort on extracorporeal membrane oxygenation that did not suffer acute neurologic injury (F [8, 52] = 3.1; p = 0.006). No patient in the study experienced cerebral hemorrhage. Flow velocities in the middle cerebral arteries of children requiring extracorporeal membrane oxygenation are significantly lower than published normative values for critically ill, mechanically ventilated, sedated children. Significant differences in measured systolic flow velocity, diastolic flow velocity, and mean flow velocity were not identified in children suffering ischemic injury compared with those who did not. However, increased pulsatility index may be a marker for ischemic injury in young infants on extracorporeal membrane oxygenation.

Using Ultrasound Elastography to Predict Which Pediatric HSCT Patients Will Develop Severe Sinusoidal Obstruction Syndrome

Introduction Hepatic sinusoidal obstruction syndrome (SOS) is a complication of hematopoietic stem cell transplantation (HSCT). Severe and very severe SOS is associated with multi-organ failure and has ∼60% mortality. SOS is classified into mild, moderate, severe and very severe based on new European Society for Blood and Marrow Transplantation (EBMT) criteria. Defibrotide treatment is recommended for severe and very severe patients. Objective Our primary objective was to determine if hepatic ultrasound shear wave elastography (SWE) can predict SOS severity in pediatric HSCT patients. Methods This is a multi-site prospective cohort study evaluating the use of SWE in pediatric HSCT patients (0-21 years) from 10/2015 to 3/2018 at 2 pediatric institutions. Site 1 subjects underwent 1 SWE within 10-days prior to start of conditioning regimen and at days +5 and +14 after HSCT. Site 2 enrolled subjects at the time of clinical suspicion for SOS and subjects received SWE examinations every other day up to 10 exams during their inpatient stay. We examined 11 time-varying variables including weight, hepatomegaly, ascites, SWE and various Doppler ultrasound variables as predictors of maximum EBMT criteria severity grade. We used the median to summarize the SWE values. Missing data on explanatory variables ( Results 55 subjects were enrolled. Most patients were male (n=33, 55%) with a median age of 8 (range 0-20) years. 21 (35%) patients developed SOS, 15 (25%) had severe or greater disease by EBMT criteria. Busulfan use is associated with an average increase of 0.6 in EBMT grade, and a 100 cm/s decrease in main portal vein velocity is associated with an average increase of 1.3 in EBMT grade. Hepatomegaly, ascites, and higher SWE stiffness also appear to be associated with greater SOS severity (p 1.95 m/s was 87.5% sensitive and 85% specific for severe or very severe SOS. Seven of eight patients with severe or very severe SOS had SWE >1.95 m/s two to thirteen days before the date of severe SOS grading. Conclusion In a group of 12 clinical and ultrasound variables, SWE velocity was an excellent predictor of the patient developing severe SOS. SWE was able to predict severe SOS 2 to 13 days before the EBMT criteria with 87.5% sensitivity and 85% specificity.

US‐Guided Percutaneous Liver Biopsy in Pediatric Liver Transplant Recipients

The present study assesses the safety of ultrasound (US)-guided percutaneous liver biopsies (PLBs) within pediatric liver allograft recipients, describes the pathological results according to early (≤12 months) and late (>12 months) posttransplantation periods, and analyzes the value of liver function tests (LFTs) and Doppler US variables in determining these results. A total of 219 US-guided PLBs in 85 pediatric patients with liver transplant (mean age 7 ± 5 years, range: 6 months to 18 years) performed between March 2005 and May 2012 were retrospectively evaluated at a single institution. Doppler US and LFT evaluation (including total bilirubin, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, alkaline phosphatase) occurred within 1 day of early (n = 92, 42%) and late term (n = 127, 58%) posttransplantation biopsies. The rate of major complications (hemorrhage requiring blood transfusion) was 0.91% (n = 2). The early versus late term biopsy results, respectively, included: cholestasis at 36% versus 18% (P = 0.003), minimal changes 16% versus 24% (not significant [NS]), acute rejection 13% versus 5% (P = 0.027), inflammatory diseases 15% versus 15% (NS), indeterminate acute rejection 11% versus 7% (NS), chronic rejection 4% versus 14% (P = 0.017), fibrotic diseases 4% versus 12% (NS), and other 0% versus 5% (NS). Neither LFT nor US variables were correlated with pathological outcomes. The rate of complications in pediatric patients after US-guided liver biopsy is low. A range of pathological results exists between early and late posttransplantation liver biopsies. LFT and Doppler US findings are not predictors of pathological results.

Non-invasive diagnosis of esophageal varices in chronic liver diseases

Background/Aims: The primary prevention of bleeding from esophageal varices is a major therapeutic issue requiring early screening of esophageal varices. Our aim was to study the diagnostic accuracy of non-endoscopic means for the diagnosis of esophageal varices. Methods: Sixty-three clinical, biochemical, endoscopic and Doppler ultrasound variables were prospectively recorded in 207 consecutive patients with chronic liver disease. Diagnostic accuracy was evaluated by discriminant analysis, first globally using all variables with diagnostic accuracy≥65% in univariate analysis, then by stepwise regression. Results: A) whole group ( n=207), 1) diagnosis of esophageal varices: diagnostic accuracy was globally 81%, and 81% with 1 variable: irregular liver surface at ultrasound, 2) Diagnosis of large esophageal varices (grades 2+3): diagnostic accuracy was globally 80%, and 79% with 2 variables: prothrombin index, γ-globulins. B) patients with cirrhosis ( n=116), 1) diagnosis of esophageal varices: diagnostic accuracy was globally 71%, and 72% with 2 variables: platelet count, prothrombin index, 2) diagnosis of large esophageal varices (grades 2+3): diagnostic accuracy was globally 71%, and 72% with 3 variables: platelet count, prothrombin index, spider naevi. The ROC curve showed that the best threshold for the diagnostic accuracy of platelet count was 160 G/I providing a sensitivity of 80% and a specificity of 58%. Platelet count ≥260 G/I has a negative predictive value ≥91%. Conclusions: Using a few non-endoscopic criteria, esophageal varices can be correctly diagnosed in 81% of patients with chronic liver disease and in 71% of patients with cirrhosis. These results show that the non-invasive screening of patients who are candidates for the primary prevention of variceal bleeding is possible, but should be improved before being used in a clinical setting.

Changes in portal hemodynamics and acute rejection in the first 2 weeks after orthotopic liver transplantation. A prospective Doppler ultrasound study.

To analyze changes in Doppler ultrasound variables of the portal vein in relation to liver biopsy findings, the authors performed a prospective study of 316 Doppler ultrasound examinations in the first 2 weeks after orthotopic liver transplantation on 23 patients. Recordings were obtained daily from the portal vein (diameter, maximum velocity, and flow). Correlations were explored between the Doppler ultrasound findings and histologic data. The chi-square test was used to analyze differences in Doppler ultrasound variables in patients with and without acute rejection. In our series of 23 patients, acute rejection was diagnosed by liver biopsy in nine of them (39%). Changes in portal vein diameter, maximum velocity, and flow did not correlate consistently with liver biopsy findings, due to a multifactorial origin. Changes in portal hemodynamics were observed in patients with hepatic artery thrombosis, portal vein stenosis, acute rejection, and sepsis. Although routine screening using Doppler ultrasound proved to be useful for the determination of rapid changes in portal hemodynamics within a short time, serial Doppler ultrasound examinations were not helpful in predicting acute rejection.

Doppler Ultrasound of the Hepatic Artery and Vein Performed Daily in the First Two Weeks After Orthotopic Liver Transplantation

To analyze changes in Doppler ultrasound variables in relation to liver biopsy findings for the diagnosis of acute rejection after orthotopic liver transplantation (OLT), the authors performed in a prospective study 316 Doppler ultrasound examinations in the first 2 weeks after OLT on 23 patients. Recordings were obtained daily from the hepatic artery (resistive index [RI]) and hepatic vein (damping index [DI]). Correlations were explored between the Doppler ultrasound findings and histologic data. The chi-square test was used to analyze differences in Doppler ultrasound variables in patients with and without acute rejection. Serial Doppler ultrasound examinations showed a significant increase in the RI in 11 of 22 patients (50%); the 23rd patient was excluded because of hepatic artery thrombosis. Despite an agreement in 15 of 22 patients (68%) no statistically significant correlation could be found (positive predictive value 6/11 = 55%; negative predictive value 9/11 = 82%; chi-square = 3.14; P > 0.05). A significant increase in the DI was observed in 14 of 23 patients (61%). However, no statistically significant correlation could be found as well with this parameter (positive predictive value 6/14 = 43%; negative predictive value 6/9 = 67%; chi-square = 0.00; P > 0.05). Serial Doppler ultrasound examinations were not helpful in predicting acute rejection.

A Comparison of Conventional Versus Anaerobic Threshold Exercise Prescription Methods in Subjects With Left Ventricular Dysfunction

This study compared conventional exercise prescription methods with an anaerobic threshold (AT) method in a population with left ventricular dysfunction (LVD) to determine: 1) if a significant number of conventionally prescribed training heart rate ranges (THR) were above anaerobic threshold; and 2) if there was a significant decrease in ventricular function at the prescribed heart rate ranges as assessed by Doppler ultrasound variables, ascending aortic blood velocity (AABV) and peak acceleration (PA). The sample consisted of twelve male subjects with documented LVD (ejection fraction < 40%) and 12 age-matched control subjects with no history of coronary artery disease. All subjects underwent a treadmill-graded exercise test (GXT). Four different exercise prescriptions were then written. Results showed that in a significant number of patients with LVD (69.4%), conventional THR ranges were beyond the AT (P < 0.001). Changes in AABV and PA showed no significant differences at the lower end of training ranges (LTR). At the higher end of the training ranges, a significant decrease (P < 0.05) was found in PA with all conventional prescription methods versus the AT method (8.7% average). Ascending aortic blood velocity changes showed a significant difference at the higher end of the training ranges for only the heart rate reserve method. This study suggests that conventional exercise prescription methods used on patients with LVD lead to a significant number of THR ranges that are beyond AT and optimal ventricular function.

A Comparison of Conventional Versus Anaerobic Threshold Exercise Prescription Methods in Subjects With Left Ventricular Dysfunction

This study compared conventional exercise prescription methods with an anaerobic threshold (AT) method in a population with left ventricular dysfunction (LVD) to determine: 1) if a significant number of conventionally prescribed training heart rate ranges (THR) were above anaerobic threshold; and 2) if there was a significant decrease in ventricular function at the prescribed heart rate ranges as assessed by Doppler ultrasound variables, ascending aortic blood velocity (AABV) and peak acceleration (PA). The sample consisted of twelve male subjects with documented LVD (ejection fraction

Cerebral blood flow in the newborn infant: Comparison of Doppler ultrasound and 133xenon clearance

Two techniques of Doppler ultrasound examination, continuous-wave and range-gated, applied to the anterior cerebral artery and to the internal carotid artery, were compared with 133xenon clearance after intravenous injection. Thirty-two sets of measurements were obtained in 16 newborn infants. The pulsatility index, the mean flow velocity, and the end-diastolic flow velocity were read from the Doppler recordings. Mean cerebral blood flow was estimated from the 133Xe clearance curves. The correlation coefficients between the Doppler and the 133Xe measurements ranged from 0.41 to 0.82. In the subset of 16 first measurements in each infant, there were no statistically significant differences between the correlation coefficients of the various Doppler ultrasound variables, but the correlation coefficients were consistently lower for the pulsatility index than for mean flow velocity or end-diastolic flow velocity, and they were consistently higher for the range-gated than for the continuous-wave Doppler technique.