Predictive value of dynamic arterial elastance for vasopressor withdrawal: a systematic review and meta-analysis.

BACKGROUND: Dynamic arterial elastance (Eadyn) has been investigated for its ability to predict hypotension during the weaning of vasopressors. Our study focused on assessing Eadyn's performance in the context of critically ill adult patients admitted to the intensive care unit, regardless of diagnosis. MAIN BODY: Our study was conducted in accordance with the Preferred Reported Items for Systematic Reviews and Meta-Analysis checklist. The protocol was registered in PROSPERO (CRD42023421462) on May 26, 2023. We included prospective observational studies from the MEDLINE and Embase databases through May 2023. Five studies involving 183 patients were included in the quantitative analysis. We extracted data related to patient clinical characteristics, and information about Eadyn measurement methods, results, and norepinephrine dose. Most patients (76%) were diagnosed with septic shock, while the remaining patients required norepinephrine for other reasons. The average pressure responsiveness rate was 36.20%. The synthesized results yielded an area under the curve of 0.85, with a sensitivity of 0.87 (95% CI 0.74-0.93), specificity of 0.76 (95% CI 0.68-0.83), and diagnostic odds ratio of 19.07 (95% CI 8.47-42.92). Subgroup analyses indicated no variations in the Eadyn based on norepinephrine dosage, the Eadyn measurement device, or the Eadyn diagnostic cutoff to predict cessation of vasopressor support. CONCLUSIONS: Eadyn, evaluated through subgroup analyses, demonstrated good predictive ability for the discontinuation of vasopressor support in critically ill patients.

TCD assessment in fulminant hepatic failure: Improvements in cerebral autoregulation after liver transplantation.

INTRODUCTION AND OBJECTIVES: Acute liver failure, also known as fulminant hepatic failure (FHF), includes a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction and hepatic encephalopathy. The objective of this study was to assess cerebral autoregulation (CA) in 25 patients (19 female) with FHF and to follow up with seventeen of these patients before and after liver transplantation. PATIENTS AND METHODS: The mean age was 33.8 years (range 14-56, SD 13.1 years). Cerebral hemodynamics was assessed by transcranial Doppler (TCD) bilateral recordings of cerebral blood velocity (CBv) in the middle cerebral arteries (MCA). RESULTS: CA was assessed based on the static CA index (SCAI), reflecting the effects of a 20-30 mmHg increase in mean arterial blood pressure on CBv induced with norepinephrine infusion. SCAI was estimated at four time points: pretransplant and on the 1st, 2nd and 3rd posttransplant days, showing a significant difference between pre- and posttransplant SCAI (p = 0.005). SCAI peaked on the third posttransplant day (p = 0.006). Categorical analysis of SCAI showed that for most patients, CA was reestablished on the second day posttransplant (SCAI > 0.6). CONCLUSIONS: These results suggest that CA impairment pretransplant and on the 1st day posttransplant was re-established at 48-72 h after transplantation. These findings can help to improve the management of this patient group during these specific phases, thereby avoiding neurological complications, such as brain swelling and intracranial hypertension.

Investigação da Relação entre Índice de Triglicerídeos-Glicose e Fluxo Lento Coronariano: Um Estudo Retrospectivo de Caso-Controle / Investigation of the Relationship Between Triglycerides-Glucose İndex and Coronary Slow Flow: A Retrospective Case-Control Study

Resumo Fundamento O fluxo lento coronariano (FLC) refere-se à opacificação retardada dos vasos distais na ausência de estenose da artéria coronária epicárdica. O mecanismo etiopatogênico do FLC ainda não está claro. Objetivos Este estudo investiga a relação entre o FLC e o índice de triglicerídeos-glicose (TyG). Métodos A amostra do estudo consistiu de 118 pacientes com FLC e 105 pacientes com fluxo coronariano normal (FCN). A taxa de fluxo coronariano foi medida por medio do método de contagem de quadros (TFC) Thrombolysis in Myocardial Infarction (TIMI) em todos os pacientes. O índice TyG foi calculado como o logaritmo do valor [triglicerídeos em jejum (mg/dL)×glicose em jejum (mg/dL)]/2. Adotou-se como estatisticamente significativo o nível de significância < 0,05. Resultados O índice TyG, lipoproteína de baixa densidade (LDL), índice de massa corporal (IMC), relação neutrófilo-linfócito (RNL) e valores de TFC, proporção masculina e proporção de fumantes foram maiores, enquanto os níveis de lipoproteína de alta densidade (HDL) foram significativamente menores no grupo FLC em comparação com o grupo FNC (p<0,05). A análise de correlação revelou que o FLC estava significativamente correlacionado com os valores do índice TyG, IMC, RNL e HDL. A mais forte dessas correlações foi entre o FLC e o índice TyG (r= 0,57, p<0,001). Além disso, a análise multivariada revelou que o índice TyG, IMC, razão RNL e sexo masculino foram preditores independentes para FLC (p<0,05). A análise da curva ROC (Receiver Operating Characteristic) indicou que um valor de corte ≥ 9,28 para o índice TyG previu FLC com sensibilidade de 78% e especificidade de 78,1% [Área sob a curva (AUC): 0,868 e 95% intervalo de confiança (IC): 0,823-0,914]. Conclusão Os achados deste estudo revelaram uma relação muito forte entre o FLC e o índice TyG.

Abstract Background Coronary slow flow (CSF) refers to delayed distal vessel opacification in the absence of epicardial coronary artery stenosis. The etiopathogenic mechanism of CSF is still unclear. Objectives This study investigates the relationship between CSF and the triglyceride-glucose (TyG) index. Methods The study sample consisted of 118 CSF patients and 105 patients with normal coronary flow (NCF). The coronary flow rate was measured via the Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) method in all patients. The TyG index was calculated as the logarithm of the [fasting triglyceride (mg/dL)×fasting glucose (mg/dL)]/2 value. A significance level of < 0.05 was adopted as statistically significant. Results The TyG index, low-density lipoprotein (LDL), body mass index (BMI), neutrophil-to-lymphocyte ratio (NLR) and TFC values, male ratio, and the ratio of smokers were higher, whereas high-density lipoprotein (HDL) levels were significantly lower in the CSF group compared to the NCF group (p<0,05). The correlation analysis revealed that CSF was significantly correlated with TyG index, BMI, NLR, and HDL values. The strongest of these correlations was between CSF and TyG index (r= 0.57, p<0.001). Additionally, the multivariate analysis revealed that TyG index, BMI, NLR ratio, and male gender were independent predictors for CSF (p<0.05). Receiver operating characteristic (ROC) curve analysis indicated that a cut-off value of ≥ 9.28 for the TyG index predicted CSF with a sensitivity of 78% and a specificity of 78.1% [Area under the curve (AUC): 0.868 and 95% Confidence Interval (CI): 0.823-0.914]. Conclusion The findings of this study revealed a very strong relationship between CSF and TyG index.

Strain Magnitude Assessed at Rest and During Stress Echocardiography in Patients with Normal Coronary Flow Reserve

Abstract Background Coronary flow and myocardial contractile performance assessed by strain magnitude increase during a dobutamine stress echocardiogram (DSE). Normal coronary flow reserve (CFR) can be attained upon completion of a DSE at age-predicted maximum heart rate (HR) (HRmax = 220 - age)] or submaximal HR [(0.85) HRmax] or before completion (early CFR). Objective To ascertain the association between delta strain and HR in patients with early normal CFR. Methods This prospective study included patients whose normal CFR was obtained before the DSE was completed. Percentage of resting HR (%HRrest) = [(HRrest ÷ HRmax) 100]% and %HR CFR = [(HR at the time of CFR attainment) ÷ (HRmax) 100]% were recorded. Strain was assessed in the left ventricular region of interest, and delta strain was calculated as the difference between the measures obtained at HRrest and after the DSE was completed. Strain agreement analysis for HRrest, %HRrest, and %HR CFR was performed using the kappa coefficient. The Shapiro-Wilk test was used to assess data normality, and the Mann-Whitney test was used to compare the groups. A p-value < 0.05 was considered statistically significant. Results Strain measured -23.3% ± 4.3% at baseline and -31.1% ± 4.9% during the DSE. In delta strain > 8 absolute points, the ROC curves showed an area under the curve of 0.874 ± 0.07 for %HRrest (p = 0.001) and an area under the curve of 0.862 ± 0.07 for %HR CFR (p = 0.001). In delta strain > 8 points, %HRrest ≤ 42.6% of HRmax and %HR CFR ≤ 62.5% of HRmax showed an accuracy of 82.9% and 79.8%, respectively. Conclusion In this study, lower HRrest and HR at the time of CFR attainment had a good association with better myocardial contractile performance, according to the change in strain magnitude.

Dataset of middle cerebral artery blood flow stability in response to high-definition transcranial electrical stimulation.

This supplementary dataset is supportive of the randomized sham-controlled, double-blind, crossover clinical trial investigating polarity- and intensity-dependent effects of high-definition transcranial electrical stimulation (HD-tDCS) applied over the right temporo-parietal junction on mean middle cerebral artery blood flow velocity (MCA-BFv) bilaterally. Data of eleven healthy right-handed adults (6 women, 5 men; mean age 31 ± 5.6 years old) were analyzed for MCA-BFv, assessed using transcranial doppler ultrasound on the stimulated and the contralateral hemisphere concomitantly, during and after 3 blocks of 2 min HD-tDCS at 1, 2, and 3 mA. Participants received three electrical stimulation conditions (anode center, cathode center, and sham) randomly ordered across different days. The collected data is publicly available at Mendeley Data. This article and the data will inform future related investigations and safety analysis of transcranial non-invasive brain stimulation.

Microsurgical arterial anastomosis in young and adult rats: an evolutive and comparative study

Purpose: To evaluate the caliber of an arterial micro-anastomosis in the young growing animal using a continuous suture technique. Additionally, late morphological changes and blood flows distal to the anastomosis were evaluated. Methods: Seventy-four Wistar rats were submitted to laparotomy to access the aorta for blood flow measurement. The aorta was sectioned using microsurgery technique and an end-to-end anastomosis with continuous suture. After a period of six months to one year, the anastomosis was checked. Results: Regarding the size of the aortas, comparing the pre- and postoperative values, there was an increase of 13.33% in adult animals and 25% in young animals, without any difference in the blood flows. Conclusions: The arteries of young rats show signs of growth at the site of the anastomosis performed with continuous suture.

Sex- and Age-Related Physiological Profiles for Brachial, Vertebral, Carotid, and Femoral Arteries Blood Flow Velocity Parameters During Growth and Aging (4-76 Years): Comparison With Clinical Cut-Off Levels.

Ultrasound-derived blood flow velocity (BFV) levels [e.g., peak systolic velocity (PSV)], intrabeat indexes (e.g., resistive), and intersegment ratios [e.g., internal/common carotid artery (ICA/CCA) PSV ratio] are assessed to describe cardiovascular physiology and health status (e.g., disease severity evaluation and/or risk stratification). In this respect, fixed cut-off values (disregard of age or sex) have been proposed to define "significant" vascular disease from BFV-derived data (parameters). However, the use of single fixed cut-off values has limitations. Accurate use of BFV-derived parameters requires knowing their physiological age-related profiles and the expected values for a specific subject. To our knowledge, there are no studies that have characterized BFV profiles in large populations taking into account: (i) data from different age-stages (as a continuous) and transitions (childhood-adolescence-adulthood), (ii) complementary parameters, (iii) data from different arteries, and (iv) potential sex- and hemibody-related differences. Furthermore, (v) there is little information regarding normative data [reference intervals (RIs)] for BFV indexes. Aims: The aims of this study are the following: (a) to determine the need for age-, body side-, and sex-specific profiles for BFV levels and derived parameters (intrabeat indexes and intersegment ratios), and (b) to define RIs for BFV levels and parameters, obtained from CCA, ICA, external carotid, vertebral, femoral, and brachial arteries records. Methods: A total of 3,619 subjects (3-90 years) were included; 1,152 were healthy (without cardiovascular disease and atheroma plaques) and non-exposed to cardiovascular risk factors. BFV data were acquired. The agreement between left and right data was analyzed (Concordance correlation, Bland-Altman). Mean and SD equations and age-related profiles were obtained for BFV levels and parameters (regression methods; fractional polynomials). Results: Left and right body-side derived data were not always equivalent. The need for sex-specific RIs was dependent on the parameter and/or age considered. RIs were defined for each studied artery and parameter. Percentile curves were compared with recommended fixed cut-off points. The equations for sex, body-side, and age-specific BFV physiological profiles obtained in the large population (of children, adolescents, and adults) studied were included (spreadsheet formats), enabling to determine for a particular subject, the expected values and potential data deviations.

Impacts of a Pressure Challenge on Cerebral Critical Closing Pressure and Effective Cerebral Perfusion Pressure in Patients with Traumatic Brain Injury.

INTRODUCTION: Cerebral critical closing pressure (CrCP) comprises intracranial pressure (ICP) and arteriolar wall tension (WT). It is the arterial blood pressure (ABP) at which small vessels close and circulation stops. We hypothesized that the increase in WT secondary to a systemic hypertensive challenge would lead to an increase in CrCP and that the "effective" cerebral perfusion pressure (CPPeff; calculated as ABP - CrCP) would give more complete information than the "conventional" cerebral perfusion pressure (CPP; calculated as ABP - ICP). OBJECTIVE: This study aimed to compare CrCP, CPP, and CPPeff changes during a hypertensive challenge in patients with a severe traumatic brain injury. PATIENTS AND METHODS: Data on ABP, ICP, and cerebral blood flow velocity, measured by transcranial Doppler ultrasound, were acquired simultaneously for 30 min both basally and during a hypertensive challenge. An impedance-based CrCP model was used. RESULTS: The following values are expressed as median (interquartile range). There were 11 patients, aged 29 (14) years. CPP increased from 73 (17) to 102 (26) mmHg (P ≤ 0.001). ICP did not change. CrCP changed from 23 (11) to 27 (10) mmHg (P ≤ 0.001). WT increased from 7 (5) to 11 (7) mmHg (P ˂ 0.005). CPPeff changed less than CPP. CONCLUSION: The CPP change was greater than the CPPeff change, mainly because CrCP increased simultaneously with the WT increase as a result of the autoregulatory response. CPPeff provides information about the real driving force generating blood movement.

Inspiratory muscle training improves cerebrovascular and postural control responses during orthostatic stress in older women.

PURPOSE: We aimed to investigate the effect of inspiratory muscle training (IMT) on, hemodynamic, cerebrovascular and postural balance responses during orthostatic stress, in older women. METHODS: Fourteen elderly women were assigned to perform IMT at 50% of maximal inspiratory pressure (MIP) (IMT group, n = 8) or placebo training at 5% MIP (Sham group, n = 6), in a counter-balanced order, using an inspiratory threshold device for 4 weeks. During the protocol, MIP was tested weekly once. In a second visit, blood pressure, heart rate, stroke volume, cardiac output, middle cerebral artery blood flow velocity (MCAv), and ventilation parameters were recorded continuously at rest and during orthostatic stress testing, which was conducted on a force plate to measure center-of-pressure (COP) oscillations (postural balance) and the electromyographic activity of the right medial gastrocnemius and tibialis anterior. RESULTS: IMT increased MIP from second to 4th week. The drops in MCAv, stroke volume, and cardiac output, as well as COP displacements during initial orthostasis decreased post-IMT. CONCLUSION: IMT improves the interplay of the respiratory pump, hemodynamic, cerebrovascular and postural balance responses during orthostatic stress in older women.

Respiratory pump contributions in cerebrovascular and postural control responses during orthostatic stress in older women.

The acute inspiratory resistive load (IRL) may increase the respiratory pump contributes to hemodynamic responses during orthostatic stress. However, IRL effects on cerebrovascular and postural control interplay is unknown. Fourteen older women (65 ±â€¯4 years) performed two orthostatic tests with spontaneous breathing through acute experimental (-9 cm.H2O) or sham load impedance (0 cmH2O) connected to a pneumotachograph for breath-by-breath recordings on a facemask. Both tests were executed on a force plate, for postural balance analysis, and electromyographic activity records of calf muscles. Blood pressure, middle cerebral artery blood velocity (MCAv), heart rate (HR), stroke volume (SV), and cardiac output (CO) were continuously recorded. IRL reduced postural instability in the first five seconds at orthostatic position compared to sham. Although the mean blood pressure and MCAv were similar in both conditions, IRL reduced the SV and CO drops, and time to recover MCAv. Therefore, IRL improved postural control, CO and MCAv responses during initial orthostasis.

Valor pronóstico del strain longitudinal, medido por velocity vector imaging, en la estenosis aórtica grave asintomática con fracción de eyección conservada / Prognostic Value of Longitudinal Strain Measured by Velocity Vector Imaging, in Asymptomatic Severe Aortic Stenosis with Preserved Ejection

RESUMEN Introducción: Se han descripto alteraciones en el strain longitudinal sistólico (SLS) en pacientes con fracción de eyección (FE) conservada. El valor pronóstico del SLS en la estenosis aórtica (EAo) grave asintomática está en discusión. Objetivos: Evaluar si la medición de SLS mediante velocity vector imaging (VVI) predice la progresión y la indicación de reemplazo valvular aórtico (RVA) en pacientes asintomáticos con EAo grave y FE conservada, inicialmente asintomáticos. Materiales y métodos: Se seleccionaron pacientes con EAo grave y FE conservada que fueron considerados asintomáticos sin indicación inicial de RVA. A todos los pacientes se les realizó un ecocardiograma que evaluó el SLS de cada segmento en dos y tres y cuatro cámaras y el SLS global por el método VVI. Además, se realizó la medición del NT-proBNP. Se consideró como punto final el requerimiento de RVA. Resultados: Se evaluaron 57 pacientes con una edad de 69 ± 8 años, 49% mujeres. Luego de dos años de seguimiento 13 pacientes (22,8%) requirieron RVA. El grupo que requirió RVA presentó menor SLS global (-15,5 ± 3,4 versus -18,9 ± 3,1, p = 0,03) y SLS en dos cámaras (-12,8 ± 5,5 versus -16,3 ± 5,6, p = 0,04). En el análisis univariado, el SLS global, en NT-proBNP y la relación E/e´ fueron predictores del punto final, mientras que, en el multivariado, solo el SLS global se comportó como predictor independiente de requerimiento de RVA (HR: 1,28 (IC 95% 1,04-1,58), p = 0,01). Conclusiones: El SLS global medido por VVI fue predictor independiente de requerimiento de RVA.

ABSTRACT Background: Longitudinal systolic strain (LSS) abnormalitiess have been described in patients with preserved ejection fraction (EF). The prognostic value of LSS in asymptomatic severe aortic stenosis (AoS) is under discussion. Objetive: The aim of this study was to assess whether LSS assessment using velocity vector imaging (VVI) predicts the progression and indication of aortic valve replacement (AVR) in asymptomatic patients with severe AoS and preserved EF. Methods: The study included patients with severe AoS and preserved EF who were considered asymptomatic and without initial indication for AVR. They underwent two, three and four-chamber echocardiography that evaluated LSS of each segment and global longitudinal strain (GLS) by VVI, as well as NT-proBNP assessment. The primary endpoint was need for AVR. Results: A total of 57 patients with mean age 69±8 years, 49% women, were included in the study. After two years of follow-up, 13 patients (22.8%) required AVR. This group had lower GLS (-15.5±3.4 vs.-18.9±3.1, p=0.03) and two-chamber LSS (-12.8±5.5 vs.-16.3±5.6, p=0.04). In univariate analysis, GLS, NT-proBNP and the E/e' ratio were predictors of the endpoint, while in the multivariate analysis, only GLS was an independent predictor of need for AVR (HR: 1.28 (95% CI 1.04-1.58), p=0.01). Conclusions: Global longitudinal strain measured by VVI was an independent predictor of need for AVR.

Transcranial Doppler ultrasound measurements of cerebral hemodynamic parameters in healthy volunteers at 2850 meters altitude. / Parámetros hemodinámicos cerebrales, determinados mediante Doppler transcraneal, en un grupo de voluntarios sanos a 2.850 metros de altura.

BACKGROUND: Transcranial Doppler ultrasound (TDU) is useful in cerebrovascular patients. TDU findings are operator-dependent; they can also be influenced by anatomical and physiological variables as well as by the altitude at which the study is done. OBJECTIVE: To report the cerebral hemodynamic parameters measured by TDU in subjects who live in Quito, Ecuador (altitude 2850 meters). MATERIAL AND METHODS: We recruited 47 volunteers with no history or clinical evidence of stroke, hypertension, metabolic disorders, or hematologic disorders; 2 patients were excluded because they did not have a viable cranial window for TDU study. Thus, we recorded mean cerebral blood flow velocity, peak systolic flow velocity, end-diastolic flow velocity, and pulsatility indices in 45 patients (28 (62.2%) women; mean age, 35.9 years). We recorded patients' age, sex, and hematocrit. We analyzed cerebrovascular hemodynamic parameters by sex and age group. RESULTS: No significant differences between hemispheres were observed in mean flow velocities, except in the anterior cerebral arteries with right predominance. Flow velocities were higher in women and in the youngest age group. No significant differences in the pulsatility indices were found between sexes or between age groups. The flow velocities in this series are lower than those reported for other series. CONCLUSIONS: The hemodynamic parameters in this series are lower than in other series and are influenced by the altitude, age, and sex.

Hydrodynamic evaluations of four mock femoral venous cannulas

Abstract Objective: To report the results of four mock femoral venous cannulas and the hydrodynamical superiority of one of them, which is the completely punched (CP) model, upon the other three. Methods: Four simulated femoral venous cannulas (single-stage, two-stage, multi-stage, and CP model) were designed from a 1/4" x 1/16" x 68 cm polyvinyl chloride (PVC) tubing line for testing. Holes on the PVC tubes were opened by a 5 mm aortic punch. In order to evaluate the cannulas' drainage performance, gelofusine was used as fluid. The fluid was drained for 60 seconds by gravitation and then measured for each model separately. Results: Mean drained volumes of single-stage, two-stage, and multi-stage cannulas were 2.483, 2.561, and 2.603 mL, respectively. However, the CP cannula provided us a mean drained volume of 2.988 mL. There were significant differences among the variables of the CP cannula and the other three mock cannulas concerning the drained fluid flow (P<0.01). Conclusion: In our study, the measured mean volumes showed us that more drainage surface area provides better fluid drainage.

Cerebral Haemodynamics following Acute Ischaemic Stroke: Effects of Stroke Severity and Stroke Subtype.

BACKGROUND: Acute ischaemic stroke (AIS) patients often show impaired cerebral autoregulation (CA). We tested the hypothesis that CA impairment and other alterations in cerebral haemodynamics are associated with stroke subtype and severity. METHODS: AIS patients (n = 143) were amalgamated from similar studies. Data from baseline (< 48 h stroke onset) physiological recordings (beat-to-beat blood pressure [BP], cerebral blood flow velocity (CBFV) from bilateral insonation of the middle cerebral arteries) were calculated for mean values and autoregulation index (ARI). Differences were assessed between stroke subtype (Oxfordshire Community Stroke Project [OCSP] classification) and severity (National Institutes of Health Stroke Scale [NIHSS] score < 5 and 5-25). Correlation coefficients assessed associations between NIHSS and physiological measurements. RESULTS: Thirty-two percent of AIS patients had impaired CA (ARI < 4) in affected hemisphere (AH) that was similar between stroke subtypes and severity. CBFV in AH was comparable between stroke subtype and severity. In unaffected hemisphere (UH), differences existed in mean CBFV between lacunar and total anterior circulation OCSP subtypes (42 vs. 56 cm•s-1, p < 0.01), and mild and moderate-to-severe stroke severity (45 vs. 51 cm•s-1, p = 0.04). NIHSS was associated with peripheral (diastolic and mean arterial BP) and cerebral haemodynamic parameters (CBFV and ARI) in the UH. CONCLUSIONS: AIS patients with different OCSP subtypes and severity have homogeneity in CA capability. Cerebral haemodynamic measurements in the UH were distinguishable between stroke subtype and severity, including the association between deteriorating ARI in UH with stroke severity. More studies are needed to determine their clinical significance and to understand the determinants of CA impairment in AIS patients.

Are high flow arteriovenous accesses associated with worse haemodialysis? / Acessos arteriovenosos de alto débito estão associados a pior hemodiálise?

ABSTRACT Introduction: An arteriovenous (AV) access flow (Qa) of 400 mL/min is usually sufficient for an effective hemodialysis (HD), but some accesses continue developing and become high flow accesses (HFA). Some authors postulated that an HFA might shift a significant portion of dialyzed blood from the cardiac output, which could decrease HD efficiency and lead to volume overload. Objective: The aim of our study was to evaluate if HFA is associated with reduced HD efficiency and/or volume overload in prevalent HD patients. Methods: We performed a 1-year retrospective study and assessed HD efficiency by the percentage of sessions in which the Kt/V > 1.4 and volume overload by bioimpedance spectroscopy. Results: The study included 304 prevalent HD patients with a mean age of 67.5 years; 62.5% were males, 36.2% were diabetics, with a median HD vintage of 48 months. Sixteen percent of the patients had a HFA (defined as Qa > 2 L/min). In multivariate analysis, patients with HFA presented higher risk of volume overload (OR = 2.67, 95%CI = 1.06-6.71) and severe volume overload (OR = 4.06, 95%CI = 1.01-16.39) and attained dry weight less frequently (OR = 0.37, 95%CI = 0.14-0.94). However, HFA was not associated with lower Kt/V. Conclusion: Our results suggest that patients with HFA have higher risk of volume overload. However, contrarily to what has been postulated, HFA was not associated with less efficient dialysis, measured by Kt/V. Randomized controlled trials are needed to clarify these questions.

RESUMO Introdução: Um débito de sangue de acesso arteriovenoso (AV) (Qa) de 400 mL/min é geralmente suficiente para uma hemodiálise (HD) eficaz, mas alguns acessos continuam se desenvolvendo e se tornam acessos de alto débito (AAD). Alguns autores postularam que um AAD poderia desviar uma porção significativa do sangue dialisado do débito cardíaco, o que poderia diminuir a eficiência da HD e levar à sobrecarga de volume. Objetivo: O objetivo do nosso estudo foi avaliar se o AAD está associado à redução da eficiência da HD e/ou à sobrecarga de volume em pacientes prevalentes em HD. Métodos: Foi realizado um estudo retrospectivo de 1 ano, e avaliada a eficiência da HD pela porcentagem de sessões em que o Kt/V > 1,4 e a sobrecarga de volume avaliada pela bioimpedância. Resultados: O estudo incluiu 304 pacientes prevalentes em HD, com média de idade de 67,5 anos; 62,5% eram do sexo masculino; 36,2% eram diabéticos, com uma mediana de tempo em HD de 48 meses. Dezesseis por cento dos pacientes apresentavam AAD (definida como Qa > 2 L/min). Na análise multivariada, os pacientes com AAD apresentaram maior risco de sobrecarga de volume (OR = 2,67; IC95% = 1,06-6,71) e sobrecarga severa de volume (OR = 4,06; IC95% = 1,01-16,39) e atingiram o peso seco com menor frequência (OR = 0,37, IC 95% = 0,14-0,94). No entanto, o AAD não foi associado uma menor razão Kt/V. Conclusão: Nossos resultados sugerem que pacientes com AAD apresentam maior risco de sobrecarga de volume. No entanto, ao contrário do que foi postulado, o AAD não foi associado à diálise menos eficiente, medida pelo Kt/V. Ensaios clínicos randomizados são necessários para esclarecer essas questões.

Acute effects of walking and combined exercise on oxidative stress and vascular function in peripheral artery disease.

The aim of this study was to compare the effects of a single session of walking and combined exercise on oxidative stress and vascular function in peripheral arterial disease patients. Thirteen patients with peripheral arterial disease underwent two experimental sessions in random order: walking (ten sets of 2-min walking at the speed corresponding to the onset of claudication pain with 2-min interval between sets) and combined exercise (1 × 10 reps in eight resistance exercises plus five-two-minute sets of walking). Before and after the exercise, vascular function (blood flow, leg vascular resistance and blood-flow postreactive hyperaemia) and oxidative stress (malondialdehyde and plasma nitrite levels) were obtained. Blood flow increased similarly after both sessions, whilst leg vascular resistance decreased similarly after both sessions. Plasma nitrite increased only after the combined exercise. Malondialdehyde decreased after both sessions, and the decrease was greater after combined exercise. As a conclusion, a single session of combined exercise improves blood flow and leg vascular resistance similarly to walking session; however, combined exercise promoted better effects on oxidative stress.

Understanding the Influence of Flow Velocity, Wall Motion Filter, Pulse Repetition Frequency, and Aliasing on Power Doppler Image Quantification.

OBJECTIVES: Although power Doppler imaging has been used to quantify tissue and organ vascularity, many studies showed that limitations in defining adequate ultrasound machine settings and attenuation make such measurements complex to be achieved. However, most of these studies were conducted by using the output of proprietary software, such as Virtual Organ computer-aided analysis (GE Healthcare, Kretz, Zipf, Austria); therefore, many conclusions may not be generalizable because of unknown settings and parameters used by the software. To overcome this limitation, our goal was to evaluate the impact of the flow velocity, pulse repetition frequency (PRF), and wall motion filter (WMF) on power Doppler image quantification using beam-formed ultrasonic radiofrequency data. METHODS: The setup consisted of a blood-mimicking fluid flowing through a phantom. Radiofrequency signals were collected using PRFs ranging from 0.6 to 10 kHz for 6 different flow velocities (5-40 cm/s). Wall motion filter cutoff frequencies were varied between 50 and 250 Hz. RESULTS: The power Doppler magnitude was deeply influenced by the WMF cutoff frequency. The effect of using different WMF values varied with the PRF; therefore, the power Doppler signal intensity was dependent on the PRF. Finally, we verified that power Doppler quantification can be affected by the aliasing effect, especially when using a PRF lower than 1.3 kHz. CONCLUSIONS: The WMF and PRF greatly influenced power Doppler quantification, mainly when flow velocities lower than 20 cm/s were used. Although the experiments were conducted in a nonclinical environment, the evaluated parameters are equivalent to those used in clinical practice, which makes them valuable for aiding the interpretation of related data in future research.

Arterial hypertension impact on cerebral blood flow in patients with Alzheimer's disease / Impacto da hipertensão arterial sobre fluxo de sangue cerebral em pacientes com a doença de Alzheimer

Background: Studies show the potential deterioration of brain vascularization and probable involvement of hypertension in Alzheimer disease (AD). Objective: The objective was to evaluate the potential impact of hypertension on cerebral vascular flows in a sample of Alzheimer's patients. Methods: 19 patients with AD, including 10 with hypertension (aHT+) and 9 without hypertension (aHT-) were recruited. They underwent clinical evaluation and phase-contrast MRI protocol for flow assessment. Cerebral arterial flow distributions were evaluated using kurtosis and skewness indices at the intracranial and extracranial levels. Results: No significant differences were found in the mean arterial flow, pulse flow and kurtosis between the levels in the AD aHT+ population. There was a significant difference in skewness between extra- and intracranial levels (p = 0.01). No significant differences were found in the mean arterial flow between the levels in the AD aHT- population. A significant difference was observed in the pulse flow (p = 0.03), kurtosis (p = 0.02) and skewness (p = 0.008) between the levels. At the extracranial level we did not find any significant differences in the mean arterial flow, pulse flow or skewness between aHT+ and aHT-. There was a significant difference in kurtosis at the extracranial level between the aHT+ and aHT- (p = 0.03). At the intracranial level, there were no significant differences in all parameters. Conclusion: Results showed a difference between cerebral vasculature in AD for aHT+ and aHT- groups. This is probably related to the loss of arterial compliance induced by the degradation of the vascular system.

Introdução: Estudos demonstram a potencial deterioração da vascularização cerebral e a provável relação da hipertensão na doença de Alzheimer (DA). Objetivo: O objetivo foi avaliar o potencial impacto da hipertensão no fluxo vascular cerebral numa amostra de pacientes de Alzheimer. Métodos: foram selecionados 19 pacientes com DA, incluindo 10 com hipertensão (aHT+) e 9 sem hipertensão (aHT+). Foram submetidos a avaliação clínica e a um protocolo de ressonância magnética de contraste de fase para avaliação de fluxo. A distribuição de fluxo arterial cerebral foi avaliada através dos índices de curtose e assimetria nos níveis intra e extracraniano. Resultados: Não foram encontradas diferenças significativas no fluxo arterial médio, no fluxo de pulso e curtose entre os níveis da população DA aHT+. Houve uma diference significativa na assimetria entre os níveis extra e intracranianos (p = 0,01). Não foram encontradas diferenças significativas no fluxo arterial médio entre os níveis da população DA aHT-. Uma diferença significativa foi observada no fluxo de pulso (p = 0,03), na curtose (p = 0,02) e na assimetria (p = 0,008) entre os níveis. Não foram observadas diferenças significativas no fluxo arterial médio, no fluxo de pulso ou na assimetria entre aHT+ e aHT- para o nível extracraniano. Foi observada diferença significativa na curtose extracraniana entre aHT+ e AHT- (p = 0,03). Não houve diferença significativa em todos os parâmetros do nível intracraniano. Conclusão: Os resultados mostraram uma diferença entre a vasculatura cerebral nos grupos de DA aHT+ e aHT-. Isso está provavelmente relacionado à perda de complacência arterial induzida pela degradação do sistema vascular.

Effects of obesity on retrobulbar flow hemodynamics: color Doppler ultrasound evaluation / Efeitos da obesidade na hemodinâmica do fluxo retrobulbar: avaliação por ultrassom doppler colorido

ABSTRACT Purpose: To evaluate intraocular pressure (IOP) and extraocular orbital vessels with color Doppler ultrasound (CDU) and investigate the effects of obesity on retrobulbar blood flow. Methods: Fifty-nine patients were included in this prospective study. Patients were divided into two groups according to body mass index: Group 1 (31 obese patients) and Group 2 (28 non-obese patients). IOP was measured with a Goldmann applanation tonometer, and CDU was used to evaluate the retrobulbar vessels. Results: The mean IOP was 18 ± 6.68 mmHg in the obese group and 13.71 ± 1.60 mmHg in the control group (p<0.001). When the CDU values for the central retinal artery were compared between the groups, the pulsatility index was found to be significantly lower in the obese group than in the control group (p<0.001). When the CDU values for the ophthalmic artery (OA) were compared between the groups, the peak systolic velocity (p<0.001) and end-diastolic velocity (p=0.002) values were found to be significantly lower in the obese group than in the control group. Conclusions: Obese patients have a higher mean IOP and lower flow velocity than non-obese patients. Increased IOP together with decreased retrobulbar blood flow, particularly in obese individuals, may increase the risk of glaucoma development.

RESUMO Objetivo: Avaliar a pressão intraocular (PIO) e vasos orbitários extraoculares com ultrassom Doppler colorido (UDC) e investigar os efeitos da obesidade sobre o fluxo sanguíneo retrobulbar. Métodos: Cinquenta e nove pacientes foram incluídos neste estudo prospectivo. Os pacientes foram divididos em dois grupos de acordo com o índice de massa corpo ral (IMC): Grupo 1 (31 pacientes obesos) e Grupo 2 (28 não obesos). As pressões intraoculares (PIOs) foram medidas com tonômetro de aplanação de Goldmann e o UDC foi utilizada para a avaliação de vasos retrobulbar. Resultados: As PIOs foram 18 ± 6,68 mmHg nos pacientes obesos e 13,71 ± 1,60 mmHg nos grupos controle (p<00,001). Quando os valores da artéria central da retina (ACR) foram comparados entre os grupos controle e obeso. O índice pulsátil (PI) foi marcadamente menor no grupo obeso (p<00,001). Quando os valores da artéria oftálmica (AO) dos grupos obesos e de controle foram comparados. Os valores de Velocidade do pico sistólico (PSV) (p<00,001) e velocidade diastólica final (EDV) (p=00,002) foram significativamente mais baixos no grupo obeso. Conclusão: Pacientes obesos têm maior PIO do que os pacientes não obesos. Os pacientes obesos têm diminuição nas velocidades de fluxo da AO. O aumento da PIO. Juntamente com a diminuição do fluxo sanguíneo retrobulbar, especialmente em indivíduos obesos, pode aumentar o risco de desenvolvimento de glaucoma.

Application of shortwave diathermy to lower limb increases arterial blood flow velocity and skin temperature in women: a randomized controlled trial.

BACKGROUND: Shortwave diathermy (SWD) and microwave diathermy (MWD) are frequently used by physical therapists to treat musculoskeletal conditions. The therapeutic benefits are usually associated with an increase in tissue temperature; however, there is no consensus on the changes in blood flow. OBJECTIVES: 1) To evaluate the behavior of temperature and arterial blood flow after the application of SWD and MWD to the lower limb of healthy women aged 18-30 and 2) to assess whether changes in limb positioning can influence SWD response. METHOD: Among the subjects analyzed, 40 women were eligible to participate in the trial and were randomly allocated to the SWD group or the MWD group. Each group received 20min of diathermy. After receiving the interventions, all patients crossed over to the other group, but the devices were detuned (sham). SWD was applied to the posterior compartment of the thigh and leg, with the knee in 0° and 90° of flexion, and the MWD applied to the posterior thigh. Skin temperature evaluation (digital infrared thermography) and assessment of blood flow velocity (Doppler ultrasound) were performed immediately before and 10 and 20min after the application. RESULTS: Arterial blood flow increased after SWD diathermy (vs. Sham), but not after MWD diathermy. SWD promoted skin heating at the end of therapy in all areas analyzed, remaining above baseline even 20min after the end of the application. MWD diathermy promoted skin heating in the posterior thigh, reflecting a rise in the temperature of the popliteal fossa area that remained for 10min after the end of the application. CONCLUSION: The increase in arterial blood flow velocity depends on the size of the heating area, since it was only observed in the application of the SWD. However, after 20min of application, the position of the lower leg did not affect the heating.