Increased Cardiovascular Risk in Young Patients with CKD and the Role of Lipid-Lowering Therapy.

PURPOSE OF REVIEW: Chronic kidney disease (CKD) is associated with a significantly increased risk of cardiovascular disease (CVD). This review summarizes known risk factors, pathophysiological mechanisms, and current therapeutic possibilities, focusing on lipid-lowering therapy in CKD. RECENT FINDINGS: Novel data on lipid-lowering therapy in CKD mainly stem from clinical trials and clinical studies. In addition to traditional CVD risk factors, patients with CKD often present with non-traditional risk factors that include, e.g., anemia, proteinuria, or calcium-phosphate imbalance. Dyslipidemia remains an important contributing CVD risk factor in CKD, although the mechanisms involved differ from the general population. While statins are the most commonly used lipid-lowering therapy in CKD patients, some statins may require dose reduction. Importantly, statins showed diminished beneficial effect on cardiovascular events in patients with severe CKD and hypercholesterolemia despite high CVD risk and effective reduction of LDL cholesterol. Ezetimibe enables the reduction of the dose of statins and their putative toxicity and, in combination with statins, reduces CVD endpoints in CKD patients. The use of novel drugs such as PCSK9 inhibitors is safe in CKD, but their potential to reduce cardiovascular events in CKD needs to be elucidated in future studies.

Heart failure with preserved ejection fraction is the most frequent but commonly overlooked phenotype in patients on chronic hemodialysis.

Introduction: Heart failure (HF) is a serious complication of end-stage kidney disease (ESKD). However, most data come from retrospective studies that included patients on chronic hemodialysis at the time of its initiation. These patients are frequently overhydrated, which significantly influences the echocardiogram findings. The primary aim of this study was to analyze the prevalence of heart failure and its phenotypes. The secondary aims were (1) to describe the potential of N-terminal pro-brain natriuretic peptide (NTproBNP) for HF diagnosis in ESKD patients on hemodialysis, (2) to analyze the frequency of abnormal left ventricular geometry, and (3) to describe the differences between various HF phenotypes in this population. Methods: We included all patients on chronic hemodialysis for at least 3 months from five hemodialysis units who were willing to participate, had no living kidney transplant donor, and had a life expectancy longer than 6 months at the time of inclusion. Detailed echocardiography together with hemodynamic calculations, dialysis arteriovenous fistula flow volume calculation, and basic lab analysis were performed in conditions of clinical stability. Excess of severe overhydration was excluded by clinical examination and by employing bioimpedance. Results: A total of 214 patients aged 66.4 ± 14.6 years were included. HF was diagnosed in 57% of them. Among patients with HF, HF with preserved ejection fraction (HFpEF) was, by far, the most common phenotype and occurred in 35%, while HF with reduced ejection fraction (HFrEF) occurred only in 7%, HF with mildly reduced ejection fraction (HFmrEF) in 7%, and high-output HF in 9%. Patients with HFpEF differed from patients with no HF significantly in the following: they were older (62 ± 14 vs. 70 ± 14, p = 0.002) and had a higher left ventricular mass index [96(36) vs. 108(45), p = 0.015], higher left atrial index [33(12) vs. 44(16), p < 0.0001], and higher estimated central venous pressure [5(4) vs. 6(8), p = 0.004] and pulmonary artery systolic pressure [31(9) vs. 40(23), p = 0.006] but slightly lower tricuspid annular plane systolic excursion (TAPSE): 22 ± 5 vs. 24 ± 5, p = 0.04. NTproBNP had low sensitivity and specificity for diagnosing HF or HFpEF: with the use of the cutoff value of 8,296 ng/L, the sensitivity of HF diagnosis was only 52% while the specificity was 79%. However, NTproBNP levels were significantly related to echocardiographic variables, most significantly to the indexed left atrial volume (R = 0.56, p < 10-5) and to the estimated systolic pulmonary arterial pressure (R = 0.50, p < 10-5). Conclusions: HFpEF was by far the most common heart failure phenotype in patients on chronic hemodialysis and was followed by high-output HF. Patients suffering from HFpEF were older and had not only typical echocardiographic changes but also higher hydration that mirrored increased filling pressures of both ventricles than in those of patients without HF.

Significant differences between two commonly used bioimpedance methods in hemodialysis patients.

INTRODUCTION: Bioimpedance methods are currently used abundantly in patients on chronic hemodialysis. In this population, their most important role is to determine the level of fluid volume, respectively its intra- and extracellular components. There are several bioimpedance devices on the market. In this project, we compared two frequently used devices: Body Composition Monitor and InBody S10. MATERIALS AND METHODS: We invited patients on chronic hemodialysis who are being treated in our institution. Inclusion criteria were: clinically stable condition, lack of artificial joints, pacemakers, or other implanted metal objects. The examinations were performed just prior to hemodialysis by both methods 5 minutes apart. Patients were examined in the supine position after 15 minutes at rest to stabilize body fluids. Studied parameters were those that are obtainable by both methods: total body water (TBW) (L), extracellular water (ECW) (L) and intracellular water (ICW) (kg), lean tissue mass (LTM) (L), and fat tissue mass (kg). RESULTS: We included 14 participants (aged 64.4 ± 18.0 years). Statistically and clinically significant differences between data from compared devices were observed for all variables. Inbody S10 overestimated TBW by 2.58 ± 2.73 L and ICW by 4.56 ± 2.27 L in comparison to BCM. The highest difference (27%) was measured for LTM and ICW 22%. LTM, fat, and ECW were higher when measured by BCM (LTM by 8.54 ± 6.43 kg, p < 0.001; fat by 3.41 ± 4.22, p = 0.01; ECW by 2.01 ± 0.89 L, p < 0.001). CONCLUSION: The differences between tested devices were significant not only statistically, but also clinically. These two devices cannot be used interchangeably for dry weight setting of hemodialysis patients.

Arteriovenous Hemodialysis Access Stenosis Diagnosed by Duplex Doppler Ultrasonography: A Review.

Arteriovenous fistula (AVF) is currently the hemodialysis access with the longest life expectations for the patients. However, even the AVF is at risk for many complications, especially the development of stenosis. The latter can not only lead to inadequate hemodialysis but also lead to AVF thrombosis. Duplex Doppler ultrasonography is a very precise method, in the hands of experienced professionals, for the diagnosis of AVF complications. In this review, we summarize the ultrasound diagnostic criteria of significant stenoses and their indication for procedural therapy.

Skin autofluorescence corresponds to microvascular reactivity in diabetes mellitus.

Advanced glycation accelerated by chronic hyperglycaemia contributes to the development of diabetic vascular complications throughout several mechanisms. One of these mechanisms is supposed to be impaired microvascular reactivity, that precedes significant vascular changes. The aim of this study was to find an association between advanced glycation, the soluble receptor for AGEs (sRAGE), and microvascular reactivity (MVR) in diabetes. Skin autofluorescence (SAF), which reflects advanced glycation, was assessed by AGE-Reader, MVR was measured by laser Doppler fluxmetry and evaluated together with sRAGE in 43 patients with diabetes (25 Type 1 and 18 Type 2) and 26 healthy controls of comparable age. SAF was significantly higher in patients with diabetes compared to controls (2.4 ± 0.5 vs. 2.0 ± 0.5 AU; p < 0.01). Patients with diabetes with SAF > 2.3 AU presented significantly worse MVR in both post-occlusive reactive hyperaemia (PORH) on the finger and forearm, and thermal hyperaemia (TH), compared to patients with SAF < 2.3 AU. SAF was age dependent in both diabetes (r = 0.41, p < 0.01) and controls (r = 0.45, p < 0.05). There was no association between SAF and diabetes control expressed by glycated haemoglobin. A significant relationship was observed between SAF and sRAGE in diabetes (r = 0.56, p < 0.001), but not in controls. A significant inverse association was found between SAF and MVR on the forearm in diabetes (PORH: r = -0.42, p < 0.01; TH: r = -0.46, p < 0.005). Both advanced glycation expressed by higher SAF or sRAGE and impaired MVR are involved in the pathogenesis of vascular complications in diabetes, and we confirm a strong interplay of these processes in this scenario.

CZecking heart failure in patients with advanced chronic kidney disease (Czech HF-CKD): Study protocol.

BACKGROUND: Heart failure (HF) is a frequent cause of morbidity and mortality of end-stage kidney disease (ESKD) patients on hemodialysis. It is not easy to distinguish HF from water overload. The traditional HF definition has low sensitivity and specificity in this population. Moreover, many patients on hemodialysis have exercise limitations unrelated to HF. Therefore, we postulated two new HF definitions ((1) Modified definition of the Acute Dialysis Quality Improvement working group; (2) Hemodynamic definition based on the calculation of the effective cardiac output). We hypothesize that the newer definitions will better identify patients with higher number of endpoints and with more advanced structural heart disease. METHODS: Cohort, observational, longitudinal study with recording predefined endpoints. Patients (n = 300) treated by hemodialysis in six collaborating centers will be examined centrally in a tertiary cardiovascular center every 6-12 months lifelong or till kidney transplantation by detailed expert echocardiography with the calculation of cardiac output, arteriovenous dialysis fistula flow volume calculation, bio-impedance, and basic laboratory analysis including NTproBNP. Effective cardiac output will be measured as the difference between measured total cardiac output and arteriovenous fistula flow volume and systemic vascular resistance will be also assessed non-invasively. In case of water overload during examination, dry weight adjustment will be recommended, and the patient invited for another examination within 6 weeks. A composite major endpoint will consist of (1) Cardiovascular death; (2) HF worsening/new diagnosis of; (3) Non-fatal myocardial infarction or stroke. The two newer HF definitions will be compared with the traditional one in terms of time to major endpoint analysis. DISCUSSION: This trial will differ from others by: (1) detailed repeated hemodynamic assessment including arteriovenous access flow and (2) by careful assessment of adequate hydration to avoid confusion between HF and water overload.

New Porcine Model of Arteriovenous Fistula Documents Increased Coronary Blood Flow at the Cost of Brain Perfusion.

Background: Arteriovenous fistulas (AVF) represent a low resistant circuit. It is known that their opening leads to decreased systemic vascular resistance, increased cardiac output and other hemodynamic changes. Possible competition of AVF and perfusion of other organs has been observed before, however the specific impact of AVF has not been elucidated yet. Previous animal models studied long-term changes associated with a surgically created high flow AVF. The aim of this study was to create a simple AVF model for the analysis of acute hemodynamic changes. Methods: Domestic female pigs weighing 62.6 ± 5.2 kg were used. All the experiments were held under general anesthesia. The AVF was created using high-diameter ECMO cannulas inserted into femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Near-infrared spectroscopy sensors, flow probes and flow wires were inserted to study brain and heart perfusion. Results: AVF blood flow was 2.1 ± 0.5 L/min, which represented around 23% of cardiac output. We observed increase in cardiac output (from 7.02 ± 2.35 L/min to 9.19 ± 2.99 L/min, p = 0.0001) driven dominantly by increased heart rate, increased pulmonary artery pressure, and associated right ventricular work. Coronary artery flow velocity rose. On the contrary, carotid artery flow and brain and muscle tissue oxygenation measured by NIRS decreased significantly. Conclusions: Our new non-surgical AVF model is reproducible and demonstrated an acute decrease of brain and muscle perfusion.

Effect of Intra-arrest Transport, Extracorporeal Cardiopulmonary Resuscitation, and Immediate Invasive Assessment and Treatment on Functional Neurologic Outcome in Refractory Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial.

Importance: Out-of-hospital cardiac arrest (OHCA) has poor outcome. Whether intra-arrest transport, extracorporeal cardiopulmonary resuscitation (ECPR), and immediate invasive assessment and treatment (invasive strategy) is beneficial in this setting remains uncertain. Objective: To determine whether an early invasive approach in adults with refractory OHCA improves neurologically favorable survival. Design, Setting, and Participants: Single-center, randomized clinical trial in Prague, Czech Republic, of adults with a witnessed OHCA of presumed cardiac origin without return of spontaneous circulation. A total of 256 participants, of a planned sample size of 285, were enrolled between March 2013 and October 2020. Patients were observed until death or day 180 (last patient follow-up ended on March 30, 2021). Interventions: In the invasive strategy group (n = 124), mechanical compression was initiated, followed by intra-arrest transport to a cardiac center for ECPR and immediate invasive assessment and treatment. Regular advanced cardiac life support was continued on-site in the standard strategy group (n = 132). Main Outcomes and Measures: The primary outcome was survival with a good neurologic outcome (defined as Cerebral Performance Category [CPC] 1-2) at 180 days after randomization. Secondary outcomes included neurologic recovery at 30 days (defined as CPC 1-2 at any time within the first 30 days) and cardiac recovery at 30 days (defined as no need for pharmacological or mechanical cardiac support for at least 24 hours). Results: The trial was stopped at the recommendation of the data and safety monitoring board when prespecified criteria for futility were met. Among 256 patients (median age, 58 years; 44 [17%] women), 256 (100%) completed the trial. In the main analysis, 39 patients (31.5%) in the invasive strategy group and 29 (22.0%) in the standard strategy group survived to 180 days with good neurologic outcome (odds ratio [OR], 1.63 [95% CI, 0.93 to 2.85]; difference, 9.5% [95% CI, -1.3% to 20.1%]; P = .09). At 30 days, neurologic recovery had occurred in 38 patients (30.6%) in the invasive strategy group and in 24 (18.2%) in the standard strategy group (OR, 1.99 [95% CI, 1.11 to 3.57]; difference, 12.4% [95% CI, 1.9% to 22.7%]; P = .02), and cardiac recovery had occurred in 54 (43.5%) and 45 (34.1%) patients, respectively (OR, 1.49 [95% CI, 0.91 to 2.47]; difference, 9.4% [95% CI, -2.5% to 21%]; P = .12). Bleeding occurred more frequently in the invasive strategy vs standard strategy group (31% vs 15%, respectively). Conclusions and Relevance: Among patients with refractory out-of-hospital cardiac arrest, the bundle of early intra-arrest transport, ECPR, and invasive assessment and treatment did not significantly improve survival with neurologically favorable outcome at 180 days compared with standard resuscitation. However, the trial was possibly underpowered to detect a clinically relevant difference. Trial Registration: ClinicalTrials.gov Identifier: NCT01511666.

Reduction of arteriovenous access blood flow leads to biventricular unloading in haemodialysis patients.

AIMS: Patients on chronic haemodialysis have a wide range of changes in cardiac function and structure, including left ventricular hypertrophy, dilation and diastolic dysfunction or pulmonary hypertension. All these changes were linked to increased mortality in previous studies. High-flow arteriovenous fistulas (AVF) are supposed to be a factor contributing to their development. This study investigated the early effect of surgical AVF blood flow (Qa) reduction on these changes in patients with or without heart failure changes. METHODS AND RESULTS: Forty-two patients in chronic haemodialysis programme with high-flow AVF (Qa over 1500 mL/min), indicated for surgery for ≥1 of the following indications: 1.manifest heart failure; 2.hand ischemia; 3.advanced structural heart changes detected by echocardiography. The patients underwent echocardiography on selection visit, before blood flow reducing surgery and six weeks thereafter. The Qa reduction led to decrease of left ventricular mass (p = 0.02), end-diastolic volume (p = 0.008), end-diastolic diameter (p = 0.003) and left atrial volume (p = 0.0006). Diastolic function improved. Similarly, right ventricular diameter and right atrial volume decreased (p = 0.000001 and 0.00009, respectively) together with the decrease of estimated pulmonary artery systolic pressure. 81% of patients suffered from pulmonary hypertension prior to surgery, only 36% thereafter. CONCLUSION: The surgical restriction of the hyperkinetic circulation leads to several improvements of heart structure and function, which was linked to higher mortality in other studies. The beneficial effect of Qa reduction is present even in patients without symptoms of heart failure. The contribution of AVF must be considered with structural or functional heart changes.

The effect of high-flow arteriovenous fistulas on systemic haemodynamics and brain oxygenation.

AIMS: High-flow arteriovenous fistula (AVF) for haemodialysis leads to profound haemodynamic changes and sometimes to heart failure (HF). Cardiac output (CO) is divided between the AVF and body tissues. The term effective CO (COef) represents the difference between CO and AVF flow volume (Qa) and better characterizes the altered haemodynamics that may result in organ hypoxia. We investigated the effects of Qa reduction on systemic haemodynamics and on brain oxygenation. METHODS AND RESULTS: This is a single-centre interventional study. Twenty-six patients on chronic haemodialysis with high Qa (>1500 mL/min) were indicated for surgical Qa reduction for HF symptoms and/or signs of structural heart disease on echocardiography. The included patients underwent three sets of examinations: at 4 months and then 2 days prior and 6 weeks post-surgical procedure. Clinical status, echocardiographical haemodynamic assessment, Qa, and brain oximetry were recorded. All parameters remained stable from selection to inclusion. After the procedure, Qa decreased from 3.0 ± 1.4 to 1.3 ± 0.5 L/min, P < 0.00001, CO from 7.8 ± 1.9 to 6.6 ± 1.5 L/min, P = 0.0002, but COef increased from 4.6 ± 1.4 to 5.3 ± 1.4 L/min, P = 0.036. Brain tissue oxygen saturation increased from 56 ± 11% to 60 ± 9%, P = 0.001. CONCLUSIONS: Qa reduction led to increased COef. This was explained by a decreased proportion of CO running through the AVF in patients with Qa > 2.0 L/min. These observations were mirrored by higher brain oxygenation and might explain HF symptoms and improved haemodynamics even in asymptomatic high Qa patients.

Short-term manual compression of hemodialysis fistula leads to a rise in cerebral oxygenation.

BACKGROUND: Decreased cerebral perfusion and oxygenation are common in hemodialysis patients. Magnitude of the arteriovenous fistula involvement in this phenomenon is not known. The aim of this study was to investigate the effect that a short-term arteriovenous fistula flow interruption has on cerebral oxygenation and to review and suggest possible explanations. METHODS: In 19 patients, basic laboratory and clinical data were obtained and arteriovenous fistula flow volume was measured by ultrasonography. Baseline regional cerebral oxygen saturation (rSO2) was measured by near-infrared spectroscopy. Manual pressure was then applied on the fistula, resulting in total blood flow interruption. After 1 min of manual compression, rSO2 and blood pressure values were noted again. The compression-related change in rSO2 was assessed, as well as its association with arteriovenous fistula flow volume, blood pressure, and other parameters. RESULTS: Mean cerebral rSO2 increased after arteriovenous fistula compression (from 53.6% ± 11.4% to 55.6% ± 10.8%; p = 0.000001; 95% confidence interval = 1.39-2.56). The rSO2 increase was higher in patients with lower rSO2 at baseline (r = -0.46; p = 0.045). CONCLUSION: A significant rise in cerebral oxygenation was observed following the manual compression of arteriovenous fistula. Therefore, the arteriovenous fistula could have a role in impaired cerebral oxygenation in hemodialysis patients.

Long-term trends in fog occurrence in the Czech Republic, Central Europe.

Fog is a very important and complex atmospheric phenomenon of the utmost importance for the environment and for human society. For practical reasons, fog occurrence is observed regularly at meteorological stations worldwide. Decreasing trends in fog frequency reported from numerous regions have been often associated with either decreasing pollution or climate change, including increasing temperature and changes in atmospheric circulation. We have examined the data on fog occurrence from twelve Czech sites representing different environments (urban, rural, mountain), geographical areas, and altitudes across the country. For our analysis we used long-term records from the time period of 1961-2018, covering both the ambient air's heavily polluted periods of the 1970s and 1980s and the cleaner period, following the adoption of new, more stringent legislation and effective countermeasures after the 1990s. We applied a generalised additive model (GAM) framework as a flexible, semiparametric regression approach to address nonlinear trend shapes in a formalised and unified way. In particular, we employed a penalised spline approach with cross-validated penalty coefficient estimation. Our study confirmed non-linear behaviour for both year-to-year trends and annual seasonality. Our results showed further that over the analysed, almost sixty-year period, fog occurrence has decreased significantly at all the examined sites, though the pattern of the long-term change differed among individual sites. Moreover, we have found significant seasonality in fog occurrence, though it is different at individual sites. Furthermore, apart from the overall annual fog probability change over the years, at some sites the fog's seasonal profile has also deformed substantially over the long term.

Diastolic dysfunction in asymptomatic hemodialysis patients in the light of the current echocardiographic guidelines.

The prevalence of the left ventricular hypertrophy (LVH) is very high in end-stage renal disease treated by hemodialysis. Diastolic dysfunction is a frequent consequence and leads to the development of heart failure with preserved ejection fraction. New American/European echocardiographic guidelines for the assessment of diastolic function simplified the evaluation and were published recently. The aim of this study was to reveal if the new guidelines stratify asymptomatic hemodialysis patients by the levels of brain-natriuretic peptide (BNP). A cohort of 46 patients hemodialyzed in one center with the lack of overt heart failure, systolic dysfunction, arrhythmia or significant valvular disease were examined by echocardiography before and after a single hemodialysis and blood samples for BNP analysis were drawn at both occasions. The LVH was present in 53% of patients, concentric remodeling in another 17%. Higher indexed left ventricular mass was related to higher BNP levels (r = 0.58, p = 0.0001). Before hemodialysis, diastolic dysfunction was present in 61%: grade 1 in 25%, grade 2 in 21% and grade 3 in 8%. The higher grade of diastolic dysfunction was associated with the incremental increase of BNP. The post-dialysis echocardiography did not allow the assessment of diastolic function in as many as 37% of patients. Our study has shown that the application of the current guidelines for the assessment of diastolic function based on simple four criteria differentiate hemodialysis symptomless patients with preserved systolic function according to BNP levels. BNP levels also rose together with the left ventricular mass. The ratio E/e' medial seemed to be a better predictor of increased BNP than E/e' lateral or E/e' averaged.

Revisiting fog as an important constituent of the atmosphere.

We examined observation-based fog occurrence at three Czech monitoring sites: Praha 4 - Libus, Kosetice and Churánov, representing different environments - urban, rural and mountain - over a time span of 27 years (1989-2015). We searched for a simple model describing fog occurrence fitting the observed air pollution and meteorological data. For our analysis we used a generalized additive model, GAM, with (penalized) spline components to capture possible nonlinear and a priori unknown functional relationships. In order to cope with the binary nature of the data (indicators of fog presence on individual days), we employed a logistic regression GAM model fitted by a maximizing penalized likelihood (where the penalty coefficients were estimated via cross-validation). After testing several physically motivated models, being guided by AIC and physical interpretation of the components, we arrived at a model which uses the following explanatory variables: relative humidity, ambient SO2 concentrations, ambient NOx concentrations, air temperature and seasonality. All associations between the response and the analysed explanatory variables were highly significant. According to our results, the most important explanatory variables modelling the fog probability were relative humidity and air pollutants. Interestingly, we observed an increasing trend in fog occurrence at all three sites under review starting around the mid 2000s. CAPSULE: The most important explanatory variables modelling the fog probability at three Central European sites were humidity, SO2 and NOx. An increasing trend in fog occurrence has been observed since the mid 2000s.

Decrease of muscle strength in vascular access hand due to silent ischaemia.

BACKGROUND:: Creation of vascular access leads to considerable local haemodynamic changes with decreased hand perfusion. Distal limb tissues then represent a model of hand ischaemia effect on muscles. The aim of our study was to investigate how the presence of vascular access influences the hand muscle strength in end-stage renal disease patients. METHODS:: We included 52 chronically haemodialysed patients with upper limb access without clinical signs of hand ischaemia. Muscle strength was evaluated by dynamometry. Finger pressure was measured on the second and fourth fingers and averaged for further analysis. Thenar tissue oxygenation (rSO2) was analysed using near-infrared spectroscopy. All examinations were performed in both the hands. Basic laboratory analysis was added. Data were processed with unpaired t-test and correlation analysis. RESULTS:: Hands with dialysis access had lower values of handgrip strength (54.2 ± 29.1 lbs vs 48.6 ± 23.4 lbs, p = 0.0006), systolic finger pressure (127.1 ± 32.0 mmHg vs 101.4 ± 31.6 mmHg, p < 10-8) and of thenar rSO2 (45.8% ± 12.9% vs 42.5% ± 13.3%, p = 0.002). Muscle strength (handgrip) was directly related to the thenar oxygenation ( r = 0.36; p = 0.014) and to the finger systolic pressure ( r = 0.38; p = 0.007) on the access extremity. On the extremity without dialysis access, handgrip strength was inversely related to patient's age ( r = -0.41, p = 0.003), dialysis vintage ( r = -0.32, p = 0.02) and red cell distribution width ( r = -0.37, p = 0.01). CONCLUSION:: The presence of dialysis access leads to the decrease of finger pressure, oxygenation, and also muscle strength even in the absence of clinically overt hand ischaemia. All these parameters are interrelated. This study underlines the consequences of inadequate muscle perfusion.

Low Cerebral Oxygenation Is Associated with Cognitive Impairment in Chronic Hemodialysis Patients.

BACKGROUND/AIMS: High rates of cognitive impairment (CI) are an alarming problem in patients undergoing chronic hemodialysis (HD). Its pathophysiology remains unclear and there are indications that brain ischemia might be one of the key causes. Cerebral tissue oxygenation, as measured by near-infrared spectroscopy, is known to be decreased in HD patients. However, it is unknown whether CI is associated or not associated with lower cerebral oxygenation in these patients. The primary aim of our study was to probe this possible association. Our secondary aim was to assess other factors possibly related to cerebral ischemia and CI. METHODS: Thirty-nine patients treated by chronic HD were included in this cross-sectional study. All measurements were performed before the initiation of an HD session. The Montreal Cognitive Assessment (MoCA) was administered according to published recommendations. Regional saturation of oxygen (rSO2) of the left frontal lobe was measured using the INVOS 5100C device. Basic medical history and laboratory data were recorded, and handgrip strength was analyzed. We used the unpaired t test to compare the rSO2 and other variables between cognitively normal patients (MoCA score ≥26) and those who displayed CI (MoCA score <26). Multiple linear regression analysis was used to adjust for principal confounders. RESULTS: Cognitively impaired patients had lower brain rSO2 values compared to cognitively normal patients (48 ± 9 vs. 57 ± 10%, p = 0.01). Among other variables, higher red cell distribution width (15.8 ± 1.9 vs. 13.8 ± 1.6%, p = 0.01) and lower hand grip strength (49.2 ± 23.3 vs. 99.3 ± 31.4 lbs, p < 0.001) also displayed a significant association with CI. The relation between rSO2 and MoCA score was significant after adjustment for age and gender (p = 0.007). CONCLUSION: Decreased brain oxygenation is associated with weaker cognitive performance in patients undergoing chronic HD. Further understanding the causes of cerebral ischemia in HD patients could lead to the prevention of cognitive decline in this population.

Factors influencing dialysis arteriovenous graft survival.

PURPOSE: Dysfunction and loss of patency of dialysis arteriovenous grafts (AVGs) are serious causes of morbidity in patients on dialysis. Various risk factors associated with shorter AVG patency have been blamed, but the results of the studies were controversial. The aim of this study was to assess if associated diseases, biochemical markers and other parameters associated with atherosclerosis influence patency of AVGs in a large vascular access centre. METHODS: We conducted a retrospective study that included patients with AVGs patent for at least 3 weeks after creation. We included variables associated with atherosclerosis into the analysis (coronary artery disease, diabetes mellitus, chronic heart failure, arterial hypertension, smoking history and cholesterol and triglyceride levels) and characteristics of the graft (shape, feeding artery).The data was assessed using log-rank (Cox-Mantel) test. The differences were shown using Kaplan-Meier graphs. The observation period was limited to 1000 days after access creation. RESULTS: Overall, 338 patients were included in the study. Significantly higher risk of access failure was associated with presence of coronary artery disease (p = 0.0035). Higher serum cholesterol levels were associated with longer survival of the graft in 1000 days of surveillance (p = 0.04). CONCLUSIONS: Coronary artery disease negatively influences the cumulative patency of vascular access. Higher serum cholesterol levels are associated with lower AVG failure risk over a 1000-day period, which probably corresponds to the worse disease status of the patients with lower cholesterol values.

Tissue ischemia worsens during hemodialysis in end-stage renal disease patients.

BACKGROUND: Cognitive deficit is a common problem in end-stage renal disease (ESRD) patients. Ultrafiltration and hemodialysis lead to profound hemodynamic changes. The aim of this pilot study was to describe brain and hand oxygenation values in ESRD patients and their changes during hemodialysis. METHODS: Twenty-seven patients treated by chronic hemodialysis and 17 controls patients of the same age were included in the study. Regional saturation of oxygen (SrO2) was measured at the brain frontal lobe and at the hand with dialysis access using the INVOS 5100C. In 17 of ESRD patients, SrO2 was also monitored throughout hemodialysis. Finger systolic blood pressure and basic hemodialysis and laboratory data were collected. RESULTS: Dialysis patients had lower brain and also hand SrO2 values at rest (51.5 ± 10.9 vs. 68 ± 7%, p<0.0001 and 55 ± 16 vs. 66 ± 8%, p = 0.03, respectively). Both values further decreased during the first 35 minutes of hemodialysis (brain SrO2 to 47 ± 8%, p<0.0001 and hand to 45 ± 14%, p<0.0001, respectively). The brain SrO2 decrease was related to the ultrafiltration rate, the hand SrO2 decrease to the finger pressure and to blood hemoglobin. CONCLUSIONS: Chronic dialysis patients suffer from tissue ischemia and that even worsens after the beginning of hemodialysis. This observation may contribute to the understanding of cognitive deficit etiology.