Impact of Residual Renal Function on Volume Status in Chronic Renal Failure

Effects of Empagliflozin on Fluid Overload, Weight, and Blood Pressure in CKD

SIGNIFICANCE STATEMENT

SGLT2 inhibitors reduce risk of kidney progression, AKI, and cardiovascular disease, but the mechanisms of benefit are incompletely understood. Bioimpedance spectroscopy can estimate body water and fat mass. One quarter of the EMPA-KIDNEY bioimpedance substudy CKD population had clinically significant levels of bioimpedance-derived "Fluid Overload" at recruitment. Empagliflozin induced a prompt and sustained reduction in "Fluid Overload," irrespective of sex, diabetes, and baseline N-terminal pro B-type natriuretic peptide or eGFR. No significant effect on bioimpedance-derived fat mass was observed. The effects of SGLT2 inhibitors on body water may be one of the contributing mechanisms by which they mediate effects on cardiovascular risk.

BACKGROUND

CKD is associated with fluid excess that can be estimated by bioimpedance spectroscopy. We aimed to assess effects of sodium glucose co-transporter 2 inhibition on bioimpedance-derived "Fluid Overload" and adiposity in a CKD population.

METHODS

EMPA-KIDNEY was a double-blind placebo-controlled trial of empagliflozin 10 mg once daily in patients with CKD at risk of progression. In a substudy, bioimpedance measurements were added to the main trial procedures at randomization and at 2- and 18-month follow-up visits. The substudy's primary outcome was the study-average difference in absolute "Fluid Overload" (an estimate of excess extracellular water) analyzed using a mixed model repeated measures approach.

RESULTS

The 660 substudy participants were broadly representative of the 6609-participant trial population. Substudy mean baseline absolute "Fluid Overload" was 0.4±1.7 L. Compared with placebo, the overall mean absolute "Fluid Overload" difference among those allocated empagliflozin was -0.24 L (95% confidence interval [CI], -0.38 to -0.11), with similar sized differences at 2 and 18 months, and in prespecified subgroups. Total body water differences comprised between-group differences in extracellular water of -0.49 L (95% CI, -0.69 to -0.30, including the -0.24 L "Fluid Overload" difference) and a -0.30 L (95% CI, -0.57 to -0.03) difference in intracellular water. There was no significant effect of empagliflozin on bioimpedance-derived adipose tissue mass (-0.28 kg [95% CI, -1.41 to 0.85]). The between-group difference in weight was -0.7 kg (95% CI, -1.3 to -0.1).

CONCLUSIONS

In a broad range of patients with CKD, empagliflozin resulted in a sustained reduction in a bioimpedance-derived estimate of fluid overload, with no statistically significant effect on fat mass.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03594110 ; EuDRACT: 2017-002971-24 ( https://eudract.ema.europa.eu/ ).

Left atrial reservoir strain is an outstanding predictor of adverse cardiovascular outcomes in patients undergoing maintenance hemodialysis: Assessment via three-dimensional speckle tracking echocardiography

Background

There is a paucity of literature focusing left atrium (LA) in patients undergoing maintenance hemodialysis (MHD).

Hypothesis

We used three‐dimensional speckle tracking echocardiography (3DSTE) to evaluate LA in MHD patients and to explore its predictive value for adverse outcomes.

Methods

Echocardiography was performed on 130 consecutively enrolled MHD patients without previous cardiac diseases. Conventional and 3DSTE parameters of LA were obtained. The MHD cohort was then followed and the end point was major adverse cardiovascular events (MACEs). LA strain indices, including reservoir strain (LASr), conduit strain (LAScd), and contractile strain (LASct), were measured and compared between patients with and without MACEs.

Results

Patients were prospectively followed up for a median of 40.5 (interquartile range: 26.3–48.0) months. During follow‐up, 43 patients met the end point. These patients had larger LA size and reduced LA strains (LA maximal volume indexed: 45.1 ± 11.9 vs. 33.8 ± 6.9ml/m²; LASr: 20.2 ± 3.5 vs. 27.2 ± 3.3%; LAScd: −12.3 ± 5.2 vs. −14.5±4.0%; LASct: −8.0 ± 4.2 vs. −13.2 ± 3.7%; all p<.05), compared with those without MACEs. Multivariable regression analysis showed LASr was the strongest predictor of MACEs (hazard ratio, 0.69; 95% confidence interval, 0.54–0.89; p=.004). Univarite Kaplan–Meier analysis revealed the incidence of MACEs in the impaired LASr (<24.2%) group was significantly higher than in the normal LASr group (log rank p<.001).

Conclusions

LASr derived from 3DSTE is an independent predictor of MACEs and cardiac death in MHD patients, superior to LV parameters and LA volume indices.

Cause of postoperative mortality in patients with end-stage renal disease

Background: The number of patients with end-stage renal disease (ESRD) who are dependent on hemodialysis is increasing rapidly. As a result, more patients with ESRD need surgery. These patients have a significantly higher risk of postoperative death than those with normal kidney function. Therefore, this study analyzed the causes of postoperative mortality in ESRD patients undergoing surgery under general anesthesia and the risk factors for postoperative mortality.Methods: This retrospective analysis examined the mortality of ESRD patients, 20 to 80 years old, undergoing surgery under general anesthesia. We excluded patients who underwent cardiac, cancer, or emergency surgery or organ transplantation from the analysis. The primary outcome was the cause of postoperative 30-day mortality in ESRD patients. We also assessed the mortality rate and risk factors.Results: There were 2,459 eligible ESRD patients. When patients underwent multiple surgeries during the study period, only the last surgery was considered. In total, 167 patients died during the study period, including 65 within 30 days postoperatively. The cause of death was sepsis in 22 cases (33.8%) and a major cardiac event in 16 (24.6%). Atrial fibrillation, current angina, previous myocardial infarction, asthma, lower hemoglobin and albumin levels, and a larger intraoperative colloid volume were likely to increase mortality. Conclusions: Our study suggests that immunological issues have a significant role in the death of ESRD patients after general anesthesia.

Removal of Protein-Bound Uremic Toxins by Liposome-Supported Peritoneal Dialysis

Background:Protein-bound uremic toxins (PBUTs) are poorly cleared by peritoneal dialysis (PD). This study aimed to enhance PBUT removal in PD by adding a binder to the peritoneal dialysate and to evaluate the feasibility and efficacy of liposome-supported PD (LSPD) to increase the removal of PBUTs compared with albumin PD.Methods:Removal of p-cresyl sulfate (PCS), indoxyl sulfate (IS), and indole-3-acetic acid (3-IAA) was first evaluated in an in vitro PD model using artificial plasma preloaded with test solutes. Male Sprague-Dawley rats (n = 24) were then subjected to 5/6 nephrectomy and fed for 16 weeks to establish end-stage renal failure, after which they were treated with either conventional glucose-based PD, albumin-based PD, or liposome-based PD. Removal of PBUTs and small water-soluble solutes was determined during a 6-hour PD dwell.Results:In vitro experiments showed that adding albumin as a toxin binder to the dialysate markedly increased the removal of PCS, IS, and 3-IAA compared with the control. The uptake capacity of liposomes was comparable with that of albumin for PCS and 3-IAA, though slightly inferior for IS. In vivo PD in uremic rats demonstrated that LSPD resulted in higher intraperitoneal concentrations and more total mass removal for PBUTs than the conventional glucose-based PD, which was comparable with albumin PD.Conclusions:Supplementing conventional glucose-based PD solutions with a binder could efficiently increase the removal of PBUTs. This preliminary study suggested that LSPD may be a promising alternative to albumin PD for increasing PBUT removal in the development of next-generation PD solutions for PD patients.

Effects of Omega-3 Fatty Acids on Markers of Inflammation in Patients With Chronic Kidney Disease: A Controversial Issue

Chronic kidney disease (CKD) is a global problem which contributes to a significant morbidity and mortality in China. Concomitant inflammatory state further boosts the mortality due to cardiovascular events in patients with CKD undergoing dialysis. There is a general notion that Omega-3 fatty acids including docosahexaenoic acids (DHA) and eicosapentaenoic (EPA) have certain health benefits perhaps via the regulation of inflammation. However, the anti-inflammatory effect of omega-3 fatty acids in patients with CKD is controversial. We analyzed the data of oral supplementation of omega-3 fatty acids in CKD patients by searching literature on database from inception to August 2016. The analysis included randomized controlled trials (RCTs) derived from multiple databases, and the effect of omega-3 fatty acids supplementation versus the control cohorts were compared. All of the data analysis was calculated by RevMan 5.2. A total of 12 RCTs involving 487 patients were included in the meta-analysis. Among them 254 patients received omega-3 fatty acids and 233 patients served as controls who received placebo. The meta-analysis revealed no statistical significance in serum levels of C-reactive protein (CRP) (SMD, -0.20; 95% CI, -0.44 to 0.05; P = 0.11), IL-6 (SMD, 0.00; 95% CI, -0.33 to 0.33; P = 0.99) and TNF-α (SMD, 0.14; 95% CI, -0.17 to 0.44; P = 0.38) between the omega-3 fatty acids supplementation group and control. This suggested that there is insufficient evidence to conclude the benefit of omega-3 fatty acids oral supplementation in reducing serum levels of CRP, IL-6 and TNF-α in patients with CKD.

Long-term impacts of hemodialysis on the right ventricle: Assessment via 3-dimensional speckle-tracking echocardiography

BACKGROUND

Right ventricular (RV) dysfunction is a major cause of death in patients undergoing maintenance hemodialysis (MHD). We used 3-dimensional speckle-tracking echocardiography (3DSTE) to evaluate long-term impacts of MHD on RV function.

HYPOTHESIS

In this study, RV dysfunction in MHD patients will be revealed and studied in depth by 3DSTE.

METHODS

Echocardiography was performed on 110 consecutively enrolled individuals: 30 controls and 80 patients with MHD. Conventional echocardiographic parameters and 3DSTE parameters were obtained and compared between groups. Univariate and multivariate logistic regression analysis identified independent predictors of intradialytic hypotension (IDH).

RESULTS

Compared with the control group, RV end-diastolic volume (RVEDV) was markedly enlarged (46.1 ± 11.8 mL/m² vs 42.3 ± 8.6 mL/m² ; P = 0.047), whereas RV ejection fraction (RVEF) was significantly lower in the MHD group (50.6% ± 5.8% vs 55.2% ± 3.7%; P < 0.001). RV global, septal, and lateral wall longitudinal strains were also decreased in the MHD group (-18.2 ± 3.6 vs -22.6 ± 4.3%; -13.1 ± 3.8 vs -17.5 ± 5.5%; and -23.4 ± 4.7 vs -27.7 ± 4.0%, respectively; all P < 0.001). RVEF (odds ratio [OR]: 0.72, 95% confidence interval [CI]: 0.51 to 1.01, P = 0.038) and history of diabetes (OR: 11.14, 95% CI: 1.16 to 106.71, P = 0.036) were 2 independent predictors of IDH. Ultrafiltration rate was an independent factor associated with RVEF (β = -0.01, 95% CI: -0.019 to 0.001, P = 0.039).

CONCLUSIONS

RVEF by 3DSTE could be an important predictor of IDH in MHD patients, and lower ultrafiltration rate was protective for RVEF. 3DSTE may have potential in RV evaluation and risk stratification in MHD patients.

Anesthetic management in a patient of autosomal dominant polycystic kidney disease with end stage renal disease undergoing endovascular coiling for multiple intracranial aneurysms

A 27-year-old woman of autosomal dominant polycystic kidney disease presented with multiple intracranial aneurysms at anterior communicating artery and left middle cerebral artery bifurcation. She was undergoing hemodialysis every alternate day and was waiting for a renal transplantation. Endovascular coiling of both these aneurysms was performed under general endotracheal anesthesia. During the procedure special precaution was taken with regard to intra-procedural fluid management and maintenance of cerebral perfusion pressure. The procedure remained uneventful during which a stable hemodynamics was maintained. In this report, the implication of intraprocedural fluid infusion by the neuroradiologist its possible influence on overall anesthetic management has been described.

Predialysis hypotension is not a predictor for mortality in long-term hemodialysis patients: insight from a single-center observational study

Introduction

Predialysis hypotension has been noted to be a predictor of mortality in hemodialysis (HD) patients. Previous studies evaluating the impact of predialysis hypotension on the mortality of HD patients did not exclude patients with diabetes mellitus (DM) or cardiovascular disease.

Methods

Eight hundred and sixty-six patients on maintenance HD were recruited. Clinical parameters were recorded and subjected to the analysis of predictors of predialysis hypotension and mortality.

Results

Multivariate logistic regression analyses indicated that DM (odds ratio [OR]: 0.439, P=0.002), hypertension history (OR: 0.634, P=0.022), Kt/V Daugirdas (OR: 2.545, P=0.001), anuria (OR: 2.313, P=0.002), serum phosphate (OR: 0.833, P=0.010), and serum triglyceride (OR: 1.002, P=0.012) were associated with predialysis hypotension. Multivariate Cox regression analysis showed that age (P<0.001), male sex (P=0.029), anuria (P=0.004), and DM (P=0.011) were associated with higher probability of 24- and 36-month mortality. Predialysis hypotension was not associated with higher probability of 12-, 24-, and 36-month mortality.

Conclusion

Predialysis hypotension is not a predictor of 12-, 24-, and 36-month survival in patients without DM and with higher dialysis adequacy.

Association between Clinical and Doppler Echocardiographic Parameters with Sudden Death in Hemodialysis Patients

BACKGROUND

Sudden cardiac death (SCD) is the leading cause of death in maintenance hemodialysis (HD) patients, but there is little information about underlying risk factors.

OBJECTIVES

Evaluate the association between clinical and echocardiographic variables with SCD on HD patients.

METHODS

Retrospective nested case-control study on chronic HD patients who were prospectively followed. The primary endpoint was SCD. Variables were compared by Student t test, Mann-Whitney or Chi-Square, and independent predictors of SCD were evidenced by multivariate logistic regression.

RESULTS

We followed 153 patients (50 ± 15 years, 58% men) for 23 ± 14 months and observed 35 deaths, 17 of which were SCD events. When compared to the control group (matched for gender, age, and body mass index) there were no differences regarding time on dialysis, traditional biochemical parameters, blood pressure, smoking, use of cardiovascular protective drugs, ejection fraction, left ventricular dimensions, and diastolic function indices. On the other hand, in the SCD group, we found a higher prevalence of previous heart failure, acute myocardial infarction and diabetes, greater left ventricular mass index, greater left atrial size and lower global myocardial performance. After multivariate logistic regression analysis, diabetes (OR = 2.6; CI = 1.3-7.5; p = 0.023) and left ventricular mass index ≥ 101 g/m2.7 (OR = 1.04; CI = 1.01-1.08; p = 0.028) showed independent association with SCD events.

CONCLUSIONS

HD patients with diabetes mellitus and left ventricular hypertrophy appear to have the highest risk of SCD. Preventive and therapeutic strategies should be encouraged in addressing these risk factors to minimize the occurrence of SCD in HD patients.

Serum concentrations of p-cresyl sulfate and indoxyl sulfate, but not inflammatory markers, increase in incident peritoneal dialysis patients in parallel with loss of residual renal function

BACKGROUND

High serum concentrations of the protein-bound uremic retention solutes p-cresyl sulfate (PCS) and indoxyl sulfate (IndS) and inflammation are associated with increased cardiovascular morbidity and mortality in chronic kidney disease. Renal clearance contributes to up to 80% of the total clearance of PCS and IndS in peritoneal dialysis (PD) patients. Cross-sectional studies evaluating the impact of residual renal function (RRF) on serum concentrations of PCS, IndS, and circulating inflammatory markers have yielded conflicting results. ♢

METHODS

To clarify this issue, we carried out a prospective observational cohort study in incident PD patients (n = 35; 19 men; mean age: 55 ± 17 years). Midday blood samples were collected and analyzed for total serum PCS, IndS, C-reactive protein, and high-sensitivity interleukin 6. Peritoneal and renal clearances were calculated from urine and dialysate collections, and RRF was calculated as the mean of renal urea nitrogen and creatinine clearances. Patients were assessed 1, 6, 12, and 24 months after PD start. Differences between time points were analyzed using linear mixed models (LMMs). ♢

RESULTS

Residual renal function declined significantly over time (LMM p < 0.0001). Peritoneal clearances of both toxins tended to increase, but did not compensate for the declining renal clearances. Serum concentrations of PCS and IndS increased significantly over time (LMM p = 0.01; p = 0.0009). In contrast, total mass removal of both toxins remained stable. Circulating inflammatory markers did not change over time. ♢

CONCLUSIONS

Our data indicate that serum concentrations of PCS and IndS, but not inflammatory markers, increase in incident PD patients in parallel with loss of RRF.

Circulating vascular endothelial growth factor (VEGF) and its soluble receptor 1 (sVEGFR-1) are associated with inflammation and mortality in incident dialysis patients

BACKGROUND

Vascular endothelial growth factor (VEGF) and its soluble receptor 1 (sVEGFR-1) predict mortality in nondialyzed chronic kidney disease (CKD) stage 3-5 patients and prevalent hemodialysis (HD) patients. We investigated determinants of VEGF and sVEGFR-1 as well as their relationship with all-cause mortality in incident dialysis patients.

METHODS

In this longitudinal cohort study of 211 CKD 5 patients [64% males, mean age of 54 ± 12 years and median glomerular filtration rate (GFR) 5.9 [interquartile range (IQR), 4.6-7.2 mL/min/1.73 m2] who were enrolled at initiation of renal replacement therapy, demographics, clinical characteristics, including comorbidities and laboratory data were obtained at the beginning of the study. After 12 months, blood was again drawn from 95 dialysis patients [42 HD patients and 53 peritoneal dialysis (PD) patients]. The 211 patients were followed up for a median of 29 (IQR, 15-37) months for survival analysis. Plasma was also obtained from 47 healthy controls.

RESULTS

VEGF and sVEGFR-1 levels did not change significantly after 12 months on HD or PD. The sVEGFR-1, but not VEGF levels, differed between the patients and the healthy controls. VEGF and sVEGFR-1 correlated with high-sensitivity C-reactive protein (hsCRP; rho = 0.19, P = 0.01 and rho = 0.16, P = 0.03; respectively), leukocyte count (rho = 0.22; P < 0.01 and rho = 0.23; P < 0.01; respectively) and sVEGFR-1 correlated also with interleukin-6 (IL-6) (rho = 0.21, P < 0.01). In Kaplan-Meier analysis, a high VEGF level was associated with increased all-cause mortality (Chi-square = 5.8, P = 0.02) which remained after adjustments for age, gender, body mass index (BMI), IL-6, GFR and comorbidities [hazard ratio, HR: 3.08, 95% confidence intervals (CI) 1.48-6.42]. Whereas sVEGFR-1 per se did not predict mortality, a high sVEGFR-1 level in patients with concomitant high IL-6 was associated with increased all-cause mortality (HR 2.83, 95% CI 1.32-6.06) which remained significant after adjustments for age, gender, BMI and comorbidities (HR 2.33, 95% CI 1.06-5.14) but not after adjusting also for GFR.

CONCLUSIONS

The circulating levels of VEGF and sVEGFR-1 are associated with biomarkers of inflammation. VEGF predicts all-cause mortality, independent of inflammation, while an elevated sVEGFR-1 level increased the mortality risk in inflamed patients.

Left ventricular mass in chronic kidney disease and ESRD

Chronic kidney disease (CKD) and ESRD, treated with conventional hemo- or peritoneal dialysis are both associated with a high prevalence of an increase in left ventricular mass (left ventricular hypertrophy [LVH]), intermyocardial cell fibrosis, and capillary loss. Cardiac magnetic resonance imaging is the best way to detect and quantify these abnormalities, but M-Mode and 2-D echocardiography can also be used if one recognizes their pitfalls. The mechanisms underlying these abnormalities in CKD and ESRD are diverse but involve afterload (arterial pressure and compliance), preload (intravascular volume and anemia), and a wide variety of afterload/preload independent factors. The hemodynamic, metabolic, cellular, and molecular mediators of myocardial hypertrophy, fibrosis, apoptosis, and capillary degeneration are increasingly well understood. These abnormalities predispose to sudden cardiac death, most likely by promotion of electrical instability and re-entry arrhythmias and congestive heart failure. Current treatment modalities for CKD and ESRD, including thrice weekly conventional hemodialysis and peritoneal dialysis and metabolic and anemia management regimens, do not adequately prevent or correct these abnormalities. A new paradigm of therapy for CKD and ESRD that places prevention and reversal of LVH and cardiac fibrosis as a high priority is needed. This will require novel approaches to management and controlled interventional trials to provide evidence to fuel the transition from old to new treatment strategies. In the meantime, key management principles designed to ameliorate LVH and its complications should become a routine part of the care of the patients with CKD and ESRD.

Applying Translational Research in Understanding Complications and Defining Targets for Intervention: Inflammation in PD as a Model

The bench-to-bedside approach to translational research is becoming increasingly important to efficiently advance understanding of the mechanisms underlying disease and to improve the quality of patient care. Although this investigation model has been practiced since the early days of the therapy, robust research platforms built to practice translational research have only recently been structured in the field of peritoneal dialysis. Experience with a translational research environment that generated most of the information cited in this overview is the core of this manuscript. The central investigation theme described is how to approach the cardiovascular complications of peritoneal dialysis. The research question was, could the continuous activation of inflammatory pathways be central in this process and represent a relevant target for interventions?

The Impact of Living Donor Kidney Transplantation on Markers of Cardiovascular Risk in Chronic Kidney Disease Patients

BACKGROUND

Kidney transplant (Tx) patients present a reduced cardiovascular (CV) mortality in comparison to the dialysis population, but in comparison to the general population, it is still several-fold higher.

METHODS

We studied risk factors for CV disease in a group of 38 patients (50% males, median age 36 years) who underwent a living donor Tx at the baseline and after 3 +/- 1 and 9 +/- 2 months.

RESULTS

The prevalence of overweight increased from 26 to 54% after Tx (p < 0.001). The mean systolic blood pressure decreased significantly after the Tx (148 +/- 27.6 vs. 126 +/- 12.7 mm Hg). There was a significant increase in LDL (97 +/- 30 vs. 114 +/- 35) and hematocrit (33.8 +/- 4.4 to 42 +/- 5.7%) levels and a significant reduction in fibrinogen levels (394 +/- 91 vs. 366 +/- 100 mg/dl) after 9 months as compared to the baseline. Obesity and dislipidemia were significantly correlated with inflammation. Significant changes in left ventricle mass index (293 +/- 116 vs. 241 +/- 96) were observed after the Tx. Patients with a low glomerular filtration rate (GFR) in the follow-up evaluation presented higher LDL (128 +/- 7 vs. 99 +/- 7 mg/dl; p < 0.05) and higher fibrinogen levels (399 +/- 21 vs. 332 +/- 22 mg/dl; p < 0.05) compared to patients with a high GFR.

CONCLUSION

Most of the risk factors analyzed (particularly the uremia-related) improved after the renal Tx, which could justify the positive impact of Tx on the development of CV disease. Inflammation and dyslipidemia were related to renal dysfunction after the Tx, suggesting that complete restoration of renal function may have an impact on reducing CV mortality in CKD patients treated with renal Tx.

Superior dialytic clearance of β2-microglobulin and p-cresol by high-flux hemodialysis as compared to peritoneal dialysis

Both residual renal and dialytic clearance confer to the total solute clearance in dialysis patients. Dialytic clearances of the middle molecule beta-microglobulin (beta(2)M) and the protein-bound solute p-cresol (pcr) are generally believed to be higher with peritoneal dialysis (PD) as compared to hemodialysis (HD). Supportive data, however, are lacking. We performed a single-center cross-sectional observational study including 70 unselected patients treated with either high-flux HD (n=20) or PD (n=50). Mid-day serum levels (PD) and time-averaged concentrations (HD) of the water-soluble solutes urea nitrogen, creatinine and phosphate, the middle molecule beta(2)M, and the protein-bound solute pcr were determined. Dialytic solute clearances (l/week/1.73 m(2)) were calculated from total dialysate collection during the mid-week session in HD and 24 h dialysate collection in PD. Renal clearances were calculated for each of the respective solutes from a timed urine collection. Total clearances were obtained by summation. HD delivered significantly higher clearances of all retention solutes studied. This superiority was especially pronounced for pcr (30.9+/-62.7 vs 4.4+/-2.3, HD vs PD, P<0.0001) and beta(2)M (28.6+/-6.6 vs 5.8+/-3.1, HD vs PD, P<0.0001). Renal clearances, conversely, were significantly higher in patients on PD. Serum levels of all solutes but pcr were significantly lower in HD than in PD. Both a higher residual renal function and a lower generation rate contribute to the lower pcr levels in PD. In conclusion, superior dialytic clearance of both water-soluble solutes, beta(2)M, and pcr is achieved by high-flux HD as compared to PD.

Associations between renal function, volume status and endotoxaemia in chronic kidney disease patients

Inflammation is an important predictor of increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD), but the mechanisms behind the chronic activation of the immune system are not clearly understood. CKD patients develop fluid overload, which has been proposed to be a stimulus for inflammatory activation due to the translocation of macromolecules from the gut. We hypothesize that fluid overload is associated with signs of systemic inflammation and endotoxaemia in stages 1-5 CKD patients. The aim of this prospective study was to evaluate the associations between renal function, fluid status [evaluated by the inferior vena cava diameter (IVCD) and the collapsibility index (CI)], systemic inflammation [plasma levels of C-reactive protein (CRP), fibrinogen and albumin] and endotoxaemia (through the Limulus amebocyte lysate enzymatic assay) in a group of CKD patients in our out-patient clinic. The population consisted of 74 (mean of 57; range 23-83 years of age; 47% males) CKD patients with glomerular filtration rate (based on the mean of urea and creatinine clearances) of 34 ml/min. Both albumin (Rho = 0.25; P = 0.05) and fibrinogen (Rho= - 0.48; P < 0.0001) were significantly correlated to glomerular filtration rate (GFR). According to the IVCD, 84% of the patients were fluid overloaded, while 83% were considered overloaded by the CI. Signs of endotoxaemia were detected in all patients. Endotoxin levels were higher in patients with signs of fluid overload (0.85 +/- 0.11ng/l) when compared with patients with normal values of IVCD (0.61 +/- 0.05 ng/l; P < 0.05). Endotoxin levels correlated to both IVCD (Rho=0.33, P < 0.005) and CI (Rho = -0.25, P < 0.05). There was no correlation between endotoxin levels and GFR, CRP or fibrinogen. In summary, although most CKD patients presented signs of fluid overload that was associated with endotoxaemia, there was no association between endotoxaemia and systemic inflammation, suggesting the endotoxaemia may not be the main determinant of the inflammatory status in this group of patients.

Influence of Genomic Loci on Measures of Chronic Kidney Disease in Hypertensive Sibships

Genomewide linkage analyses were conducted of serum creatinine, estimated GFR (eGFR), and urine albumin-creatinine ratio (UACR) in search of genetic susceptibility loci for chronic kidney disease in 1351 black (median age 63 yr, 70% women, 79% hypertensive) and 1022 white individuals (median age 61 yr, 56% women, 75% hypertensive) from sibships in which two or more members had essential hypertension diagnosed before age 60 yr. After adjustment for gender, age, diabetes, and use of angiotensin inhibitors, the logarithm-transformed measure of serum creatinine was heritable in both ethnic groups (0.45 in black individuals [P < 0.001]; 0.39 in white individuals [P < 0.001]), as was eGFR (0.52 in black individuals [P < 0.001]; 0.39 in white individuals [P < 0.001]). Log UACR was heritable in black individuals (0.30, P < 0.001) but not in white individuals (0.12; P = 0.059). In black individuals, the univariate maximum multipoint logarithm of odds scores (MLS) were observed on chromosome 7 for log serum creatinine (MLS = 3.65, at 43 cM from pter; P = 0.00002) and eGFR (MLS = 2.52, at 45 cM from pter; P = 0.00033) and for log UACR (MLS = 2.91, at 112 cM from pter; P = 0.00012). In white individuals, only one MLS for log serum creatinine and one for eGFR achieved the logarithm of odds score criterion for "suggestive" evidence of linkage (2 < or = MLS < 3), both on chromosome 3 (at 211 and 209 cM, respectively); however, none did so for log UACR. In black individuals, bivariate linkage analyses of log serum creatinine and pulse pressure (i.e., systolic-diastolic BP) provided "suggestive" evidence of a region on chromosome 5 with pleiotropic effects on both traits (MLS = 3.62, at 85 cM from pter; P = 0.00023). These findings support the utility of genetic linkage analyses for identification of novel risk factors that influence measures of chronic kidney disease, particularly among black individuals.

Residual Renal Function and Volume Control in Peritoneal Dialysis Patients

BACKGROUND

Fluid overload is not uncommon in patients on continuous ambulatory peritoneal dialysis (CAPD). Previous studies suggested that residual renal function (RRF) played an important role in maintaining fluid balance. However, good fluid status should be a balance between fluid intake and removal. Therefore, in the present study, we investigated the effect of RRF on patients' fluid status after focusing on the balance between fluid intake and removal in CAPD patients.

METHODS

In this cross-sectional study, 195 stable CAPD patients in a single center were included. Patients were divided into three groups according to their urine output: anuric group with urine < or =100 ml/day, oliguric group with urine < or =400 ml/day and UO >400 ml group with urine >400 ml/day. Fluid status was evaluated by bioimpedance analysis and mean arterial pressure (MAP). The sodium removal and plasma sodium concentration were also measured. All the patients were educated to try to achieve good volume control by focusing on salt and fluid intake and their removals.

RESULTS

There were 51, 31 and 113 patients in anuric, oliguric and UO >400 ml group, respectively. Anuric patients were older and had been on CAPD longer than that of the oliguric and UO >400 ml patients (p < 0.05). The urine output in the three groups were 9.28 +/- 22.68, 236.13 +/- 75.43 and 1,013.34 +/- 541.54 ml/day, respectively (p < 0.001). Bioimpedance analysis showed that the differences of extracellular water, intracellular water and total body water were not statistically significant among the three groups. However, there was significant difference in MAP among the three groups (MAP in anuric, oliguric and UO >400 ml groups were 93.27 +/- 13.35, 96.63 +/- 9.94 and 102.36 +/- 13.70 mm Hg, p < 0.01), and UO >400 ml group had higher MAP than anuric and oliguric groups (p < 0.05). The total sodium removal (renal + peritoneal) in anuric, oliguric and UO >400 ml groups were 96.44 +/- 60.18, 98.95 +/- 73.82 and 134.64 +/- 72.44 mmol/day, respectively (p < 0.01). The UO >400 ml group also had higher plasma sodium concentration than anuric and oliguric groups (plasma sodium in the three groups were 137.49 +/- 3.43, 137.82 +/- 2.63 and 139.15 +/- 3.30 mmol/l, respectively; p < 0.01).

CONCLUSIONS

This study showed that extracellular water among anuric, oliguric and UO >400 ml groups was not significantly different, which suggested that RRF may be not so important as expected in maintaining good volume status. The higher blood pressure in patients with higher RRF and higher sodium and fluid removal in the present study suggested restricting salt and fluid intake might be more important for better blood pressure control in CAPD patients.

Time Profiles of Peritoneal and Renal Clearances of Different Uremic Solutes in Incident Peritoneal Dialysis Patients

BACKGROUND

Residual renal function (RRF) contributes substantially to the adequacy of peritoneal dialysis (PD). In the presence of RRF, maintenance of an adequate fluid balance is facilitated, level of systemic inflammation is lower, and renal endocrine functions are preserved. The beneficial impact of RRF also may be related to the preservation of specific renal elimination mechanisms, such as tubular metabolism or secretion, which are crucial for the removal of some uremic retention solutes.

METHODS

Time profiles of peritoneal and renal clearances of urea nitrogen (60 d), creatinine (113 d), phosphate (96 d), the middle molecule beta2-microglobulin (beta2M; 11.8 kd), and the protein-bound solute p-cresol (108 d) were investigated prospectively in 24 incident PD patients. Data were analyzed by using the linear mixed models procedure.

RESULTS

During a median follow-up of 7.2 months (range, 5.6 to 8.6 months), RRF (P = 0.001) and 24-hour urine volume (P = 0.004) declined significantly. Twenty-four-hour peritoneal drainage volume increased (P < 0.0001). Renal clearances of urea nitrogen (P = 0.0002), creatinine (P = 0.001), and phosphate (P = 0.001) decreased. Peritoneal clearances of these solutes increased (P = 0.002, P < 0.0001, and P < 0.0001, respectively). There was a decline in renal clearances of beta2M (P = 0.0004) and p-cresol (P < 0.0001). No change in peritoneal clearances of these solutes was noted (P = 0.188 and P = 0.559, respectively).

CONCLUSION

Increasing PD dose may compensate for deteriorating RRF with respect to the elimination of water-soluble solutes. This is not the case for the middle molecule beta2M and the protein-bound solute p-cresol.

Chronic systemic inflammation in dialysis patients: an update on causes and consequences

Despite marked improvements in dialysis technology during the last 20 years, the age-adjusted mortality rate in end-stage renal disease (ESRD) patients treated by dialysis is still unacceptably high and comparable to that of many cancer patients with metastases. The main cause of the increased mortality in ESRD patients is cardiovascular disease (CVD), which is twice as common and advances at twice the rate already in patients with early stages of chronic kidney disease as compared to the general population. Although traditional risk factors for CVD are common in dialysis patients, they can only in part explain the very high prevalence of CVD in this patient group. Recent evidence demonstrates that chronic inflammation, a non-traditional risk factor which is a commonly observed in dialysis patients, may cause progressive atherosclerotic CVD and malnutrition, itself an important risk factor for the development of CVD, by several pathogenetic mechanisms. The causes of inflammation in dialysis are multifactorial and include both dialysis-related and unrelated factors. While the long-term effects of chronic inflammation may be most important in the pathogenesis of CVD, the acute-phase reaction may also cause vascular damage by several pathogenic mechanisms. Indeed, it seems logical to speculate that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) in ESRD would improve survival and decrease co-morbidity in dialysis patients. As there are currently no established guidelines for the treatment of chronic inflammation in ESRD patients, more studies on the long-term effects of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status, as well as outcome in this patient group, are clearly warranted and will be helpful in identifying precisely which pathways are most involved in the pathogenic process.