Can a reduction in extracellular fluid volume result in increased serum albumin in peritoneal dialysis patients?

Serum albumin at 1 year after peritoneal dialysis predicts long-term outcomes on continuous ambulatory peritoneal dialysis

Background

Hypoalbuminemia at baseline is a powerful predictor of long-term outcomes in peritoneal dialysis patients. However, the levels of serum albumin are dynamically changed during PD. The present study investigated whether the improvement of hypoalbuminemia during PD can affect the patients’ outcomes.

Methods

436 consecutive incidents continuous ambulatory peritoneal dialysis patients were involved in this study. Demographic, hematologic, biochemical, and dialysis-related data at baseline as well as 1 year after PD were collected. All patients were followed for at least 1 year for mortality.

Results

Among the 436 patients, the mean age was 48.44 ± 14.98 years, with 58.26% males and 18.12% prevalence of diabetes. The mean follow-up time was 48.25 ± 24.05 months. During the follow-up period, a total of 68 patients died. Serum albumin was 34.35 ± 5.65 g/L at baseline, which increased to 37.39 ± 5.05 g/L at 1 year after PD. Multivariate linear regression analysis showed that sex, age, BMI, diabetic nephropathy, as well as albumin at baseline were independently associated with albumin at 1 year. Every 1 year of age rise would result in a 3.9% increase in the risk of mortality (HR = 1.039, 95%CI 1.016–1.061, p = 0.001). Every 1 g/L increase in albumin at 1 year after PD confers an 8.7% decrease in the risk of mortality (HR = 0.913, 95%CI 0.856–0.973, p = 0.005).

Conclusion

The level of serum albumin was increased in the first year of PD. Serum albumin after 1 year of PD predicted mortality in peritoneal dialysis.

Pro-inflammatory cytokines as potential predictors for intradialytic hypotension

Background

Intradialytic hypotension (IDH) is a common complication in maintaining hemodialysis (MHD) patients. Immune activation might be part of the mechanisms. However, the association between pro-inflammatory cytokines and blood pressure (BP) has not been deeply explored. So we aim to evaluate the potential role of pro-inflammatory cytokines in IDH.

Methods

MHD patients starting hemodialysis before January 2016 were enrolled in our retrospective study. Patients' characteristics, laboratory results, and intradialytic BP were collected. IDH was defined as nadir systolic BP ≤ 90 mmHg during hemodialysis. The definition of IDH group was that those who suffered from more than one hypotensive event during one month after the enrollment (10% of dialysis treatments). Spearman correlation analysis and logistic regression were employed to explore the relationship between pro-inflammatory cytokines and IDH.

Results

Among 390 patients, 72 were identified with IDH (18.5%). High levels of serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were observed in the IDH group (p < 0.001). Both TNF-α and IL-1β positively correlated with predialysis BP (p < 0.01). Receiver operating characteristic curve (ROC) analysis was used to evaluate the diagnostic accuracy of serum IL-1β and TNF-α for IDH. The area under the curve of IL-1β was 0.772 (95% CI: 0.708-0.836, p < 0.01), and that of TNF-α was 0.701 (95% CI: 0.620-0.781, p < 0.01). After adjusting for patients' characteristics, biochemical parameters, comorbid conditions, predialysis BP, and medications, elevated TNF-α and IL-1β were still risk factors for IDH.

Conclusion

Pro-inflammatory cytokines (TNF-α and IL-1β) could be potential predictors for IDH.

Serum CA125 a potential marker of volume status for peritoneal dialysis patients?

INTRODUCTION

Serum cancer antigen 125(SeCA125) has been reported to be increased in patients with heart failure and correlate with both extracellular water (ECW) overload and poor prognosis. Ultrafiltration failure and ECW overload are a major cause of peritoneal dialysis (PD) technique failure. We wished to determine whether SeCA125 could also be a marker of volume status in PD patients.

METHODS

We contemporaneously measured SeCA125, serum N terminal brain natriuretic peptide (NTproBNP) and ECW by bioimpedance in adult PD patients attending for outpatient assessment of peritoneal membrane function.

RESULTS

The median SeCA125 was 19 (12-33) U/mL in 489 PD patients, 61.3% male, median age 61.5 (interquartile range 50-75) years. SeCA125 was positively associated with the ratio of ECW/total body water (TBW) (r = 0.29, p < 0.001), 4-h peritoneal dialysate to serum creatinine ratio (r = 0.23, p < 0.001), NTproBNP) (r = 0.18, p < 0.001), and age (r = 00.17, p = 0.001) and negatively with 24-h PD ultrafiltration volume (r = -0.28, p < 0.001) serum albumin (r = -0.22, p < 0.001), and echocardiographic left ventricular ejection fraction (r = -0.20, p < 0.001), but not with residual renal function or C-reactive protein. Patients with above the median SeCA125, had greater median ECW/TBW 0.403(IQR 0.394-0.410) vs 0.395(0.387-0.404), p < 0.001 and NTproBNP (6870 (IQR 1936-20096) vs 4069 (1345-12291) vs) pg/mL, p = 0.03.

CONCLUSION

Heart failure studies have reported SeCA125 is a marker of ECW overload. Our retrospective analysis suggests that SeCA125 is also associated with ECW volume in PD patients. Further studies are required to determine whether serial measurements of SeCA125 trend with changes in ECW status in PD patients and can be used to aid volume assessments.

Tracking hydration status changes by bioimpedance spectroscopy in children on peritoneal dialysis

BACKGROUND

This 6-month prospective longitudinal study investigates the association between hydration status changes using bioimpedance spectroscopy (BIS) and systolic blood pressure (SBP), pulse pressure (PP), and serum albumin (sAlb) changes in children on peritoneal dialysis (PD).

METHODS

Thirteen patients (median age: 12.58 years) were enrolled. Normal hydration, moderate hydration, severe overhydration, and dehydration were defined as -7% ≤ relative overhydration (Re-OH) < +7%, +7% ≤ Re-OH < +15%, Re-OH ≥ +15%, and Re-OH < -7%, respectively. Automated office blood pressure z-score, sAlb, and weight z-score were recorded.

RESULTS

Fifty-two Re-OH measurements were recorded: three in five, four in five, five in two, and seven in one patient, respectively. SBP was higher and sAlb lower in cases with severe overhydration (9 readings) (p < 0.001, p < 0.001), but distribution of these parameters did not differ between normal hydration/dehydration (28 readings) and moderate overhydration (15 readings) cases. In patients with hydration status change, SBP and PP were higher while sAlb lower in cases with higher hydration status level (p = 0.026, p = 0.05, and p = 0.109, respectively). In all patients, visit-to-visit SBP, PP, and sAlb changes were correlated to Re-OH changes (rs = 0.693, p < 0.001; rs = 0.643, p < 0.001; rs = -0.444, p = 0.008, respectively) but not to weight changes (rs = 0.052, p = 0.754; rs = 0.034, p = 0.838; rs = -0.156, p = 0.378, respectively). Visit-to-visit Re-OH changes, which were >+4% or <-4%, were linearly correlated to SBP (r = 0.858, p < 0.001), PP (r = 0.757, p < 0.001), and sAlb (r = -0.699, p = 0.002) changes.

CONCLUSION

In children on PD, longitudinal Re-OH changes are superior to weight changes in assessing volume-dependent variations of SBP, PP, and sAlb. Routine BIS application, rather than single BIS measurements, seems useful in the intra-patient monitoring of hydration status.

The Effect of Normalization of Ecw Volume as a Marker of Hydration in Peritoneal Dialysis Patients and Controls

♦ Objectives

We measured extracellular water (ECW) and intracellular water (ICW) volumes in peritoneal dialysis (PD) patients and controls to determine the effect of ICW variation on ECW/ICW ratio and to compare alternative ratios of ECW to height, height2, weight, and body surface area (BSA).

♦ Patients and Methods

We measured body water compartments by deuterium oxide and bromide dilution in 29 PD patients (14 M, 15 F) and 31 controls (15 M, 16 F).

♦ Results

ECW was similar in PD patients (17.58 ± 3.58 L) and controls (17.20 ± 2.97 L), p = NS. ICW was nonsignificantly lower in PD patients (17.58 ± 4.88 L) than in controls (19.71 ± 5.08 L), p = NS. ECW/ICW was greater in PD patients (1.06 ± 0.32) than in controls (0.92 ± 0.25), p = 0.057, and was inversely correlated with ICW in PD patients ( r = –0.733, p < 0.0001) and controls ( r = –0.721, p < 0.0001). In contrast, ECW/height, ECW/height2, ECW/weight, and ECW/BSA were similar for the two groups.

♦ Conclusions

ECW/ICW is affected by changes in ICW as well as by ECW varying with hydration. ECW/ICW ratio leads to the spurious impression of overhydration in subjects with smaller ICW volumes. ECW/ICW does not reflect hydration alone and other methods of expressing ECW as a measure of hydration need further evaluation.

Relationship of Demographic, Dietary, and Clinical Factors to the Hydration Status of Patients on Peritoneal Dialysis

Objectives

To establish which clinical factors are associated with an increased proportion of extracellular fluid (ECF) in peritoneal dialysis (PD) patients.

Design

A single-center, cross-sectional analysis of 68 stable PD patients.

Method

Bioelectrical impedance measurements (RJL, single frequency; RJL Systems, Clinton, Michigan, USA) of resistance and reactance were used to determine the proportion of ECF comprising total body water (TBW) in 68 stable PD patients attending for routine clearance and membrane studies. All patients underwent detailed dietetic, adequacy, and membrane function tests. Blood pressure and antihypertensive requirements were also documented.

Results

Significant gender differences in body composition were observed, such that women had lower absolute TBW and fat-free mass per kilogram body weight, but proportionately more ECF for a given TBW, mean ECF:TBW 0.5 ± 0.03 versus 0.44 ± 0.05, p < 0.005. In view of this, patients were split into two groups, defined as “over-” or “normally” hydrated, either by using the single discriminator (median ECF:TBW = 0.47) for the whole population, which resulted in groups distorted by gender, or by using different discriminators according to gender (women: 0.49, men 0.45). In both analyses, overhydrated patients were older, had significantly lower plasma albumin, less total fluid removal per kilogram body weight, and higher peritoneal solute transport. When split by a single discriminator, the overhydrated patients had lower sodium removal and significantly less intracellular fluid volume due to an excess of women in this group who also had less residual function and had been on dialysis longer. Using gender-specific discrimination, overhydrated patients were heavier due to expansion of the ECF volume: 20 ± 4.1 L versus 16 ± 3.3 L, p < 0.001. Stepwise multivariate analysis found age ( p = 0.001), albumin ( p = 0.009), and fluid losses per kilogram body weight ( p = 0.025) to be independent predictors of gender-adjusted hydration status. Sodium intake did not vary according to hydration status.

Conclusion

Gender influences the assessment of hydration status of PD patients when employing bioimpedance, such that women tend to have more ECF. Taking this into account, age, albumin, and achieved fluid removal appear to be independently associated with hydration status, whereas peritoneal solute transport is not. Advice on dietary sodium should take account of hydration status and achievable losses.

What is the Link between Poor Ultrafiltration and Increased Mortality in Anuric Patients on Automated Peritoneal Dialysis? Analysis of Data from Eapos

Background

Primary analysis of the European Automated Peritoneal Dialysis Outcomes Study (EAPOS) found that patients with daily ultrafiltration (UF) below a predefined target of 750 mL at baseline experienced increased mortality and continuing low UF over 2 years.

Setting

Multicenter, prospective observational study of prevalent, functionally anuric patients on automated peritoneal dialysis (APD) treated to predefined standards.

Methods

Secondary data analysis to determine clinical covariates that might support a link between poor UF and outcome, including pattern of comorbidity, prescription, nutrition as determined by Subjective Global Assessment (SGA), membrane function, and blood pressure (BP). Ultrafiltration was treated as a categorical (comparing patients above and below target at baseline) and continuous dependent variable in univariate and multivariate regression. The relationship between BP and survival was also explored.

Results

Of 177 patients recruited from 28 centers across Europe, 43 were below the UF target at baseline. Compared to those above target, there were no differences in the spread of comorbidity, type of APD prescription, SGA, BP, hemoglobin, HCO3, or parathyroid hormone, at baseline or at any later time. At baseline, plasma calcium and, at 12 months, plasma phosphate were lower in the low UF group. There was a weak positive correlation between baseline systolic or diastolic BP and UF, which remained on multivariate analysis but accounted for just 9% of the variability in BP. There was no clear relationship between baseline BP and survival, although, if anything, low BP was associated with earlier death. Poor UF was associated with lower mean dialysate glucose concentration during the first 4 months and with consistently worse membrane function.

Conclusions

The increased mortality associated with poor UF is likely multifactorial and not easily explained by clear differences in comorbidity, nutritional state, or other indices of treatment at baseline. The lower plasma phosphate suggests a subsequent fall in appetite. Poor BP control is unlikely to be the explanation, and a link between lower BP, reduced UF, and earlier death is suggested. Failure to achieve adequate UF due to worse membrane function remains an important and potentially reversible or preventable cause.

Inflammation and Extracellular Volume Expansion are Related to Sodium and Water Removal in Patients on Peritoneal Dialysis

Background

Inflammation is an important risk for mortality in dialysis patients. Extracellular fluid volume (ECFv) expansion, a condition commonly seen in peritoneal dialysis (PD) patients, may be associated with inflammation. However, published support for this relationship is scarce.

Objectives

To quantify the proportion of patients on PD with inflammation and to analyze the role of ECFv expansion and the factors related to these conditions.

Design

A prospective, multicenter cross-sectional study in six hospitals with a PD program.

Patients and Methods

Adult patients on PD were studied. Clinical data, body composition, and sodium and fluid intake were recorded. Biochemical analysis, C-reactive protein (CRP), and peritoneal and urinary fluid and sodium removal were also measured.

Results

CRP values positive (≥ 3.0 mg/L) for inflammation were found in 147 (80.3%) and negative in 36 patients. Patients with positive CRP had higher ECFv/total body water (TBW) ratio (women 47.69 ± 0.69 vs 47.36 ± 0.65, men 43.15 ± 1.14 vs 42.84 ± 0.65; p < 0.05), higher serum glucose (125.09 ± 81.90 vs 103.28 ± 43.30 mg/dL, p < 0.03), and lower serum albumin (2.86 ± 0.54 vs 3.17 ± 0.38 g/dL, p < 0.001) levels. They also had lower ultrafiltration (1003 ± 645 vs 1323 ± 413 mL/day, p < 0.005) and total fluid removal (1260 ± 648 vs 1648 ± 496 mL/day, p < 0.001), and less peritoneal (15.59 ± 162.14 vs 78.11 ± 110.70 mEq/day, p < 0.01) and total sodium removal (42.06 ± 142.49 vs 118.60 ± 69.73 mEq/day, p < 0.001). In the multivariate analysis, only ECFv/TBW was significantly ( p < 0.04) and independently associated with inflammation. ECFv/TBW was correlated with fluid removal ( r = 0.16, p < 0.03) and renal sodium removal ( r = 0.2, p < 0.01).

Conclusion

The data suggest that ECFv expansion may have a significant role as an inflammatory stimulus. The results disclose a relationship between the two variables, ECFv expansion and inflammation, identified as independent risk factors for mortality in PD patients.

Evaluation of nutritional status and prognostic impact assessed by the prognostic nutritional index in children with chronic kidney disease

To evaluate the nutritional status of children with chronic kidney disease (CKD) before dialysis via a series of indexes, and investigate the prognostic impact of nutritional status in these patients assessed by the Prognostic Nutritional Index (PNI).Fifty-four children with CKD before dialysis were enrolled in this study. The nutritional status was evaluated by different indexes, including dietary intake, anthropometry data and biochemical parameters. Additionally, PNI is calculated as 10 × serum albumin (g/dL) + 0.005 × lymphocyte count (/mm). Glomerular filtration rate (GFR) of patients with different PNI scores was followed up.Thirty-four patients (63.0%) experienced unreasonable dietary intake, and the patients with CKD stage 4 were characterized by lower energy intake. The height was the most affected anthropometry parameter. Additionally, 46 patients (85.2%) suffered from anemia. The serum albumin of 42 patients (77.8%) was <35 g/L, while 34 cases (63.0%) had increased cholesterol and triglyceride. According to the PNI scores, the patients were divided into 3 groups: high-PNI (PNI ≥ 38), middle-PNI (35 ≤ PNI < 38), and low-PNI (PNI < 35). Of the 54 patients, the PNI was <35 in 29 (53.7%) and ≥38 in 13 (24.1%). The patients with CKD stage 4 were belonged to the low-PNI group. At follow-up, GFR decreased significantly in patients with low-PNI scores compared with the high-PNI group (P < .05).Malnutrition, as a common complication of CKD, has a prognostic impact in children with CKD before dialysis, as assessed by the PNI score.

The association of overhydration with chronic inflammation in chronic maintenance hemodiafiltration patients

INTRODUCTION

Achieving euvolemia is one of the major challenges when treating end-stage renal disease (ESRD) patients receiving maintenance renal replacement therapy. Fluid overload is recognized as an independent predictor of mortality in ESRD, but its association with chronic inflammation is less well explored especially in chronic maintenance hemodiafiltration.

METHODS

We performed a cross-sectional study of 87 prevalent ESRD patients receiving chronic maintenance hemodiafiltration (vintage 66.5 ± 57.1 months) with bioimpedance analysis to characterize the degree of percent overhydration (OH%). We also compared the levels of inflammatory markers, including C-reactive protein (CRP), serum albumin, neutrophil/lymphocyte ratio (NLR), and hemoglobin red cell distribution width (RDW) for the overhydrated (OH% ≥ 15%) versus euvolemic (OH% < 15%) groups. Linear regression analysis was performed to explore relationships between the degree of OH and inflammatory indicators.

FINDINGS

The cohort represented an all-European population with a mean age of 60.9 ± 14.7 years and prevalence of diabetes mellitus of 27%. The entire cohort's OH% was 14.9% ± 5.1% (range -11.1% to 39.0%); further, the <15% group of patients' OH% was 8.0% ± 8.5% versus 20.9% ± 5.1% in the OH% ≥ 15% group (P < 0.0001). Forty-seven patients (53%) were overhydrated by traditional criteria (OH% ≥15%) and 20 patients (23%) were severely overhydrated (OH% > 20%). The euvolemic (OH% <15%) versus severely overhydrated (OH% > 20%) groups had significant differences in markers of inflammation: CRP (9.8 ± 10.6 vs. 21.5 ± 21.6 mg/L, P < 0.006), serum albumin (37.6 ± 02.9 vs. 34.5 ± 5.3 g/L, P < 0.004), and NLR (3.06 ± 1.25 vs. 3.92 ± 2.04; P < 0.004). On linear regression, significant correlations were found between OH% and CRP (r = 0.2899, P < 0.006), serum albumin (r = -0.3670; P < 0.0005), RDW (r = 0.2992; P < 0.005), and NLR (r = 0.2900; P < 0.006).

DISCUSSION

In a prevalent hemodiafiltration cohort, OH was common and correlated with several inflammatory markers.

Peritoneal protein clearance predicts mortality in peritoneal dialysis patients

BACKGROUND

Peritoneal protein clearance has been suggested to be a marker of peritoneal inflammation and systemic endothelial dysfunction.

METHODS

We enrolled 711 consecutive incident PD patients. Baseline peritoneal protein clearance and other clinical information were reviewed. All patients were followed for at least 1 year for all-cause and cardiovascular mortality.

RESULTS

The average PD effluent protein loss was 6.41 ± 2.16 g/day; peritoneal protein clearance was 97.15 ± 41.55 mL/day. The average duration of follow-up was 50.8 ± 36.2 months. Multivariate linear regression analysis showed that serum albumin, C-reactive protein, and mass transfer area coefficients of creatinine were independently associated with peritoneal protein clearance. By multivariate Cox regression analysis, age, Charlson comorbidity score, volume of overhydration and peritoneal protein clearance were independent predictors of all-cause mortality. Every 10 mL/day increase in peritoneal protein clearance confers 10.4% increase in risk of all-cause mortality (95% confidence interval 2.6-18.7%, p = 0.008). Peritoneal protein clearance was also associated with cardiovascular mortality by univariate analysis, but the association became insignificant after adjusting for confounding factors Cox regression analysis.

CONCLUSIONS

Baseline peritoneal protein clearance is an independent predictor of all-cause mortality in incident PD patients. Routine measurement of peritoneal protein clearance may facilitate patient risk stratification.

Muscle wasting in chronic kidney disease

Loss of lean body mass is a relevant component of the cachexia, or protein energy wasting (PEW), syndrome. Reduced muscle mass seems to be the most solid criterion for the presence of cachexia/PEW in patients with chronic kidney disease (CKD), and those with greater muscle mass loss have a higher risk of death. Children with CKD have many risk factors for lean mass and muscle wasting, including poor appetite, inflammation, growth hormone resistance, and metabolic acidosis. Mortality risks in patients with CKD increases as body mass index (BMI) and weight decreases. However, data regarding cachexia/PEW and muscle wasting in children with CKD is scarce due to lack of consensus in diagnostic criteria and an appropriate investigative methodology. Further research is urgently needed to address this important complication in the pediatric CKD setting, which may have fundamental impact on clinical outcomes.

Increase in Extracellular Hydration Status After Initiating Peritoneal Dialysis Electively

Renal replacement therapy is designed to treat uremic symptoms and correct hypervolemia. We hypothesized that starting peritoneal dialysis (PD) should reduce overhydration, and we measured body composition and hydration status using bioimpedance in PD patients prior to training and then at the first assessment of peritoneal membrane function. We studied 100 consecutive patients with a planned start to PD, without peritoneal infections or mechanical catheter problems, mean age 54.7 ± 17.1 years, 57% male and 25% diabetic. Extracellular water (ECW) overhydration increased from -0.06 (-1.21 to 0.97) L to 0.96 (0.50 to 3.01) L, p < 0.001. Fat mass increased from 22.7 ± 11.1 to 23.7 ± 11.3 kg, p = 0.007). The change in ECW/total body water (TBW) was associated with age (β 0.065, p < 0.001), increasing comorbidity (β 1.107, p = 0.005), faster peritoneal protein transport (β 1.84, p < 0.04), and negatively with serum albumin (β -0.208, p < 0.001), and residual renal function (β -0.725, p = 0.026). Patients who had an increase in ECW/TBW had higher C-reactive protein (CRP) both before starting (16.8 ± 24.1 vs 7.7 ± 18.9 mg/L), and when established on PD (15.0 ± 31.8 vs 4.6 ± 5.1 mg/L), p < 0.05. Rather than a reduction in ECW hydration status, overhydration increased after starting PD. This was greater for older more comorbid patients and those with an inflammatory milieu and lower residual renal function. These factors should be considered when deciding upon initial PD prescriptions to limit ECW overhydration before information on peritoneal membrane function becomes available.

Fluid Overload and Inflammation Axis

Extracellular fluid overload (FO), which is assessed using bioimpedance technologies, is an important predictor of outcome in dialysis patients and in patients with early stages of chronic kidney disease. While traditional cardiovascular abnormalities are assumed to mediate this risk, recently also, the importance of noncardiovascular factors, such as systemic inflammation and malnutrition has been shown. While both FO and inflammation are independent risk factors for mortality, recent studies have shown that their combined presence can lead to a cumulative risk profile. From a pathophysiologic viewpoint, FO and inflammation can also be mutually reinforcing. Inflammation could contribute to FO by hypoalbuminemia, capillary leakage, and a (unnoticed) decline in lean and/or fat tissue mass resulting in incorrect estimation of dry weight. Reciprocally, FO could lead to inflammation by the translocation of endotoxins through a congested bowel wall or by a proinflammatory effect of tissue sodium. The relative importance of these putative factors is, however, not clear yet and epidemiological studies have shown no clear temporal direction regarding the relationship between FO and inflammation. FO and inflammation appear to be part of (dynamic) clusters of risk factors, including malnutrition and hyponatremia. Technology-guided fluid management of the often vulnerable dialysis patient with FO and inflammation cannot yet be based on evidence from randomized controlled trials, in which these specific patients were in general not included. In the absence of those trials, treatment should be based on identifying actionable causes of inflammation and on the judicious removal of excess volume based on frequent clinical reassessment.

Impact of Diabetes on Extracellular Volume Status in Patients Initiating Peritoneal Dialysis

BACKGROUND

Recent reports have highlighted that diabetic patients with kidney failure are at increased risk of technique failure and transfer to haemodialysis within 90 days of initiating peritoneal dialysis (PD). We wished to determine whether there were differences between diabetic and non-diabetic patients within the first 3 months of starting PD.

METHODS

We reviewed results of corresponding bioimpedance and the 1st test of peritoneal membrane function (PET) in consecutive patients, 6-10 weeks after initiating PD electively.

RESULTS

Adult patients numbering 386 - 230 males (59.6%), 152 (39.4%) diabetic, 188 (48.7%) white, mean age 57.3 ±16.9 years - were studied. Although weight, residual renal function and peritoneal clearances were not different, diabetic patients had greater extracellular water to total body water (ECW/TBW; 40.4 ± 1.1 vs. 39.2 ± 1.4) and % ECW excess (9.6 [6.3-12.3] vs. 4.9 [0.7-8.9]), lower serum albumin (35.2 ± 4.7 vs. 37.8 ± 4.9 g/L), greater fat mass index (9.5 ± 4.2 vs. 7.7 ± 4.2), and although mean arterial blood pressure was similar, arterial pulse pressure was greater (66.9 ± 10.8 vs. 54.3 ± 17.3 mm Hg, all p < 0.001). On multivariate analysis, glycated haemoglobin was associated with pulse pressure (standardised β 0.24, p < 0.001), N terminal brain natriuretic peptide (β 0.24, p < 0.001), ECW/TBW (β 0.19, p = 0.012) and negatively with serum albumin (β -0.14, p = 0.033) and creatinine (β -0.18, p = 0.02).

CONCLUSION

Diabetic patients electively starting PD were found to have greater ECW/TBW ratios and ECW excess 6-10 weeks after starting PD compared to non-diabetics, despite similar PET. Increased ECW could predispose diabetic patients to be at greater risk of volume overload.

Dialysis modality and nutritional status are associated with variability of inflammatory markers

BACKGROUND

Inflammation is a common feature in dialysis patients and is associated with cardiovascular complications and poor outcome. Measuring the variability of inflammatory markers may help in understanding underlying factors triggering inflammation. Whether the inflammatory pattern in hemodialysis (HD) and peritoneal dialysis (PD) patients differs has scarcely been studied. Here we explored factors associated with the magnitude and variability of inflammation markers in HD and PD patients.

METHODS

In two 3-month, prospective cohort studies comprising 228 prevalent HD and 80 prevalent PD patients, interleukin-6 (IL-6) and high-sensitivity C-reactive protein (CRP) were measured in blood samples drawn each month and every week, respectively. Information on comorbidity, protein-energy wasting (PEW) and medications was gathered at baseline, and information on symptoms potentially related to inflammation was gathered weekly. A mixed-effect model was used for multivariate analysis of factors linked to CRP and IL-6 variation.

RESULTS

IL-6 and CRP levels were higher and showed higher variability in HD versus PD patients [median IL-6 8.3 (interquartile range, IQR, 5.3-14.5) versus 6.7 (IQR 4.2-10.0) pg/mL, P < 0.001 and median CRP 6.1 (IQR 2.5-14.0) versus 5.4 (IQR 1.6-9.0) mg/L, P < 0.001). PEW predicted increased inflammation variability after correcting for age, sex, dialysis vintage, modality and comorbidity. Increased comorbidity predicted IL-6, but not CRP, variability.

CONCLUSIONS

Circulating concentrations as well as variability of IL-6 and CRP levels were higher in HD as compared with PD patients. In HD and PD patients, short-term variability of IL-6 and CRP levels associated strongly with PEW, while comorbidity was related to IL-6 but not to CRP variability.

Clinical Significance of the Edema Index in Incident Peritoneal Dialysis Patients

Background

Proper monitoring for volume overload is important to improve prognosis in peritoneal dialysis (PD) patients. The association between volume status and residual renal function (RRF) remains an unresolved issue. The aim of the present study was to evaluate the association between the edema index and survival or RRF in incident PD patients.

Patients and Methods

We identified all adults who underwent PD. The edema index was defined as the ratio of extracellular fluid to total body fluid. Participants with available data regarding survivorship or non-survivorship during the first year after PD initiation were included in the area under the receiver operating characteristic curve analysis. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. Participants were divided into two groups according to the cutoff value of their baseline edema indices: High (>cutoff value) and Low (≤cutoff value). Survivors during the first year after PD initiation were divided into two groups according to the initial and 1-year edema index: Non-improvement (maintenance of criteria in the initial Low group during the year) and Other (all participants except those in the Non-improvement group).

Results

In total, 631 patients were enrolled in the present study. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. The respective mean initial RRF values (mL·min^-1·1.73 m^-2) in the Low and High groups, respectively, were 4.88 ± 4.09 and 4.21 ± 3.28 in men (P = 0.108), and 3.19 ± 2.57 and 2.98 ± 2.70 in women (P = 0.531). There were no significant differences between groups in either sex. The respective mean RRF values at 1 year after PD initiation in the Low and High groups, respectively, were 3.56 ± 4.35 and 2.73 ± 2.53 in men, and 2.80 ± 2.36 and 1.85 ± 1.51 in women. RRF at 1 year after PD initiation was higher in the Low group than in the High group (men: P = 0.027; women: P = 0.001). In men, the cumulative 5-year survival rates were 78.7% and 46.2% in the Low and High groups, respectively, whereas in women, rates were 77.2% and 58.8% in the Low and High groups, respectively. For survivors during the first year after PD initiation, the Non-improvement group was associated with a poor survival rate compared with the Other group for both sexes.

Conclusion

A high edema index was associated with mortality in incident PD patients at baseline and follow-up. The edema index may be used as a new marker for predicting mortality in PD patients.

Effect of renal impairment on the pharmacokinetics, efficacy, and safety of albiglutide

BACKGROUND

Chronic kidney disease is frequently present in patients with type 2 diabetes mellitus (T2DM). New therapeutic options in this patient subpopulation are needed.

OBJECTIVES

Assess the effect of renal impairment on the pharmacokinetics (PK), efficacy, and safety of albiglutide in single- and multiple-dose studies.

METHODS

Pharmacokinetics, safety, and efficacy of once weekly albiglutide in patients with T2DM was assessed from a single-dose (30 mg), nonrandomized, open-label study (N = 41) including subjects with normal and varying degrees of renal impairment, including hemodialysis, and a pooled analysis of 4 phase 3, randomized, double-blind (1 open-label), active or placebo-controlled multiple-dose studies. The pooled analysis of the latter 4 studies (N = 1113) was part of the population PK analysis, which included subjects with normal and varying degrees of renal impairment (mild, moderate, severe) treated with albiglutide (30 to 50 mg) to primary end points of 26 to 52 weeks.

RESULTS

Single-dose PK showed area-under-the-curve ratios (and 90% CIs) of 1.32 (0.96-1.80), 1.39 (1.03-1.89), and 0.99 (0.63-1.57) for the moderate, severe, and hemodialysis groups, respectively, relative to the normal group. Results indicate that modest increases in plasma concentration of albiglutide were observed with the severity of renal impairment. There was a trend for more glycemic lowering as the estimated glomerular filtration rate decreased. The severe group had a higher frequency of gastrointestinal (eg, diarrhea, constipation, nausea, and vomiting) and hypoglycemic (with background sulfonylurea use) events compared with patients with mild or moderate renal impairment.

CONCLUSION

The PK, efficacy, and safety data indicate that albiglutide has a favorable benefit/risk ratio in patients with T2DM and varying degrees of renal impairment, and the need for a dose adjustment is not suggested. Experience in patients with more severe renal impairment is very limited, so the recommendation is to use albiglutide carefully in this population.

CLINICAL TRIAL REGISTRATION

(ClinicalTrials.gov):NCT00938158, NCT00849017, NCT00838916, NCT00839527, NCT0198539.

Practical considerations when prescribing icodextrin: a narrative review

BACKGROUND

Icodextrin is a peritoneal dialysis solution that is commonly used to increase ultrafiltration during the long dwell. The other major clinical benefit of icodextrin is that it is glucose-sparing, which may help preserve peritoneal membrane function. Since it has a different chemical composition than dextrose, and with its increasing use, there are several clinical considerations healthcare providers must familiarize themselves with prior to prescribing icodextrin.

SUMMARY

Failure to recognize these special properties of icodextrin can lead to adverse events reaching patients. This narrative review explores the hemodynamic, metabolic, and idiopathic effects of icodextrin to facilitate the safe use of icodextrin in peritoneal dialysis.

KEY MESSAGES

Hemodynamic effects include hypotension from enhanced ultrafiltration contributing to loss of residual kidney function. Metabolic effects include the chemical structure of icodextrin interfering with biochemical assays, resulting in misleading glucose readings on non-specific glucometers. Idiopathic adverse effects include a diffuse rash and sterile peritonitis. It is also important to remember that not all antibiotic combinations have undergone stability testing in icodextrin. This narrative review will help healthcare providers to confidently prescribe icodextrin to maximize its benefit in peritoneal dialysis patients.

Tolvaptan increases urine and ultrafiltration volume for patients with oliguria undergoing peritoneal dialysis

BACKGROUND

Hypoalbuminemia caused by peritoneal dialysate protein loss, frequently occurs in patients on peritoneal dialysis (PD) and is associated with an increased risk of death. We investigate whether PD dialysis exchange volume (PD volume) could be reduced with tolvaptan (TVP) through increased urine volume (UV).

METHODS

The study included 11 stable patients with oliguria undergoing PD. The following parameters were examined-diuretic response and the effect of TVP on peritoneal ultrafiltration (UF), body weight, serum albumin, sodium, arm muscle area (AMA), PD volume, dialysis efficiency calculator (K t/V), and urine and serum osmolarity (OSM).

RESULTS

The average UV increased from 428 ± 178 to 906 ± 285 mL (p = 0.018 by paired t test). Average weekly PD volume decreased from 28,836 ± 5,699 to 23,872 ± 3,569 mL (p = 0.04 by paired t test). Average UF increased from 283 ± 147 to 575 ± 135 mL (p = 0.019 by paired t test). On the other hand, there was no significant difference in the average dialysate K t/V before and after TVP treatment. Serum sodium, AMA, and serum albumin levels were not statistically different before and after TVP treatment. The urine and serum OSM ratio of effective cases before TVP treatment was higher than that of ineffective cases (p = 0.024 by unpaired t test).

CONCLUSION

Our results indicate that TVP is useful for patients on continuous ambulatory PD who have oliguria and high urine osmolarity. Furthermore, we can reduce PD volume to maintain their nutritional status.

Extracellular volume expansion in peritoneal dialysis patients

INTRODUCTION

Cardiovascular mortality remains high among peritoneal dialysis (PD) patients. Several small studies have suggested that PD patients are volume expanded, and as such this could be a cardiovascular risk factor. We therefore wished to investigate factors which could lead to extracellular water (ECW) expansion.

METHODS

Retrospective cross-sectional audit of 600 prevalent, adult PD patients attending two tertiary university PD centers, with corresponding assessments of PD adequacy, transport status, and multifrequency bioimpedance measurements of extracellular water to total body water (ECW/TBW).

RESULTS

600 PD patients, median age 57.5 (46.9-67.9) years, 54% male, 31% diabetic, 47.6% Caucasoid, median PD vintage 16 (3.7-38) months, (64% prescribed icodextrin, 34% hypertonic glucose dialysates, and 74% antihypertensive medications). Mean ECW 15.1±0.2 L, ICW 20±0.2 L, ECW/TBW ratio 0.437±0.007. On multivariate analysis %ECW/TBW was associated with age (F=13.1 ß=0.045 p=0.000), number of antihypertensive medications (F=10.3 ß=0.43 p=0.001), log CRP (F=12.9 ß=1.3 p=0.000), and negatively with serum albumin (F=25 ß=-0.22 p=0.000), and residual renal function (urine volume mL F=9.96 ß=-0.001 p=0.002) (weekly Kt/Vurine F=8.82 ß=-2.05, p=0.003).

CONCLUSIONS

Overhydration as assessed by ECW/TBW is prevalent in adult PD patients, and is associated with loss of residual renal function, inflammation, malnutrition and hypertension - as assessed by antihypertensive medications. As this was a retrospective cross-sectional audit, whether loss of residual renal function, inflammation, and protein energy wasting lead to volume expansion remains to be determined in prospective longitudinal studies.

Nutrition in infants and very young children with chronic kidney disease

Provision of adequate nutrition is a cornerstone of the management of infants and very young children with chronic kidney disease (CKD). Very young children with CKD frequently have poor spontaneous nutritional intake. Because growth depends strongly on nutrition during early childhood, growth in very young children with CKD is often suboptimal. In this review we will consider the mechanisms and manifestations of inadequate nutritional status in very young children with CKD, mechanisms mediating inadequate nutritional intake, and the optimal nutritional management of this special population. In addition, we suggest an approach to the assessment of nutritional status, including the use of body mass index in infants. Five major nutritional components are considered: energy, macronutrients, fluids and electrolytes, micronutrients, and calcium/phosphorus/vitamin D. The use of adjunctive therapies, including appetite stimulants, treatment of gastroesophageal reflux and gastric dysmotility, enhanced dialytic clearance, and growth hormone, is also briefly discussed.

Comparison of volume status in asymptomatic haemodialysis and peritoneal dialysis outpatients

BACKGROUND

The majority of haemodialysis (HD) patients gain weight between dialysis sessions and thereby become volume overloaded, whereas peritoneal dialysis (PD) is a more continuous technique. Cardiovascular mortality and hypertension is increased with both treatment modalities. We therefore wished to compare volume status in PD and HD to determine whether PD patients are chronically volume overloaded, as a risk factor for cardiovascular mortality. Study Design, Setting and Participants:We retrospectively audited 72 healthy HD patients and 115 healthy PD patients attending a university hospital dialysis centre for routine outpatient treatment, who had multi-frequency bioimpedance measurements of extracellular water to total body water (ECW/TBW).

RESULTS

The groups were well matched for age, sex, weight and ethnicity, PD patients had greater urine output [1,075 (485-1,613) vs. 42.5 (0-1,020) ml/day, p < 0.001], but there was no difference in antihypertensive prescription (63.5 vs. 76.4%), mean arterial blood pressure (post-dialysis 101.6 ± 1.5 mm Hg vs. pre-dialysis 102 ± 2.4 mm Hg), although post-dialysis arterial blood pressure was lower than in PD patients (96.4 ± 3.1 mm Hg, p < 0.05). The ratio of ECW/TBW fell after HD (pre-dialysis 0.394 ± 0.001 vs. post-dialysis 0.389 ± 0.004, p < 0.001) and was similar in the PD group to the group before HD (0.393 ± 0.001), and greater than that in the group after HD (p < 0.001). ECW/TBW was greater than the normal reference range in 30% PD patients, 28% patients before HD and 20% patients after HD.

CONCLUSIONS

Overhydration is common in healthy stable PD outpatients, and ECW volumes in PD patients are not dissimilar to those of pre-dialysis HD patients. The role of chronic volume overload as a risk factor for cardiovascular disease needs further investigation.

Cachexia and protein-energy wasting in children with chronic kidney disease

Children with chronic kidney disease (CKD) are at risk for "cachexia" or "protein-energy wasting" (PEW). These terms describe a pathophysiologic process resulting in the loss of muscle, with or without loss of fat, and involving maladaptive responses, including anorexia and elevated metabolic rate. PEW has been defined specifically in relation to CKD. We review the diagnostic criteria for cachexia and PEW in CKD and consider the limitations and applicability of these criteria to children with CKD. In addition, we present an overview of the manifestations and mechanisms of cachexia and PEW. A host of pathogenetic factors are considered, including systemic inflammation, endocrine perturbations, and abnormal neuropeptide signaling, as well as poor nutritional intake. Mortality risk, which is 100- to 200-fold higher in patients with end-stage renal disease than in the general population, is strongly correlated with the components of cachexia/PEW. Further research into the causes and consequences of wasting and growth retardation is needed in order to improve the survival and quality of life for children with CKD.

Volume status in peritoneal dialysis

Fluid homeostasis is one of the fundamental roles of the kidney and a crucial aspect in clinical management of patients on peritoneal dialysis (PD). Volume status has an important impact on the outcome of PD patients. Fluid excess leads to accelerated development of cardiovascular disease. Volume status may also impact on disorders and assessment of nutritional state. While ultrafiltration and residual urine volume have featured prominently in PD research, the importance of fluid intake and thirst in PD patients has received relatively little attention. Despite older studies suggesting that fluid overload is common in PD, current PD techniques can produce sufficient fluid removal to achieve good control of fluid, with associated cardiac benefits in PD patients. One of the major challenges is to apply these techniques to obtain ideal volume status in patients. Bioelectrical impedance analysis appears to be the most promising technique currently available to guide fluid management.

Comparison of Outcomes on Continuous Ambulatory Peritoneal Dialysis versus Automated Peritoneal Dialysis: Results from a USA Database

Background and Objective

Automated peritoneal dialysis (APD) is being increasingly used as an alternative to continuous ambulatory peritoneal dialysis (CAPD). However, there has been concern regarding reduced sodium removal leading to hypertension and resulting in a faster decline in residual renal function (RRF). The objective of the present study was to compare patient and technique survival and other relevant parameters between patients treated with APD and patients treated with CAPD.

Methods

Data for incident patients were retrieved from the database of the Renal Research Institute, New York. Treatment modality was defined 90 days after the start of dialysis treatment. In addition to technique and patient survival, RRF, blood pressure, and laboratory parameters were also compared.

Results

179 CAPD and 441 APD patients were studied. Mean as-treated survival was 1407 days [95% confidence interval (CI) 1211 - 1601] in CAPD patients and 1616 days (95% CI 1478 - 1764) in APD patients. Adjusted hazard ratio (HR) for mortality was 1.31 in CAPD compared to APD (95% CI 0.76 - 2.25, p = NS). Unadjusted as-treated technique survival was lower in CAPD compared to APD, with HR 2.84 (95% CI 1.65 - 4.88, p = 0.002); adjusted HR was 1.81 (95% CI 0.94 - 3.57, p = 0.08). Peritonitis rate was 0.3 episodes/ patient-year for CAPD and APD; exit-site/tunnel infection rate was 0.1 and 0.3 episodes/patient-year for CAPD and APD respectively (p = NS).

Conclusions

Patient survival was not significantly different between APD and CAPD patients, whereas technique survival appeared to be higher in APD patients and could not be explained by differences in infectious complications. No difference in blood pressure control or decline in RRF was observed between the 2 modalities. Based on these results, APD appears to be an acceptable alternative to CAPD, although technique prescription should always follow individual judgment.

Relevância do estado de hidratação na interpretação de parâmetros nutricionais em diálise peritoneal

OBJETIVO: Identificar determinantes do estado de hidratação de pacientes em diálise peritoneal crônica, bem como investigar os efeitos da sobrecarga líquida sobre o estado nutricional. MÉTODOS: Foi feito estudo transversal, realizado em 2006, avaliando 27 pacientes em diálise peritoneal crônica, acompanhados no Hospital das Clínicas da Faculdade de Medicina de Botucatu (SP), quanto a parâmetros clínicos, dialíticos, laboratoriais, antropométricos e de bioimpedância elétrica. Para avaliar a influência de parâmetros sobre o estado de hidratação empregou-se modelo de regressão linear múltipla. A amostra foi estratificada quanto ao estado de hidratação pela relação entre água extracelular e água corporal total (0,47 para homens e 0,52 para mulheres), parâmetros obtidos por meio de bioimpedância elétrica. Comparações foram realizadas por análise de covariância, Mann-Whitney, Qui-quadrado ou teste exato de Fisher. Considerou-se significância estatística quando p≤0,05. RESULTADOS: Pacientes com maior volume urinário e em modalidade dialítica automatizada apresentaram melhor estado de hidratação. Pacientes com maior sobrecarga líquida, comparados àqueles com menor sobrecarga, apresentaram menor ângulo de fase (M=4,2, DP=0,9 vs M=5,7, DP=0,7º; p=0,006), menor albumina (M=3,06, DP=0,46 vs M=3,55, DP=0,52g/dL; p=0,05) e maior % prega cutânea tricipital (M=75,3, DP=36,9 vs M=92,1, DP=56,9%; p=0,058), sem outras evidências antropométricas. CONCLUSÃO: Pode-se sugerir que os níveis reduzidos de albumina e ângulo de fase nos pacientes com maior sobrecarga líquida não estiveram relacionados a pior estado nutricional. Para o diagnóstico nutricional em vigência de sobrecarga líquida, deve-se considerar o conjunto de variáveis obtidas por diversos métodos, buscando relacioná-las e interpretá-las de maneira abrangente, possibilitando um diagnóstico nutricional fidedigno.

Cardiothoracic ratio association with mortality in patients on maintenance peritoneal dialysis

The cardiothoracic ratio (CTR) indicates the left ventricular size; however, the significance of the CTR in patients on maintenance peritoneal dialysis (PD) remains unclear. In this study, 335 PD patients were enrolled and demographic, biochemical, co-morbidity, and dialysis-related data were obtained. The factors determining CTR were further analyzed. All patients were followed up for two years to investigate the mortality risks. We defined a normal CTR as less than the mean CTR value, mild cardiomegaly as a CTR between the mean and mean + 1 SD, and moderate-to-severe cardiomegaly as more than the mean CTR + 1 SD. Among the 335 patients, 163 patients were classified as having a normal CTR (<49.2%), 112 patients as having mild cardiomegaly (CTR 49.2-55.7%), and 60 patients as having moderate-to-severe cardiomegaly (CTR > 55.7%). χ(2) -analysis showed that the incidences of malnutrition and anemia were significantly higher in patients with severe cardiomegaly than in patients of the other groups. The CTR was positively correlated with age, but negatively correlated with albumin and hemoglobin levels. Twenty-six patients (7.7%) had died by the end of the study. Cox multivariate analysis revealed that the CTR significantly predicts all-cause two-year mortality in PD patients on maintenance PD; therefore, the CTR correlates with the nutritional and anemic status of PD patients and is a reliable predictor for all-cause two-year mortality. The analytical results of this study support continued efforts to reduce the CTR and treat underlying causes in patients with cardiomegaly.

Normalized bioimpedance indices are better predictors of outcome in peritoneal dialysis patients

BACKGROUND

While phase angle of bioimpedance analysis (BIA) has great survival-predicting value in dialysis populations, it is known to be higher in male than in female subjects. In this study, we aimed to explore the factors influencing the predictive value of phase angle and to identify the appropriate physics terms for normalizing capacitance (C) and resistance (R).

METHODS

We formulated body capacitive index (BCI), C(BMI) (capacitance × height(2)/weight), body resistive index (BRI), R(BMI) (resistance × weight/height(2)), and CH(2) (capacitance × height(2)). We also studied H(2)/R, R/H, and reactance of a capacitor/height (X(C) /H). There are 3 components in this study design: (1) establishment of normal values in a control Malaysian population, (2) comparison of these with a CAPD population, and (3) prediction of survival within a CAPD population. We initially performed a BIA study in 206 female and 116 male healthy volunteers, followed by a prospective study in a cohort of 128 CAPD patients [47 with diabetes mellitus (DM), 81 non-DM; 59 males, 69 females] for at least 2 years. All the parameters during enrolment, including BIA, serum albumin, peritoneal equilibrium test, age, and DM status, were analyzed. Outcome measurement was survival.

RESULTS

In healthy volunteers, both genders had the same BCI (2.0 nF kg/m(2)). On the contrary, female normal subjects had higher BRI than male normal subjects (median 15 642 vs 13242 Ω kg/m(2), p < 0.001) due to higher fat percentage (35.4% ± 0.4% vs 28.0% ± 0.6%, p < 0.001), resulting in a lower phase angle (mean 5.82 ± 0.04 vs 6.86 ± 0.07 degrees, p < 0.001). Logistic regression showed that BCI was the best risk indicator in 128 CAPD patients versus 322 normal subjects. In age- and body mass index (BMI)-matched head-to-head comparison, BCI had the highest χ(2) value (χ(2) = 102.63), followed by CH(2) (or H(2)/X(C); χ(2) = 81.00), BRI (χ(2) = 20.54), and X(C)/H (χ(2) = 20.48), with p value < 0.001 for these parameters. In comparison, phase angle (χ(2) = 11.42), R/H (χ(2) = 7.19), and H(2)/R (χ(2) = 5.69) had lower χ(2) values. 35 (27.3%) patients died during the study period. Univariate analysis adjusted for DM status and serum albumin level demonstrated that non-surviving patients had significantly higher CH(2) (245 vs 169 nF m(2), p < 0.001) and BCI (4.0 vs 2.9 nF m(2)/kg, p = 0.005) than patients that survived. CH(2) was the best predictor for all-cause mortality in Cox regression analysis, followed by BCI, phase angle, and X(C)/H.

CONCLUSION

Measures that normalize, such as BCI and CH(2), have higher risk discrimination and survival prediction ability than measures that do not normalize, such as phase angle. Unlike phase angle, measurement of BCI overcomes the gender effect. In this study, the best risk indicator for CAPD patients versus the general population is BCI, reflecting deficit in nutritional concentration, while CH(2) reflects total nutritional deficit and thus is the major risk indicator for survival of CAPD patients.

Plasma volume, albumin, and fluid status in peritoneal dialysis patients

BACKGROUND AND OBJECTIVES

Peritoneal dialysis (PD) patients may be overhydrated especially when inflammation is present. We hypothesized that patients with a plasma albumin below the median value would have measurable overhydration without a proportional increase in plasma volume (PV).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We investigated a cross-sectional sample of 46 prevalent PD patients powered to detect a proportional increase in PV associated with whole body overhydration and hypoalbuminemia. PV was determined from (125)I-labeled albumin dilution, absolute total body water from D dilution (TBW(D)), and relative hydration from multifrequency bioimpedance analysis (BIA; Xitron 4200) expressed as the extracellular water (ECW):TBW(BIA) ratio.

RESULTS

Whereas patients with plasma albumin below the median (31.4 g/dl) were overhydrated as determined both by BIA alone (ECW:TBW(BIA) 0.49 versus 0.47, P < 0.036) and the difference between estimated TBW(BIA) and measured TBW(D) (3.55 versus 0.94 L, P = 0.012), corrected PV was not different (1463 versus 1482 ml/m(2), NS). Mean PV was not different from predicted, and its variance did not correlate with any other clinical measures. Multivariate analysis showed that the only independent predictor of whole body overhydration was reduced plasma albumin.

CONCLUSIONS

Hypoalbuminemia is an important determinant of tissue overhydration in PD patients. This overhydration is not associated with an increased plasma volume. Attempts to normalize the ECW:TBW ratio in hypoalbuminemic, inflamed PD patients may lead to hypovolemia and loss of residual renal function.

Effect of different synthetic membranes on laboratory parameters and survival in chronic haemodialysis patients

Background. A number of studies suggested that the type of dialysis membrane is associated with differences in long-term outcome of patients undergoing haemodialysis, both in terms of morbidity and mortality. In the majority of dialysis units, synthetic membranes are being used. However, no studies are available so far for comparison between different biocompatible membranes. Therefore, we studied the influence of high- and low-flux polysulphone membranes (PS) in comparison with polymethylmethacrylate (PMMA) membranes on mortality and morbidity on the basis of various laboratory parameters. Methods. In a cohort study, data of 260 consecutive haemodialysis patients entering our dialysis unit in the years 2003-07 were collected, comparing 435 PS patient-years and 85 PMMA patient-years. PMMA membranes (n = 33) were used for those patients who did not tolerate (e.g. for pruritus) PS membranes (n = 227). Low-flux dialysers (n = 233) were compared with high-flux (n = 37). Laboratory values were evaluated by unpaired t-test, and mortality was evaluated by log-rank test and Cox regression analysis adjusted for age, diabetes and laboratory parameters. Results. Patients in our dialysis unit had a high cardiovascular risk as demonstrated by a proportion of 63% of peripheral arterial disease. Despite this, cumulative survival was almost 60% after 5 years on dialysis. It was slightly but not significantly higher in patients on PMMA (68%) compared with PS dialysers (54%) and on high-flux (61%) versus low-flux membranes (54%). After accounting for the confounding effect of age and diabetes in the multivariate Cox regression analysis, there was no impact of the membranes used (high- or low-flux, PMMA or PS) on survival. Only age at the onset of dialysis showed a significant influence on survival (P ≤ 0.001). Independent predictors of mortality in all patients in the multivariate Cox regression analysis were age, haemoglobin, leucocytes, C-reactive protein (CRP) and creatinine. Laboratory parameters between the high- and low- flux groups were not different. PS-treated patients showed significantly (P ≤ 0.05) higher values for leucocytes, thrombocytes, ferritin, and CRP and lower values for haemoglobin, transferrin, creatinine, uric acid, creatine kinase (CK), and sodium than PMMA-treated patients. Irrespective of the membrane used, in deceased patients, the following laboratory values were higher than for patients alive: leucocytes, thrombocytes, ferritin and CRP; the following were lower: haemoglobin, iron, total protein, urea, creatinine, uric acid and CK. Conclusions. The data of 260 severely ill haemodialysis patients showed a slightly, but not significantly, reduced mortality in patients treated with PMMA membranes in comparison with PS and with high-flux membranes compared with low-flux. High- or low-flux membranes exhibited no difference in laboratory values. However, in PMMA patients, laboratory data with respect to inflammation, anaemia and nutrition were significantly improved compared with the PS group. A similarly positive laboratory pattern was seen in patients alive compared with patients deceased with both membrane types. The favourable effect of PMMA membranes may be explained by the reduced activation of catabolic components and inflammation, which, in turn, would result in an improved nutrition and better response to recombinant human erythropoietin.

Hydration status does not influence peritoneal equilibration test ultrafiltration volumes

BACKGROUND AND OBJECTIVES

The peritoneal equilibration test (PET) was developed some 25 yr ago and has been used to help prescribe peritoneal dialysis. However, PET is affected by several factors, including diabetes and inflammation. It was speculated that extracellular fluid overload would increase PET ultrafiltration volumes, and therefore the usefulness of the PET in routine clinical practice was audited.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from 211 consecutive patients attending a university teaching hospital for a standard PET who had multifrequency bioimpedance performance were analyzed to determine which factors affected net PET ultrafiltration volumes.

RESULTS

Net PET ultrafiltration volume was independent of gender, age, diabetes, residual renal function, peritoneal dialysis prescriptions (modes and dialysates), extracellular fluid volume, or C-reactive protein (CRP). There was an inverse regression with serum albumin and sodium on multiple logistical regression analysis (F = 13.4, P < 0.001 and F = 10.1, P = 0.001, respectively) and a positive regression with 24-h net peritoneal ultrafiltration volumes (F = 15.5, P < 0.001). As expected, there was a strong correlation with net sodium losses (r = 0.99, P < 0001).

CONCLUSIONS

It was found that PET test ultrafiltration volume in routine clinical practice was not affected by CRP, hyperglycemia, or extracellular fluid volume overload. Ultrafiltration volumes were increased in those patients with reduced serum sodium and albumin, most likely because of inflammation and protein malnutrition.

Inflammation and Oxidative Stress Markers by Pentoxifylline Treatment in Rats with Chronic Renal Failure and High Sodium Intake

BACKGROUND

Inflammation is a risk factor for mortality in patients with chronic renal failure (CRF). Prevention of extracellular fluid volume expansion and the use of certain drugs such as pentoxifylline (PF) may reduce inflammation and oxidative stress. The aim of this study is to analyze the effect of dietary sodium and PF treatment on the levels of inflammation and oxidative stress markers in rats with CRF.

METHODS

CRF was induced in rats by 5/6 nephrectomy. Different groups of rats with CRF received low sodium (LNa, 0.01% sodium chloride [NaCl] in the diet), normal sodium (NNa, 0.05% NaCl in the diet), or high sodium diet (HNa, as in NNa plus 0.015% NaCl in the drinking water). An additional group received HNa plus PF treatment (25 mg/kg in the drinking water) for 60 days. Circulating creatinine, tumor necrosis factor alpha (TNF-alpha), nitrites, thiols, malondialdehyde (MDA), and advanced oxidation protein products (AOPP) were measured.

RESULTS

Higher sodium intake was associated with higher serum creatinine levels (median; interquartile range), LNa, 1.255; 0.715, NNa, 1.305; 0.495, HNa, 2.015; 1.115 mg/dL (p < 0.05), TNF-alpha levels, LNa, 2.7; 23.6, NNa, 36.7; 47.7, HNa, 263.7; 126.5 pg/mL, and AOPP, LNa, 31.72; 7.55, NNa, 45.89; 9.38, HNa, 60.41; 37.42 microg/mL. MDA was not modified by sodium intake. PF treatment decreased serum TNF-alpha (151.7 pg/mL, p < 0.5) and AOPP (49.83 micromol/L, p < 0.03), and increased nitrites and thiols levels when compared with HNa rats.

CONCLUSIONS

High sodium intake increases the serum concentration of inflammation and oxidative stress markers; these changes are prevented by PF treatment.

Peritoneal Transport Status Influence on Atherosclerosis/Inflammation in CAPD Patients

OBJECTIVE

Peritoneal transport status is one of the main determinants of dialysis adequacy and dialysis-related complications in end-stage renal disease patients receiving continuous ambulatory peritoneal dialysis (CAPD). In this study we aimed to investigate the relationship between peritoneal transport characteristics and known promoters of atherosclerosis in a group of patients receiving CAPD for a minimum of 36 months.

DESIGN AND PARTICIPANTS

We performed a cross-sectional study of a cohort of 84 patients with end-stage renal disease (37 men, 47 women; age, 44.0 +/- 15.7 years; dialysis duration, 40.3 +/- 8.1 months) who were receiving CAPD for minimum 36 months. Peritoneal transport characteristics were identified after a peritoneal equilibration test (PET) determined at the third month of CAPD using Dialysate/Plasma (D/P) reference values. Patients were classified according to one of four peritoneal transport types: high (H), high-average (HA), low-average (LA), and low (L). After PET, patients were grouped as high (H/HA group, n = 51) or low (L/LA group, n = 33) transporters. The patient groups' clinical and laboratory data before dialysis and after initiation of the CAPD were collected retrospectively. The patients' follow-up data were retrieved for the diagnosis of any atherosclerosis-related event after the initiation of CAPD. The following events were collected, including myocardial infarction, having been diagnosed as having coronary artery disease by angiography or myocardium scintigraphy, cerebrovascular accident, and development of clinically evident peripheral arterial disease.

RESULTS

A comparison of follow-up data revealed that the H/HA transport characteristic was associated with lower albumin (P < .01), higher C-reactive protein (CRP) (P < .0001) levels, and higher recombinant human erythropoietin (rHuEPO) needs (P < .001) when compared with the L/LA type. During follow-up, 28 patients showed an atherosclerosis-related event. Twenty-two of these were in the H/HA group (43.1%), whereas only six were in the L/LA group (18.1%, P < .01). Reanalysis of 18 patients with atherosclerosis-related events and high CRP levels (> 10 mg/L) showed that 15 were in the H/HA and 3 were in the L/LA group. Sixty-eight percent of the H/HA patients with atherosclerosis and 50% of the L/LA patients with an atherosclerotic event also had chronic inflammation (P < .001). A Pearson correlation analysis showed that there was a positive correlation between D/P creatinine levels and 36-month mean CRP levels (r = 0.608, P < .0001), and a negative correlation between D/P creatinine levels and 36-month mean albumin levels (r = -0.299, P < .005).

CONCLUSIONS

This study shows that the high transporter peritoneal membrane characteristic is a risk factor for inflammatory state in patients with end-stage renal disease. High-transporter patients are at an increased risk of atherosclerosis when compared with their low-transporter counterparts through chronic inflammation.

Diabetic patients can do as well on peritoneal dialysis as nondiabetic patients

BACKGROUND

It is not uncommon that diabetic peritoneal dialysis (PD) patients are volume overloaded and this may have contributed to the inferior outcome of diabetic patients. In the present cohort study, we compared the difference between diabetics and nondiabetics during the first year of PD after implementing strict volume control.

METHODS

Seventeen diabetic and 40 nondiabetic incident PD patients were followed for 1 year. Fluid status was evaluated by bioimpedance analysis and blood pressure. Nutritional status was evaluated by subjective global nutritional assessment.

RESULTS

At the initiation, compared with the nondiabetics, diabetics had a significantly higher extracelluar volume, systolic blood pressure and lower serum albumin. One year later, there were no statistical differences in these parameters between the two groups. The prevalence of malnutrition decreased in all patients, although malnutrition remained slightly higher in diabetic patients.

CONCLUSIONS

Our study suggests that diabetics can do as well as nondiabetics on PD. Appropriate diabetic care, especially strict volume control, may be critical for the success of diabetic patients on PD treatment.

Association between C-reactive protein levels and N-terminal pro-B-type natriuretic peptide in pre-dialysis patients

BACKGROUND

The prevalence of inflammation is high among patients with chronic renal failure but the reason of inflammation is unclear. We test the hypothesis that inflammation in chronic renal failure could be the consequence of an increased left-ventricular wall tension related to ventricular dysfunction, hypervolemia or both.

METHODS

For assessing left-ventricular filling pressure, plasma level of N-terminal pro-B-type natriuretic peptide (N-BNP) was used, as B-type natriuretic peptide is secreted from the cardiac ventricles in response to increased wall tension. N-BNP levels and C-reactive protein (CRP) were measured on the same day in 75 pre-dialysis patients. A previous history of cardiomiopathy with systolic dysfunction was present in 27 (36%) of them.

RESULTS

The levels of N-BNP were not normally distributed (mean: 2,589 +/- 4,514 pg/ml; median: 789 pg/ml). The distribution of CRP levels was also not normal (mean: 15 +/- 27 mg/l; median: 5 mg/l). Both parameters correlated significantly (r: 0.41; p < 0.005). N-BNP was higher (p < 0.001) in patients with known ventricular dysfunction. Excluding these patients, the correlation between N-BNP and CRP was stronger (r: 0.88; p < 0.001). Univariate analysis in these patients without known cardiomyopathy showed that N-BNP levels also correlated with systolic and diastolic blood pressure (r: 0.54; p < 0.005) and inversely with creatinine clearance (r: -0.43; p < 0.01), serum albumin (r: 0.6; p < 0.001) and hemoglobin levels (r: 0.37; p < 0.05). CRP levels correlated significantly (p < 0.01) with the same parameters as N-BNP in univariate analysis. However, in multiple stepwise regression analysis in which CRP was the dependent variable, only the association with N-BNP remained significant (r: 0.87; p < 0.001).

CONCLUSIONS

Our results suggest a link between left-ventricular filling pressure and inflammation in patients with advanced renal insufficiency. The importance of strict volume control in these patients, in order to reduce left-ventricular pressure and therefore inflammation, should be considered.

Strong Association Between Volume Status and Nutritional Status in Peritoneal Dialysis Patients

BACKGROUND

Malnutrition is a strong predictor of mortality in maintenance peritoneal dialysis (PD) patients. Various factors have been identified to contribute to the development of malnutrition. The present study tried to investigate the possible role of fluid overload in the development of malnutrition.

METHODS

Twenty-eight PD patients were included in this study. Fluid status was evaluated by means of repeated bioimpedance analysis, and nutritional status was assessed by means of handgrip strength and subjective global assessment. All patients were followed up closely for 9 months. Based on changes in bioimpedance analysis data, patients were divided into group A (with continuous and steadily improved fluid status; n = 18) and group B (with consistent fluid overload; n = 10).

RESULTS

There were no differences in sex, age, and height between the 2 groups. In group A, patients' extracellular water (ECW) volume decreased significantly during follow-up, whereas intracellular water (ICW) volume increased significantly (both P < 0.001). In group B, ECW volume increased significantly, whereas ICW volume increased at an early stage and then decreased. The ratio of ECW to total-body water decreased significantly in group A, but increased significantly in group B. Along with the improvement in fluid status, nutritional status in group A also improved significantly (the prevalence of malnutrition decreased from 66.7% to 11.1%; P < 0.01). However, in group B, nutritional status deteriorated significantly (handgrip strength decreased from 238.33 +/- 88.93 to 216.1 +/- 86.19 N; P < 0.05; and the prevalence of malnutrition increased from 40% to 50%).

CONCLUSION

Our data suggest there is a strong association between fluid status and nutritional status. Improved fluid status is associated with improvement in nutritional status, whereas deterioration in fluid status is associated with the development of malnutrition.

Circulating soluble vascular cell adhesion molecule 1: Relationships with residual renal function, cardiac hypertrophy, and outcome of peritoneal dialysis patients

BACKGROUND

Vascular cell adhesion molecule 1 (VCAM-1) is involved in leukocyte-endothelial cell interaction and has a pivotal role in inflammation. Whether it contributes to excessive mortality in dialysis patients remains uncertain. In this study, we examined circulating soluble VCAM-1 (sVCAM-1) in relation to different clinical and biochemical parameters, as well as mortality and cardiovascular events, in peritoneal dialysis (PD) patients.

METHODS

Values for serum sVCAM-1, together with C-reactive protein (CRP), homocysteine, albumin, lipid profile, blood hemoglobin, and indices of dialysis adequacy, were determined at study baseline, and echocardiography was performed in 160 long-term PD patients. Patients were followed up for a mean of 35 +/- 16 (SD) months.

RESULTS

Serum sVCAM-1 levels were elevated in our continuous ambulatory PD (CAPD) patients and showed a negative correlation with residual glomerular filtration rate (GFR; P < 0.001) and low-density lipoprotein (LDL) cholesterol level (P = 0.004), but a positive correlation with left ventricular mass index (P = 0.025). Using Kaplan-Meier analysis, overall survival rates at 2 years were 96.2%, 75.2%, and 50.6% for patients in the lower, middle, and upper tertiles of sVCAM-1 levels, respectively (P < 0.0001). Fatal and nonfatal cardiovascular event-free survival rates were 58.2%, 56.9%, and 19.4% for patients in the lower, middle, and upper tertiles, respectively (P < 0.0001). Using Cox regression analysis with adjustment for confounding covariates, every 100-ng/mL increase in sVCAM-1 level was associated with 8% (95% confidence interval, 1.03 to 1.13) and 5% (95% confidence interval, 1.00 to 1.10) increases in risk for death and fatal and nonfatal cardiovascular events, respectively. Its significance for all-cause mortality remained with additional adjusting for LDL cholesterol level, but was lost when adjusting for residual GFR. Its association with cardiovascular events became insignificant when adjusting for LDL cholesterol level or residual GFR. Furthermore, patients with both sVCAM-1 and CRP levels elevated at the 50th percentile or greater were associated with the greatest death and fatal and nonfatal cardiovascular event rates compared with those with either CRP or sVCAM-1 level elevated at the 50th percentile or greater.

CONCLUSION

Circulating sVCAM-1 levels show an important link with residual renal function, LDL cholesterol level, and cardiac hypertrophy in CAPD patients. Furthermore, residual renal function, which correlates inversely with circulating sVCAM-1 level, shows an important association with all-cause mortality and cardiovascular events and displaces sVCAM-1 level from the models for all-cause mortality and future cardiovascular events in CAPD patients. Additional study is needed to explore possible mechanistic links between inflammation, soluble adhesion molecules, residual renal function, and cardiac hypertrophy in CAPD patients.

Evaluation of handgrip strength as a nutritional marker and prognostic indicator in peritoneal dialysis patients

BACKGROUND

Serum albumin has limitations as a nutritional marker in patients undergoing peritoneal dialysis (PD) in that it is affected by inflammation, systemic disease, overhydration, and urinary and dialysate protein loss. Handgrip strength is a simple, easily performed bedside test that has been shown to correlate with lean body mass in patients close to inception of dialysis.

OBJECTIVE

We evaluated the associations of handgrip strength with other clinical factors and examined its relations with mortality and cardiovascular death in PD patients.

DESIGN

We prospectively enrolled 233 chronic PD patients and assessed handgrip strength and other variables at baseline and then followed the patients for a mean (+/-SD) of 30 +/- 14 mo.

RESULTS

Baseline handgrip strength was significantly associated with age, sex, height, diabetes, residual glomerular filtration rate (GFR), and hemoglobin but not with C-reactive protein (CRP). After adjustment for age, sex, and height, handgrip strength was most strongly correlated with lean body mass on the basis of creatinine kinetics (r = 0.334, P < 0.001), followed by serum albumin and subjective global assessment. Both men and women who died had lower handgrip strengths than did those who remained alive (P < 0.001). After control for age, sex, diabetes, atherosclerotic vascular disease, GFR, hemoglobin, CRP, and serum albumin, greater handgrip strength was predictive of lower all-cause [hazards ratio (HR): 0.95 (95% CI: 0.92, 0.99); P = 0.005] and cardiovascular [HR: 0.94 (0.90, 0.98); P = 0.004] mortality.

CONCLUSIONS

Handgrip strength not only is a marker of body lean muscle mass but also provides important prognostic information independent of other covariates, including CRP and serum albumin. Our data suggest that handgrip strength may be used in conjunction with serum albumin as a nutrition-monitoring tool in patients undergoing PD.

Measuring nutritional status in children with chronic kidney disease

Children with chronic kidney disease (CKD) are at risk of protein-energy malnutrition. Existing clinical practice guidelines recognize this and recommend specific methods to assess nutritional status in patients with CKD. This review summarizes the methods for nutritional assessment currently recommended in the United States for children with CKD and details the strengths and limitations of these techniques in the clinical setting. Dietary assessment, serum albumin, height, estimated dry weight, weight/height index, upper arm anthropometry, head circumference, and the protein equivalent of nitrogen appearance are reviewed. We also describe methods for body-composition assessment, such as dual-energy X-ray absorptiometry, bioelectrical impedance analysis (BIA), total body potassium, densitometry, and in vivo neutron activation analysis, pointing out some advantages and disadvantages of each. In CKD, fluid overload is the most important factor leading to misinterpretation of nutritional assessment measures. Abnormalities in the distribution of fat and lean tissue may also compromise the interpretation of some anthropometric measures. In addition, metabolic abnormalities may influence the results obtained by some techniques. Issues specific to evaluating nutritional status in the pediatric population are also discussed, including normalization of nutritional measures to body size and sexual maturity. We stress the importance of expressing body-composition measures relative to height in a population in whom short stature is highly prevalent.