Ultrafiltration and dry weight-what are the cardiovascular effects?

The Association between Echocardiographic Parameters of Heart Failure with Preserved Ejection Fraction and Fluid Status Biomarkers in Hemodialysis Patients

Overhydration and cardiac function abnormalities are common in hemodialysis patients. The association of N-terminal prohormone for brain natriuretic peptide (NT-proBNP) and other fluid status biomarkers with echocardiographic parameters of heart failure with preserved ejection fraction (HFpEF) is scarcely investigated in this population. A total of 100 separate measurements performed in 50 dialysis patients (29 male, aged 60 ± 17 years) in NYHA class II/II and preserved left ventricle ejection fraction were analyzed. Plasma levels of NT-proBNP, mid-regional prohormone for atrial natriuretic peptide (MR-proANP) and copeptin (CPP) were measured. The E/e' ratio as an index of HFpEF and other echocardiographic parameters were calculated. An E/e' ratio >9 was associated with higher median right ventricular systolic pressure (RVSP) and LVMI values. Left atrium volume index (LAVI) as well as NT-proBNP and MR-proANP, but not CPP levels were significantly higher in this group. In a stepwise multivariate analysis, only CPP and IL-6 levels were found to be independently associated with the E/e' ratio in the study group, whereas NT-proBNP and MR-proANP were associated only with left heart structure parameters and LVEF. Of the analyzed biomarkers, only the CPP level was found to be independently associated with the E/e' ratio in maintenance hemodialysis patients.

High sodium intake and fluid overhydration predict cardiac structural and functional impairments in chronic kidney disease

Background

High sodium intake and fluid overhydration are common factors of and strongly associated with adverse outcomes in chronic kidney disease (CKD) patients. Yet, their effects on cardiac dysfunction remain unclear.

Aims

The study aimed to explore the impact of salt and volume overload on cardiac alterations in non-dialysis CKD.

Methods

In all, 409 patients with CKD stages 1-4 (G1-G4) were enrolled. Daily salt intake (DSI) was estimated by 24-h urinary sodium excretion. Volume status was evaluated by the ratio of extracellular water (ECW) to total body water (TBW) measured by body composition monitor. Recruited patients were categorized into four groups according to DSI (6 g/day) and median ECW/TBW (0.439). Echocardiographic and body composition parameters and clinical indicators were compared. Associations between echocardiographic findings and basic characteristics were performed by Spearman's correlations. Univariate and multivariate binary logistic regression analysis were used to determine the associations between DSI and ECW/TBW in the study groups and the incidence of left ventricular hypertrophy (LVH) and elevated left ventricular filling pressure (ELVFP). In addition, the subgroup effects of DSI and ECW/TBW on cardiac abnormalities were estimated using Cox regression.

Results

Of the enrolled patients with CKD, the median urinary protein was 0.94 (0.28-3.14) g/d and estimated glomerular filtration rate (eGFR) was 92.05 (IQR: 64.52-110.99) mL/min/1.73 m2. The distributions of CKD stages G1-G4 in the four groups was significantly different (p = 0.020). Furthermore, compared to group 1 (low DSI and low ECW/TBW), group 4 (high DSI and high ECW/TBW) showed a 2.396-fold (95%CI: 1.171-4.902; p = 0.017) excess risk of LVH and/or ELVFP incidence after adjusting for important CKD and cardiovascular disease risk factors. Moreover, combined with eGFR, DSI and ECW/TBW could identify patients with higher cardiac dysfunction risk estimates with an AUC of 0.704 (sensitivity: 75.2%, specificity: 61.0%). The specificity increased to 85.7% in those with nephrotic proteinuria (AUC = 0.713). The magnitude of these associations was consistent across subgroups analyses.

Conclusion

The combination of high DSI (>6 g/d) and high ECW/TBW (>0.439) independently predicted a greater risk of LVH or ELVFP incidence in non-dialysis CKD patients. Moreover, the inclusion of eGFR and proteinuria improved the risk stratification ability of DSI and ECW/TBW in cardiac impairments in CKD.

Higher extracellular water to total body water ratio was associated with chronic kidney disease progression in type 2 diabetes

AIM

We studied the association between extracellular volume status and chronic kidney disease (CKD) progression; and the role of extracellular volume excess as a potential mediator in the relationship between matrix metalloproteinases (MMP)-2 and CKD progression in Type 2 diabetes mellitus (T2DM).

METHODS

We conducted a prospective cohort study of 1079 T2DM patients. Bioelectrical impedance analysis (BIA) was performed to assess body fluid status.

RESULTS

After up to 8.6 years of follow-up, 471 (43.7%) patients experienced CKD progression. In the fully adjusted model, extracellular water (ECW)/ total body water (TBW)ratios 0.39-0.40 and > 0.40 were associated with 45% and 78% higher risk of CKD progression respectively. Patients with an increase in ECW/TBW ratio had 40% higher risk of CKD progression compared to those with no change or reduction of ECW/TBW ratio. Higher ECW/TBW ratio accounted for 17.4% of the relationship between MMP-2 and CKD progression in T2DM (p = 0.026).

CONCLUSIONS

Extracellular volume excess was independently associated with CKD progression in T2DM. Higher ECW/TBW ratio mediated the positive association between MMP-2 and CKD progression. Further studies are needed to elucidate the role of extracellular volume excess in deterioration of renal function.

Clinical characteristics of hyponatremia in patients receiving nutrition support : A cross-sectional study evaluated by bioelectrical impedance analysis

Background & aims : We investigated the contributing factors of hyponatremia in patients on nutrition support using bioelectrical impedance analysis (BIA). Methods : Thirty patients administered enteral or parenteral nutrition support for at least 72 hours were studied. We collected nutritional and electrolyte intake, serum biochemical parameters, and body composition measured by BIA. Patients were classified into two groups according to their serum sodium levels : (1) Normanatremia group, 135-145 mEq / L (n = 18) and (2) Hyponatremia group, less than 135 mEq / L (n = 12), and their characteristics were analyzed. Results : There were no significant differences between the Normonatremia and Hyponatremia groups in terms of energy, protein, and sodium intake. Serum biochemical parameters other than serum sodium and chloride levels were comparable between the two groups. On the other hand, the ratio of extracellular water to total body water (ECW / TBW) obtained by BIA was significantly higher in the Hyponatremia group than in the Normonatremia group. Further, an elevated ECW / TBW significantly and negatively correlated with serum albumin level. Conclusions : Regardless of sodium intake, higher ECW / TBW was associated with hyponatremia in patients on nutrition support. ECW / TBW may be an important clinical parameter relevant to the nutritional care of hyponatremia. J. Med. Invest. 68 : 112-118, February, 2021.

Non-invasive venous waveform analysis (NIVA) for volume assessment in patients undergoing hemodialysis: an observational study

BACKGROUND

Accurate assessment of volume status to direct dialysis remains a clinical challenge. Despite current attempts at volume-directed dialysis, inadequate dialysis and intradialytic hypotension (IDH) are common occurrences. Peripheral venous waveform analysis has recently been developed as a method to accurately determine intravascular volume status through algorithmic quantification of changes in the waveform that occur at different volume states. A noninvasive method to capture peripheral venous signals is described (Non-Invasive Venous waveform Analysis, NIVA). The objective of this proof-of-concept study was to characterize changes in NIVA signal with dialysis. We hypothesized that there would be a change in signal after dialysis and that the rate of intradialytic change in signal would be predictive of IDH.

METHODS

Fifty subjects undergoing inpatient hemodialysis were enrolled. A 10-mm piezoelectric sensor was secured to the middle volar aspect of the wrist on the extremity opposite to the access site. Signals were obtained fifteen minutes before, throughout, and up to fifteen minutes after hemodialysis. Waveforms were analyzed after a fast Fourier transformation and identification of the frequencies corresponding to the cardiac rate, with a NIVA value generated based on the weighted powers of these frequencies.

RESULTS

Adequate quality (signal to noise ratio > 20) signals pre- and post- dialysis were obtained in 38 patients (76%). NIVA values were significantly lower at the end of dialysis compared to pre-dialysis levels (1.203 vs 0.868, p < 0.05, n = 38). Only 16 patients had adequate signals for analysis throughout dialysis, but in this small cohort the rate of change in NIVA value was predictive of IDH with a sensitivity of 80% and specificity of 100%.

CONCLUSIONS

This observational, proof-of-concept study using a NIVA prototype device suggests that NIVA represents a novel and non-invasive technique that with further development and improvements in signal quality may provide static and continuous measures of volume status to assist with volume directed dialysis and prevent intradialytic hypotension.

Transfusion Use and Hemoglobin Levels by Blood Conservation Method After Cardiopulmonary Bypass

BACKGROUND

Guidelines recommend modified ultrafiltration (MUF) and cell washing for blood conservation after cardiopulmonary bypass (CPB), although information on outcomes is lacking. This research compared online MUF (ultrafiltration of the patient's entire circulating volume) with off-line MUF (ultrafiltration of the residual CPB volume) and centrifugation (cell washing of the residual CPB volume).

METHODS

This prospective cohort study enrolled 99 consecutive patients, grouped by method (group I, online MUF, n = 35; group II, off-line MUF, n = 30; group III, centrifugation, n = 34). Primary outcome was transfusion by 18 hours. Secondary outcomes were 18-hour hemoglobin levels, fluid balance (weight change), and biomarker levels indicating coagulation and organ function.

RESULTS

By 18 hours, 22.9%, 6.7%, and 14.7% of group I, II, and III patients, respectively, had undergone transfusion (P = .19). Percentage weight gain differed by group (group I, 5.7%; group II, 1.3%; group III, 4.5%; P < .0001). Baseline to 18-hour hemoglobin change also differed by group, with the group I increase significantly exceeding that of group II (P = .002) but not differing from group III (P = .36). After adjustment for European System for Cardiac Operative Risk Evaluation II (EuroSCORE), weight gain, and transfusion, only the group II to III difference remained significant (P = .002).

CONCLUSIONS

Online MUF does not appear to offer a reduction in blood transfusion over other methods. Although patients undergoing online MUF had greater improvement in baseline to 18-hour hemoglobin compared with patients undergoing off-line MUF, this benefit appeared attributable to fluid shifting. Off-line MUF was associated with the least frequent transfusions. Although online MUF does not appear to reduce blood transfusion, larger prospective randomized controlled studies are required for confirmation.

Hypervolemia-Induced Immune Disturbances Do Not Involve IL-1ß but IL-6 and IL-10 Activation in Haemodialysis Patients

Dysregulated fluid homeostasis is frequent in haemodialysis (HD) patients and is linked to inflammation which may be elicited by endotoxemia. The impact of hypervolemia on immune cells has not been studied in detail. Therefore, we analysed the hypervolemic activation of peripheral blood mononuclear cells (PBMCs) in HD with special focus on the NLRP3 inflammasome response. First, 45 HD were included in the observational study. Immune parameters including cell counts, caspase-1, oxidative stress, cytokine gene expression and serum analysis (IL-1ß, IL-6, IL-10) were all measured at two time points. Fluid status was evaluated by electrical bioimpedance vector analysis, defining hypervolemia (H) as >75 vector percentile. Then, 17 patients were classified as hypervolemic (H-HD), 19 as normovolemic (N-HD) and 9 failed to meet the inclusion criteria. Monocytes were elevated and lymphocytes were decreased by hypervolemia. NLRP3 inflammasome components, caspase-1 and IL-1ß expression were not statistically different between the two groups. Serum IL-6 levels were significantly elevated in H-HD. IL-10 mRNA transcripts were elevated by 2-fold in H-HD but were not efficiently translated. We conclude that the NLRP3 inflammasome is not activated by hypervolemia thus refuting the thesis that endotoxemia may be a main driver for inflammation in H-HD. Nevertheless, inflammation is generally higher in H-HD compared to N-HD patients and is not sufficiently balanced by anti-inflammatory mechanisms.

Evaluation of one year of frequent dialysis on fluid load and body composition using calf bioimpedance technique

OBJECTIVE

The primary aim of this study was to evaluate the effect of increased frequency of dialysis (FHD) on change in fluid status and body composition using segmental bioimpedance.

APPROACH

Twelve stable HD patients were switched from 3 times/week to 6 times/week HD (FHD). Systolic blood pressure (SBP), body mass and body mass index (BMI) were measured pre- and post-HD. Calf resistance (R ₅) at 5 kHz was measured using a multifrequency bioimpedance device (Hydra 4200). Calf resistivity (ρ  =  R ₅ * area/length), normalized resistivity (CNR  =  ρ/BMI) and calf extracellular volume (cECV) were calculated. Fat mass was measured by Futrex body composition analyzers (Futrex 6100, Futrex Tech, Inc.). All measurements were performed at baseline (BL) and monthly for up to one year.

MAIN RESULTS

Nine patients completed one year of FHD. Compared to BL, body weight and cECV decreased, and CNR increased significantly by the first month but did not change thereafter. SBP pre-HD decreased significantly by the end of the first month with further reduction until month 12. Additionally, antihypertensive medication decreased significantly from baseline by month 4 and remained stable from month 6 throughout the rest of the study. The post-HD CNR in five of nine patients reached the range of normal (>18.5 10^-2 * Ohm * m³ kg^-1 for males and  >19.1 10^-2 * Ohm * m³ kg^-1 for females) after 1 year FHD. In patients who returned to 3 times/week dialysis, CNR decreased significantly in the first week, and this was associated with increases in body weight and SBP.

SIGNIFICANCE

Reduction of fluid overload with no alteration of body composition was observed in this study. Accordingly, improving fluid status was confirmed by reducing BP and use of antihypertensive drugs together with increase in CNR. Measurement of fluid status by CNR in hemodialysis patients is a new method to quantitatively assess hydration potentially creating a target for volume of fluid removal.

Lung Ultrasound B-lines Occurrence in Relation to Left Ventricular Function and Hydration Status in Hemodialysis Patients

Background and objective: Reliable assessment of the fluid status in hemodialysis (HD) patients is often difficult. A lung ultrasound with an assessment of the B-lines (“lung comets” (LCs)) number is a novel hydration status measure. However, the occurrence of left ventricular dysfunction may have a significant effect on pulmonary congestion and further modulate the LC number. The aim of this study was to analyze to what extent left ventricular dysfunction, pulmonary hypertension, and hypervolemia affect the occurrence of LC in a cohort of prevalent HD patients. Material and methods: This cross-sectional study included 108 assessments performed in 54 patients who attended thrice weekly outpatient HD. Each patient’s fluid status was evaluated twice, prior to HD sessions, using echocardiography, LC number assessment, measurement of inferior vena cava (IVC) diameters, and bioelectric impedance analysis (BIA). Patients were stratified into three subgroups according to their LC number. Results: There were 76 separate assessments with mild (<14), 16 with moderate (14–30), and 16 with severe (>30) LC occurrence. There was a negative correlation between the LC number and left ventricular ejection fraction (LVEF), and positive correlations between the LC number and mitral gradient, and the left and right atrium area and volume, but not with the BIA-derived relative fluid overload. Multivariate linear regression analysis revealed that the LC number was proportionally related to the mitral gradient (β = 0.407 (0.247–0.567), p < 0.001) and IVC max diameter (β = 0.219 (0.060–0.378), p < 0.01), and was inversely related to LVEF (β = −0.431 (−0.580 to −0.282), p < 0.001). Conclusions: The number of LCs appears to reflect both overhydration and left ventricular dysfunction in our HD patients cohort. Therefore, heart failure must be considered as an important factor limiting the usefulness of LCs number assessment in this population.

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

BACKGROUND

Cognitive deficit is a common problem in end-stage renal disease (ESRD) patients. Ultrafiltration and hemodialysis lead to profound hemodynamic changes. The aim of this pilot study was to describe brain and hand oxygenation values in ESRD patients and their changes during hemodialysis.

METHODS

Twenty-seven patients treated by chronic hemodialysis and 17 controls patients of the same age were included in the study. Regional saturation of oxygen (SrO2) was measured at the brain frontal lobe and at the hand with dialysis access using the INVOS 5100C. In 17 of ESRD patients, SrO2 was also monitored throughout hemodialysis. Finger systolic blood pressure and basic hemodialysis and laboratory data were collected.

RESULTS

Dialysis patients had lower brain and also hand SrO2 values at rest (51.5 ± 10.9 vs. 68 ± 7%, p&lt;0.0001 and 55 ± 16 vs. 66 ± 8%, p = 0.03, respectively). Both values further decreased during the first 35 minutes of hemodialysis (brain SrO2 to 47 ± 8%, p&lt;0.0001 and hand to 45 ± 14%, p&lt;0.0001, respectively). The brain SrO2 decrease was related to the ultrafiltration rate, the hand SrO2 decrease to the finger pressure and to blood hemoglobin.

CONCLUSIONS

Chronic dialysis patients suffer from tissue ischemia and that even worsens after the beginning of hemodialysis. This observation may contribute to the understanding of cognitive deficit etiology.

Tributyltin chloride induces renal dysfunction by inflammation and oxidative stress in female rats

Tributyltin chloride (TBT) is an organometallic pollutant that is used as a biocide in antifouling paints. TBT induces several toxic and endocrine-disrupting effects. However, studies evaluating the effects of TBT on renal function are rare. This study demonstrates that TBT exposure is responsible for improper renal function as well as the development of abnormal morphophysiology in mammalian kidneys. Female rats were treated with TBT, and their renal morphophysiology was assessed. Morphophysiological abnormalities such as decreased glomerular filtration rate and increased proteinuria levels were observed in TBT rats. In addition, increases in inflammation, collagen deposition and α-smooth muscle actin (α-SMA) protein expression were observed in TBT kidneys. A disrupted cellular redox balance and apoptosis in kidney tissue were also observed in TBT rats. TBT rats demonstrated reduced serum estrogen levels and estrogen receptor-α (ERα) protein expression in renal cortex. Together, these data provide in vivo evidence that TBT is toxic to normal renal function and that these effects may be associated with renal histopathology complications, such as inflammation and fibrosis.

Association between ratio of measured extracellular volume to expected body fluid volume and renal outcomes in patients with chronic kidney disease: a retrospective single-center cohort study

Background

Excess extracellular volume is a major clinical problem in patients with chronic kidney disease (CKD). However, whether the extracellular volume status is associated with disease progression is unclear. We investigated the association between the extracellular volume status and renal outcomes.

Methods

We performed a retrospective cohort study of 149 patients with CKD who underwent bioelectrical impedance analysis (BIA) from 2005 to 2009. Patients were categorized according to tertiles of extracellular volume status. The extracellular volume status was assessed by examining the ratio of extracellular water measured by BIA (ECW_BIA) to the total body water calculated using the Watson formula (TBW_Watson). The main outcomes were adverse renal outcomes as defined by a decline of ≥50% from the baseline glomerular filtration rate or initiation of renal replacement therapy.

Results

A higher %ECW_BIA/TBW_Watson ratio tended to be associated with older age, male sex, diabetes mellitus, resistant hypertension, lower renal function, lower serum albumin levels, higher proteinuria levels, and a higher frequency of furosemide use. In the multivariate analysis, proteinuria remained independently associated with the %ECW_BIA/TBW_Watson ratio. Both the intracellular and extracellular water volumes decreased with age (correlation between ICW and age, r = -0.30, P < 0.001; correlation between ECW and age, r = -0.17, P = 0.03). Consequently, the %ECW_BIA in the body fluid composition increased with age. During a median follow-up of 4.9 years, patients in the highest tertile of the %ECW_BIA/TBW_Watson ratio were at greater risk of adverse renal outcomes (16.6 per 100.0 patient years) than were those in the lowest tertile (8.1 per 100.0 patient years) or second tertile (5.6 per 100.0 patient years) (log-rank P = 0.005). After adjustment for covariates, the %ECW_BIA/TBW_Watson ratio was significantly associated with adverse renal outcomes (hazard ratio, 1.21; 95 % confidence interval, 1.10–1.34; P < 0.001).

Conclusions

The ECW_BIA/TBW_Watson ratio was independently associated with adverse renal outcomes. Proteinuria was independently associated with the extracellular volume status. The balance between ICW and ECW changes with age in that the percentage of ECW content in the body fluid composition increases. Elderly patients with CKD may thus be susceptible to volume overload.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2369-15-189) contains supplementary material, which is available to authorized users.

Cardiorenal syndrome type 4: a review

There is a bidirectional and complex relationship between the heart and kidneys. This interaction is physical, chemical as well as biological and is also reflected in a strong connection between renal and cardiovascular diseases. Cardiorenal syndrome type 4 (CRS type 4) is characterized by primary chronic kidney disease (CKD) leading to an impairment of cardiac function, with ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. The incidence of CKD is increasing, and CRS type 4 is becoming a major public health problem associated with a high morbidity and mortality. In this study, we briefly review the epidemiology and pathophysiology of CRS type 4, the role of biomarkers in its early identification, and its management.

Identification of impeding factors for dry weight achievement in end-stage renal disease after appropriate kidney graft function

The aim of this study was to evaluate the factors that prevent dry weight achievement in patients with end-stage renal disease (ESRD) in renal replacement therapy through the change in their body weight after kidney transplant (KT) compared with 1 week before KT. The study included 188 ESRD patients of diverse etiology who received living kidney transplantation with normal immediate graft function, 62.2% were male, age 29 ± 11 years old. All patients were on renal replacement therapy for at least 1 month before KT with either hemodiafiltration (N = 106), hemodialysis (N = 25), or peritoneal dialysis (N = 57). Based on body weight difference (after transplant-before transplant), patients with body weight difference ≤2 kg were considered as being close to their dry weight (Group 1, N = 112), whereas patients with body weight difference >2 kg were considered as being overhydrated (Group 2, N = 76). Clinical and biochemical characteristics were obtained from the medical records at three periods of time: time of ESRD initiation (baseline), 1 week before undergoing KT, and 1 week after KT. The mean time (± standard deviation) from renal replacement therapy initiation to the week before KT was 9.2 ± 5 months. Group 2 had a higher proportion of men, antihypertensive use, peritoneal dialysis, and higher urine output during all periods. Before KT, Group 2 had higher systolic and diastolic blood pressures than Group 1. After KT, both systolic and diastolic blood pressures decreased in Group 2, whereas no change occurred in Group 1. Before KT, Group 2 had higher levels of blood urea nitrogen, creatinine, uric acid, and phosphorous compared with Group 1. Compared with baseline, Group 1 had more optimal blood urea nitrogen, creatinine, and uric acid parameters before KT than Group 2. After KT, all parameters improved with respect to baseline in both groups. Hemoglobin, albumin, and sodium were similar between groups, except for higher hemoglobin in Group 2 than Group 1 after KT. Multivariate regression analysis showed that male sex, peritoneal dialysis, and systolic blood pressure before KT were independent risk factors for overhydration. In conclusion, high systolic blood pressure and peritoneal dialysis were two independent modifiable variables associated with overhydration before KT. Assessment of the body weight change after KT is a useful tool to evaluate dry weight, in addition to identifying variables associated with poor volume control. This could allow adjustment of clinical and dialysis parameters in future patients.

Long-term efficacy of intermittent peritoneal dialysis using various doses

The objective of the present study was to investigate the long-term clinical efficacy of intermittent peritoneal dialysis (IPD) using various doses and to explore the most suitable dialysis dose and practice pattern for patients. A total of 52 inpatients/outpatients who had undergone IPD for more than 5 years were recruited and divided into three groups according to the dialysis dose: 4 liters in Group A, 6 liters in Group B and 8 liters in Group C. The dwell time was 4 h. All patients were fasted overnight. The dialysis adequacy, nutritional status, complication control, blood pressure and intra-abdominal infection were determined and observed among these patients. Barthel index (BI) and Hamilton Depression Scale (HAMD) were employed to measure the activities of daily living (ADL) and degree of depression, respectively. The dialysis adequacy and ultrafiltration volume in Group A were lower than those in Groups B and C, but the residual urine volume was larger than that in the latter two groups. In addition, there was a marked difference in the control of complications between Group A and Groups B and C. When compared to Groups A and B, the nutritional status in Group C was significantly decreased, the mean arterial pressure and intra-abdominal infection rates were dramatically increased, and the HAMD scores were also higher (P<0.05). No significant difference was noted in the BI. For patients undergoing long-term IPD, individualized dialysis dose may benefit the dialysis adequacy, nutritional status, control of complications, blood pressure, rate of intra-abdominal infection, ADL and depression.

Time-dependent associations between total sodium removal and mortality in patients on peritoneal dialysis

PURPOSE

To determine if the time-dependent association between total sodium removal and mortality in patients on continuous ambulatory peritoneal dialysis (CAPD) is confounded by markers of diet and nutrition.

METHODS

The study enrolled 305 incident patients who started CAPD between July 2002 and February 2007. All patients were followed until death or censoring in February 2008. Demographics, blood pressure, and markers of volume and inflammation were collected at baseline. Biochemistry, fluid and solute removal, and diet and nutrition parameters were collected quarterly and thus calculated as time-averaged values.

RESULTS

Mean age of the study patients was 59.4 years, 42.3% were men, and 40.3% had diabetes. During the 31.4-month follow-up, 74 patients died. The time-averaged daily total sodium removal (TSR) in the overall cohort was 2.67 g (range: 2.02 g-3.47 g). Participants with a high time-averaged TSR tended to experience higher fluid, sodium, urea, and creatinine removal, mainly as a result of better residual renal function (RRF). They also had a higher nutrient intake and a higher lean body mass. Time-dependent TSR was an independent predictor of death, including when adjusted for age, Charlson index, time-dependent hemoglobin, RRF, and peritoneal transport rate (hazard ratio: 0.84; 95% confidence interval: 0.70 to 1.00; p=0.05), but the predictive effect disappeared in multivariate models after further individual adjustment for time-dependent total energy intake, total protein intake, serum albumin, and lean body mass. By contrast, the predictive effect did not disappear if the only adjustment was for time-dependent RRF.

CONCLUSIONS

The time-dependent association between TSR and mortality in patients on peritoneal dialysis can be largely explained by diet and nutrition parameters.

Relationship of increased circulating adrenomedullin with cardiac dysfunction, inflammation, oxidative stress and volume overload in hemodialysis patients

Adrenomedullin (AM) is a peptide involved in cardiovascular homeostasis. The aim of our study was to investigate whether circulating AM might be related to cardiac function, volume overload, oxidative stress and inflammation in hemodialysis patients. Plasma adrenomedullin, C-reactive protein (CRP), oxidized LDL (ox-LDL), lipoprotein (a), systolic and diastolic cardiac functions were assessed before hemodialysis in 80 patients as well as in 40 healthy control subjects. Plasma adrenomedullin levels were significantly higher in the hemodialysis group compared to the control group. Plasma adrenomedullin levels were negatively correlated with systolic and diastolic blood pressure, S/D ratio, deceleration time, left ventricular ejection fraction, ox-LDL and lipoprotein (a). However, it was positively correlated with CRP, delta body weight, mitral E/A wave, and inferior vena cava diameter. Higher plasma adrenomedullin levels may provide a possible index of cardiac dysfunction, systemic inflammation, and volume overload conditions in haemodialysis patients with concomitant cardiovascular disease. In addition, the negative correlation between ox-LDL, lipoprotein (a) and adrenomedullin may suggest that endogenous AM is an important protective factor in anti-atherosclerosis and might be useful as a new target for prevention and therapy for the disease.

Lipoprotein lipase disturbances induced by uremia and hemodialysis

Factors such as malnutrition, physical inactivity, uremic toxins, and inflammation are known to influence the activity of lipoprotein lipase (LPL), an important enzyme in metabolism of blood lipids. In patients with chronic kidney disease these factors are common and may result in a decreased LPL activity. This is particularly so in patients on hemodialysis. Further, during each dialysis treatment, the use of heparin (or low molecular weight heparin) induces a release of LPL from its normal binding sites at the plasma membrane of endothelial cells. This results in an increased degradation of the enzyme and a relative lack of LPL activity for up to 10 hours from the start of the dialysis. Thus, the use of conventional anticoagulation for hemodialysis, in addition to the consequences of the uremic state, may cause a severe functional deficiency of LPL. This in turn may have deleterious effects on energy metabolism and may contribute to the increased risk for cardiovascular disease in this vulnerable group of patients.

The value of sequential dialysis, mannitol and midodrine in managing children prone to dialysis failure

The uremic state impairs compensatory responses to ultrafiltration (UF). Intradialytic symptoms and hypotension can result and lead to premature discontinuation of treatment and sub-optimal dialysis. We report the benefits of mannitol, sequential dialysis and midodrine in reducing dialysis failures in those children prone to intradialytic hypotension. Prophylactic mannitol halved the odds of intradialytic symptoms and hypotension and increased UF volumes. Sequential dialysis halved the odds of symptoms but hypotension persisted. In one patient with refractory hypotension, only intradialytic midodrine consistently maintained acceptable intradialytic blood pressures, reduced intradialytic symptoms and increased the UF potential.

Evaluating methods for improving ultrafiltration in pediatric hemodialysis

Adequate ultrafiltration (UF) is necessary for good health, but it can be hindered by the development of intradialytic symptoms and hypotension. To determine whether sodium ramping, UF profiles and mannitol could improve UF in children, we instituted a standardized prescription for chronic hemodialysis in our unit. We prospectively analyzed 506 treatments from ten patients. Ultrafiltration volumes up to 9.7% of dry weight were obtained with an overall mean of 5.4%. Mannitol reduced the risk of intradialytic symptoms by 64% (p < 0.05) with a mean UF volume of 6.2%. Step sodium ramping from 148-138 mmol/l reduced the odds of intradialytic symptoms (p = 0.1) and hypotension (p < 0.05) with no difference in the mean UF compared with linear profiles. All UF profiles were associated with an increased risk of intradialytic symptoms, but the effect was only statistically significant with profile 2 (stepwise UF reduction). Overall intradialytic morbidity occurred in 10% of the treatments. Notwithstanding the study limitations, UF volumes higher than traditional recommendations of 5% of the dry weight were achieved with the use of mannitol and 148-138 mmol/l sodium ramping. Despite this, the desired dry weight was not achieved in 66% of our treatments. No clear benefit was seen with UF profiles.

Minimized weight gain between hemodialysis contributes to a reduced risk of death

The risk of death is higher in dialysis patients compared to age matched healthy subjects, the main reason being cardiovascular. This prospective study investigated if the extent of ultrafiltration was of importance for the outcome.

MATERIAL AND METHODS

88 hemodialysis patients were included and followed prospectively. The outcome was registered in regard to death, acute myocardial infarction or coronary vascular intervention. The extent of ultrafiltration needed at dialysis was calculated as a mean during the observation period as were other variables. The mean extent of ultrafiltration was compared for patients who had survived without end-points (group 1, n=53) versus those who reached any end-point during the period (group 2, n=35).

RESULTS

In total, 40% of the patients reached end-point during the observation period. There was no difference at baseline between the groups in regard to age, prevalence of diabetes mellitus or history of previous cardiovascular disease, KT/V, residual renal function ultrafiltration need, C-reactive protein, s-albumin, cholesterol, LDL-cholesterol, HDL-cholesterol, appetite or wellbeing, while triglyceride was lower in group 2 (p=0.035). The observation period for group 1 was at a mean 24.7 months (SD13.1) and for those in group 2 at a mean 13.8 (+/-11.7 months, p<0.001). Patients representing group 1 at 24 and 30 months had less need of ultrafiltration than those in group 2. Thus, the need of ultrafiltration was about 27% lower at 24 months (for 29 persons in group 1: 3.63+/-1.93 weight% versus 4.97+/-1.70 weight% for 9 patients from group 2, p=0.046) and 46% at 30 months (for 18 from group 1: 3.48+/-1.95 versus 6.45+/-1.55 for 3 from group 2, p=0.030). C-reactive protein did not differ significantly between the groups during the period.

CONCLUSION

After a prolonged period of 24 months the extent of ultrafiltration need seems to be important for the outcome of the patients. Thereby those with higher need of ultrafiltration had worse prognosis. It seems important to motivate patients to reduce the extent of fluid intake between dialysis to prolong survival.

Residual renal function and dialysis modality: Is it really beneficial to preserve residual renal function in dialysis patients? (Review Article)

Residual renal function (RRF) contributes to the achievement of treatment adequacy in stage 5 chronic kidney disease (CKD-5) patients. It may facilitate patients' acceptance of renal replacement therapy (RRT) in allowing reduction of treatment time duration and minimising dietary and fluid restriction. It has been confirmed to improve dialysis patient outcomes. Attempts to preserve RRF in incident Stage 5 chronic kidney disease patients are still subject to intense controversies in the nephrology community. The aim of this review is to analyse the role of renal replacement modalities in the maintenance of RRF in dialysis patients. Under the scope of this manuscript, four questions are explored: Is the preservation of residual renal function an objective for dialysis adequacy? Does dialysis modality affect the decline of RRF? What are the factors implicated by this loss of RRF? At what expense can the maintenance of RRF be achieved in dialysis patients? Preservation of RRF is undoubtedly an interesting means to enhance the efficacy of renal replacement therapy and reduce dietary fluid restriction but it should not be considered as a goal of dialysis adequacy in dialysis patients. Further, preservation of RRF must be considered as a permanent trade-off between patient comfort and chronic fluid volume overload.

Extravascular lung water index: A new method to determine dry weight in chronic hemodialysis patients

To assess the dry weight of chronic hemodialysis (HD) patients, the extravascular lung water index (ELWI) as a volume parameter was investigated to identify fluid overload. Forty-two patients (30 males, 12 females) with a mean age of 55.7+/-13.0 years who were clinically not overhydrated were connected to the PiCCO system before starting HD treatment. We determined ELWI (normal range 3-7 mL/kg) and the following parameters: global end-diastolic volume index (GEDI, normal range 680-800 mL/m(2)) and intrathoracic blood volume index (ITBI, normal range 850-1000 mL/m(2)) before and after HD to assess the volume status. Brain natriuretic peptide (BNP), aldosterone, and renin as vasoactive hormones were measured at the beginning and at the end of HD treatment as well. In 28 of the 42 patients (67%), elevated values of ELWI were found, indicating interstitial volume overload. There were significant correlations between ELWI and cardiac function index (p=0.003; Pearson's coefficient -0.451), global ejection fraction (p=0.012; Pearson's coefficient -0.389), ITBI (p=0.004; Pearson's coefficient 0.437), and GEDI (p=0.004; Pearson's coefficient 0.437). No significant relations among ELWI and mean arterial pressure (MAP), BNP, aldosterone, and renin were found. In conclusion, the use of ELWI is safe in chronic HD patients and identifies fluid-overloaded patients, who show no obvious signs of hypervolemia. The determination of ELWI is an excellent method to quantify the exact volume in chronic HD patients.

Adrenomedullin reflects cardiac dysfunction, excessive blood volume, and inflammation in hemodialysis patients

BACKGROUND

Plasma adrenomedullin (AM) reflects cardiac dysfunction and predicts survival after myocardial infarction. The present study was designed to investigate whether the mature AM (mAM) reflects status of cardiac function, systemic blood volume, or inflammation in hemodialysis patients with cardiovascular disease, and whether mortality and additional cardiovascular morbidity can be predicted by mAM.

METHODS

Plasma levels of mAM, atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), norepinephrine (NE), and C-reactive protein (CRP) before hemodialysis were measured in 67 chronic hemodialysis patients with cardiovascular disease, along with 2-dimensional and Doppler echocardiographic variables.

RESULTS

By univariate regression analysis, mAM correlated negatively with pulmonary venous flow velocity ratio and left ventricular (LV) ejection fraction and positively with LV inflow velocity ratio, LV end-diastolic, end-systolic volume indexes, plasma CRP level, and removal fluid volume by ultrafiltration. Multivariate stepwise regression analysis revealed that mAM reflected all variables better than log [ANP], log [BNP], and log [NE]. During a 1-year follow-up period, 7 patients died and 8 had additional cardiovascular events. Event-free Kaplan-Meier curves based on the median mAM (4.55 pmol/L) showed that patients with high plasma mAM levels had higher mortality and morbidity than those with low plasma mAM levels (P = 0.0056). By Cox multivariate proportional hazard analysis, mAM was related to mortality and morbidity [hazard ratio (HR) 4.55, 95% CI 1.2-16.8, P= 0.023).

CONCLUSION

Plasma mAM reflects cardiac dysfunction, excessive blood volume, and inflammation better than ANP, BNP, and NE, resulting in a predictor of mortality and cardiovascular morbidity in hemodialysis patients with cardiovascular disease.