Does hydration status influence kidney volume in autosomal dominant polycystic kidney disease?

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive kidney disease where the size of the kidneys is correlated to the stage of kidney failure. Total kidney volume (TKV) is used as a prognostic marker to determine disease stage, progression, and possible effect of treatment. It has been shown that water restriction is associated with reduced kidney volume in healthy subjects. The aim of this study was to evaluate the relationship between TKV and hydration status in ADPKD patients. 40 ADPKD patients with chronic kidney disease stage 1 - 3 were randomized to either 3 hours of water restriction (n = 21) or 1 hour of water loading (n = 19; intake: 20 mL/kg). The patients had a mean age of 38 years (19 - 73) and mean plasma creatinine level of 91 (54 - 178) µmol/L. Magnetic resonance imaging of the kidneys was performed before and after intervention, and TKV was measured using the ellipsoid formula. Water restriction resulted in an insignificant 0.67% increase in TKV (median: 1.48, interquartile range (IQR): 6.1, range: -1. - 4.5). Water loading resulted in an insignificant 2.67% increase in TKV (median: 3.18, IQR: 11.4, range: -3.6 - 7.8). Interestingly, a 7.09% increase in right-kidney volume was found after water loading (median: 5.58, IQR: 9.4 range: 1.9 - 11.3, p < 0.05), whereas the left-kidney volume showed an insignificant decrease of 0.18% after water loading (median: -1.65, IQR: 18.0, range: -12.5 - 5.5). We found in ADPKD patients that neither short-term water restriction nor acute water loading had significant effects, suggesting that the use of TKV for disease staging is independent of hydration level in these patients.

Shared decision-making in dialysis choice has potential to improve self-management in people with kidney disease: A qualitative follow-up study.

AIMS: To explore how patients remained involved in their treatment and care of their own health following a shared decision-making intervention for dialysis choice. DESIGN: A follow-up study using semi-structured interviews. METHODS: Individual interviews with 13 patients were conducted immediately following their participation in a shared decision-making intervention for dialysis choice and again 3 months after initiating dialysis. This study reports findings from the follow-up interviews 3 month after dialysis initiation. Data were collected from August 2017-February 2019 and analysed using systematic text condensation. RESULTS: The analysis revealed five main findings, which indicated differing levels of: (a) involvement in the decision-making process; (b) involvement in treatment; (c) involvement in care of own health; (d) involvement of a relative; and (e) support from healthcare professionals. CONCLUSIONS: Following the shared decision-making intervention, patients who chose home-based treatment had become more involved in their treatment and care of their own health. The involvement of relatives and support from healthcare professionals contributed positively to this. In contrast, patients who had chosen hospital-based treatment were less involved in their treatment. IMPACT: Shared decision-making in dialysis choice has potential to improve self-management in people with kidney disease. However, support from healthcare professionals for patients and their relatives should be prioritized in an effort to increase all patients' involvement in their treatment and care of their own health.

Hyperpolarised 13C-MRI metabolic and functional imaging: an emerging renal MR diagnostic modality.

Magnetic resonance imaging (MRI) is a well-established modality for assessing renal morphology and function, as well as changes that occur during disease. However, the significant metabolic changes associated with renal disease are more challenging to assess with MRI. Hyperpolarized carbon-13 MRI is an emerging technique which provides an opportunity to probe metabolic alterations at high sensitivity by providing an increase in the signal-to-noise ratio of 20,000-fold or more. This review will highlight the current status of hyperpolarised 13C-MRI and its translation into the clinic and how it compares to metabolic measurements provided by competing technologies such as positron emission tomography (PET).

Choice of dialysis modality: patients' experiences and quality of decision after shared decision-making.

BACKGROUND: Patients with kidney failure experience a complex decision on dialysis modality performed either at home or in hospital. The options have different levels of impact on their physical and psychological condition and social life. The purpose of this study was to evaluate the implementation of an intervention designed to achieve shared decision-making for dialysis choice. Specific objectives were: 1) to measure decision quality as indicated by patients' knowledge, readiness and achieved preferences; and 2) to determine if patients experienced shared decision-making. METHOD: A mixed methods descriptive study was conducted using both questionnaires and semi-structured interviews. Eligible participants were adults with kidney failure considering dialysis modality. The intervention, based on the Three-Talk model, consisted of a patient decision aid and decision coaching meetings provided by trained dialysis coordinators. The intervention was delivered to 349 patients as part of their clinical pathway of care. After the intervention, 148 participants completed the Shared Decision-Making Questionnaire and the Decision Quality Measurement, and 29 participants were interviewed. Concordance between knowledge, decision and preference was calculated to measure decision quality. Interview transcripts were analysed qualitatively. RESULTS: The participants obtained a mean score for shared decision-making of 86 out of 100. There was no significant difference between those choosing home- or hospital-based treatment (97 versus 83; p = 0.627). The participants obtained a knowledge score of 82% and a readiness score of 86%. Those choosing home-based treatment had higher knowledge score than those choosing hospital-based treatment (84% versus 75%; p = 0.006) but no significant difference on the readiness score (87% versus 84%; p = 0.908). Considering the chosen option and the knowledge score, 83% of the participants achieved a high-quality decision. No significant difference was found for decision quality between those choosing home- or hospital-based treatment (83% versus 83%; p = 0.935). Interview data informed the interpretation of these results. CONCLUSIONS: Although there was no control group, over 80% of participants exposed to the intervention and responded to the surveys experienced shared decision-making and reached a high-quality decision. Both participants who chose home- and hospital-based treatment experienced the intervention as shared decision-making and made a high-quality decision. Qualitative findings supported the quantitative results. TRIAL REGISTRATION: The full trial protocol is available at ClinicalTrials. Gov ( NCT03868800 ). The study has been registered retrospectively.

Brain swelling during dialysis: A randomized trial comparing low-flux hemodialysis with pre-dilution hemodiafiltration
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Osmotic changes in plasma are assumed to cause cerebral swelling in hemodialysis patients. We investigated the acute effect of low-flux hemodialysis (HD) (removal of small molecules) and pre-dilution hemodiafiltration (pre-HDF) (additional removal of larger molecules) on cerebral compartment volumes using quantitative magnetic resonance imaging (MRI) in chronic uremic patients. Twelve patients underwent a session of HD and pre-HDF in a randomized crossover study with equal ultrafiltration. MRI was performed immediately before and after dialysis. A linear correlation was found between changes in gray matter and plasma osmolarity (HD: r2 = 0.83; HDF: r2 = 0.73) but not between changes in white matter volume and plasma osmolarity (HD: r2 = 0.02; HDF: r2 = 0.004). Total brain volume increased by 1.8 ± 1.7% (18.7 ± 17.4 mL) (mean ± SD) during HD and 2.0 ± 0.9% (22.3 ± 10.7 mL) during pre-HDF. Gray matter volume increased: HD 3.8% (from -3.6 to 9.7) and pre-HDF 4.2% (from -2.8 to 14.3). White matter volume did not change significantly. Reduction ratio of urea (molecular weight (MW) 0.06 kDa) (HD: 68%; pre-HDF: 69.7%) and ß2-microglobulin (MW 11.7 kDa) (HD: -13.7%; pre-HDF: 67.2%) separated the treatments. This study showed that HD and pre-HDF caused equal acute cerebral swelling of the grey matter. This appeared to be driven by small solute change in plasma interacting linearly with gray matter volume regardless of additional removal of larger molecules or ultrafiltration.
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Hemodialysis Using High Cut Off Filters in Light Chain Cast Nephropathy.

BACKGROUND/AIM: Hemodialysis using high cutoff (HCO) filters possibly improves renal function in diseases with light chain (LC) overproduction and acute kidney injury. We established the effect of HCO dialysis on renal outcome in consecutive patients with malignant monoclonal gammopathies and LC cast nephropathy. METHODS: LC concentration was measured before and after each dialysis session in 10 patients receiving HCO dialysis and bortezomib-based chemotherapy, and their renal function was monitored by plasma creatinine. RESULTS: The number of HCO sessions ranged from 4 to 34 (mean 13). Six patients recovered kidney function, 3 regained partial function while 1 patient continued chronic dialysis. Patients with the largest reductions in LC during HCO treatments had the lowest creatinine at 6 and 9 months of follow-up. For comparison, only 2 out of 10 patients in a historic control group recovered kidney function. CONCLUSION: HCO dialysis combined with bortezomib results in good renal recovery with kidney function being dependent on the degree of LC lowering.

Angiotensin blockade and progressive loss of kidney function in hemodialysis patients: a randomized controlled trial.

BACKGROUND: Glomerular filtration rate (GFR) declines during long-term dialysis treatment. In peritoneal dialysis, blockade of the renin-angiotensin-aldosterone system reduces GFR decline. Observational studies suggest that similar treatment may preserve kidney function in hemodialysis (HD). STUDY DESIGN: A multicenter, randomized, placebo-controlled, double-blinded trial, with 1-year follow-up. SETTING & PARTICIPANTS: Adult HD patients with urine output >300mL/24h, HD vintage less than 1 year, and cardiac ejection fraction >30%. Patients were included from 6 HD centers. INTERVENTION: Patients were randomly assigned to placebo or the angiotensin II receptor blocker irbesartan, 300mg daily. Target systolic blood pressure (BP) was 140mm Hg. OUTCOMES & MEASUREMENTS: Primary outcomes were change in GFR measured as the mean of creatinine and urea renal clearance together with urine volume. Secondary outcomes were change in albuminuria, renin-angiotensin II-aldosterone hormone plasma levels, and time to anuria. RESULTS: Of 82 patients randomly assigned (41 patients in each group), 56 completed 1 year of treatment. The placebo and irbesartan groups were comparable at baseline in terms of sex balance (26 vs 30 men), mean age (62 vs 61 years), median HD vintage (137 vs 148 days), mean HD time (10 vs 11h/wk), median urine volume (1.19 vs 1.26L/d), and mean GFR (4.8 vs 5.7mL/min/1.73m(2)). The target BP level was reached in both groups and BP did not differ significantly between groups over time. Adverse-event rates were similar. GFR declined by a mean of 1.7 (95% CI, 1.2-2.3) and 1.8 (95% CI, 1.1-2.4) mL/min/1.73m(2) per year in the placebo and irbesartan groups, respectively. Mean difference (baseline values minus value at 12 months) between groups was -0.0 (95% CI, -0.8 to 0.8). In each group, 4 patients became anuric. LIMITATIONS: GFR decline rates were lower than expected, reducing the power. CONCLUSIONS: At equal BP levels, we found that irbesartan treatment did not affect the decline in GFR or urine volume significantly during 1 year of treatment in HD patients. Irbesartan treatment was used safely in the studied population.

Hemodynamic effects of low versus high dialysate bicarbonate concentration in hemodialysis patients.

INTRODUCTION: Hemodialysis treatment using standard dialysate bicarbonate concentrations cause transient metabolic alkalosis possibly associated with hemodynamic instability. The aim of this study was to perform a detailed comparison of high and low dialysate bicarbonate in terms of blood pressure, intradialytic hemodynamic parameters, orthostatic blood pressure, and electrolytes. METHODS: Fifteen hemodialysis patients were examined in a single-blind, randomized, controlled, crossover study. Participants underwent a 4-h hemodialysis session with dialysate bicarbonate concentration of 30 or 38 mmol/L with 1 week between interventions. Blood pressure was monitored throughout hemodialysis, while cardiac output, total peripheral resistance, stroke volume, and central blood volume were assessed with ultrasound dilution technique (Transonic). Orthostatic blood pressure was measured pre- and post-hemodialysis. FINDINGS: With similar ultrafiltration (UF) volume (2.6 L), systolic blood pressure (SBP) tended to decrease more during high dialysate bicarbonate compared to low dialysate bicarbonate; the mean (95% confidence interval) between treatment differences in SBP were: 8 (-4; 20) mmHg (end of hemodialysis) and 7 (0; 15) mmHg (post-hemodialysis). Stroke volume decreased whereas total peripheral resistance increased significantly more during high dialysate bicarbonate compared to low dialysate bicarbonate with mean between treatment differences: Stroke volume: 12 (1; 23) mL; Total peripheral resistance: -2.9 (-5.3; -0.5) mmHg/(L/min). Cardiac output tended to decrease more with high dialysate bicarbonate compared to low dialysate bicarbonate with mean between treatment difference 0.7 (0.0; 1.4) L/min. High dialysate bicarbonate caused alkalosis, hypocalcemia, and lower plasma potassium, whereas patients remained normocalcemic with normal pH during low dialysate bicarbonate. Orthostatic blood pressure response after dialysis did not differ significantly. DISCUSSION: The use of high dialysate bicarbonate compared to low dialysate bicarbonate was associated with hypocalcemia, alkalosis, and a more pronounced hypokalemia. During hemodialysis with UF, a better preservation of blood pressure, stroke volume, and cardiac output may be achieved with low dialysate bicarbonate compared to high dialysate bicarbonate.

Vitamin K supplementation and arterial calcification in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial.

BACKGROUND: Arterial calcification is associated with cardiovascular mortality in dialysis patients. Active matrix Gla protein (MGP) is a vitamin K-dependent inhibitor of arterial calcification. Elevated plasma concentrations of inactive MGP, i.e. dephosphorylated-uncarboxylated MGP (dp-ucMGP), are prevalent in dialysis patients. MGP inactivity might contribute to arterial calcification. We investigated whether vitamin K supplementation had an effect on arterial calcification in chronic dialysis patients. METHODS: In a 2-year, double-blind, placebo-controlled intervention trial, 48 dialysis patients were randomized to vitamin K [menaquinone-7 (MK-7), 360 µg daily] or placebo. MK-7 in serum and dp-ucMGP in plasma were used to assess vitamin K status. Carotid-femoral pulse wave velocity (cfPWV) and scores of coronary arterial calcification (CAC) and abdominal aortic calcification (AAC) were used to assess arterial calcification. RESULTS: Thirty-seven participants completed Year 1, and 21 completed Year 2. At Year 2, serum MK-7 was 40-fold higher, and plasma dp-ucMGP 40% lower after vitamin K supplementation compared with placebo {mean dp-ucMGP difference: -1380 pmol/L [95% confidence interval (CI) -2029 to -730]}. There was no significant effect of vitamin K supplementation on cfPWV [mean difference at Year 2: 1.2 m/s (95% CI -0.1 to 2.4)]. CAC Agatston score increased significantly in vitamin K supplemented participants, but was not significantly different from placebo [mean difference at Year 2: 664 (95% CI -554 to 1881)]. AAC scores increased in both groups, significantly so within the placebo group at Year 1, but with no significant between-group differences. CONCLUSIONS: Vitamin K supplementation improved vitamin K status, but did not hinder or modify the progression of arterial calcification in dialysis patients.

Comparison of self- and nurse-measured office blood pressure in patients with chronic kidney disease.

OBJECTIVE: As blood pressure (BP) control is very important in chronic kidney disease (CKD), we investigated how office BP is influenced by the measurement circumstances and compared nonautomated self- and nurse-measured BP values. MATERIALS AND METHODS: Two hundred stage 1-5 CKD patients with scheduled visits to an outpatient clinic were randomized to either self-measured office BP (SMOBP) followed by nurse-measured office BP (NMOBP) or NMOBP followed by SMOBP. The participants had been educated to perform the self-measurement in at least one previous visit. The SMOBP and NMOBP measurement series both consisted of three recordings, and the means of the last two recordings during SMOBP and NMOBP were compared for the 174 (mean age 52.5 years) with complete BP data. RESULTS: SMOBP and NMOBP showed similar systolic (135.3 ± 16.6 vs 136.4 ± 17.4 mmHg, Δ = 1.1 mmHg, P = 0.13) and diastolic (81.5 ± 10.2 vs 82.2 ± 10.4 mmHg, Δ = 0.6 mmHg, P = 0.09) values. The change in BP from the first to the third recording was not different for SMOBP and NMOBP. In 17 patients, systolic SMOBP was ≥10 mmHg higher than NMOBP and in 28 patients systolic NMOBP exceeded SMOBP by ≥10 mmHg. The difference between systolic SMOBP and NMOBP was independent of CKD stage and the number of medications, but significantly more pronounced in patients above 60 years. CONCLUSION: In a population of CKD patients, there is no clinically relevant difference in SMOBP and NMOBP when recorded at the same visit. However, in 25% of the patients, systolic BP differs ≥10 mmHg between the two measurement modalities.

The hemodynamic effect of calcium ion concentration in the infusate during predilution hemofiltration in chronic renal failure.

BACKGROUND: It is the prevailing view that convective dialysis techniques stabilize blood pressure. Calcium concentration in the substitution fluid may be important in this respect. The aim of this study is to investigate the influence of calcium ion concentration in the substitution fluid on hemodynamic stability during predilution hemofiltration (HF). METHODS: We conducted a randomized, crossover, blinded, controlled trial with 12 stable long-term hemodialysis patients without diabetes. Each patient was randomly assigned to substitution fluid with a calcium ion (iCa) concentration of 2.5 mEq/L (1.25 mmol/L; low-calcium session [L-HF]) or 3.5 mEq/L (1.75 mmol/L; high-calcium session [H-HF]) during 4.5 hours of predilution HF with a volume of 1.24 +/- 0.09 L/kg dry body weight and a temperature of 37 degrees C. Ultrafiltration was kept constant in each patient. Blood pressure (mean, systolic [SBP], and diastolic blood pressure [DBP]), pulse rate, arterial and venous temperature, energy transfer, and relative blood volume were measured at 15-minute intervals. Cardiac output, total peripheral resistance, stroke volume, and iCa were measured hourly. The 2 treatments were matched with the exception of iCa concentration. RESULTS: A significant intratreatment reduction in cardiac output and stroke volume was shown to the same extent for both groups. Intertreatment comparisons showed a significantly lower mean arterial pressure, SBP, DBP, and total peripheral resistance in the L-HF compared with the H-HF group. CONCLUSION: iCa concentration of 3.5 versus 2.5. mEq/L (1.75 versus 1.25 mmol/L) in the infusate during predilution HF stabilized blood pressure, possibly because of greater peripheral resistance rather than through changes in cardiac performance.

Short and Long-Term Effects of the Angiotensin II Receptor Blocker Irbesartan on Intradialytic Central Hemodynamics: A Randomized Double-Blind Placebo-Controlled One-Year Intervention Trial (the SAFIR Study).

BACKGROUND AND AIM: Little is known about the tolerability of antihypertensive drugs during hemodialysis treatment. The present study evaluated the use of the angiotensin II receptor blocker (ARB) irbesartan. DESIGN: Randomized, double-blind, placebo-controlled, one-year intervention trial. SETTING AND PARTICIPANTS: Eighty-two hemodialysis patients with urine output >300 mL/day and dialysis vintage <1 year. INTERVENTION: Irbesartan/placebo 300 mg/day for 12 months administered as add-on to antihypertensive treatment using a predialytic systolic blood pressure target of 140 mmHg in all patients. OUTCOMES AND MEASUREMENTS: Cardiac output, stroke volume, central blood volume, total peripheral resistance, mean arterial blood pressure, and frequency of intradialytic hypotension. RESULTS: At baseline, the groups were similar regarding age, comorbidity, blood pressure, antihypertensive medication, ultrafiltration volume, and dialysis parameters. Over the one-year period, predialytic systolic blood pressure decreased significantly, but similarly in both groups. Mean start and mean end cardiac output, stroke volume, total peripheral resistance, heart rate, and mean arterial pressure were stable and similar in the two groups, whereas central blood volume increased slightly but similarly over time. The mean hemodynamic response observed during a dialysis session was a drop in cardiac output, in stroke volume, in mean arterial pressure, and in central blood volume, whereas heart rate increased. Total peripheral resistance did not change significantly. Overall, this pattern remained stable over time in both groups and was uninfluenced by ARB treatment. The total number of intradialytic hypotensive episodes was (placebo/ARB) 50/63 (P = 0.4). Ultrafiltration volume, left ventricular mass index, plasma albumin, and change in intradialytic total peripheral resistance were significantly associated with intradialytic hypotension in a multivariate logistic regression analysis based on baseline parameters. CONCLUSION: Use of the ARB irbesartan as an add-on to other antihypertensive therapy did not significantly affect intradialytic hemodynamics, neither in short nor long-term, and no significant increase in hypotensive episodes was seen. TRIAL REGISTRATION: Clinicaltrials.gov NCT00791830.

Endogenous markers for estimation of renal function in peritoneal dialysis patients.

OBJECTIVE: This method comparison study, conducted at the peritoneal dialysis (PD) outpatient clinic of the Department of Renal Medicine, Aarhus University Hospital, Denmark, set out to evaluate the accuracy and reproducibility of methods for estimating glomerular filtration rate (GFR) based on endogenous markers in PD patients. PATIENTS: The 12 consecutive patients included in the study were examined twice while in a stable condition. All patients finished the study. Inclusion criteria were age 18 years or older, ability to collect 24-hour urine, and urine production greater than 300 mL in 24 hours. MAIN OUTCOME MEASURES: The methods for estimating GFR using endogenous markers included the average of urinary clearances of creatinine and urea [U-Cl(crea-urea)] and two equations using the serum concentration of cystatin C [eGFR(CysC)]. The resulting GFR estimates were compared with those obtained using urinary and corrected plasma clearances of (51)Cr-EDTA [U-Cl(EDTA) and cP-Cl(EDTA)], the corrected plasma clearance being plasma clearance minus dialysate clearance. RESULTS: Compared with the U-Cl(EDTA), the U-Cl(crea-urea) GFR estimate was 12% higher [95% confidence limits (CL): 3%, 21%]. Although significantly different (p = 0.01), the latter two methods showed the best agreement. The estimates obtained using the eGFR(CysC) methods were skewed from y = x compared with the estimates obtained using other methods, indicating strong bias, probably because of extrarenal elimination. The cP-Cl(EDTA) estimate was 34% (95% CL: 26%, 42%), higher than the U-Cl(EDTA) estimate (p < 0.001). The reproducibility (coefficients of variation) differed significantly between methods: cP-Cl(EDTA), 7%; U-Cl(EDTA), 14%; U-Cl(crea-urea), 18%; and both eGFR(CysC) methods, 3%. CONCLUSIONS: In PD patients, GFR may be estimated as U-Cl(crea-urea) when complete urine collection is performed, taking into account an overestimation of approximately 12%. The available equations for eGFR(CysC) seem to be inaccurate; further development and validation is desirable. Omitting the eGFR(CysC) methods, cP-Cl(EDTA) was the most reproducible method and might be useful in certain situations.

Renal and cardiovascular effects of irbesartan in dialysis patients--a randomized controlled trial protocol (SAFIR study).

INTRODUCTION: Cardiovascular (CV) events are a major cause of morbidity and mortality in haemodialysis (HD) patients. Hypertension, increased arterial stiffness and left ventricular (LV) hypertrophy are highly prevalent and are often poorly controlled. Volume overload is an important factor and survival could be improved by treatment strategies that preserve residual renal function (RRF), reduce blood pressure, and decrease arterial stiffness and LV hypertrophy. Angiotensin II receptor blocker (ARB) treatment can prevent CV events in patients with hypertension and heart failure. However, few data exist in patients with chronic renal failure and it is not known whether ARB treatment improves clinical outcome in HD patients. MATERIAL AND METHODS: This is a randomized, controlled and double-blinded intervention study. A total of 82 HD patients from six Danish HD centres will be treated for a year with an ARB (irbesartan) or placebo. The inclusion criteria are urine output > 300 ml/day, dialysis vintage < 1 year and LV ejection fraction > 30%. The primary outcomes are change in RRF, LV hypertrophy, arterial stiffness and intra-dialytic haemodynamics. CONCLUSION: If ARB-treatment improves RRF and intermediate CV endpoints in a group of newly started HD patients, it may improve the survival for this high risk population. FUNDING: The trial is investigator-initiated, investigator-driven and supported by the Danish Agency for Science, Technology and Innovation and several private foundations.

Effect of mechanical brushing on survival and hemodynamic characteristics of tunneled hemodialysis catheters.

PURPOSE: Tunneled catheters used for hemodialysis treatment often become dysfunctional due to deposition of clotting material within the catheter lumen. In a retrospective study design we investigated the effect of mechanical brushing of dysfunctional tunneled catheters using a metal guide wire with simultaneous installation of urokinase. MATERIALS AND METHODS: During a period of 26 months all together 24 different catheters in 21 chronic hemodialysis patients were brushed due to insufficient blood flow or increased arterial or venous line pressures resulting in repeated alarms during dialysis treatments. RESULTS: Median functional survival after brushing was 45 days with 8 catheters being exchanged (n=5) or rebrushed (n=3) within 10 dialysis sessions (4 weeks). After 2 months all together 13 (54%) catheters were exchanged due to repeated dysfunction and by 3 months functional survival was only about 35%. The catheters needing exchange were characterized by low flow and high arterial line resistance already in the dialysis sessions immediately following the brushing procedure. Median survival of the exchanged catheters was considerably longer (>400 days) as compared to the brushed catheters. CONCLUSIONS: In conclusion mechanical brushing of dysfunctional tunneled hemodialysis catheters can prolong short term function but only affects long term catheter survival in a minority of the patients.

Preserving residual renal function in dialysis patients: an update on evidence to assist clinical decision making.

It has been documented that preservation of residual renal function in dialysis patients improves quality of life as well as survival. Clinical trials on strategies to preserve residual renal function are clearly lacking. While waiting for more results from clinical trials, patients will benefit from clinicians being aware of available knowledge. The aim of this review was to offer an update on current evidence assisting doctors in clinical practice.

Increasing fill volume reduces cardiac performance in peritoneal dialysis.

BACKGROUND: It is generally accepted that peritoneal dialysis (PD) affects systemic haemodynamics less than haemodialysis, but little is known about changes in haemodynamics during PD. It is unknown if increasing PD volume causes changes in cardiovascular haemodynamics possibly increasing the demand on the heart even during normal daily activities. METHODS: Fifteen stable PD patients were included in this randomized, controlled, open-label crossover study. After drainage, we measured blood pressure, pulse rate and cardiac output (CO) after 30 min in the supine position. The measurements were repeated 5 min later in an upright position. Subsequently, following fill, the measurements were repeated after 30 min in the supine and 5 min later in the upright position. The two procedures were repeated twice. The fill was either 2 l or 3 l of dialysate. CO was measured with a non-invasive device based on foreign gas rebreathing. Stroke volume (SV) and total peripheral systemic resistance were calculated. RESULTS: In the supine position, no difference was found between drained and 2 l fill. With 3 l fill both SV and CO decreased and total peripheral systemic resistance increased, while pulse rate and mean arterial blood pressure remained unchanged. In the upright position, SV and CO decreased and total peripheral systemic resistance increased. Pulse rate and mean arterial blood pressure were unchanged independent of fill volume when compared with the drained situation. During postural change, no significant differences were found between drained and 2 l and 3 l fill. CONCLUSION: The present study showed that cardiac performance decreased when increasing fill volume from 2 to 3 l in the supine position. The decreased cardiac performance was already present after 2 l fill in the upright position and did not change negatively by increasing fill. It was also shown that cardiovascular response from the supine to upright position was preserved.

Predilution hemodiafiltration displays no hemodynamic advantage over low-flux hemodialysis under matched conditions.

BACKGROUND: It is the prevailing view that convective dialysis techniques stabilize blood pressure. The aim of this study was to compare the intrasession hemodynamics during high-dose predilution hemodiafiltration (HDF) and low-flux hemodialsis, under strict controlled conditions. METHODS: Twelve stable hemodialysis patients were investigated in a randomized crossover blinded controlled trial. The patients were allocated to one session of predilution HDF (substitution fluid 1.20 +/- 0.10 L/kg body weight) and one session of hemodialysis at 4(1/2) hours. To eliminate confounding factors, dialysis dose, ultrafiltration volume and arterial temperature were matched. At the start of the dialysis the patients' core temperature was "locked" by an automatic feedback system regulating the dialysate temperature; thereby, patients' temperature was kept stable throughout the whole treatment. The calcium-ion concentration in the substitution/dialysis fluid was 1.25 mmol/L. Cardiac output was measured hourly by the ultrasound velocity dilution method. RESULTS: Mean blood pressure, cardiac output, stroke volume, cardiac work, and relative blood volume was significantly reduced in both treatments. Total peripheral resistance increased significantly in both groups. Ultrafiltration volume, cardiopulmonary recirculation, Kt/V, and total energy transfer were similar for hemodialysis and HDF. The pulse rate showed no significant change throughout both sessions. No significant differences were revealed between hemodialysis and HDF. CONCLUSION: The hemodynamics of predilution HDF and low-flux hemodialysis displayed a similar profile during matched conditions. An acute circulatory benefit of convective solute removal over diffusive could not be demonstrated.