Do patients dialysing with higher ultrafiltration rates report more intradialytic symptoms and longer postdialysis recovery times?

BACKGROUND: Many hemodialysis (HD) patients report intradialytic symptoms, and take time to recover postdialysis. To improve quality of life, patient groups have highlighted the need to reduce postdialysis fatigue and other peridialytic symptoms. As compartmental shifts of fluid during dialysis have been proposed to cause peridialytic symptoms we investigated whether patients dialysing with higher ultrafiltration rates (UFR) reported more intradialytic symptoms and recovery times. METHODS: We reviewed the hospital records of HD patients who completed a self-reported intradialytic symptom questionnaire, using a visual analogue scale, who had contemporaneous midweek pre- and postdialysis segmental bioimpedance measurements. RESULTS: Six hundred and five patients returned the peridialytic symptom questionnaire with pre- and postdialysis bioimpedance measurements. The majority were male (64.8%), mean age 64.2 ± 15.6 years, duration of dialysis treatment 26.8 (10.7-59.2) months, 85% treated by hemodiafiltration and mean dialysate temperature 35.4 ± 0.4°C. We divided patients into terciles according to UFR adjusted for weight, and there was a greater fall in the ratio of extracellular water (ECW) to total body water (TBW) postdialysis in the nonfistula arm from the lower to middle to higher tercile (0.8 (0-1.54) vs. 1.28 (0.52-1.85) vs. 1.54 (0.78-2.52)), trunk (1.5 (0.74-2.27) vs. 1.53 (0.99-2.2) vs. 1.98 (1.18-2.66)), left leg (1.56 (0.49-2.25) vs. 1.77 (1.24-2.43) vs. 2.08 (1.18-2.95)), lower versus higher tercile p < 0.05. However, no differences in intradialytic symptoms or postdialysis recovery times between the UFR terciles were observed. CONCLUSION: There were no differences in self-reported intradialytic symptoms or postdialysis recovery times with differing UFRs, despite changes in intracompartmental fluid shifts as measured by changes in ECW/TBW.

Changes in blood glucose and lactate concentrations with hemodialysis.

INTRODUCTION: Blood glucose concentrations are recognized to vary during hemodialysis (HD), with hypoglycemia reported with glucose-free dialysates. As glucose can be converted to lactate, and conversely lactate to glucose, we wished to study factors associated with peri-dialytic changes in blood glucose. METHODS: We prospectively collected data including patient profile, dialysis prescription, hemodynamic parameters, medications, dialysis adequacy and monthly blood tests for three consecutive months. All patients used a 100 mg/dl glucose dialysate. Linear mixed model, general estimated equation and binary logistic regression were used for analysis. RESULTS: We studied 157 sessions in 55 patients, median age 67.1 (58.5-72.6) years, 67% male, 71% diabetic, 40% prescribed insulin, dialysis vintage 20.4 (10.7-57.7) months. Mean single pool Kt/Vurea and normalized protein nitrogen appearance rate (nPNA) were 1.70 ± 0.34 and 1.01 ± 0.30 g/kg/day respectively. Hypoglycemia (<70 mg/dl) occurred during 10 sessions (6.4%). 25% of non-diabetes experienced hypoglycemia. The % change in peri-dialytic blood glucose was associated with the % change in lactate (estimate of fixed effect = 0.23 p < 0.001) and pre-HD glucose (estimate of fixed effect = 0.09, p < 0.001). The fall in glucose was not associated with urea clearance, consumption of food, administration of insulin or antidiabetic medications, nPNA, body mass index, or pyridoxine concentrations. CONCLUSIONS: Peri-dialytic hypoglycemia cannot simply be explained by dialyzer clearance, as the corresponding fall in lactate would potentially suggest increased gluconeogenesis. Despite using a glucose containing dialysate, asymptomatic hypoglycemia occurred in 6.4% of sessions, suggesting a role for peri-dialytic blood glucose monitoring and avoiding fasting during dialysis.

Aortic Pulse Wave Velocity in Peritoneal Dialysis Patients Is Not Simply Associated with Extracellular Water Expansion.

BACKGROUND: Cardiac death is increased in peritoneal dialysis (PD) patients. Pulse wave velocity (PWV) is a measurement of arterial stiffness, and previous reports linked PWV to increased extracellular water (ECW). As cyclers and icodextrin are increasingly used, we wished to determine whether this association between PWV and ECW remains. METHODS: We measured aortic PWV (aPWV) and bioimpedance (InBody, Seoul, South Korea) in consecutive PD patients attending for peritoneal membrane testing. RESULTS: 189 patients were included, 62.4% male, mean age 63.1 ± 15.2 years, 45.3% diabetic, median dialysis duration 12.3 (6.5-25.1) months, 71.4% using cyclers, weight 73.0 ± 16.1 kg, systolic blood pressure 142 ± 21 mm Hg, aPWV 10.4 ± 5.1 m/s. aPWV was associated with pulse pressure (r = 0.26, p = 0.001), Davies comorbidity score (r = 0.18, p = 0.013), and N-terminal pro-brain-type natriuretic peptide (NTproBNP; r = 0.18, p = 0.011). Patients with aPWV ≥10 m/s were older (65.9 ± 13.6 vs. 60.1 ± 16.3 years, p < 0.01) with a higher ECW-to-total body water ratio (0.400 ± 0.012 vs. 0.396 ± 0.013, p < 0.05), but ECW/height was not different (8.52 ± 2.32 vs. 8.75 ± 1.78 L/m), as was NTproBNP (2,472 [788-5,422] vs. 1,234 [410-6,230] ng/L). On multivariable testing, aPWV was positively associated with ß-blocker prescription (standardised ß coefficient [Stß] 0.3, 95% confidence limits [95% CL] 0.7-2.6, p = 0.001) and negatively with icodextrin prescription (Stß 0.19, 95% CL -0.2 to -2.1, p = 0.04). CONCLUSIONS: Compared to previous studies, we did not find an independent association between aPWV and ECW and estimates of ECW excess, using the InBody bioimpedance device, suggesting that vascular stiffness in PD patients is more complex than simple ECW volume expansion in PD patients.

Reduction in Aortic Pulse Wave Velocity Is Associated with a Short-Term Reduction in Dual-Energy X-Ray Absorptiometry Lumbar Spine Bone Mineral Density T Score.

INTRODUCTION: Increased vascular stiffness is a risk factor for mortality. We wished to determine whether changes in vascular stiffness are associated with changes in bone mineral density (BMD) in peritoneal dialysis patients. METHODS: We measured vascular stiffness by aortic pulse wave velocity (aPWV) and BMD by dual electron absorptiometry (DXA) scanning and compared T scores to compensate for differences in patient ages and gender. RESULTS: Twenty-four patients had repeat aPWV measurements and DXA scans, median 12.4 months apart. aPWV decreased in 15 and increased in 9. As there were more women in the group with an increase in aPWV, we used gender-adjusted DXA T scores Total body T scores fell in both groups, but median T scores remained positive for those with an increase in aPWV, whereas negative T scores on both scans for those with a decrease in or stable aPWV. Lumbar spine T scores fell in those with a reduction in aPWV (-1.6 [-2.4 to 0.6] to -2.1 [-2.4 to 0.3], p < 0.05), whereas there was no significant decrease in those with an increase in aPWV (-0.5 [-1.1 to 0.15] to -0.7 [-1.7 to 0.6]). There were no changes in femoral neck T scores. CONCLUSIONS: Our study reinforces the hypothesis of a link between bone disease and vascular disease in dialysis patients. Lumbar spine DXA includes imaging of the aorta and will include aortic calcification, and as such a reduction in lumbar spine T score without a change in femoral neck T score suggests a reduction in aortic calcification. Although our study requires additional confirmation, our data would suggest that changes in aPWV could be used as a surrogate for changes in vascular calcification in the investigation of interventions designed to reduce vascular calcification.

Soluble CD146 and B-type natriuretic peptide dissect overhydration into functional components of prognostic relevance in haemodialysis patients.

Background: Accurate volume status evaluation and differentiation of cardiac and non-cardiac components of overhydration (OH) are fundaments of optimal haemodialysis (HD) management. Methods: This study, by combining bioimpedance measurements, cardiovascular biomarkers and echocardiography, aimed at dissecting OH into its major functional components, and prospectively tested the association between cardiac and non-cardiac components of OH with mortality. In the first part, we validated soluble CD146 (sCD146) as a non-cardiac biomarker of systemic congestion in a cohort of 30 HD patients. In the second part, we performed a prospective 1-year follow-up study in an independent cohort of 144 HD patients. Results: sCD146 incrementally increased after the short and long intervals after HD (+53 ng/mL, P = 0.006 and +91 ng/mL, P < 0.001), correlated with OH as determined by bioimpedance and well-diagnosed OH (area under the receiver operating characteristics curve 0.72, P = 0.005). The prevalence of OH was lower for low-sCD146 and low-BNP patients (B-type natriuretic peptide, 29%) compared with subjects with either one or both biomarkers elevated (65-74%, P < 0.001). Notably, most low-BNP but high-sCD146 subjects were overhydrated. Systolic dysfunction was 2- to 3-fold more prevalent among high-BNP compared with low-BNP patients (44-68% versus 21-23%, chi-square P < 0.001), regardless of sCD146. One-year all-cause mortality was markedly higher in patients with high-BNP (P = 0.001) but not with high-sCD146. In multivariate analysis, systolic dysfunction and BNP, but not OH, were associated with lower survival. Conclusions: The combination of BNP and sCD146 dissects OH into functional components of prognostic value. OH in HD patients is associated with higher mortality only if resulting from cardiac dysfunction.

Incremental Hemodialysis - A European Perspective.

Most patients initiating hemodialysis have residual renal function (RRF). Whereas RRF is monitored prior to commencing hemodialysis, once dialysis is started most centres simply rely on dialyzer urea clearance to determine adequate uremic toxin clearance and disregard the effect of RRF. However sustaining RRF is important for the dialysis patient, as RRF reduces inter-dialytic weight gains, increases middle molecule and protein bound toxin clearances and is associated with better quality of life assessments. Paradoxically, more frequent dialysis and longer dialysis sessions appear to be associated with more rapid loss of RRF. As such, starting patients with less frequent or shorter dialysis sessions, depending upon individual patient comorbidity, may lead to better preservation of RRF. However to prevent inadequate uremic toxin clearance or volume overload, RRF needs to be regularly monitored. Unfortunately, the 24-hour urine collection for urea and creatinine clearance remains the mainstay for RRF assessment. This measurement chiefly represents glomerular clearance rather than tubular function, but the latter may be also important for the dialysis patients. Incremental dialysis with less initial dialysis treatment may lower costs and will allow others to dialyze more frequently. The key to start a successful incremental hemodialysis approach is the regular monitoring of the patient, so that as RRF is lost an appropriate decision can be made regarding increasing dialysis session duration and frequency on an individual patient basis or consider switching modalities to hemodiafiltration.

Enhancing dialyser clearance-from target to development.

Products of metabolism accumulate in kidney failure and potentially have toxic effects. Traditionally these uraemic toxins are classified as small, middle-sized and protein-bound toxins, and clearance during dialysis is affected by diffusion, convection and adsorption. As current dialysis practice effectively clears small solutes, increasing evidence supports a toxic effect for middle-sized and protein-bound toxins. Therefore, newer approaches to standard dialysis practice are required to look beyond urea clearance. Current dialysers have been developed to effectively clear small solutes and secondly to increase middle-sized toxin clearances. However, there is no ideal dialyser which can effectively clear all uraemic toxins. Advances in nanotechnology have led to improvements in manufacturing, with the production of smoother membrane surfaces and uniformity of pore size. The introduction of haemodiafiltration has led to changes in dialyser design to improve convective clearances. Both diffusional and convectional clearances can be increased by changing dialyser designs to alter blood and dialysate flows, and novel dialyser designs using microfluidics offer more efficient solute clearances. Adjusting surface hydrophilicity and charge alter adsorptive properties, and greater clearance of protein-bound toxins can be achieved by adding carbon or other absorptive monoliths into the circuit or by developing composite dialyser membranes. Other strategies to increase protein-bound toxins clearances have centred on disrupting binding and so displacing toxins from proteins. Just as the hollow fibre design replaced the flat plate dialyser, we are now entering a new era of dialyser designs aimed to increase the spectrum of uraemic toxins which can be cleared by dialysis.

Increasing Haemodialytic Clearances as Residual Renal Function Declines: An Incremental Approach.

Many patients with chronic kidney disease start undergoing thrice-weekly haemodialysis (HD), aiming for an HD sessional dialyzer urea clearance target, irrespective of whether they have residual renal function (RRF). While increasing sessional dialyzer urea clearance above a target of 1.2 has not been shown to improve patient survival, it has been shown that the preservation of RRF improves patient self-reported outcomes and survival. Observational studies have suggested that initiating twice-weekly HD schedules leads to greater preservation of RRF. This has led to the concept of following an incremental approach to initiating HD, steadily increasing the amount of weekly dialyzer clearance as RRF decreases. Incremental dialysis practice requires the regular assessment of RRF to prevent inadequate delivery of dialysis treatment. Once RRF is lost, then the dialysis schedule and modality need to be adjusted to try to increase the middle-sized solute clearance and protein-bound toxins.

Psychological Stress Can Be Decreased by Traditional Thai Massage.

OBJECTIVE: The purpose of this study was to investigate the immediate effects of traditional Thai massage (TTM) on psychological stress and heart rate variability (HRV). MATERIAL AND METHOD: Thirty healthy participants were randomly allocated in two groups, a TTM group (n = 15) who received a 1-hour session with moderate pressure of whole body TTM or a control group (n=15) who rested on the bedfor 1 hour All ofthem were given a 10-minute mental arithmetic test to induce psychological stress after which they received a 1-hour session of TTM or bed rest. Psychological stress and HR V were measured at baseline and immediately after mental arithmetic test, and immediately after TTM or bed rest. RESULTS: The studyfound that psychological stress was signficantly increased (p<0.05) after mental arithmetic test in both groups. Comparison on these measures between immediately after mental arithmetic test and after TTM or bed rest revealed that psychological stress was significantly decreased (p<0.05) and HR Vwas significantly increased (p<0.05) in both groups. Root mean square of successive differences (RMSSD) and low frequency were significantly increased (p<0.05) only in the TTM group. However; all of these measures were found without significant difference when groups were compared. CONCLUSION: TTM and bed rest could decrease psychological stress and HRV

Delayed post-dialysis recovery times are associated with relative changes in intracellular and extracellular fluid ratios between different body compartments.

INTRODUCTION: Hemodialysis patient groups have advocated reducing dialysis fatigue and symptoms. We investigated whether compartmental fluid shifts were associated with peri-dialytic fatigue and symptoms. METHODS: Sessional dialysis records of patients reporting both a short and delayed recovery (<1 h and ≥1 h) with corresponding bioimpedance measurements were reviewed. RESULTS: One hundred and twenty-four patients reported both short and delayed recovery times, mean age 66.0 ± 14.8 years, 66.1% male. Differences between sessions included higher distress thermometer [4 (1-6) vs. 3 (0-5)], fatigue [4 (0-9) vs. 2 (0-7)], total symptom scores [20.5 (12.3-34.5) vs. 16 (7-28)], change in extracellular water to total body water ratios between body compartments [right leg/left arm 2.36 (1.23-4.19) vs. 1.28 (0.12-2.01), all p < 0.01] with delayed recovery, and more hemodialysis than hemodiafiltration sessions (χ2 4.6, p = 0.02). CONCLUSION: Sessions with prolonged recovery times were associated with more peri-dialytic symptoms, psychological distress, and hemodialysis mode, and greater changes in compartmental fluid shifts.