Hyperkalaemia during massive blood transfusion in paediatric craniofacial surgery

Children undergoing major craniofacial surgery (MCFS) often require transfusion in excess of one blood volume. Therefore they were the subject of a retrospective review which looked at the longitudinal trend of plasma potassium concentration [K⁺] during surgery. Ten of eleven children had a statistically significant increase in plasma potassium concentration during their intraoperative course and in five the potassium concentration exceeded 5.5 mmol · L^?1. This was in contrast to the stable intraoperative plasma [K⁺] observed in a control group which did not receive blood transfusion. All MCFS children received a blood transfusion with red blood cell concentrates (RBCconc). The age of the units of RBCconc which had been transfused was 16.1 ± 8.4 days. The amount of extracellular potassium in 28 units of RBCconc was determined in order to estimate the amount of free potassium (K_dose) which the MCFS group received. The plasma [K⁺] in units of RBCconc < 1 week of age was < 20 mmol · L^?1, whereas in units aged > 2 weeks it was > 40 mmol · L^?1. The estimated K_dose was 0.2–1.6 mmol · kg^?1. We concluded that the amount of extracellular potassium in units of RBCconc was clinically important and may give rise to hyperkalaemia during massive blood transfusion.     

High- or low-potassium solutions for the storage of abdominal and thoracic organs

Background: Clinically, intracellular type solutions are the most widely used solutions to preserve organs. The optimal ion composition of preservation solutions, however, is still unknown and extracellular-type solutions have frequently been superior to intracellular solutions in various experimental studies. Materials and methods: In this study, we measured extracellular (interstitial) electrolyte concentrations in rat livers, kidneys, hearts and lungs at 4°C by means of microdialysis sampling. Results: After 24 h cold ischaemia, [Na⁺]_int and [K⁺]_int were 104±25 mmol/l and 6.5±0.7 mmol/l in hearts, 92±12 mmol/l and 6.9±1.0 mmol/l in livers, 115±22 mmol/l and 6.3±0.9 mmol/l in kidneys and 87±17 mmol/l and 6.4±0.6 mmol/l in lungs. After preservation of organs in intracellular-type solutions, [Na⁺]_int was significantly lower for each organ (range from 69±8 mmol/l to 73±20 mmol/l) and [K⁺]_int was significantly higher (range from 8.0±1.7 mmol/l to 9.8±1.0 mmol/l). In no instance did the interstitial electrolyte concentration equilibrate with the intracellular electrolyte concentration. When the diffusion gradient from the vascular space to the interstitial space was calculated for Na⁺ and K⁺, a significantly higher barrier was found for K⁺ than for Na⁺ (P<0.001 and P<0.01 for hearts). Conclusions: These studies indicate that during cold storage of rat hearts, lungs, livers and kidneys, intra- and extracellular electrolytes do not equilibrate. Ion exchange stabilises at extracellular Na⁺ concentrations between 87 mmol/l and 115 mmol/l and K⁺ concentrations between 6.3 mmol/l and 6.9 mmol/l. Storage of organs in solutions with extracellular-type ion compositions might improve graft function and survival not only after lung and liver but also after heart and renal preservation. Received: 4 August 1999 In revised form: 23 February 2000 Accepted: 24 February 2000     

The Effects of Angiotensin Converting Enzyme Inhibitors on Potassium Homeostasis in Dialysis Patients With and Without Residual Renal Function

Hyperkalemia is exacerbated by angiotensin converting enzyme inhibitors (ACE‐I). Distal potassium (K⁺) secretion is negligible in anuric patients. ACE‐I therapy may reduce renal, peritoneal, and colonic K⁺ losses. We examined the effect of ACE‐I therapy on serum, urinary, and dialysate K⁺ in a cross‐section of peritoneal and hemodialysis patients. Serum, 24‐h urine K⁺, and peritoneal dialysate excretion K⁺ levels were measured and the results were compared in the various dialysis and treatment groups. Eighty‐one hemodialysis (HD) and 32 peritoneal dialysis (PD) patients were included. Serum K⁺ in HD patients with no residual renal function (RRF) was higher in those receiving ACE‐I therapy (P = 0.02). Serum K⁺ levels in HD patients receiving ACE‐I treatments with RRF was similar to that in oligoanuric HD patients not receiving an ACE‐I. Urinary K⁺ excretion was significantly reduced in those on ACE‐I therapy versus those not on an ACE‐I (P < 0.05). Mean serum K⁺ was lower in PD versus HD patients (P < 0.05). PD patients with no RRF on ACE‐I therapy had higher serum K⁺ concentrations (P = 0.002) and dialysate K⁺ excretion was lower (P = 0.05), in comparison with PD patients not on an ACE‐I. PD patients with RRF on ACE‐I therapy had higher serum K⁺ concentrations compared with those not on ACE‐I therapy (P = 0.03). Both urinary and dialysate K⁺ excretion were reduced (P = 0.001 and P = 0.002, respectively). ACE‐I therapy increases serum K⁺ concentration in dialysis patients. PD patients have relatively lower serum K⁺ levels compared with HD patients. In PD patients, ACE‐I therapy reduces dialysate K⁺. These changes may result from reduced peritoneal movement of K⁺.     

Does Potassium Ion Concentration Affect Lung Preservation?

+ , 0 mmol/l K⁺; (2) 150 mmol/l Na⁺, 5 mmol/l K⁺; (3) 20 mmol/l Na⁺, 135 mmol/l K⁺; and (4) 0 mmol/l Na⁺, 155 mmol/l K⁺. All four solutions possessed the same osmolarity, the same pH in the same temperature, and the same buffer action. Lungs were preserved at 7°C in these solutions for 24 h and evaluated in a rat lung perfusion system with perfluorochemical emulsion. Pressure-limited perfusions with pressure-limited ventilation were carried out for 20 min before and after preservation. Thereafter, the recovery ratios of pulmonary arterial flow (Q˙), tidal volume (V _T), oxygen tension of the pulmonary venous effluent (P_PVO₂), and wet-to-dry ratios were compared. The recovery ratios of Q˙ were better in low, but not zero, potassium solutions, whereas wet-to-dry ratios were kept lower in high potassium solutions. No difference in pulmonary compliance or gas exchange was observed against a great change in potassium ion concentration. Therefore, the potassium ion concentration did not play a major role in lung preservation. (Received for publication on June 19, 1996; accepted on May 12, 1997)     

Electrophysiological properties of osteoblastlike cells from the cortical endosteal surface of rabbit long bones

Summary The mean transmembrane potential of cultured osteoblastlike cells isolated from the cortical endosteal surface of rabbit long bones was −16.9±0.64 mV (n=335). Elevation of potassium concentration in medium caused a decrease in potential. As the external concentration of potassium reached 15 mmol/liter and above, there was a linear relationship between the potassium concentration in log scale and the membrane potential with a slope of −13 mV per 10-fold change in external potassium concentration. Dibutyryladenosine 3′,5′-cyclic monophosphate, parathyroid extract, hydrocortisone, and sodium fluoride all depolarized the membrane of osteoblast-like cells after both short (1–2 h) and long (24 h) exposures at suitable doses, whereas calcitonin and prostaglandin E₂ hyperpolarized the membrane after long exposures. The Na⁺, K⁺ and Cl⁻ concentrations of cultured osteoblastlike cells were 0.538, 0.984, and 0.358 mmol/g protein or 52.6, 96.3, and 35.0 mmol/liter cell water, respectively. The protein content of these cells was 8.18±0.6 g/100 g cells and the water content was 83.7 g/100 g cells. The above-mentioned chemical and hormonal preparations in doses that produced significant changes in the membrane potential of these cultured cells did not alter their electrolyte or protein contents 24 h after exposure. Intracellular pH of cultured osteoblastlike cells as determined by [¹⁴C]-dimethyloxazolidine-2,4-dione and³H₂O averaged 7.03 ± 0.11 when the pH of culture medium was maintained at 7.4. Calculations based on the values for the membrane potential and the electrolyte concentrations observed in this study indicate that Na⁺, and H⁺, and Cl⁻ are actively transported out of the cells and K⁺ into the cells.     

Phosphate Kinetics During Weekly Cycle of Hemodialysis Sessions: Application of Mathematical Modeling

Both hyperphosphatemia and hypophosphatemia are associated with increased morbidity and mortality among patients on dialysis. The control of serum phosphate concentration is a considerable clinical problem. Our study aimed to improve understanding of phosphate kinetics in patients on dialysis using mathematical modeling. Three consecutive hemodialysis sessions with breaks of 2–2–3 days were monitored in 25 patients. Phosphate concentration was measured every hour and 45 min after the end of dialysis in blood serum and every 30 min in dialysate during each session. Volume of fluid compartments and body composition were assessed by bioimpedance. The pseudo one‐compartment model was applied to describe the profile of phosphate in blood serum during intra‐ and interdialytic periods of 1‐week cycle of three hemodialysis sessions. Model parameters, such as phosphate internal clearance (K_M) and the rate of phosphate mobilization (R_M), were correlated with the reduction of serum phosphate concentration during dialysis (C_post/C_pre) and with equivalent continuous clearance (ECC) for phosphate. K_M correlated negatively with predialysis serum phosphate concentration. There was significant positive correlation between R_M and age. Postdialysis volume of phosphate central compartment was lower than, but correlated to, extracellular water volume. Parameters of the pseudo one‐compartment model, phosphate internal clearance, and the rate of phosphate inflow to the central compartment (the one accessible for dialysis) from other phosphate body reservoirs correlated with the indices of dialysis adequacy, such as reduction of serum phosphate and ECC. The pseudo one‐compartment model can be successfully extended from a single hemodialysis to the standard weekly cycle of sessions and the model parameters strongly correlate with the adequacy parameters of dialytic removal of phosphate.     

INSULIN AND MINERALOCORTICOIDS INFLUENCE ON EXTRARENAL POTASSIUM METABOLISM IN CHRONIC HEMODIALYSIS PATIENTS

Insulin-mineral corticoids effects on extrarenal K⁺ metabolism in dialysis patients. During the inter-dialytic interval in dialyzed patients, hydrogen and potassium ions are regulated by extrarenal mechanisms. We studied the hormonal and acidotic effects on the extrarenal potassium metabolism, in selected, anuric and stable, hemodialysis patients. Fifteen patients, were grouped according to the mean mid-week pre-dialysis K⁺ over the past 12 months: > 6.0 mEq/L (G1, n = 5), = 5.1–6.0 mEq/L (G2, n = 5), ≤5.0 mEq/L (G3, n = 5). After a mid-week hemodialysis session and 12 h fasting, they received 1 g/Kg glucose p.os (A). Insulin, aldosterone, renin, pH, HCO₃^?, glucose, body weight, blood pressure and heart rate were measured before and 60′ after the meal. We recorded the same parameters, except insulin, in 15 patients, similarly grouped, before hemodialysis (T0) and on 3 consecutive off dialysis days (T1–T3); G1 received fluorohydrocortisone (FHC) 0.1 mg–0.3 mg/day, according to body weight and G3 spironolactone (SLT) 200 mg per day. G2 were controls (B). (A) A significant rise in glycemia (81 ± 23 to 157 ± 52 mg/dL, P < 0.001) and insulin (11.8 ± 6.2 to 46.8 ± 19.5 μU/mL, P<0.001), with a drop in K⁺ (5.1 ± 0.6 to 4.8 ± 0.7 mEq/L, P= 0.001) and aldosterone (453 ± 373 to 383 ± 364 pg/mL, P<0.01), were noted at T60 vs. T0, in all groups. Insulin levels correlated negatively (r = ?0.54, P<0.04) to serum K⁺ at T60, in all patients. (B) No major pH, HCO₃ and aldosterone changes were observed in the 3 groups. Despite that, K⁺ dropped in G1 by FHC (6.7 ± 0.9 to 5.9 ± 0.6 mEq/L, P<0.05), rose in G3 by SLT (4.4 ± 0.4 to 5.4 ± 0.3 mEq/L, P<0.05) and remained unchanged in controls (5.8 ± 0.2 to 5.8 ± 0.6 mEq/L), (T0 vs T3 pre-dialysis values). Glucose significantly lowered K^? by promoting adequate insulin secretion. Drugs affecting aldosterone action significantly influenced potassium metabolism. Acid-base balance was not important in K⁺ handling in steady state anuric dialysis patients.     

Automated individualization of dialysate sodium concentration reduces intradialytic plasma sodium changes in hemodialysis

In standard care, hemodialysis patients are often treated with a center‐specific fixed dialysate sodium concentration, potentially resulting in diffusive sodium changes for patients with plasma sodium concentrations below or above this level. While diffusive sodium load may be associated with thirst and higher interdialytic weight gain, excessive diffusive sodium removal may cause intradialytic symptoms. In contrast, the new hemodialysis machine option “Na control” provides automated individualization of dialysate sodium during treatment with the aim to reduce such intradialytic sodium changes without the need to determine the plasma sodium concentration. This proof‐of‐principle study on sodium control was designed as a monocentric randomized controlled crossover trial: 32 patients with residual diuresis of ≤1000 mL/day were enrolled to be treated by high‐volume post‐dilution hemodiafiltration (HDF) for 2 weeks each with “Na control” (individually and automatically adjusted dialysate sodium concentration) versus “standard fixed Na” (fixed dialysate sodium 138 mmol/L), in randomized order. Pre‐ and post‐dialytic plasma sodium concentrations were determined at bedside by direct potentiometry. The study hypothesis consisted of 2 components: the mean plasma sodium change between the start and end of the treatment being within ±1.0 mmol/L for sodium‐controlled treatments, and a lower variability of the plasma sodium changes for “Na control” than for “standard fixed Na” treatments. Three hundred seventy‐two treatments of 31 adult chronic hemodialysis patients (intention‐to‐treat population) were analyzed. The estimate for the mean plasma sodium change was ?0.53 mmol/L (95% confidence interval: [?1.04; ?0.02] mmol/L) for “Na control” treatments and ?0.95 mmol/L (95% CI: [?1.76; ?0.15] mmol/L) for “standard fixed Na” treatments. The standard deviation of the plasma sodium changes was 1.39 mmol/L for “Na control” versus 2.19 mmol/L for “standard fixed Na” treatments (P = 0.0004). Whereas the 95% CI for the estimate for the mean plasma sodium change during “Na control” treatments marginally overlapped the lower border of the predefined margin ±1.0 mmol/L, the variability of intradialytic plasma sodium changes was lower during “Na control” versus “standard fixed Na” treatments. Thus, automated dialysate sodium individualization by “Na control” approaches isonatremic dialysis in the clinical setting.     

Effect of Radiocontrasts on Selected Membrane Transport Systems

Background. This study was aimed at examining the effects of radiocontrast agents on selected membrane transport functions. Methods. The effect of diatrizoate sodium (DS), diatrizoate meglumine (DM), and diatrizoate compound (DC) on Na⁺/K⁺ pump activity and number, L-arginine, and choline transports were evaluated in erythrocytes of normal individuals and patients undergoing cardiac catheterization. Results. Normal individuals' erythrocytes potassium influxes were 1.50 ± 0.35, 1.32 ± 0.37, 1.28 ± 0.30, and 1.01 ± 0.25 mmol/L cell/h in control, DS, DM, and DC groups, respectively (P = 0.004; DC vs. control). Patients exposure to Hypaque M-76® significantly diminished Na⁺/K⁺ pump activity (1.40 ± 0.36 before, vs. 1.27 ± 0.40 mmol/L cell/h after; P = 0.039). The number of Na⁺/K⁺ pumps was reduced (156 ± 36 vs. 143 ± 34 pumps/erythrocyte; P = 0.015) in presence of DS. L-arginine and choline transports changed only at high radiocontrast concentrations. Conclusion. Selective changes in erythrocytes membrane transport function take place on exposure to radiocontrasts.     

Carbon Dioxide and Acetate‐Free Biofiltration: A Relationship to be Investigated

As the name reveals, acetate‐free biofiltration (AFB) is featured by lack of acetate and this would seem to allow better hemodynamic stability. However, AFB also has a unique characteristic of carbon dioxide (CO₂)‐free dialysate, whereas all other modern dialysis techniques imply an overload of CO₂ from dialysate to the patient. This notwithstanding the role of CO₂ in tolerance to dialysis treatment, both AFB and all other dialysis techniques seem not investigated in due depth. Specifically, the amount of CO₂ coming back to the patient's bloodstream during AFB and bicarbonate dialysis (BD) is unknown. We measured partial pressure of CO₂ (pCO₂) in blood samples withdrawn from the venous line of the extracorporeal circuit during BD and subsequently during AFB in 22 stable chronic hemodialysis outpatients. The amount of CO₂ coming back to the patient's bloodstream is higher in BD (59.1 ± 4.0 mmol/L) than in AFB (42.8 ± 4.5 mmol/L, P < 0.0001). Such difference exceeds 30%. Moreover, shifting from BD to AFB shows, notably for each patient, the reduction of pCO₂ toward physiological values. BD implies CO₂ overload from dialysate, whereas AFB does not. Further studies are required to evaluate if AFB would be the most appropriate dialysis technique in patients affected by chronic, but especially acute, lung diseases.     

Impaired EDHF-Mediated Relaxation in Porcine Pulmonary Micro-Arteries by Cold Storage with University of Wisconsin and Euro-Collins Solutions

Background: Vascular endothelium plays a key role in regulation of vascular tone. Hyperkalemia has been demonstrated to impair the EDHF‐mediated endothelial function in coronary circulation. University of Wisconsin (UW) and Eruo‐collins (EC) solutions are used for organ preservation in transplantation surgery. The potassium concentration in UW or EC solutions is as high as 125 mmol/L or 115 mmol/L, respectively. This study was designed to examine whether hyperkalemia or storage with UW and EC solutions affects the relaxation mediated by EDHF in the porcine pulmonary micro‐arteries. Methods: Porcine pulmonary micro‐artery rings (diameter 200–450 μm) were studied in myograph (n = 8 in each group). After incubation with hyperkalemia (K⁺ 125 mmol/L, at 37° C), UW or EC solutions (at 4° C for 4 hours), EDHF‐mediated relaxation induced by bradykinin (BK, ?10 to ?6.5 log M) in the presence of inhibitors for cyclooxygenase (Indomethacin, 7 μM), nitric oxide synthase (N^G‐nitro‐_L‐arginine, 300 μM), and oxyhemoglobin (20 μM) was compared with control (Krebs' solution) in precontraction with U₄₆₆₁₉ (?7.5 log M). Results: The EDHF‐mediated relaxation to BK was 69.6 ± 6.3% compared with 97.1 ± 1.7% (p= 0.003) in control (no inhibitors). After incubation with hyperkalemia, the relaxation significantly decreased (38.6 ± 3.0% vs. 59.1 ± 7.4%, p= 0.03 ). Storage with UW or EC solutions also significantly decreased the relaxation (49.3 ± 7.3% vs. 65.2 ± 3.5%, p= 0.04 and 51.9 ± 8.4% vs. 60.3 ± 6.1%, p= 0.02 , respectively). Conclusions: In porcine pulmonary micro‐arteries, exposure to hyperkalemia or storage with UW or EC solutions at 4°C for 4 hours impairs the EDHF‐mediated endothelial function. The clinical significance of this effect should be further studied.     

Pharmacokinetics of Certoparin During In Vitro and In Vivo Dialysis

The efficacy and safety of certoparin in the prophylaxis of clotting during hemodialysis have recently been proven. Different to other low‐molecular weight heparins (LMWHs), certoparin does not accumulate in maintenance dialysis patients for unknown reasons. The purpose of the present study was to examine the impact of the dialysis procedure on the removal of certoparin. In a subgroup of the MEMBRANE study consisting of 12 patients, the pharmacokinetics of certoparin during hemodialysis was determined by means of the anti‐Xa activity. In addition, the elimination of certoparin into continuously collected dialysate was assessed. Further, in vitro experiments with human blood‐simulating high‐flux hemodialysis and hemofiltration were performed to quantify the elimination and the sieving coefficients S_K of the two LMWHs certoparin and enoxaparin compared with unfractionated heparin (UFH). The surrogate marker middle molecules inulin and myoglobin served as reference solutes during the experiments. Finally, the adsorption of ¹²⁵iodine‐radiolabeled certoparin onto the synthetic dialysis membrane was quantified. The clinical study reconfirmed the absence of bioaccumulation of certoparin with anti‐Xa activities between <0.01 and 0.02 IU/mL after 24 h. A short plasma half‐life time of 2.0 ± 0.7 h was determined during hemodialysis. Of the total certoparin dose injected intravenously prior to hemodialysis, only 2.7% was eliminated into dialysate. The in vitro experiments further revealed only 6% of certoparin to be adsorbed onto the dialysis membrane. The anti‐Xa activities of certoparin and enoxaparin slowly declined during in vitro hemofiltration to 87.3 ± 5.5 and 82.5 ± 9.4% of baseline, respectively, while inulin and myoglobin concentrations rapidly decreased. The anti‐Xa activity of UFH remained unchanged. The S_K of both LMWH and UFH was very low in hemofiltration and particularly in hemodialysis with values ≤0.1. The elimination kinetics during hemodialysis suggests strong protein‐binding of certoparin. Different from LMWH significantly cleared by the kidneys, the relatively short half‐life time of certoparin of only 2 h during hemodialysis allows a more reliable control of the anti‐coagulatory effects and decreases the risk of bleeding complications. Dialytic removal does not significantly contribute to the clearance of certoparin in maintenance dialysis patients.     

Sequential hypertonic haemodialysis in children

Sequential hypertonic dialysis (SHD) was studied in two binephrectomized children over a period of 6 weeks. Each dialysis session comprised four periods of 45 min. The concentration of sodium in the dialysate [Na(D)] during the first period was 190 mmol/l and during the second period 140 mmol/l. The sequence was then repeated. The sodium-free water clearance [C(ONa)] was calculated from the measurements of the ultrafiltrate clearance and of the sodium clearance. Despite the short periods of hypertonic dialysis, C(ONa) was positive, suggesting that water was removed from the intracellular compartment as well as from the extracellular fluid. The transfer of fluid from the intracellular space improved circulatory stability during rapid removal of large volumes of fluid by ultrafiltration. SHD was also associated with increased removal of potassium and phosphate. Comparison of clinical parameters before and during SHD showed a tendency towards increased sodium balance and the possibility of raised cardiovascular morbidity. SHD stabilized blood volume during ultrafiltration, encouraging removal of uraemic toxins. SHD with this levels of Na(D) is only a study dialysis method.     

Low-sodium haemodialysis without fluid removal improves blood pressure control in chronic haemodialysis patients

SUMMARY: Hypertension is an important and well‐established risk factor for both cardiovascular and cerebrovascular disease. Hypertension is much more common in patients on renal replacement therapy than in the general population. Up to 80% of patients on renal replacement therapy are hypertensive and about 50% of dialysis patients die from cardiovascular causes. Salt and water overload are major factors exacerbating hypertension in the dialysis population. This was a prospective crossover study of 10 patients examining the effect of haemodialysis for 2 weeks using usual (Na⁺ 138–140 mmol/L) sodium dialysate with a 2‐week period of low (reduced by an average of 5 mmol/L Na⁺ to 133 mmol/L on average) sodium dialysate on inter‐dialytic ambulatory blood pressure (ABPM) and trans‐thoracic bioimpedance (TTB). Ten patients, mean age 67 years, completed the study (two women and eight men). No patient became severely hyponatraemic during the study period. Mean 48 h inter‐dialytic blood pressure (BP) fell from 141/83 to 133/78 (P < 0.01). Mean arterial BP measured immediately prior to TTB fell from 92.8 mmHg to 87.5 mmHg (P < 0.01) during the low‐sodium haemodialysis period. Afterload (systemic vascular resistive index – SVRI) measured by TTB fell significantly during the low‐sodium haemodialysis period (SVRI on Na⁺‐140 = 3426 cf. Na⁺‐134 = 2281; P = 0.01). Dialysate sodium reduction without extra fluid removal had a beneficial effect on inter‐dialytic 48‐h blood pressure in chronic stable haemodialysis patients. Lowering dialysate sodium reduced the systemic vascular resistance index as measured by TTB. Reduction of dialysate sodium was well tolerated, although mild dizzines and cramps did occur. These data suggest that sodium overload and water overload may have independent effects on BP and that simple‐to‐achieve and modest changes in dialysate sodium could usefully augment the action of antihypertensives in dialysis patients.     

Comparison of dialysis adequacy at two dialysate potassium concentrations

SUMMARY: It has been suggested that haemodialysis adequacy is greater dialysing against a 3 mmol/L potassium dialysate concentration than against a 1 mmol/L potassium concentration. As most dialysis patients dialyse against 1 or 2 mmol/L potassium, the dialysis adequacy at these two potassium concentrations was compared. Ten stable haemodialysis patients were randomly assigned to dialyse against 1 mmol/L potassium dialysate (K1) followed by 2 mmol/L potassium dialysate (K2) or vice versa. All other dialysis parameters were held stable. The mean urea reduction ratio was 68.3 ± 6.2 using K1 and 69.5 ± 6.4 using K2 ( P < 0.05 using Wilcoxon for paired data). The Kt / V , however, did not differ (1.39 ± 0.23 for K1 and 1.41 ± 0.23 for K2). The urea rebound was also not different between K1 and K2, with a trend to higher rebound using K2. The percentage rebound in urea was 6.0 ± 2.5 for K1 and 7.1 ± 2.8% for K2. In this setting, K2 dialysate offered no advantage in terms of urea rebound or Kt/V. Based on previously published data, a dialysate potassium concentration of 3 mmol/L may be required to achieve significant benefit in terms of dialysis adequacy.     

Does a reduction in dialysate sodium improve blood pressure control in haemodialysis patients?

Introduction: There has been debate as to the value of lower sodium dialysates to control blood pressure in haemodialysis patients, as sodium is predominantly removed by ultrafiltration. Methods: Re‐audit of clinical practice following reduction in dialysate sodium concentration. Results: Overall dialysate sodium concentration decreased from 138.9 ± 1.7 to 137.8 ± 1.7 mmol/L (mean ± standard deviation), resulting in a reduction in pre‐ and post‐dialysis mean arterial pressure (MAP) of 4 mmHg (from 100.6 ± 15.6 to 97.1 ± 15.6, P < 0.01 and from 91.7 ± 15.6 to 87.1 ± 14.6, P < 0.001 respectively), yet fewer patients were prescribed antihypertensives (49.6 vs 60.6%), and less antihypertensive medications/patient (mean 0.86 vs 1.05), ultrafiltration requirements (2.8% vs 3.2% body weight, P < 0.001), and symptomatic intradialytic hypotension (0.19 vs 0.28 episodes per week, P < 0.001). A multivariable model showed that for a dialysate sodium of 136 mmol/L, younger patients had higher MAP than older patients (0.35 mmHg lower MAP/year older; but with a dialysate sodium of 140 mmol/L, there was minimal association of MAP with age (0.07 mmHg higher MAP/year older). Conclusion: Change in clinical practice, amounting to a modest reduction in dialysate sodium was associated with a reduction not only in pre‐ and post‐dialysis blood pressures, but also ultrafiltration requirements and symptomatic intradialytic hypotension. However, this effect on blood pressure was most marked for older patients and women, within minimal effects for younger patients, and lesser effects for men, suggesting that dialysate sodium reduction alone may help improve blood pressure control, but requires additional factors such as dietary sodium restriction to be effective in younger male patients.     

Protective Roles of Polyethylene Glycol and Trimetazidine against Cold Ischemia and Reperfusion Injuries of Pig Kidney Graft

Ischemia‐reperfusion injury (IRI) represents an allo‐independent risk factor which favors chronic allograft nephropathy (CAN). Here we analyzed the influence of preservation solutions on the function of autotransplanted pig kidneys over 1–16 weeks after surgery. Kidneys were cold‐flushed and cold‐stored for 24 or 48 h either in University of Wisconsin (UW), modified‐UW Hôpital Edouard Herriot, polyethylene glycol 20 kDa (PEG)‐supplemented preservation solutions with low K⁺ (ECPEG) or high K⁺ (ICPEG) content. Animals autotransplanted with kidneys cold‐stored for 24 h in ECPEG exhibited the greatest levels of creatinine clearance (C_cr: 161 ± 12 mL/min, n = 10) and the lowest levels of proteinuria (0.5 ± 0.03 mg/mL) 16 weeks after surgery as compared with pigs autotransplanted with kidneys cold‐stored in the other solutions tested (C_cr ranging from 80 and 140 mL/min). Similar differences, but with lower C_cr levels, were achieved after a prolonged period of cold‐storage(48 h). ECPEG better preserved the kidneys from monocytes/macrophages and CD4⁺ T cells infiltrations, VCAM‐1 and MHC class II overexpressions and occurrence of renal interstitial fibrosis (2%) as compared with the other preservation solutions (5%–20%). Adding the anti‐ischemic drug trimetazidine (TMZ) to the preservation solutions, particularly ECPEG, further improved the quality of the week‐16 post‐transplanted kidneys (C_cr: 182 ± 12 mL/min, n = 10). These findings demonstrated that adding PEG to extracellular‐like (with low K⁺ content) preservation solutions in combination with TMZ significantly improved the long‐term outcome of kidney grafts in this model of autotransplanted pig kidney.     

A comparison between residual renal function and peritoneal clearance for Na/H2O and urea removal in peritoneal dialysis patients

Background: To compare the Na/H₂O and urea removal between residual renal function (RRF) and peritoneal clearance (PC) in peritoneal dialysis patients. Try to explore the difference between RRF and PC in prognosis of chronic kidney disease patients who need peritoneal dialysis (PD) treatment. Methods: Weekly Na/H₂O and urea removal by PC and RRF were investigated individually. Independent samples t-test was carried out to compare the efficiency of removal between RRF and PC treatment. Pearson correlated analysis was applied to reveal the relationship between Na/H₂O and urea removal and Kt/V. Results: Although a higher Na/H₂O removal rate by RRF was showed in this investigation, the difference was not statistical significant compared to the one by PC. On the other hand, urea removal by RRF was obviously higher than PC. For every 0.1?Kt/V, Na/H₂O removal by RRF was distinctly higher than PD. The Na and H₂O removal of RRF were 147.88?±?83.72?mmol and 46.54?±?39.11?mmol, respectively; and the ones of PD were 11.40?±?6.08?mmol and 4.47?±?4.79?mmol. By using statistical assay, the correlations relevance between Na/H₂O removal and Kt/V in RRF were showed stronger than in PC. However, the total removal of Na/H₂O showed a poor correlation with Kt/V in both RRF and PC. Conclusions: The removal efficiency of RRF is much higher than PC. This study suggests that it is important to adjust dialysis program when RRF gets declined. Also the correlation between Na/H₂O removal rate and Kt/V is an important monitoring factor for the patients who are receiving peritoneal dialysis.     

Substitution of Acetic Acid for Hydrochloric Acid in the BicarbonateBuffered Dialysate

Abstract: In a multicenter study including 5 dialysis units, blood acetate changes during 4 h dialysis sessions in 141 patients treated with a 4 mM acetate-containing bicarbonate dialysate (ABD) were evaluated and compared to the values of 114 patients using an acetate-free bicarbonate dialysate (AFD). Acetate-free bicarbonate dialysate was delivered by a dialysis machine from the mixing with water for dialysis of a 1/26.2 bicarbonate concentrate, and a 1/35 acid-concentrate in which acetic acid was substituted for hydrochloric acid (Soludia, Fourquevaux, France). This new type of dialysate was routinely in use for 3 years on average (range, from 2 to 5 years). All patients fasted before and during dialysis. Blood samples were withdrawn at the start and at the end of dialysis sessions. The acetate plasma concentration was determined using the acetyl-CoA synthetase enzymatic method (Boehringer, Manheim, Germany). In patients treated with ABD whose predialysis blood acetate levels were in the physiologic range of ≤100 μM (n = 113), the acetate plasma concentration increased from a predialysis mean value of 22 ± 3 μM to a postdialysis mean value of 222 ± 11 μM in 88 patients (78% of patients) whereas the acetate plasma concentration changes remained in the range of physiologic values from 21 ± 6 to 58 ± 7 μM in the other 25 patients. In contrast, patients treated with AFD whose predialysis blood acetate levels were in the physiologic range (n = 108), acetate plasma concentration increased from a predialysis mean value of 49 ± 6 μM to 160 ± 19 μM in only 13 patients (12% of patients) whereas acetate plasma concentration changes remained in the range of physiologic values of 23 ± 2 to 41 ± 3 μM in most of the patients of this group. In this study, a significant number of patients, whether receiving standard or acetate-free bicarbonate dialysates, exhibited an extremely high acetate plasma concentration at the start of the dialysis session. Hyperacetatemia was controlled with AFD in patients whose predialysis acetate plasma concentration of 316 ± 82 decreased to 55 ± 23 μM (n = 6) at the end of the dialysis session whereas the acetate plasma concentration remained high when the predialysis concentration was 580 ± 76 μM, with a postdialysis concentration of 233 ± 39 μM (n = 28). It is concluded that in patients whose predialysis blood acetate levels were in the physiologic range, acetate-containing bicarbonate dialysate induces hyperacetatemia whereas postdialysis blood acetate remains in the normal range in such dialysis patients treated with acetate-free dialysate. Chronic hyperacetatemia, which could be found in dialysis patients, is well controlled by dialysis using an acetate-free dialysate.