Sodium ramping reduces hypotension and symptoms during haemodialysis

OBJECTIVES

To evaluate the effectiveness of sodium ramping (profiling) in reducing hypotensive episodes and symptoms during haemodialysis.

DESIGN

Prospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

Thirteen patients who experienced frequent episodes of hypotension and/or symptoms such as cramps, dizziness, chest pain, nausea, vomiting, and headache during haemodialysis in the preceding 4 weeks.

INTERVENTIONS

Each patient was switched from standard haemodialysis with a constant dialysate sodium concentration of 135 to 140 mmol/L to a ramped sodium haemodialysis for a period of 4 weeks. During this time the dialysate sodium concentration was ramped linearly downwards from 150 mmol/L at the beginning of dialysis to 140 mmol/L at the end of dialysis.

MAIN OUTCOME MEASURES

Intradialytic hypotensive episodes, intradialytic symptoms, nursing interventions, systolic and diastolic blood pressures, and interdialytic weight gain.

RESULTS

A total of 248 haemodialysis sessions undertaken by 13 patients were analysed. Switching from constant sodium haemodialysis to ramped sodium haemodialysis resulted in a significant reduction in the number of intradialytic hypotensive episodes from 5.8 (standard deviation, 6.4) to 2.2 (3.3) [P<0.05], the total number of intradialytic symptoms from 7.1 (3.4) to 0.9 (1.3) [P<0.01], and nursing interventions from 11.3 (6.3) to 1.7 (3.9) [P<0.01]. Post-dialysis systolic and diastolic blood pressures were higher during ramped sodium haemodialysis compared with constant sodium haemodialysis (systolic blood pressure, 139 [standard deviation, 23] vs 133 [22] mm Hg, P<0.001; diastolic blood pressure, 77 [11] vs 74 [13] mm Hg, P<0.01), and there was a trend towards a smaller drop in blood pressure after dialysis. The interdialytic weight gain with sodium ramping haemodialysis was greater compared with constant sodium haemodialysis (3.1 [standard deviation, 1.0] vs 2.7 [1.1] kg, P<0.001).

CONCLUSION

Sodium ramping during haemodialysis effectively reduces hypotensive episodes and intradialytic symptoms. Post-dialysis blood pressure is better maintained. A side-effect of sodium ramping is a greater interdialytic weight gain.

Therapeutic approach in patients with dysnatraemias

BACKGROUND

Rapid correction of dysnatraemias is frequently associated with increased morbidity and mortality. Therefore, it is important to estimate the proper volume and type of infusate required to change the serum sodium concentration predictably. The aim of this study is to evaluate the utility or/and the accuracy of the Adrogue-Madias formula in managing patients with hyponatraemia and hypernatraemia.

METHODS

Among the 317 patients who either on admission to our internal medicine clinic or during their hospitalization were found to have hyponatraemia or hypernatraemia, we studied 189 patients (59.6%) in whom the administration of intravenous solutions was required for the correction of dysnatraemias.

RESULTS

Twelve hours after starting the administration of intravenous solutions the anticipated as well as the achieved serum sodium concentration were as follows: in volume depleted patients 130.2+/-4.1 vs 131.3+/-5.2 meq/l (n = 45; P = NS), in syndrome of inappropriate antidiuretic hormone secretion (SIADH) patients 127.4+/-5.7 vs 128.9+/-5.9 meq/l (n = 10; P = NS), in patients with diuretic-induced hyponatraemia 123.8+/-6 vs 125.5+/-5.6 meq/l (n = 29; P = NS), in patients with primary polydipsia 122.5+/-0.7 vs 129+/-1.4 meq/l (n = 2; P = 0.02), while in patients with hypernatraemia 153.6+/-7.5 vs 156.5+/-8.9 meq/l (n = 92; P = 0.021). Furthermore, 24 h from the initiation of the therapeutic intervention the expected and the achieved serum sodium concentrations were 130+/-4 vs 135.6+/-3.3 meq/l (n = 15; P = 0.002) in patients with volume depletion, 128.1+/-4.8 vs 130+/-4.5 meq/l (n = 15; P = NS) in patients with diuretic-induced hyponatraemia and 151.5+/-6.4 vs 153.3+/-8.3 meq/l (n = 67; P = NS) in patients with hypernatraemia.

CONCLUSIONS

The formula that has been proposed by Adrogue and Madias predicted with relative accuracy the changes in serum sodium concentration in almost all patients. Thus, it should be considered as a very useful tool for the management of dysnatraemias. However, special attention should be paid when this equation is used in patients with hyponatraemia due to extracellular volume depletion after euvolaemia's restoration and primary polydipsia in order to avoid rapid correction of hyponatraemia.

Effect of trimethoprim-sulfamethoxazole on Na and K+ transport properties in the rabbit cortical collecting duct perfused in vitro

BACKGROUND

In this study, the membrane mechanisms of hyperkalemia caused by trimethoprim-sulfamethoxazole (TMP-SMX) combination antibiotics were assessed in the cortical collecting duct (CCD).

METHODS

We used the microelectrode technique and flux measurements, and examined the effects of TMP and SMX on electrical properties of the apical and basolateral membranes in the rabbit CCD perfused in vitro.

RESULTS

TMP in the lumen caused increases in apical membrane voltage, fractional apical membrane resistance (fRA), and transepithelial resistance (RT), all effects which were completely inhibited by luminal amiloride, but not by luminal Ba2+. The luminal TMP inhibited both net Na+ reabsorption and K+ secretion in the CCD. TMP in the bath slightly but significantly depolarized transepithelial voltage and basolateral membrane voltage without influencing fRA or RT. SMX in the lumen or bath had no effect on barrier voltages or resistances.

CONCLUSION

TMP mainly acts on the apical membrane of the CCD, inhibits the amiloride-sensitive macroscopic Na+ conductance in this membrane, and thereby decreases the net driving force for K+ exit across the membrane, resulting in an inhibition of K+ secretion. SMX in the lumen or bath had no effect on the CCD.

Cardiorenal abnormalities associated with high sodium intake: correction by spironolactone in rats

Reversal by the mineralocorticoid receptor antagonist spironolactone on cardiac and renal abnormalities, associated with long-term (since weaning) administration of a high (2 and 8% NaCl chow, HS2 and HS8) sodium diet, was assessed in Sprague-Dawley rats. At the age of 5 mo, spironolactone (20 or 100 mg/kg, gavage) or placebo were given for 14 days to HS2 and HS8 rats. A group fed a regular diet (0.8% NaCl, NS) remained untreated. High sodium intake had no detectable effect on blood pressure; however, cardiac mass index and cross-sectional area of the carotid artery, as well as albuminuria, were increased only in the HS8 group compared with the control group on NS diet. In addition, a marked reduction in glomerular filtration rate (by 40%), associated with a nonproportional fall in renal plasma flow (thus resulting in a decrease in filtration fraction), was observed only in the HS8 group. No change in cardiac and renal fibrosis was detected. Production of the reactive oxygen species (ROS) by aortic tissue was increased in HS8 rats, whereas ROS production by the heart was unaffected. Only the high dose of spironolactone was effective, as it markedly reversed the cardiac hypertrophy and renal hypofiltration associated with the HS8 feeding. The changes were observed in the absence of any effect on systemic blood pressure and production of ROS. These observations favor aldosterone’s role in the deleterious effects of marked and prolonged increases in sodium intake.

Expression of endothelial nitric oxide synthase is suppressed in the renal vasculature of angiotensinogen-gene knockout mice

We have attempted to elucidate the mechanism by which endothelial-type nitric oxide synthase (eNOS) is regulated in the kidney, with special reference to the role of renal hemodynamics and angiotensin II (Ang II). We compared angiotensinogen gene knockout (Atg-/-) mice, which lacked Ang II (resulting in sodium/water depletion and severe hypotension), with wild-type (Atg+/+) mice. Using Western blot analysis and the NADPH diaphorase histochemical reaction, we found that the expression and activity of eNOS were markedly lower in the renal vessels of Atg-/- mice compared with wild-type (Atg+/+) mice. Dietary salt loading significantly enhanced renal eNOS levels and increased blood pressure in Atg-/- mice, but severe hypotension almost abolished the effects of salt loading. In contrast, in Atg+/+ mice, altered salt intake or hydralazine had no effect on renal eNOS levels. These results suggest that perfusion pressure plays an essential role in maintaining renal vascular eNOS activity, whereas Ang II plays a supportive role, especially when renal circulation is impaired.

[Effect of sodium-rich diet and captopril on the functional state of kidney in rats with experimental hyperthyreosis]

The administration of thyroxin (10 microg/100 g body weight, 7 days) in rats leads to an increase in the renal excretion of proteins and nitrates. Under the conditions of hypo- and normosodium diet, thyroxin decreased the rate of glomerular filtration. Hypersodium diet and captopril increased the rate of glomerular filtration in rats with experimental hyperthyreosis. The maximum level of renal excretion in hyperthyreoidal rats was observed on the background of sodium-rich diet.

[Coupling of protease activity and sodium loading with intestinal absorption of amino acids]

Membrane-bound serine proteases to play a certain role in activation of sodium transport in epithelial cells. To were found explain the protease activity and sodium-dependent L-tryptophan transport across chicken small intestine interaction, four experiments were conducted. One hundred chicks were fed diets that contained 0; 0.3; 3 or 6% of supplemental NaCl and were given distillated water ad libitum. Signs of salt toxicity observed were as follows: a decreased body weight, increased heart and kidney weights, formation of secondary lysosomes in enterocytes and lymphocytes. Such chickens were in the state of negative nitrogen balance. Intestinal absorption of L-tryptophan correlated with mucosal protease activity during increased dietary sodium chloride intake. Recent in vitro and in vivo experiments indicate that enterocyte proteases may be of critical importance in activation of sodium-dependent intestinal transporters for L-tryptophan.

Randomized calcineurin inhibitor cross over study to measure the pharmacokinetics of co-administered enteric-coated mycophenolate sodium

Enteric-coated mycophenolate sodium (EC-MPS) (myfortic) is an advanced formulation delivering mycophenolic acid (MPA), designed to improve MPA-related upper gastrointestinal adverse events by delaying the release of MPA until the small intestine. A randomized, calcineurin inhibitor crossover, steady-state pharmacokinetic study in stable renal transplant patients receiving EC-MPS demonstrated increased MPA exposure of 19% higher, MPA C(max,ss) 19% lower and MPA C(min,ss) approximately twofold higher with tacrolimus, than cyclosporine microemulsion. No study drug-related adverse events were recorded, but mean blood glucose concentration was higher in patients receiving tacrolimus (p = 0.031). The dose changes in relation to MPA exposure in patients is dependent on the clinical situation and may not always be warranted. These observations should be taken into consideration when switching from one calcineurin inhibitor to another, but the final dosage should be based on both this pharmacokinetic data and the clinical situation.

Effects of sodium intake on plasma potassium and renin angiotensin aldosterone system in conscious dogs

AIMS

The operating range of the renin-angiotensin-aldosterone system is ill-defined. This study quantifies renin-angiotensin-aldosterone system activity as a function of sodium intake.

METHODS

Renin-angiotensin-aldosterone system variables were measured daily after a sudden reduction in sodium intake (3.0-0.5 mmol kg(-1) day(-1)) or at steady states generated by eight levels of sodium intake (0.5-8.0 mmol kg(-1) day(-1)). Potassium intake was 2.79 +/- 0.03 mmol kg(-1) day(-1). Arterial blood pressure was measured invasively. Hormone concentrations were determined by radioimmunoassays. Glomerular filtration rate and plasma volume were determined by standard methods.

RESULTS

Sudden sodium intake reduction doubled plasma renin activity and angiotensin II, and tripled aldosterone on day 1 with only small non-significant additional changes on the following days. Different levels of sodium intake did not affect arterial blood pressure, heart rate, and plasma concentrations of sodium, angiotensinogen, atrial natriuretic peptide, vasopressin, glomerular filtration rate and diuresis. With increasing sodium intake, plasma volume increased by 0.47 +/- 0.04 mL (kg body mass)(-1) (unit increase in Na intake)(-1) (P < 0.01), and plasma potassium decreased with the slope -0.038 mm [(mmol Na+ intake) (kg body mass)(-1) day(-1)](-1) (P = 0.001) while plasma renin-activity, angiotensin II, and aldosterone decreased systematically as expected.

CONCLUSIONS

A step reduction in sodium intake alters renin-angiotensin-aldosterone system activity on day 1 with little further change the subsequent 4 days. Week-long increases in sodium intake decreases renin-angiotensin-aldosterone system activity, increases plasma volume, and decreases plasma potassium. Isolated decreases in sodium intake increase aldosterone secretion via volume-mediated action on the renin-angiotensin system and via increases in plasma potassium.

Relative nephroprotection during Escherichia coli O157:H7 infections: association with intravenous volume expansion

OBJECTIVE

The hemolytic uremic syndrome (HUS) consists of hemolytic anemia, thrombocytopenia, and renal failure. HUS is often precipitated by gastrointestinal infection with Shiga toxin-producing Escherichia coli and is characterized by a variety of prothrombotic host abnormalities. In much of the world, E coli O157:H7 is the major cause of HUS. HUS can be categorized as either oligoanuric (which probably signifies acute tubular necrosis) or nonoligoanuric. Children with oligoanuric renal failure during HUS generally require dialysis, have more complicated courses, and are probably at increased risk for chronic sequelae than are children who experience nonoligoanuric HUS. Oligoanuric HUS should be avoided, if possible. The presentation to medical care of a child with definite or possible E coli O157:H7 infections but before HUS ensues affords a potential opportunity to ameliorate the course of the subsequent renal failure. However, it is not known whether events that occur early in E coli O157:H7 infections, particularly measures to expand circulating volume, affect the likelihood of experiencing oligoanuric HUS if renal failure develops. We attempted to assess whether pre-HUS interventions and events, especially the volume and sodium content of intravenous fluids administered early in illness, affect the risk for developing oligoanuric HUS after E coli O157:H7 infections.

METHODS

We performed a prospective cohort study of 29 children with HUS that was confirmed microbiologically to be caused by E coli O157:H7. Infected children were enrolled when they presented with acute bloody diarrhea or as contacts of patients who were known to be infected with E coli O157:H7, or if they had culture-confirmed infection, or if they presented with HUS. HUS was defined as hemolytic anemia (hematocrit <30%, with fragmented erythrocytes on peripheral-blood smear), thrombocytopenia (platelet count of <150000/mm3), and renal insufficiency (serum creatinine concentration that exceeded the upper limit of normal for age). A wide range of pre-HUS variables, including demographic factors, clinical history, medications given, initial laboratory values, and volume and content of parenteral fluid administered, were recorded and entered into analysis. Estimates of odds ratios were adjusted for possible confounding effects using logistic regression analysis. Twenty-nine children who were <10 years old, had HUS confirmed to be caused by E coli O157:H7, and were hospitalized at the Children's Hospital and Regional Medical Center, Seattle, were studied. The main outcome measured was development of oligoanuric renal failure. Oligoanuria was defined as a urine output <0.5 mL/kg per hour for at least 24 consecutive hours.

RESULTS

As a group, the children with oligoanuric renal failure presented to medical attention and were evaluated with laboratory testing later than the children with nonoligoanuric renal failure. On initial assessments, the children with oligoanuric outcomes had higher white blood cell counts, lower platelet counts and hematocrits, and higher creatinine concentrations than the children with nonoligoanuric outcomes, but these determinations probably reflect later points of these initial determinations, often when HUS was already developing. Stool cultures were obtained (medians of 3 vs 2 days, respectively) and positive (medians of 7 vs 4 days, respectively) at later points in illness in the children in the oligoanuric than in the nonoligoanuric group. Intravenous volume expansion began later in illness in the children who subsequently developed oligoanuric renal failure than in those whose renal failure was nonoligoanuric (medians: 4.5 vs 3.0 days, respectively). Moreover, the 13 patients with nonoligoanuric renal failure received more intravenous fluid and sodium before HUS developed (1.7- and 2.5-fold differences, respectively, between medians) than the 16 patients with oligoanuric renal failure. These differences were even greater when the first 4 days of illness were examined, with 17.1- and 21.8-fold differences, respectively, between medians. In a multivariate analysis adjusted for age, gender, antibiotic use, and free water volume administered intravenously to these children during the first 4 days of illness, the amount of sodium infused remained associated with protection against developing oligoanuric HUS. Dialysis was used in each of the children with oligoanuric renal failure and in none of the children with nonoligoanuric renal failure. The median length of stay in hospital after the diagnosis of HUS was 12 days in the oligoanuric group and 6 days in the nonoligoanuric group.

CONCLUSIONS

Early recognition of and parenteral volume expansion during E coli O157:H7 infections, well before HUS develops, is associated with attenuated renal injury failure. Parenteral hydration in children who are possibly infected with E coli O157:H7, at the time of presentation with bloody diarrhea and in advance of culture results, is a practice that can accelerate the start of volume expansion during the important pre-HUS interval. Rapid assessment of stools for E coli O157:H7 by microbiologists and reporting of presumptive positives immediately can alert practitioners that patients are at risk for developing HUS and can prompt volume expansion in children who are not already being so treated. Our data also suggest that isotonic intravenous solutions might be superior to hypotonic fluids for use as maintenance fluids. Children who are infected with E coli O157:H7 and are given intravenous volume expansion need careful monitoring. This monitoring should be even more assiduous as HUS evolves.

Acute respiratory distress syndrome is a serious complication of microwave coagulation therapy for liver tumors

BACKGROUND

Acute respiratory distress syndrome (ARDS), also known as noncardiogenic pulmonary edema, is a severe complication in cirrhotic patients undergoing microwave coagulation therapy (MCT) for liver tumor. In this study, cirrhotic patients with ARDS after MCT were compared with others without ARDS.

METHODS

Four patients with ARDS after open MCT and 17 other patients without ARDS were compared in terms of preoperative status, intraoperative findings, and postoperative management.

RESULTS

The preoperative Child-Pugh score and intraoperative amount of irradiation showed no significant differences were observed. The postoperative cumulative water balance until the third day was 1,692 +/- 1,315 mL for the ARDS group and 165 +/- 1,524 mL for the non-ARDS group (P = .079), and by the fourth day the respective values were 1,992 +/- 1,585 mL and 66 +/- 1,685 mL, showing a significant difference (P = .049). The postoperative cumulative sodium administration until the third day was 510 +/- 132 mEq for the ARDS group and 362 +/- 122 mEq for the non-ARDS group with a significant difference (P = .044), and by the fourth day the respective values were 642 +/- 141 mEq and 477 +/- 160 mEq (P = .073). Of the 17 patients in the non-ARDS group, 6 were given aldosterone antagonist until the fourth postoperative day, but it was not administered to any of the patients in the ARDS group.

CONCLUSIONS

The water balance and sodium administration have to be closely monitored to prevent cirrhotic patients undergoing MCT from developing ARDS. Aldosterone antagonist appears to be useful for the prevention of ARDS.

Self-administered subcutaneous fluid infusion at home in the management of fluid depletion and hypomagnesaemia in gastro-intestinal disease

BACKGROUND AND AIMS

In short bowel fistula and some other gastrointestinal (GI) diseases, salt, water and magnesium (Mg) balance may continue negative despite oral treatment, even in patients with adequate nutritional status. This study describes the use of self-administered subcutaneous fluid infusions (HSCF) to treat this problem.

PATIENTS & METHODS

HSCF was administered to patients with GI failure and adequate macro-nutrient status (BMI) when GI salt, water and magnesium balance continued negative despite optimal diet, drug and supplemental treatment. Mg depletion was confirmed using the Mg load test. Patients were taught to self-administer 0.5-1.0 l 0.9% saline +/-0.5 l 5% dextrose +/-2-4 mmol MgSO4 subcutaneously by gravity drip during 6-12 h overnight, 3-7 days/week. Water and Na balance were assessed (weight, serum creatinine, urea, Na) at baseline and at 1 and 3 months of treatment, but also monitored carefully during the first few days of treatment. Serum Mg was measured at baseline and at 2 and 4 weeks.

RESULTS

In 10 patients (mean age 65.3+/-13.5 years) Na and water balance was rapidly restored. At baseline, 1 and 3 months, serum biochemical results were: Eight patients received 8-28 mmol MgSO4/week in the infused fluid. Serum Mg [0.7-1.0 mmol] at baseline, 2 and 4 weeks was 0.49+/-0.06, 0.79+/-0.18, 0.83+/-0.10 mmol/l (P=0.002). Tolerance was good; transient oedema developed in 2 patients, resolved by reducing infusion dose. No patient developed hypokalaemia.

CONCLUSIONS

Subcutaneous self-administered fluid infusion at home (HSCF) is an easily managed, safe and effective method of restoring and maintaining water, salt and Mg balance in patients with large GI fluid losses but adequate macronutrient status, particularly in the frail or elderly in whom home parenteral nutrition may be difficult.

Dipsogenic stimulation in ibotenic DRN-lesioned rats induces concomitant sodium appetite

The main purpose of this study was to investigate whether dipsogenic stimuli influences the sodium appetite of rats with ibotenic acid lesion of the dorsal raphe nucleus (IBO-DRN). Compared to control, rats microinjected with phosphate buffer (PB-DRN), the ingestion of 0.3M NaCl was enhanced in IBO-DRN at 21 and 35 days after DRN lesion under a protocol of fluids and food deprivation. Despite of similar dipsogenic response observed both in IBO-DRN and PB-DRN treated with isoproterenol (ISO, 300 microg/kg, sc), the 0.3M NaCl intake was again significantly enhanced in IBO-DRN at 21 and 35 days post-lesion. Finally, treatment with polyethylene glycol (PEG, MW=20,000, 20%, w/v, 16.7 ml/kg, sc) induced higher dipsogenic response in IBO-DRN than PB-DRN at 21 day after lesion. In addition, IBO-DRN also expressed higher sodium appetite than PB-DRN, concomitantly with a drinking response. These results suggest that ibotenic lesion of DRN promote an increase of the brain angiotensinergic response, possibly settled within the subfornical organ, through paradigms which increase circulating ANG II levels. The current paper supports the hypothesis that the ibotenic lesion of DRN suppresses a serotonergic component implicated on the modulation of the sodium appetite and, therefore, furthering homeostatic restoration of extracellular fluid volume.

Effects of Feeding Propionate and Calcium Salts of Long-Chain Fatty Acids on Transition Dairy Cow Performance

Multiparous Holstein cows (n = 40) were used in a randomized complete block design to determine the effects of feeding Ca and Na salts (1:1, wt/wt) of propionate and Ca salts of long-chain fatty acids (LCFA) on transition cow performance. All cows were fed the same basal diet once daily for ad libitum intake. Treatments (g/d) were 320 cornstarch (CS) as a control, 120 propionate (PRO), 120 propionate and 93 LCFA (PF1), and 178 propionate and 154 LCFA (PF2). Treatments were hand-mixed into the upper one-third of the TMR from 2 wk pre- through 3 wk postpartum. Intakes were recorded from 21 d pre- through 21 d postpartum. Energy density and crude protein were 1.54 and 1.65 Mcal/kg and 14.4 and 18.8% for pre- and postpartum diets, respectively. All cows received a common diet from 22 to 70 days in milk (DIM). Milk composition was analyzed on d 7, 14, and 21. Blood was sampled at 14, 7, and 2 d prepartum and 2, 7, 14, and 21 DIM. Pre- and postpartal dry matter intake (DMI) averaged 11.9 and 16.4 kg/d, respectively, and did not differ among treatments. A diet x week interaction for postpartal DMI was observed as cows fed PF2 consumed 2 kg/d less DM during wk 2 relative to other treatments. Milk yields from 22 to 70 DIM were 48.8, 48.5, 47.8, and 51.3 kg/d for CS, PRO, PF1, and PF2, respectively, and were not significantly affected by treatments. Milk true protein (3.32 vs. 3.16%) was increased and MUN (12.5 vs. 14.4 mg/dL) was decreased for CS relative to other treatments. Milk fat yield from cows fed PRO tended to be greater than those fed PF1 (1.58 vs. 1.29 kg/d). Plasma glucose, insulin, and beta-hydroxybutyrate were not affected by treatments. The PF2 treatment tended to decrease NEFA in plasma relative to PF1 over all times measured (492 and 670 muEq/L) and significantly decreased plasma NEFA relative to those fed PF1 postpartum (623 and 875 muEq/L). Relative to PF1, feeding propionate and LCFA at the higher level in this experiment improved energy balance postpartum as evidenced by decreased concentrations of plasma NEFA.

Biological half-life of bromide in the rat depends primarily on the magnitude of sodium intake

The parallel course of the excretion rates of bromide and sodium ions was demonstrated in adult male and female rats administered simultaneously with potassium 82Br-bromide and 24Na-sodium chloride. The animals were exposed to various intakes of sodium ions accompanied with five different anions: Br-, Cl-, HCO3-, ClO4-, and SCN-. Regardless of the anion accompanying the sodium ion, the excretion rates of 82Br- and 24Na+ ions were proportional to the magnitude of sodium intake in the animals. Hence, we have proved our hypothesis that the biological half-life of bromide depends on the magnitude of sodium intake rather than on the intake of chloride.

Need for low sodium concentration and frequent cycles of 3.86% glucose solution in children treated with acute peritoneal dialysis

In acute renal failure (ARF) in the setting of a pediatric intensive care unit, most authors report the use of frequent cycles of (often low-volume) high-glucose solutions. That approach results in appropriate H2O ultrafiltration, but not in appropriate sodium removal, as a consequence of the sieving coefficient of sodium. That in turn leads not only to inefficient treatment of intravascular fluid overload, but also frequently to hypernatremia. The problem can be resolved by the use of low-sodium (127 mmol/L) dialysis solution. In the present prospective study in children, we performed peritoneal dialysis using a pharmacy-made solution containing 127 mmol/L sodium and 3.86% glucose, comparing that solution with conventional glucose solution. We calculated the ultrafiltration rate and the sodium removal. We observed no statistical difference in ultrafiltration rate, but a significantly increased sodium extraction. Children with acute overload during ARF may benefit if low-sodium solution is used in place of conventional dialysate. A low-sodium solution does not attenuate the pure ultrafiltration rate, but does result in higher sodium extraction, reducing intravascular volume and plasma sodium levels.

Drug labeling; sodium labeling for over-the-counter drugs. Final rule

The Food and Drug Administration (FDA) is issuing a final rule amending the regulations for sodium labeling for over-the-counter (OTC) drug products by extending the sodium content labeling requirement to rectal drug products containing sodium phosphate/sodium biphosphate (sodium phosphates). FDA is taking this action because people with certain medical conditions are at risk for an electrolyte imbalance to occur when using rectal sodium phosphates products. Serious adverse events and deaths have occurred because of the high level of sodium present in these products. This final rule is part of FDA's ongoing review of OTC drug products.

Clinical consequences of an individualized dialysate sodium prescription in hemodialysis patients

BACKGROUND

Predialysis plasma sodium (Na(+)) concentration is relatively constant in hemodialysis (HD) patients, and a higher dialysate Na(+) concentration can promote an increase in the interdialytic fluid ingestion to achieve an individual's osmolar set point, and individualization of dialysate Na(+) concentration may improve interdialytic weight gain (IDWG), blood pressure (BP), and HD-related symptoms.

METHODS

Twenty-seven nondiabetic, non-hypotension prone HD patients were enrolled in a single-blind crossover study. Subjects underwent nine consecutive HD sessions with the dialysate Na(+) concentration set to 138 mEq/L (standard Na(+) HD), followed by nine sessions wherein the dialysate Na(+) was set to match the patients average pre-HD plasma Na(+) measured three times during the standard Na(+) phase multiplied by 0.95 (individualized dialysate Na(+) HD). Dry weight, dialysis prescription, and medications were not modified during the six weeks of the study.

RESULTS

Pre-HD Na(+) was similar in both periods of the study (standard Na(+) HD, 134.0 +/- 1.4 mEq/L; individualized Na(+) HD, 134.0 +/- 1.5 mEq/L; P= 0.735). There was a significant decrease in interdialytic weight gain (2.91 +/- 0.87 kg vs. 2.29 +/- 0.65 kg; P< 0.001), interdialytic thirst scores, and episodes of intradialytic hypotension in the individualized Na(+) period compared with the standard phase. Pre-HD BP was lower in individualized Na(+) HD in patients with uncontrolled BP at baseline (N= 15), but not in those with controlled BP at baseline (N= 12) (DeltaBP -15.6/-6.5 mm Hg in uncontrolled vs. DeltaBP +6.4/+4.5 mm Hg in controlled, P= <0.001 for systolic BP and P= <0.001 for diastolic BP).

CONCLUSION

An individualized Na(+) dialysate based on predialysis plasma Na(+) levels decreases thirst, IDWG, HD-related symptoms, and pre-HD BP (in patients with uncontrolled BP at baseline).

Electrolyte Therapy for Refractory Seizures in Familial Dysautonomia

PURPOSE

Video-EEG in a family of three patients with slow development and familial dysautonomia demonstrated absence seizures associated with 3-Hz generalized spike-and-wave discharges. The seizures were refractory to antiepileptic drugs (AEDs).

METHODS

Treatment was given with rice-based cereal electrolyte oral solution.

RESULTS

Treatment induced seizure freedom and normalization of EEG in all three patients. Repeated video-EEG monitoring with discontinuation of AEDs and maintenance of the oral hydration therapy was associated with recurrence of epileptic activity. All three patients have remained seizure free (approximately 1 year) with a combination of topiramate and electrolytic therapy.

CONCLUSIONS

Rice-based oral electrolyte hydration therapy may play a role in prevention and control of seizures in patients with familial dysautonomia.

Role of sodium and volume in the pathogenesis of hypertension in dialysis patients. Reflections on pathophysiological mechanisms

Volume and sodium excess is the predominant factor in the pathogenesis of hypertension in dialysis patients. However, except for anephric patients, the relationship between volume status, blood pressure, and hemodynamics is not straightforward, but may vary between subgroups of patients. In general, the sensitivity of blood pressure to changes in the volume/sodium status appears to be increased in patients with end-stage renal disease. The blood pressure response to changes in the sodium/volume status may be influenced by disturbances in the activity of and response to various neurohumoral mechanisms, such as the renin-angiotensin and sympathetic nervous systems, Na-K-ATP-ase inhibitors, and the nitric oxide system. Regarding these aspects, there might be a parallel with salt-sensitive (essential) hypertension. Preliminary data showed a beneficial effect of sodium removal beyond changes in the volume status. Also of interest is the fact that prolonging dialysis time may improve blood pressure control without clear changes in the fluid status. It is hypothesized that a reduction in exchangeable sodium, by increased diffusive transport of sodium, in combination with increased removal of vasopressor substances, might be partly responsible for the observed blood pressure changes during long dialysis times. In conclusion, sodium and volume overload and neurohumoral factors coincide in the pathogenesis of hypertension in dialysis patients. Nevertheless, their exact relationship has not yet been elucidated and deserves further study.