Acute complicating symptoms during hemodialysis sessions have well correlation with deranged blood pressure regulation

Objective: This observational study was undertaken to evaluate the frequency of acute complications occurring during dialysis sessions and their association with other clinical and biochemical parameters. Method: Forty‐six maintenance hemodialysis patients were selected and evaluated. Mean of the weekly evaluations of different parameters over a three‐month period is presented here. Result: Age of study subjects was 39 ± 13 years and body mass index (BMI) 21 ± 4 kg/m². Duration of hemodialysis was 41 ± 29 months. Most of the patients were hypertensive (98%), taking multiple anti‐hypertensive drugs. Mean of the blood pressures before and at the end of dialysis sessions over the three month period were: systolic blood pressure (SBP) 159 ± 18 vs. 163 ± 22 (p < 0.05) and diastolic blood pressure (DBP) 92 ± 13 vs. 87 ± 7 mmHg (p < 0.003). Frequency of acute complicating symptoms during dialysis sessions were: headache (75%), rise in blood pressure (73%), leg cramps (67%), vomiting (60%), palpitation (58%), sweating (52%), and hypotension (35%). Raised blood pressure showed a positive correlation with headache (r = 0.50, p < 0.01) and sweating (r = 0.53, p < 0.05). Vomiting and palpitation were more frequent at low post‐dialysis blood pressure (vomiting vs. post‐SBP‐r = ?0.41, p < 0.05 and palpitation vs. post‐DBP‐r = ?0.48, p < 0.05), and these patients were likely to get inadequate dialysis (hypotension vs. Kt/V‐r = ?0.63, p < 0.01). Pre and post dialysis weight variation was 53 ± 11 vs. 51 ± 11 kg (p < 0.001), average ultrafiltration during dialysis (UF)?2.39 (0.5–4) liter and single session Kt/V was 0.95 ± 0.38. The rising tendency of post‐dialysis blood pressure correlated positively with increasing UF (SBP vs. UF‐r = 0.36, p < 0.01 and DBP vs. UF‐r = 0.25, p < 0.05). Conclusion: From this study it may be concluded that acute complications during dialysis sessions have a significant correlation with deranged blood pressure regulation, and optimum control of blood pressure could provide better dialysis.     

Hemodialysis‐induced acute pancreatitis secondary to kinked hemodialysis blood lines

Objective: Blood‐membrane interaction during hemodialysis may contribute to inflammatory process, which accelerates the development of atherosclerosis in maintenance hemodialysis patients (MHD). Vitamin E has been widely used against oxidative stress in MHD. One of the strategies for the utilization of vitamin E in MHD patients is the usage of vitamin E‐coated membrane dialyzer. We investigated the effects of vitamin E‐coated membrane dialyzer on serum C‐reactive protein and interleukin‐6, the biomarker of inflammation, compared to polysulfone membrane dialyzer. Methods: Vitamin E‐coated membrane dialyzer (1.5‐m² surface area) and synthetic polysulfone dialyzer (1.5‐m² surface area) were manipulated in a crossover clinical study for 24 weeks in 10 non‐diabetic MHD patients. Run‐in and wash‐out periods (Cellulose tri‐acetate) were performed for 4 weeks before the treatment. Pre‐ and post‐dialysis blood samples were taken at the begining and the end of each dialyzer period (12 weeks). High‐sensitivity C‐reactive protein (hs‐CRP) and interleukin‐6 (IL‐6) were examined. Results: Mean age of the patients was 54.9 years old. CRP and IL‐6 levels were similarly increased after dialysis in both groups (4.8 ± 0.7 and 37.2 ± 9.4, respectively). The CRP and IL‐6 level in vitamin E‐coated membrane dialyzer treatment were lower than in polysulfone treatment (5.0 ± 1.2, p < 0.008 and 67.2 ± 12.4, p < 0.04, respectively). Serum albumin, hemoglobin level, and white blood cell count were not affected by types of dialyzer membrane. Conclusions: In our study, hemodialysis stimulated the inflammation as the previous study. Vitamin E‐coated membrane dialyzer may diminish the inflammatory process in MHD patients and may also prevent further atherosclerosis.     

Changes in biochemical,hemodynamic, and dialysis adherence parameters in hemodialysis patients during Ramadan

This paper aimed to study the effect of Ramadan fasting on biochemical and clinical parameters and compliance for dialysis. A prospective multicenter observational cross‐sectional study comparing fasting with a non‐fasting stable adult hemodialysis patients for demographic and biochemical parameters, compliance with dialysis, inter‐dialytic weight gain, pre‐ and post‐blood pressure, and frequency of intradialytic hypotensive episodes was carried out. Six hundred thirty‐five patients, of whom 64.1% fasted, were studied. The fasters were younger (53.3 ± 16.2 vs. 58.4 ± 16.1 years; P = 0.001) but had similar duration on dialysis (P = 0.35). More fasters worked (22.0% vs. 14.6%; P = 0.001) and missed dialysis sessions during Ramadan. No differences were noted between groups in sex, diabetic status, or dialysis shift or day. There were no differences in the pre‐ and post‐dialysis blood pressure; serum potassium, albumin or weight gain; diabetic status; sex; and dialysis shift time or days. However, serum phosphorous was significantly higher in the fasting group (2.78 ± 1.8 vs. 2.45 ± 1.6 mmol/L; P = 0.045). There were no intragroup differences in any of the parameters studied when comparing the findings during Ramadan with those in the month before Ramadan. Fasters were significantly younger and more likely to be working, to miss dialysis sessions, and to have higher serum phosphorous levels. No other differences were observed.     

Effects of end‐stage renal disease and dialysis modalities on blood ammonia level

Introduction: Uremia results in a characteristic breath odor (uremic fetor) which is largely due to its high ammonia content. Earlier studies have shown a strong correlation between breath ammonia and blood urea levels and a 10‐fold reduction in breath ammonia after hemodialysis in patients with chronic kidney disease. Potential sources of breath ammonia include: (i) local ammonia production from hydrolysis of urea in the oropharyngeal and respiratory tracts by bacterial flora, and (ii) release of circulating blood ammonia by the lungs. While the effects of uremia and hemodialysis on breath ammonia are well known their effects on blood ammonia are unknown and were explored here. Methods: Blood samples were obtained from 23 hemodialysis patients (immediately before and after dialysis), 14 peritoneal dialysis patients, and 10 healthy controls. Blood levels of ammonia, creatinine, urea, and electrolytes were measured. Findings: No significant difference was found in baseline blood ammonia between hemodialysis, peritoneal dialysis and control groups. Hemodialysis procedure led to a significant reduction in urea concentration (P < 0.001) which was paradoxically accompanied by a modest but significant (P < 0.05) rise in blood ammonia level in 10 of the 23 patients studied. Change in blood ammonia pre‐ and post‐hemodialysis correlated with change in serum bicarbonate levels (r = 0.61, P < 0.01). On subgroup analysis of patients who had a rise in blood ammonia levels after dialysis, there was a strong correlation with drop in mean arterial pressure (r = 0.88, P < 0.01). The nadir intradialytic systolic blood pressure trended lower in the hemodialysis patients who had a rise in blood ammonia compared to the patients who manifested a fall in blood ammonia (124 ± 8 vs. 136 ± 6 mmHg respectively, P = 0.27). Discussion: Fall in blood urea following hemodialysis in ESRD patients was paradoxically accompanied by a modest rise in blood ammonia levels in 43% of the patients studied, contrasting prior reported effects of hemodialysis on breath ammonia. In this subgroup of patients, changes in blood ammonia during hemodialysis correlated with rise in blood bicarbonate and fall in mean arterial blood pressure.     

Inappropriately elevated endothelin‐1 plays a role in the pathogenesis of intradialytic hypertension

The aim of this study is to investigate the effects of endogenous vasoactive substances on the occurrence of intradialytic hypertension (IDH) in patients during maintenance hemodialysis. Thirty‐four maintenance hemodialysis patients were enrolled in this trial, and 17 of them were diagnosed with IDH (defined as an increase in blood pressure of at least 10 mmHg during or immediately after a hemodialysis session), while 17 age‐matched and sex‐matched controls without IDH were selected for a retrospective comparison. We collected patients' blood samples before and after a dialysis session and measured the plasma levels of N‐terminal fragment brain natriuretic peptide, renin, angiotensin‐II, aldosterone (ALD), angiotensin‐converting enzyme (ACE), endothelin‐1 (ET‐1), nitric oxide (NO), norepinephrine (NOR), and adrenomedullin. The post‐dialysis serum ET‐1 concentrations were significantly higher (4.09 ± 2.06 vs. 2.75 ± 1.34 pg/mL, P < 0.05), while the post‐dialysis ratio of NO to ET‐1 was lower (17.79 ± 5.65 vs. 24.78 ± 12.04, P < 0.05) in IDH patients compared with the control group. Post‐dialysis ALD and NOR values were significantly lower (P < 0.01) and ACE levels were significantly higher (P < 0.01) than the pre‐dialysis concentrations only in the control and not in the IDH group. All other measured factors did not differ significantly between the groups and between pre‐dialysis and post‐dialysis determinations. Compared with blood angiotensin‐II, ALD, ACE, NOR, adrenomedullin, N‐terminal fragment brain natriuretic peptide, and NO status, inappropriately elevated ET‐1 plasma concentrations may play a predominant role in the pathogenesis of IDH.     

The Clinical Impact of Increasing the Hemodialysis Dose

Good evidence suggests that improvements in dialysis efficiency reduce morbidity and mortality of hemodialysis (HD) patients. Dialysis efficiency has also been related to better control of arterial blood pressure (BP), anemia, and serum phosphorus levels, and to improvement in patients' nutritional status. Over a 2‐year period, the present self‐controlled study of 34 HD patients (23 men, 11 women; age, 52.6 ± 14.5 years; HD duration, 55.9 ± 61.2 months) looked at the effect on clinical and laboratory parameters of increasing the delivered dialysis dose under a strict dry‐weight policy. Dialysis dose was increased without increasing dialysis time and frequency. A statistically significant increase was seen in delivered HD dose: the urea reduction ratio (URR) increased to 60% ± 10% from 52% ± 8%, and then to 71% ± 7% (p < 0.001); Kt/V_urea increased to 1.22 ± 0.28 from 0.93 ± 0.19, and then to 1.55 ± 0.29 (p < 0.001). A statistically significant increase in hemoglobin concentration also occurred—to 10.8 ± 1.9 g/dL from 10.4 ± 1.7 g/dL, and then to 11.0 ± 1.3 g/dL (p < 0.05 as compared to baseline)—with no significant difference in weekly erythropoietin dose. Statistically significant decreases occurred in the systolic and diastolic blood pressures during the first year; they then remained unchanged. Systolic blood pressure decreased to 131 ± 23 mmHg from 147 ± 24 mmHg (p < 0.001); diastolic blood pressure decreased to 65 ± 11 mmHg from 73 ± 12 mmHg (p < 0.001). Serum albumin increased insignificantly to 4.4 ± 0.4 g/dL from 4.3 ± 0.4 g/dL, and then significantly to 4.6 ± 0.3 g/dL (p = 0.002 as compared to both previous values). Normalized protein catabolic rate increased significantly to 1.16 ± 0.15 g/kg/day from 0.93 ± 0.16 g/kg/ day (p < 0.001), and then to 1.20 ± 0.17 g/kg/day (p < 0.001 as compared to baseline). We conclude that the increases achieved in average Kt/V_urea per hemodialysis session by increasing dialyzer membrane area, and blood and dialysate flows, without increasing dialysis time above 4 hours, in patients hemodialyzed thrice weekly, coupled with strict dry‐weight policy, resulted in improvements in hypertension, nutritional status, and anemia.     

Intradialytic changes of serum magnesium and their relation to hypotensive episodes in hemodialysis patients on different dialysates

Magnesium is a crucial mineral, involved in many important physiological processes. Magnesium plays a role of maintaining myocardial electrical stability in hemodialysis patients. Intradialytic hypotension is a common complication of dialysis and it is more common with acetate dialysate. The significance of the intradialytic changes of magnesium and their relation to parathyroid hormone (PTH) level and calcium changes during dialysis, and their relation to hypotensive episodes during dialysis are interesting. The aim of this work is to investigate the intradialytic changes of serum magnesium in chronic hemodialysis patients with different hemodialysis modalities and the relation to other electrolytes and to PTH, and also the relation to intradialytic hypotension. The present study was conducted on 20 chronic renal failure patients. All patients were on regular hemodialysis thrice weekly 4 hr each using acetate dialysate (group I). To study the effect of an acetate-based dialysate vs. a bicarbonate-based dialysate on acute changes of magnesium, calcium, phosphorus, and PTH during a hemodialysis session, the same patients were shifted to bicarbonate dialysis (group II). All patients were subjected to full history and clinical examination, predialysis laboratory assessment of blood urea nitrogen (BUN), serum creatinine, albumin, and hemoglobin, serial assessment of magnesium, calcium, phosphorus, and parathyroid hormone at the start of the hemodialysis session, 2 hr later, and at the end of the session, blood pH, and electrocardiogram (ECG) presession and postsession. All patients were urged to fix their dry weight, diet, and current medications. None of the patients had diabetes, neoplasia, liver disease, or cachexia, nor had they been recently on magnesium-containing drugs or previously parathyroidectomized. Hemodialysis sessions were performed by volumetric dialysis machines using the same electrolyte composition. Magnesium level significantly increased in the bicarbonate group at the end of dialysis (0 hr: 2.73+/-0.87, 2 hr: 3.21+/-1.1, and at 4 hr: 5.73+/-1.45 mg/dL, p value <0.01), while it significantly decreased in the acetate group (0 hr: 3.00+/-0.58, 2 hr: 2.26+/-0.39, 4 hr: 1.97+/-0.33 mg/dL, p value <0.01). Calcium level significantly increased in the bicarbonate group (p=0.024) but not in the acetate group. Phosphorus level significantly decreased in both acetate and bicarbonate groups. PTH level did not significantly change in either group, p value > or =0.05. Blood pH significantly increased, changing from acidic to alkaline pH, with both modalities of hemodialysis. ECG showed no significant changes during sessions with either type of dialysate. Hypotension was significantly higher in group I compared with group II (p=0.01), and this hypotension was positively correlated with a decrease in serum magnesium level in group I. Intradialytic changes in serum magnesium have no correlation with intradialytic changes in serum calcium or with PTH level. However, it was significantly correlated with hypotension during the dialysis session, especially with acetate dialysate. Further investigations are needed to determine whether or not this is true in patients using bicarbonate dialysis.     

The efficiency of potassium removal during bicarbonate hemodialysis

Patients on chronic hemodialysis often portray high serum [K+]. Although dietary excesses are evident in many cases, in others, the cause of hyperkalemia cannot be identified. In such cases, hyperkalemia could result from decreased potassium removal during dialysis. This situation could occur if alkalinization of body fluids during dialysis would drive potassium into the cell, thus decreasing the potassium gradient across the dialysis membrane. In 35 chronic hemodialysis patients, we compared two dialysis sessions performed 7 days apart. Bicarbonate or acetate as dialysate buffers were randomly assigned for the first dialysis. The buffer was switched for the second dialysis. Serum [K+], [HCO3-], and pH were measured in samples drawn before dialysis; 60, 120, 180, and 240 min into dialysis; and 60 and 90 min after dialysis. The potassium removed was measured in the dialysate. During the first 2 hr, serum [K+] decreased equally with both types of dialysates but declined more during the last 2 hr with bicarbonate dialysis. After dialysis, the serum [K+] rebounded higher with bicarbonate bringing the serum [K+] up to par with acetate. The lower serum [K+] through the second half of bicarbonate dialysis did not impair potassium removal (295.9 +/- 9.6 mmol with bicarbonate and 299.0 +/- 14.4 mmol with acetate). The measured serum K+ concentrations correlated with serum [HCO3-] and blood pH during bicarbonate dialysis but not during acetate dialysis. Alkalinization induced by bicarbonate administration may cause redistribution of K during bicarbonate dialysis but this does not impair its removal. The more marked lowering of potassium during bicarbonate dialysis occurs late in dialysis, when exchange is negligible because of a low gradient.     

Malnutrition‐inflammation‐coronary calcification in pediatric patients receiving chronic hemodialysis

Malnutrition, inflammation, and renal osteodystrophy parameters with resultant coronary calcification (CC) are associated with increased cardiovascular mortality in adults. Previous pediatric studies demonstrated CC in children but none assessed for an association between inflammation, malnutrition, renal osteodystrophy, and CC. To assess CC, ultrafast computerized tomogram was obtained for 16 pediatric patients (6 females; median age 17.2 years; range 9.1–21.2 years) receiving hemodialysis for ≥2 months. Inflammation was assessed by serum IL‐6, IL‐8, and C‐reactive protein levels on the day of the computerized tomogram scan; nutrition parameters included serum albumin, cholesterol, the body mass index standard deviation score, and normalized protein catabolic rate. Renal osteodystrophy parameters included time‐averaged serum calcium, phosphorus, total PTH, and calcitriol/calcium dose. Patients received hemodialysis thrice‐weekly; mean single pool Kt/V 1.48±0.13; and mean normalized protein catabolic rate 1.27±0.17 g/kg/day. Five of 16 patients had CC. Patients with CC were older (19.1±2.1 vs. 15.4±3.1 months; P=0.03), had longer dialysis vintage (49.4±15.3 vs. 17.2±10.5 months, P=0.0002), lower serum cholesterol (122±17.7 vs. 160.4±10.6 mg/dL, P=0.02), and higher phosphorus (9.05±1.2 vs. 6.1±0.96 mg/dL, P=0.0001). Mean serum albumin and normalized protein catabolic rate did not differ for patients with CC. All patients had elevated IL‐6 and IL‐8 levels compared with healthy norms; the mean IL‐6, IL‐8, and C‐reactive protein levels were not different in patients with CC. Coronary calcification was prevalent in older children receiving maintenance hemodialysis with a longer dialysis vintage. Worse renal osteodystrophy control and malnutrition (low cholesterol) may contribute to CC development.     

Safety analysis of intermittent hemodialysis in patients with continuous flow left ventricular assist devices

Dialysis centers adopt a cautious approach when it comes to performing intermittent hemodialysis (HD) on patients with continuous flow (CF) left ventricular assist devices (LVADs) because of the potential for volume flux‐related complications and absence of pulsatile blood pressure for monitoring. Many patients have to remain hospitalized because of the inability of the dialysis centers to accept them for outpatient dialysis. In this study, the effect of HD was observed in such patients. Between June 2009 and October 2012, 139 patients received LVADs, of which 10 patients (7%) required intermittent HD postoperatively. The mean age of the patients was 53 ± 14 years and 90% were men. A total of 281 dialysis sessions were administered amounting to 1025 hours of dialysis. The mean systolic blood pressure monitored with Doppler device was 97 ± 18 mmHg. Dialysis durations averaged 218 ± 18 minutes. Mean blood flow rate was 334 ± 38 cc/min, and 2.6 ± 1.1 L was ultrafiltrated during each session. Only 15 (5.3%) sessions were interrupted or terminated in six patients. The reasons for termination were symptomatic hypotension—6 (2.1%), asymptomatic hypotension—3 (1%), ventricular tachycardia—1 (0.36%), dialysis machine malfunction—2 (0.7%), low phosphorus—2 (0.7%), and abdominal cramps—1 (0.36%). Volume expansion was necessary on three occasions. Low‐flow device alarms were registered during two (0.71%) sessions. The results showed no serious adverse effects or deaths.     

Modifications to bicarbonate conductivity: A way to increase phosphate removal during hemodialysis? Proof of concept

Introduction Hyperphosphatemia and cardiovascular mortality are associated particularly with end‐stage renal disease. Available therapeutic strategies (i.e., diet restriction, calcium [or not]‐based phosphate binders, calcimimetics) are associated with extrarenal blood purification. Compartmentalization of phosphate limits its depuration during hemodialysis. Several studies suggest that plasmatic pH is involved in the mobilization of phosphate from intracellular to extracellular compartments. Consequently, the efficiency of modified bicarbonate conductivity to purify blood phosphate was tested. Methods Ten hemodialysis patients with chronic hyperphosphatemia (>2.1 mmol/L) were included in the two three–sessions‐per week periods. Bicarbonate concentration was fixed at 40 mmol/L and 30 mmol/L in the first and second periods, respectively. Phosphate depuration was evaluated by phosphate mobilization clearance (K_M). Findings Although bicarbonatemia was lower during the second period (21.0 ± 2.7 vs. 24.4 ± 3.1 mmol/L, P < 0.01), no difference was observed in phosphatemia (2.4 ± 0.5 vs. 2.3 ± 0.4 mmol/L, P = NS). The in‐session variation of phosphate was lower (?1.45 ± 0.42 vs. ?1.58 ± 0.44 mmol/L, P < 0.05) and K_M was higher during the second period (82.94 ± 38.00 vs. 69.74 ± 24.48 mL/min, P < 0.05). Discussion The decrease of in‐session phosphate and the increase in K_M reflect phosphate refilling during hemodialysis. Thus, modulation of serum bicarbonate may play a role in controlling the phosphate pool. Even though correcting metabolic acidosis during hemodialysis remains important, alkaline excess can impair phosphate mobilization clearance. Clinical trials are needed to test the efficiency and relevance of a strategy where bicarbonatemia is corrected less at the beginning of sessions.     

Outcomes of Severe Methanol Intoxication Treated with Hemodialysis: Report of Seven Cases and Review of Literature

To identify factors associated with the outcome of severe methanol intoxication treated with hemodialysis, we analyzed the clinical course of 7 patients admitted with serum methanol level higher than 50 mg/dL, and therefore requiring hemodialysis. Four patients (group A) had adverse outcomes (1 death, 3 severe neurological deficits and/or blindness) and 3 patients (group B) had no adverse outcomes. Compared to group B, group A appeared to have a longer delay between ingestion of methanol and arrival at the emergency department (ED), a longer wait in the ED until ethanol infusion was started (3.6 ± 2.7 vs 1.3 ± 0.9 hr, p < 0.05), and, on admission, higher serum methanol (504 ± 219 vs 321 ± 228 mg/dL, p < 0.05), higher serum osmolality (460.5 ± 98.2 vs 397.6 ± 52.3 mOsm/kg, p < 0.05), higher serum osmolal gap (162.6 ± 76.7 vs 105.6 ± 52.9 mOsm/kg, p < 0.05), lower arterial pH (6.86 ± 0.08 vs 7.38 ± 0.16, p < 0.01), lower serum bicarbonate (4.6 ± 1.6 vs 19.9 ± 5.7 mmol/L, p < 0.01), and higher serum anion gap (36.5 ± 1.3 vs 14.3 ± 6.7 mEq/L, p < 0.01). Delay in the ED until hemodialysis was started did not differ (group A 6.4 ± 2.6 hr, group B 5.3 ± 3.5 hr), while duration of hemodialysis until serum methanol levels became permanently undetectable was longer in group A (15.0 ± 0.5 vs 8.4 ± 4.4 hr, p < 0.01). The ingested dose of methanol and the delay between ingestion and initiation of therapy to block methanol metabolism (ethanol infusion) and remove methanol from the body (hemodialysis) appear to be the critical factors influencing the outcome of methanol intoxication. Early diagnosis and initiation of treatment before substantial parts of the ingested methanol have been metabolized are of paramount importance in ensuring a favorable outcome.     

Arterial Hypertension Is Associated with Increased Serum Lipoprotein(a) Levels in End‐Stage Renal Disease Patients

In addition to disorders in lipoprotein metabolism, several other factors are involved in the development of atherosclerotic changes in end‐stage renal disease (ESRD) patients. One of these is arterial hypertension. We evaluated serum lipids—total cholesterol (TC), triglycerides (TG), apolipoproteins (A_I , A _II , B, E), lipoprotein(a) [Lp(a)]—in 109 ESRD patients on dialysis [46 on hemodialysis (HD); 63 on continuous ambulatory peritoneal dialysis (CAPD)] and in 45 hyperlipidemic patients without renal failure (HL group). Dialysis patients were divided in two groups. Group A included 42 hypertensive patients (mean age: 62.3 ± 15.5 years) whose blood pressure (BP) was satisfactorily controlled with anti‐hypertensive medications. Group B included 67 non hypertensive patients (mean age: 66.6 ± 11.9 years). Levels of Lp(a) were significantly higher in both the HD (p = 0.001) and the CAPD (p < 0.05) patients as compared with the HL group. When the HD and CAPD groups were divided into hypertensive and non hypertensive patients, Lp(a) levels were significantly higher in the hypertensive patients; this difference was not observed among non renal failure patients. These results indicate that arterial hypertension is associated with elevated Lp(a) serum levels in ESRD patients undergoing either HD or CAPD.     

Pre to post‐dialysis plasma sodium change better predicts clinical outcomes than dialysate to plasma sodium gradient in quotidian hemodialysis

Sodium balance across a hemodialysis treatment influences interdialytic weight gain (IDWG), pre‐dialysis blood pressure, and the occurrence of intradialytic hypotension, which associate with patient morbidity and mortality. In thrice weekly conventional hemodialysis patients, the dialysate sodium minus pre‐dialysis plasma sodium concentration (δDPNa+) and the post‐dialysis minus pre‐dialysis plasma sodium (δPNa+) are surrogates of sodium balance, and are associated with both cardiovascular and all‐cause mortality. However, whether δDPNa+ or δPNa+ better predicts clinical outcomes in quotidian dialysis is unknown. We performed a retrospective analysis of clinical and demographic data from the Southwestern Ontario Regional Home Hemodialysis program, of all patients since 1985. In frequent nocturnal hemodialysis, δPNa+ was superior to δDPNa+ in predicting IDWG (R² = 0.223 vs. 0.020, P = 0.002 vs. 0.76), intradialytic change in systolic (R² = 0.100 vs. 0.002, P = 0.02 vs. 0.16) and diastolic (R² = 0.066 vs. 0.019, P = 0.02 vs. 0.06) blood pressure, and ultrafiltration rate (R² = 0.296 vs. 0.036, P = 0.001 vs. 0.52). In short hours daily hemodialysis, δDPNa+ was better than δPNa+ in predicting intradialytic change in diastolic blood pressure (R² = 0.101 vs. 0.003, P = 0.02 vs. 0.13). However, δPNa+ was better than δDPNa+ in predicting IDWG (R² = 0.105 vs. 0.019, P = 0.04 vs. 0.68) and pre‐dialysis systolic blood pressure (R² = 0.103 vs. 0.007, P = 0.02 vs. 0.82). We also found that the intradialytic blood pressure fall was greater in frequent nocturnal hemodialysis patients than in short hours daily patients, when exposed to a dialysate to plasma sodium gradient. These results provide a basis for design of prospective trials in quotidian dialysis modalities, to determine the effect of sodium balance on cardiovascular outcome.     

Removal of vancomycin administered during dialysis by a high‐flux dialyzer

Introduction: Hemodialysis patients frequently receive vancomycin for treatment of gram‐positive bacterial infections. This drug is most conveniently administered in outpatient dialysis units during the hemodialysis treatment. However, there is a paucity of data on the removal of vancomycin by high‐flux polyamide dialyzers. Methods: This is a prospective crossover study in which seven uninfected chronic hemodialysis patients at three dialysis units received vancomycin 1 gram intravenously over one hour immediately after the dialysis treatment (Phase 1), and vancomycin 1.5 grams during the last hour of dialysis treatment using a polyarylethersulfone, polyvinylpyrrolidone, polyamide high‐flux (Polyflux 24R) dialyzer (Phase 2). There was a three‐week washout period between phases. Serial serum vancomycin concentrations were used to determine the removal of vancomycin when administered during dialysis. Findings: Dialysis removed 35 ± 15% (range 18‐56%) of the vancomycin dose when administered during the last hour of dialysis. The calculated area under the curve (AUC) of vancomycin levels for 0‐44.5 hours from the start of infusion were similar between the two phases (AUC_{Phase 1} 884 ± 124 mg‐hr/L, mean ± SD; AUC_{Phase 2} 856 ± 208 mg‐hr/L; P=0.72). Serum vancomycin concentrations immediately prior to the next dialysis treatment following vancomycin administration were also similar between the two phases (13.1 ± 2.7 mg/L in Phase 1 and 12.3 ± 3.3 mg/L in Phase 2; P=0.55). Discussion: When using a polyarylethersulfone, polyvinylpyrrolidone, and polyamide high‐flux HD membrane with a 24R Polyflux dialyzer, vancomycin can be administered during the last hour of dialysis if the dose that is prescribed for intra‐dialysis dosing is empirically increased to account for intra‐dialytic drug removal.     

Determinants of metabolic acidosis among hemodialysis patients

Metabolic acidosis is frequently present, poorly controlled, and associated with adverse effects among hemodialysis patients. Potential determinants of metabolic acidosis include endogenous acid production, administration of alkali, neutralization of acid by buffers, dilution of serum bicarbonate by interdialytic fluid gain, and loss of bicarbonate in stool. Understanding the relative importance of these determinants may help guide efforts to manage metabolic acidosis. We used chart abstraction, patient interviews, and laboratory testing to assess variables related to acid production (protein breakdown), alkali administration (dialysis dose, missed treatments, dialysate bicarbonate concentration, oral bicarbonate supplements), acid buffering (phosphorus binders), dilution of bicarbonate (interdialytic weight gain), and loss of bicarbonate in stool (diarrhea) for 190 randomly selected patients from 44 hemodialysis facilities. We used multivariate analyses to determine which potential determinants were independently associated with predialysis serum bicarbonate levels. Of all patients, 30% had metabolic acidosis (serum bicarbonate level <22 mEq/L). On multivariate analysis, metabolic acidosis was more likely with increased protein nitrogen appearance (odds ratio [OR] 1.60 per 0.2 g/kg/day, p=0.001) and less likely with increased Kt/V (OR 0.61 per 0.20 increase in Kt/V, p<0.001) and with increased calcium carbonate use (OR 0.38 per 2 g/day, p=0.003). Key determinants of metabolic acidosis among hemodialysis patients are protein breakdown, dialysis dose, and specific phosphorus binders. Further work is needed to develop interventions to address these determinants.     

Does the presence of an arteriovenous fistula alter changes in body water following hemodialysis as determined by multifrequency bioelectrical impedance assessment?

Multifrequency bioelectrical impedance assessments (MFBIAs) aid clinical assessment of hydration status for hemodialysis (HD) patients. Many MFBIA devices are restricted to whole body measurements and as many patients dialyze using arteriovenous fistulas (AVFs), we wished to determine whether AVFs affected body water measurements. We reviewed pre‐ and post‐HD segmental MFBIA measurements in 229 patients attending for midweek HD sessions. Up to 144 were dialyzed with a left arm AVF (L‐AVF), 42 with a right arm AVF (R‐AVF), and 43 by central venous access catheter (CVC). Water content and lean tissue were greater in the left compared to right arm in those patients with L‐AVFs both pre and post dialysis (pre 2.1 ± 0.7 vs. 2.0 ± 0.7 L, and post 1.9 ± 0.6 vs. 1.8 ± 0.6 L and pre 2.65 ± 0.9 vs. 2.56 ± 0.8 kg, and post 2.34 ± 0.8 vs. 2.48 ± 0.8 vs. 2.34 ± 0.8 kg, respectively) and were also greater in the right compared to left arm for those patients dialyzing with R‐AVFs (pre‐HD 1.92 ± 0.5 vs. 1.86 ± 0.6 L and post‐HD 1.79 ± 0.5 vs. 1.7 ± 0.5 L, and pre‐HD 2.47 ± 0.6 vs. 2.38 ± 0.7 kg and post‐HD 2.3 ± 0.74 vs. 1.28 ± 0.7 kg, respectively), all Ps < 0.05. There were no significant differences in arm volumes or composition pre or post dialysis in those dialyzing with CVCs. Segmental MFBIA detects differences in arm water and lean mass in patients with AVFs. The presence on an AVF increases the water content in the ipsilateral arm both pre and post HD. This increased water content of the fistula arm will not be detected by whole body bioimpedance devices.     

Heparin Use in Daily Hemodialysis

More frequent dialysis is thought to be associated with increased heparin requirements; however, limited data are available which compare heparin requirements of conventional to daily dialysis. Objectives: To determine differences in heparin dose during conventional thrice‐weekly dialysis (CHD) compared to daily hemodialysis (DHD). Methods: All patients within the daily home hemodialysis at the Northwest Kidney Centers were evaluated for heparin dose both pre‐ and post initiation of daily hemodialysis. Patients on DHD received an initial bolus of heparin, without a continuous heparin drip, and supplemental heparin midway through the dialysis run as needed to maintain adequate activated clotting times (ACTs). CHD patients received a heparin bolus, followed by initiation of heparin drip as needed to maintain adequate ACTs. Results: Of the 1117 patients who dialyze at the NKC, 55% were Caucasian, 21% African‐American, 20% Asian/Pacific Islander, and 35% were of other ethnicity. The majority of patients were greater than 60 years (56%), while 36% ranged from 40–60 years and 13% ranged from 20–40 years. Male patients constituted 54% of patients. Diabetes was the primary cause of renal disease (36%), followed by hypertension (21%) and glomerular disease (18%). Of those patients in the home hemodialysis program (n = 45), 10 patients started daily home hemodialysis using the Aksys daily home hemodialysis system. Of those, the majority was male (100%), Caucasian (78.8%) with an average age of 46.7 ± 18 years. Glomerulonephritis was the primary cause of end‐stage renal disease (40%), while the percentages of other diseases were similar [Alport's syndrome (20%), hypertension (20%) and diabetes (10%)]. Compared to initial DHD heparin requirements (10,111 ± 2219 units), CHD heparin dose requirements (6833 ± 2715 units) were significantly lower (p = 0.045); however, total heparin needs were similar between groups (10,166 ± 4380 units vs. 10,778 ± 2959 units) (p = 0.324). Conclusion: Although patients initiating DHD have greater initial heparin requirements than when on CHD, total heparin doses remain similar to those required on conventional thrice‐weekly hemodialysis. Greater initial heparin doses required during short daily dialysis appear safe compared to those of conventional dialysis.