Interdialytic Interval Research Articles

The Effect of Interdialytic Interval on Protein Metabolism: Evidence Suggesting Dialysis-Induced Catabolism

While examining protein metabolism in hemodialysis patients, we noted that lengthening the interdialytic intervals from two to three days reduced the dialysate nitrogen waste excretion (D-N2; mg/min) and lowered the patient's protein catabolic rate (PCR; g/kg/d). D-N2 was measured in the spent dialysate and PCR derived from urea kinetics while patients maintained a constant dietary intake. In the basal state (B), D-N2 decreased from 5.43 to 4.32 mg/min when the interdialytic interval was increased from two to three days (P less than 0.001). Similarly, PCR was reduced from 0.96 to 0.82 g/kg/d when the interdialytic period was extended. The same phenomenon was observed when subjects were taking either thyroid hormone (T3) or ipodate (lp) to increase or decrease body metabolism. In the T3 period, D-N2 was 6.12 and 5.06 mg/min and PCR was 1.08 and 0.92 g/kg/d, respectively, when the interdialytic intervals were two and three days (P less than 0.001). During the lp period, N-D2 was 4.78 and 4.03 mg/min and PCR was 0.88 and 0.76 g/kg/d, respectively, for the two- and three-day intervals (P less than 0.05). These data are consistent with dialysis-related protein catabolism. It appears that the longer interdialytic interval allowed the body to shift to a more anabolic state.

A Simplified Procedure to Compute Dialysis Time and Frequency by Means of Urea Kinetics

A simplified urea model is presented based on the concept of the time-averaged deviation (TAD) of the blood urea concentration and the introduction of an effective urea generation rate. The increase in the interdialytic blood urea concentration delta c is specific for the individual patient and includes the urea generation rate, distribution volume and residual kidney clearance. By measuring delta c of the largest interdialytic interval of the week the treatment frequency and duration can be calculated. Even for larger residual clearances Kr less than or equal to 5 ml/min this calculated treatment time does not differ by more than 5 min from the result of the exact urea kinetics. In vivo estimation of the urea clearances versus blood flow for the dialyzer types used is necessary for the application of urea modelling in clinical practice.

Acute anaphylactoid reactions during hemodialysis in France.

A retrospective survey of anaphylactoid reactions during dialysis in France was conducted. In 52 of 112 hemodialysis units surveyed 111 patients who had suffered one or more anaphylactoid reactions during dialysis were identified. According to the Hamilton/Adkinson classification, in 31 patients reactions were minor, in 54 patients moderate, and in 26 patients severe. Four patients died of their reactions. A preponderance of reactions (75 and 11%) occurred with cuprammonium cellulose hollow-fiber and plate dialyzers, respectively. Severe dialyzer reactions were found to occur more frequently after the long (weekend) interdialytic interval. In an in vitro study, six brands of cuprammonium cellulose hollow-fiber dialyzers were rinsed with water and the eluates analyzed by size exclusion chromatography for contaminant particles. Substantial variation in the amount of extractable material was found between dialyzers of different brands, despite the fact that all dialyzers used membranes from the same manufacturer. Previous data by others has suggested that this extractable material is a derivative of cellulose. Results of our epidemiologic survey in France are similar to those previously reported in the United States and suggest an increased incidence of dialyzer reactions with ethylene oxide-sterilized cuprammonium cellulose dialyzers. The presence of cellulose-derived particles in the rinsing fluid of such dialyzers and the possible increased incidence of reactions after the long (weekend) interdialytic interval suggest that allergy to cellulose-derived particles eluted from cellulosic dialyzers may contribute to dialyzer hypersensitivity reactions.

Pharmacokinetics of ofloxacin in patients on haemodialysis treatment.

Serum concentrations and pharmacokinetic parameters of ofloxacin were measured in 10 patients on haemodialysis treatment. Serum half-life during the interdialytic interval was 48 hours, and during haemodialysis treatment 10 hours. The decrease in serum concentrations during a 4-hour haemodialysis was 25%. After several doses of ofloxacin, saturation of the tissues and a rediffusion of ofloxacin from the tissues during haemodialysis has to be assumed. This equalizes the rate of elimination, and the serum ofloxacin concentration did not change during the last 2 hours of haemodialysis. The negative influence of phosphate binders on the resorption of ofloxacin can be confirmed. The following ofloxacin dosage regimen is recommended in haemodialysis patients: 200 mg initially, 100 mg loading dose after the first haemodialysis, then 100 mg daily.

Treatment of Hypertension in Dialysis Patients

Hypertension is common in hemodialyzed patients and constitutes an important cardiovascular risk factor. Fluid retention, inappropriate stimulation of the renin-angiotensin system, sympathetic overactivity and changes of vessel wall structure have been shown to be important factors in its pathogenesis. It has been claimed that hemofiltration permits a better control of hypertension in the interdialytic interval, although the evidence is not perfectly convincing; blood pressure tends to be lower with continuous ambulatory peritoneal dialysis. While fluid withdrawal and - within certain limits - adjustment of dialysate sodium concentration constitutes a primary line of therapy, antihypertensive medication is necessary in approximately 20% of patients. Specific problems with dialysis patients are cumulation of drugs (some cardioselective beta-blockers, alpha-methyldopa, captopril), altered dose-response relationship (diuretics) and particularly interaction with cardiovascular stability during fluid withdrawal.

Serum Sodium Concentration and Body Fluid Distribution during Interdialysis: Importance of Sodium to Fluid Intake Ratio in Hemodialysis Patients

Changes in the serum Na+ concentration and transcellular body fluid distribution during the interdialytic period were simulated as functions of body weight gain assuming that the effective extracellular osmolality consists only of sodium. Our model shows that these changes are mainly determined by the relative ratio between sodium intake and weight gain in this period. If the sodium intake-to-net fluid intake ratio is equal to the postdialytic serum [Na+], neither changes in serum [Na+] nor transcellular fluid shifts occur. When sodium intake is relatively greater than the net water intake, serum [Na+] is increased and transcellular fluid shifts will occur out of the cells. On the other hand, when the net water intake is relatively greater than the sodium intake, serum [Na+] is decreased and fluid is distributed to both the intracellular and extracellular compartments. The combined application of our models for both the intradialytic interval described previously and the interdialytic interval described here is very useful in quantitatively analyzing the overall sodium and water metabolism in dialyzed patients.

Protein losses during peritoneal dialysis

The losses of protein into dialysate have been considered a major limitation of maintenance peritoneal dialysis. We, therefore, undertook a comprehensive evaluation of protein losses in 30 patients undergoing maintenance intermittent peritoneal dialysis (IPD), 12 patients undergoing acute IPD, and 8 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The weekly loss of protein based upon the usual treatments per week was relatively similar with the three modes of dialysis. Protein losses during repeated dialyses were similar for a given patient, but there was repeated dialyses were similar for a given patient, but there was marked interpatient variation. During maintenance IPD, protein loss was 12.9 +/- (SD) 4.4 g per 10 hours of dialysis; albumin loss was 8.5 g, and IgG loss was 1.3 g. Approximately 50% of the protein loss was from the ascitic fluid accumulated during the interdialytic interval, and concentrations of most proteins in the ascitic fluid correlated with their serum levels. Serum protein concentrations were in the low, normal range and did not change during dialysis. The development of peritonitis markedly increased protein losses. During acute IPD, 23.3 +/- 16.5 g of protein were lost per 36 hours of dialysis, lower losses than those previously reported. With CAPD, 8.8 +/- 1.7 g of protein were removed per 24 hours; also immunoglobulin losses correlated with their serum concentrations. The results of these studies suggest that, in the absence of peritonitis, dialysate protein losses do not appear to limit the usefulness of peritoneal dialysis.

Subcutaneous Peritoneal Catheter: 2½Years Experience

ABSTRACTA subcutaneous peritoneal catheter (SCPC) developed at the University of Utah has been used for chronic peritoneal dialysis in this center during the last 2% years. Fifty‐six SCPC's were implanted in 48 patients for a total of 11, 260 days (30.8 patient years). The SCPC's were used for peritoneal dialysis for 7831 days (21.4 patient years) for 3356 peritoneal dialyses, the longest for 778 days (2.1 years). The SCPC remained functioning in ten patients during periods of nonuse, e. g., successful renal transplant, for 1908 days (5.2 patient years). The functional status of the SCPC was unknown in five patients lost to follow‐up for 809 days. Functional outflow obstruction episodes occurred 39 times during peritoneal dialysis (1 per 6.6 patient months); 29 of these episodes were corrected by either bedside maneuvers or minor surgical procedures. Five out of ten SCPC's removed for obstruction were successfully replaced. Twenty‐nine infections occurred (0.80% of peritoneal dialyses), resulting in nine SCPC removals (three successfully replaced). In spite of the necessary insertion of a 14‐g needle for each peritoneal dialysis, the SCPC was well accepted by the patients, mostly because of the reduced care required and the increased personal freedom gained during the interdialytic interval. The long periods of patency during nonuse (up to 397 days) further indicated the possible usefulness of the SCPC as a back‐up device for hemodialysis patients. This could greatly reduce the problems associated with temporary loss of blood access in patients on hemodialysis.

Gastric Acid Secretion, Calcitonin and Secondary Hyperparathyroidism in Uremic Patients Undergoing Regular Dialysis Therapy (RDT)

Fortyseven uremic patients on RDT underwent a gastric secretion study and a contemporary evaluation of serum levels of Calcium (Ca), Phosphate (iP), Magnesium (Mg), Alkaline Phosphatase (AP), immunoreactive gastrin (Gas), parathyroid hormone (PTH), calcitonin (CT). Secretory test (pentagastrin 6 microgram/kg) was performed in the morning, after 12 hours of fasting, in the interdialytic interval. Female patients, male patients on RDT from less 1 year and hyposecretor patients were excluded from the study. On the basis of these criteria 25 normal or hypersecretor males between 20 and 55 years old were selected. A significant positive correlation was found between PTH and CT, while a negative significant correlation was found between CT and BAO and CT and PAO. Similarly, a significant negative correlation was found between PTH and BAO and PTH and PAO. Multiple regression study showed that the negative influence of CT on BAO and PAO is more relevant than the positive influence of PTH. These data suggest that PTH and CT are involved in gastric acid secretion in uremia. Since the inhibitory effect of CT is prevailing on the stimulating effect of PTH, patients with higher levels of PTH and CT have a lower gastric acid secretion. CT might therefore be considered as a protective factor against hypersecretion in uremia.

Sweating treatment for chronic renal failure.

Sweating was induced in 3 uremic patients in an ordinary bathtub for 3 h per day to examine whether clinically significant amounts of urea could be removed. Blood urea concentrations fell in all 3 patients, and 2 of the patients had improvement in uremic syptoms. Clearances of urea by a forearm collection technique in 2 patients were 20.9 +/- 3.7 and 11.6 +/- 3.9 ml/min. Average sweat volumes were 813 +/- 62 and 566 +/- 160 ml/h. Sodium concentrations were 52 +/- 47 and 76 +/- 12 mEq/l. This removal of urea, water and salt suggests that sweating could be used to treat uremia in conjunction with charcoal hemoperfusion, in patients awaiting vascular access, or during the interdialytic interval in patients with problems with overhydration.