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Artificial insemination (AI) plays a critical role in facilitating rapid genetic and production gains within the sheep industry. However, variable rates of AI success remain a concern for the industry and a barrier to adoption. Furthermore, the degree to which female factors influence the success of intrauterine laparoscopic AI rather than natural mating remains unknown. As such, this study investigates the effect of several factors collected during the time of AI, on the success of intrauterine laparoscopic AI. Data was generously donated by artificial breeding companies and stud breeders during routine commercial AI operations. AI data was collected over 3 breeding seasons during commercial AI programs (N = 24 programs) using Merino ewes (N = 24,700). Sire ID (N = 253), time of AI following progesterone removal (approx. 43-59 h post removal), uterine tone and intra-abdominal fat (both scored 1-5) as well as age of the ewe were all recorded at the time of AI. Transcutaneous ultrasound subsequently determined pregnancy rate approximately 55 days post-AI. A multivariate regression analysis was performed and revealed pregnancy success to increase when semen was inseminated into a ewe with a uterine tone score of 4 or 5 (P < 0.001). The remaining factors fell short of significance within the multivariate model. An interclass coefficient variation matrix was also used to determine the proportion of variation contributed to AI success by random factors allocated in the model; site, sire, AI date and breeding season (45.99 %, 29.94 %, 15.15 % and 8.92 %, respectively). These results highlight the influence of uterine tone on ewe fertility following laparoscopic AI, but also that program location and the sire used can further modify this influence on pregnancy rate. These factors must now be considered in combination with semen factors per individual sire used during AI to ascertain the contribution of several factors to the success of laparoscopic AI in Australia., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Successful artificial breeding underpins rapid genetic and production gains in animal agriculture. In sheep, artificial insemination with frozen semen is performed via intrauterine laparoscopy as frozen-thawed spermatozoa do not traverse the cervix in sufficient numbers for high fertility and transcervical insemination is anatomically impossible in most ewes. Historically, laparoscopic artificial insemination has always been considered reasonably successful, but recent anecdotal reports of poor fertility place it at risk of warning adoption. Understanding the male, female and environmental factors that influence the fertility of sheep is warranted if the success of artificial insemination is to be improved and genetic progress maximised for the sheep industry. This review details the current practice of laparoscopic AI in sheep. It explores the effects of semen quantity and quality, the ewe, her preparation, and environmental conditions, on the fertility obtained following laparoscopic artificial insemination., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Prior small studies have shown multiple benefits of frequent nocturnal hemodialysis compared to conventional three times per week treatments. To study this further, we randomized 87 patients to three times per week conventional hemodialysis or to nocturnal hemodialysis six times per week, all with single-use high-flux dialyzers. The 45 patients in the frequent nocturnal arm had a 1.82-fold higher mean weekly stdKt/V(urea), a 1.74-fold higher average number of treatments per week, and a 2.45-fold higher average weekly treatment time than the 42 patients in the conventional arm. We did not find a significant effect of nocturnal hemodialysis for either of the two coprimary outcomes (death or left ventricular mass (measured by MRI) with a hazard ratio of 0.68, or of death or RAND Physical Health Composite with a hazard ratio of 0.91). Possible explanations for the left ventricular mass result include limited sample size and patient characteristics. Secondary outcomes included cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions. Patients in the nocturnal arm had improved control of hyperphosphatemia and hypertension, but no significant benefit among the other main secondary outcomes. There was a trend for increased vascular access events in the nocturnal arm. Thus, we were unable to demonstrate a definitive benefit of more frequent nocturnal hemodialysis for either coprimary outcome.

Background: Malnutrition is a common problem in hemodialysis (HD) patients and one of the most important factors influencing morbidity and mortality. More frequent HD has been shown to improve nutritional status in HD patients., Methods: The London Daily/Nocturnal Hemodialysis Study compared the nutritional status of patients receiving quotidian HD, either short daily HD (n = 11) or long nocturnal HD (n = 12), with that of 22 matched control patients receiving conventional thrice-weekly HD. A number of biochemical parameters indicative of nutritional status were measured, including protein equivalent of total nitrogen appearance (nPNA), serum albumin, serum prealbumin, dietary calcium, serum lipids, and water-soluble vitamin levels., Results: nPNA tended to increase throughout the study for both quotidian HD groups and remained unchanged in the control group, which had the lowest values (1 to 1.1 g/kg/d). Daily HD patients showed a significant increase in mean serum albumin levels at 3, 12, and 18 months. The nocturnal HD group showed a significant decrease in albumin levels at month 9, and control patients maintained relatively stable albumin levels throughout the study. Serum prealbumin levels averaged 0.04 g/dL for daily HD patients, whereas serum prealbumin levels decreased in nocturnal HD patients during the study period. Half the nocturnal HD patients had vitamin C levels lower than the reference range. Body composition data showed increased arm muscle area and maintenance of 100% to 110% of relative body weight (RBW) after several months of daily HD, whereas patients on nocturnal HD therapy showed a significant decline in RBW. There were no significant differences in lean body mass, percentage of body fat, or body mass index among the 3 study groups., Conclusion: Increased nPNA, serum albumin levels, and arm muscle area suggest that daily HD patients experienced improved nutritional status.

Objective: The objective of this study was to determine the renoprotective effects of ground flaxseed in patients with lupus nephritis., Methods: Forty patients with lupus nephritis were asked to participate in a randomized crossover trial of flaxseed. Twenty-three agreed and were randomized to receive 30 grams of ground flaxseed daily or control (no placebo) for one year, followed by a twelve-week washout period and the reverse treatment for one year. At baseline and six month intervals, serum phospholipids, flaxseed sachet counts, serum creatinine, 12-hour urine albumin excretion and urine albumin to creatinine ratios, serum viscosity and plasma lipids were measured., Results: There were eight drop-outs and of the 15 remaining subjects flaxseed sachet count and serum phospholipid levels indicated only nine were adherent to the flaxseed diet. Plasma lipids and serum viscosity were unaltered by the flaxseed supplementation whereas serum creatinine in the compliant patients during flaxseed administration declined from a mean of 0.97+/-0.31 mg/dL to a mean of 0.94+/-0.30 mg/dL and rose in the control phase to a mean of 1.03+/-0.28 mg/dL [p value <0.08]. Of the fifteen patients who completed the study, similar changes were noted [p value <0.1]. The nine compliant patients had lower serum creatinines at the end of the two-year study than the 17 patients who refused to participate [p<0.05]. Microalbumin at baseline declined in both control and flaxseed time periods, but there was a trend for a greater decline during flaxseed administration [p<0.2]., Conclusions: Flaxseed appears to be renoprotective in lupus nephritis, but this interpretation is affected by under powering due to poor adherence and potential Hawthorne effects.

The creatinine excretion (CrEx) ratio was first described as a method for detecting noncompliance in peritoneal dialysis (PD) patients. However, a high CrEx ratio is not specific for noncompliance and may also be found in compliant patients with a relatively greater lean body mass (LBM). A cohort of 44 PD patients was followed up for a mean of 13 +/- 8 months after measurement of baseline CrEx ratio to investigate whether greater values were predictive of good or poor clinical outcomes. During this follow-up, 11 patients died, 12 patients transferred to hemodialysis, 4 patients underwent transplantation, 1 patient recovered renal function, and 16 patients continued on PD. The mean CrEx ratio in all patients was 1.14 +/- 0.32. It did not differ between men and women (1.15 versus 1.13, respectively; P = 0.76) but showed a trend toward being less in patients with diabetes (1.03 versus 1.19; P = 0. 19). The mean weekly Kt/V, weekly creatinine clearance, normalized protein equivalent of nitrogen appearance, and serum albumin values were 2.18 +/- 0.57, 73.57 +/- 33.75 L/1.73 m(2), 0.80 +/- 0.22 g/kg/d, and 3.22 +/- 0.59 g/dL, respectively. Technique failure (P < 0.001) and death (P < 0.05) were significantly more common in patients with a CrEx ratio less than 1 compared with those with a CrEx ratio greater than 1. On Cox regression analysis, the CrEx ratio was the only significant predictor of technique failure and was also an independent predictor of death. High CrEx ratio is a predictor of good, rather than poor, outcome in PD patients, perhaps because it is primarily an index of nutrition. This further weakens the argument that it is a reliable or useful marker of noncompliance.

Mortality and morbidity on dialysis remains high regardless of age in spite of technological improvements. While some of this is explainable and acceptable and related to co-morbid problems such as heart disease, malignancy, diabetes, etc. much is also preventable. Data from the literature would indicate that the provision of adequate dialysis as determined by a Kt/V (urea) of > 1.2 or a urea reduction rate (URR) > 65% will improve outcome. Attention to the nutritional status of the patient should also have impact. Low serum levels of urea, creatinine, albumin, anion gap, ideal body weight, and a low dietary protein intake as suggested by a reduced protein catabolic rate, are bad prognostic features. The elderly are more likely to have these features. While many factors may contribute to or cause protein malnutrition, underdialysis should be one easily recognized and reversible cause. Underdialysis will inevitably lead to poor nutrition and have an adverse effect on outcome.

Objective: To evaluate the use of the ratio of measured to predicted creatinine excretion as an index of compliance in peritoneal dialysis (PD) patients., Design: A prospective analysis., Setting: Academic teaching hospital dialysis unit., Patients: Forty-three patients on PD., Measurements: Creatinine excretion in daily dialysate and urine collections was measured on one occasion in 10 patients and on two occasions in 33 patients, and, after adding an estimate for extrarenal creatinine degradation, was divided by predicted creatinine excretion to give a creatinine excretion ratio, which has been proposed as an index of compliance with exchanges in PD patients. Values above 1.24 have been suggested to indicate noncompliance. Lean body mass was also estimated from creatinine excretion., Results: The mean creatinine excretion ratio was 1.12, and 30% of patients had a value above 1.3. Only one patient admitted noncompliance. Studies on four consecutive days of guaranteed compliance in 7 patients with high ratios showed that creatinine excretion remained constant, suggesting that the patients were high creatinine producers rather than noncompliant. Creatinine excretion was stable when measured at intervals of days, but over months it tended to change markedly in many patients. Lean body mass estimations using creatinine excretion were low in most patients., Conclusion: Comparison of measured and predicted creatinine excretion is not a reliable indicator of noncompliance because many compliant patients consistently excrete more creatinine than predicted. The standard formulas were not validated in dialysis patients and underestimate creatinine excretion significantly in many PD patients. Existing estimates in the literature of noncompliance, using this methodology, may not be accurate. Better methods of detecting this problem are required.

Our objective was to investigate the extra cost associated with implementing an adequacy program in peritoneal dialysis (PD) and to evaluate the cost effectiveness of a variety of PD prescriptions. This was a cross-sectional study of all 37 patients attending the PD clinic at a university teaching hospital. Extra costs incurred on dialysate, tubing, and cyclers as a consequence of implementing an adequacy program in PD were measured. Costs per unit KT/V for a variety of PD prescriptions were also calculated. Thirteen patients (35%) required an alteration in prescription for adequacy reasons. The average extra costs incurred for all patients was Cdn. $2,323 per annum, which represents a 16% increase per patient. The most cost-effective prescriptions were high volume continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) with two daytime dwells. The least cost-effective prescriptions were day dry APD and high volume APD with only one daytime dwell. Significant extra expense is incurred when an adequacy program is implemented in PD. This is mainly due to the requirement to put more patients on APD. An alternative pricing policy for PD is suggested.

Flaxseed is rich in alpha-linolenic acid (alpha-LA) which has anti-atherogenic properties, and lignans which are platelet activating factor (PAF)-receptor antagonists. These constituents of flaxseed, and its beneficial effects in the MRL/lpr lupus mouse prompted us to perform this dosing study in lupus nephritis patients. Nine patients were enrolled, eight of whom completed the study. After the baseline studies, patients were given 15, 30, and 45 g of flaxseed/day sequentially at four week intervals, followed by a five-week washout period. Compliance, disease activity, blood pressure, plasma lipids, rheology, PAF-induced platelet aggregation, renal function, and serum immunology were assessed. Flaxseed-sachet count and a significant increase of serum alpha-LA indicated good compliance for 15 and 30 g doses. Total and LDL cholesterol, and blood viscosity were significantly reduced with 30 g and to a lesser extent 45 g doses. PAF-induced platelet aggregation was inhibited by all doses. There was a significant decline in serum creatinine with 30 and 45 g, and a concomitant increase in creatinine clearance with increasing flaxseed dose. Proteinuria was reduced with 30 g and to a lesser extent with 45 g of flaxseed. Complement C3 was significantly elevated by all three doses. CD11b expression on neutrophils, a measure of C3bi receptors, was significantly reduced with the 30 g dose. In conclusion, 30 g flaxseed/day was well tolerated and conferred benefit in terms of renal function as well as inflammatory and atherogenic mechanisms important in the pathogenesis of lupus nephritis.

The objective of this study was to assess the effects of flaxseed and flax oil diets in the rat renal ablation model. Flaxseed is a rich source of alpha-linolenic acid, an 18:3n3 omega-3 fatty acid, which has anti-atherogenic and anti-inflammatory properties. Flaxseed, but not flax oil, is also rich in lignans, which are platelet-activating factor-receptor antagonists. Rats were subjected to 5/6 nephrectomy, fed a regular laboratory diet (RLD) for 1 week, then divided into three groups to receive either the RLD (n = 8), a 15% flaxseed diet (n = 8), or a 15% flax oil diet (n = 7). Blood pressure, proteinuria, glomerular filtration rate, and urinary prostaglandins (thromboxane B2 and 6-keto prostaglandin F1 alpha) were measured presurgery and at 1 week (before dietary allotment) and 20 weeks postnephrectomy when blood for plasma lipids and kidneys for histology and tissue-phospholipid analyses were obtained. Blood pressure increased progressively in the RLD group but not in the flax diet groups. Plasma triglycerides and cholesterol increased in all groups, but this increase was significantly attenuated by both flax diets. Proteinuria increased 1 week postsurgery and continued to increase in the RLD group but not in the flax diet groups. Glomerular filtration rate decreased progressively, but this decline in renal function was attenuated significantly by the flax diets. Both of the flax diets prevented glomerulosclerosis and mesangial expansion. Renal alpha-linolenic acid was increased by both the flax diets (flax oil > flaxseed), but eicosapentaenoic acid increased in the flax oil group only. The flaxseed group had greater renal-arachidonic acid levels than the flax oil and RLD groups. The total omega-3 fatty acids increased twofold to threefold in the flax oil group compared with the two other groups. The total saturated fatty acids were lower and the polyunsaturated fatty acids were increased in both flax diet groups. A progressive increase in urinary thromboxane B2 occurred in the RLD group but not in the flaxseed group; the level decreased in the flax oil group. The ratio of prostaglandin F1 alpha/thromboxane B2 was preserved in the flax oil group only. In conclusion, the dietary flax seed and flax oil attenuated the decline in renal function and reduced glomerular injury with favorable effects on blood pressure, plasma lipids, and urinary prostaglandins. While we have not proven any specific synergistic effects of the constituents of the flaxseed diet, the benefits of flax-derived alpha-linolenic acid with or without lignans in the rat-5/6 renal ablation model seem clear from this experiment.

A diet supplemented with flaxseed, rich in alpha-linolenic acid and plant lignans (the latter, potent platelet-activating factor receptor antagonists), was tested in a murine model of lupus nephritis. MRL/lpr female mice (n = 25) were fed 15% flaxseed diet for 14 weeks commencing at 10 weeks of age. As controls, 30 MRL/lpr mice received a standard rodent diet without flaxseed. Isotope-glomerular filtration rate (14C-inulin clearance) was measured at 9, 16, and 24 weeks of age. Proteinuria was assessed at 2-week intervals. Spleen lymphocyte proliferation, quantitated by DNA analysis, was evaluated using flow cytometry at 9, 13, 19, and 21 weeks of age. Mortality was recorded throughout the study. Glomerular filtration rate at 16 weeks was greater in flaxseed-fed mice (0.15 +/- 0.03 mL/min) compared with controls (0.06 +/- 0.04 mL/min; P = 0.01). The onset of proteinuria (Albustix, Ames Division, Miles Laboratories, Rexdale, Ontario, Canada; > or = 2+) was delayed by 4 weeks in the flax-treated mice. The percentage of flaxseed-fed mice with proteinuria was lower than the control mice up to 21 weeks of age (39% v 58%; P = 0.01). Spleen lymphocyte proliferation (percentage of cells in S-phase) at 13 weeks of age was significantly higher in the control group (22.9 +/- 5.0, P = 0.01) but not in the flaxseed group (17.2 +/- 4.9) compared with baseline (9 weeks of age) values (13.0 +/- 3.5). Mortality was lower in the flaxseed-fed mice versus the control mice (assessed by Mantel-Haenszel (log-rank) test; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Our objective was to determine the effects of fish oil on renal function, symptoms, and serum lipids in patients with lupus nephritis. A double-blind, randomized crossover trial of fish oil versus placebo (olive oil) was done on 26 patients with confirmed systemic lupus; 21 completed the study. Intervention was fish oil or placebo, 15 g/day, for one year followed by a 10 week wash-out period, and then the reverse treatment for one year. At baseline and six month intervals, we measured platelet membrane fatty acids, indices of renal function, a disease activity index, serum lipid levels, blood pressure, serum viscosity and red cell flexibility. We found that platelet membrane phospholipids were uniformly affected by fish oil supplementation (P < 0.001) but with significant carry-over effects despite a 10 week wash-out period. Glomerular filtration rate and serum creatinine were not affected. A non-significant reduction in mean (SE) 24-hour proteinuria occurred, from 1424.1 mg (442.7) on placebo to 896.7 mg (352.2) on fish oil (P = 0.21). Fish oil lowered serum triglycerides from 1.89 (0.25) mmol/liter to 1.02 (0.11) mmol/liter (P = 0.004). VLDL cholesterol decreased markedly whether patients initially received fish oil or placebo (P = 0.004). The size of the reduction was affected by the order of treatment (P = 0.03), but parallel comparisons were significant before the crossover (P = 0.0006). With the possible exception of bleeding time, no other treatment effects were shown with fish oil. However, treatment order effects were seen in urinary IgG excretion (P = 0.03), whole blood viscosity (P < 0.0001), red cell flexibility (P = 0.004), and bleeding time (P = 0.06). In conclusion, one year of dietary supplementation with fish oil in patients with stable lupus nephritis did not improve renal function or reduce disease activity, but did alter some lipid parameters. Hitherto unreported carry-over effects and treatment order effects caused by the olive oil created a risk of type II error, and bear methodologic consideration in the design of future studies.

Dietary protein restriction and fish oil supplementation (MaxEPA) have been reported to have favourable effects on the remnant nephron model. In the present study female Munich-Wistar rats underwent 5/6 renal ablation (60 rats) or sham surgery (20 rats). The renal ablation rats were randomized one week post-surgery to receive a diet that contained either regular laboratory diet (RLD), 6% low protein diet (LPD) or 24% fish oil diet (FOD) supplementation. Mortality rates at 10 and 20 weeks post-surgery were not different amongst the RLD, LPD or FOD renal ablation cohorts. However the G.F.R. was significantly preserved in the FOD and LPD versus the RLD renal ablation rat groups. Both the LPD and FOD decreased albuminuria and gammaglobulinuria but LPD was more effective. Both dietary interventions prevented glomerulosclerosis but only LPD significantly reduced mesangial expansion. The FOD diet prevented intraglomerular fibrin formation and the LPD had no effect. The dyslipidemia noted at 20 weeks in the renal ablation group was significantly abrogated by both FOD and LPD, although only LPD prevented the heavy proteinuria. The LPD rats gained significantly less weight than the FOD and RLD cohorts. FOD exerted a significantly greater effect on blood pressure reduction than the LPD and also produced significant changes in the renal tissue phospholipids. These results indicate that protein restriction and fish oil supplementation preserve renal structure and function in the remnant nephron model but have different effects on mechanisms known to be co-factors in the progressive renal injury.

We previously hypothesized that PCR is dependent on Kt/V (urea). To test the hypothesis, 30 patients from two hemodialysis (HD) units with PCR values consistently less than 1 regardless of the Kt/V (urea) without an obvious cause (such as malignancy, peptic ulceration, etc.) were identified. These patients were randomized into an experimental group where an increase in the Kt/V (urea) was made or into a control group where a Kt/V (urea) remained unchanged. In the experimental group the minimal increment in Kt/V (urea) was 0.3 plus a minimum requirement of a Kt/V (urea) greater than or equal to 1. The control group were to maintain the existing Kt/V (urea) within +/- 0.2. Urea kinetic modeling was monitored monthly and the patients followed for three months. Of 30 patients, 18 fulfilled the criteria (9 experimental; 9 controls). In the experimental group, the initial Kt/V (urea) was 0.82 +/- 0.19 (means +/- SD); the final Kt/V (urea) was 1.32 +/- 0.21 (P = 0.000). These patients had an initial PCR of 0.81 +/- 0.08. This increased to 1.02 +/- 0.15 (P = 0.005). The control group had an initial Kt/V (urea) of 0.82 +/- 0.16. The final Kt/V (urea) was 0.87 +/- 0.15. Their initial PCR was 0.87 +/- 0.14 and the final PCR was 0.86 +/- 0.087 (P = NS). In the experimental group, the mean increments in Kt/V (urea) and PCR were 0.49 +/- 0.17 and 0.21 +/- 0.16 (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

A multicenter prospective study of short hour (SH, less than or equal to 3 hr) dialysis using a high flux membrane (AN69S) plus volumetric control (VC), versus conventional (greater than or equal to 4 hr) (CNV) cellulosic non-VC dialysis, is ongoing. The study hypothesizes that SH treatment over 1 year will provide adequate dialysis, will not increase morbidity, and may improve quality of life. To date, 112 patients have been entered, and 54 have completed 6 months, 30 by SH. There were no differences in biophysiologic parameters at 6 months. Mean hospitalization was 5.24 days per patient. The SH group had a higher (p = 0.0374) hospitalization rate because of two patients. Quality of life was similar in SH and CNV groups. The study indicates that SH dialysis is feasible, safe, and as comfortable as CNV.

Monthly urea kinetic modeling is performed [service Kt/V (urea)] to ensure that dialysis prescriptions provide patients a Kt/V greater than or equal to 1 and yield a protein catabolic rate (PCR) greater than or equal to 0.8. The frequency with which the dialysis prescription (physician's order +/- 5%, p +/- 5%) was achieved was calculated by three methods: 1) CompuMod (3 ureas; computer derived), 2) Jindal-Goldstein, and 3) Daugirdas, (2 and 3% reduction of urea). Ten patients were followed serially over 1 month for a total of 120 dialyses. Mean Kt/V values for each method were: prescription, 1.54 +/- 0.36; service, 1.40 +/- t0.63; CompuMod, 1.33 +/- 0.27; Jindal-Goldstein, 1.55 +/- 0.24; and Daugirdas, 1.33 +/- 0.23. The percentages of dialyses within the p +/- 5% were 12.4%, CompuMod; 12.8%, Jindal-Goldstein and 14.3%, Daugirdas. The percentages above p +/- 5% were 20.4%, CompuMod; 47%, Jindal-Goldstein; and 21.4%, Daugirdas. The percentages below p +/- 5% were 67.3%, CompuMod; 40.2%, Jindal-Goldstein; and 64.3%, Daugirdas. The CompuMod and Daugirdas methods of assessment of Kt/V were significantly lower (p less than 0.001) than the prescribed Kt/V, whereas the Jindal-Goldstein estimate was not. The authors conclude that dialysis patients rarely achieve their prescribed Kt/V. The service Kt/V, therefore, is not a useful parameter for prescribing dialysis therapy. The CompuMod and Daugirdas methods are the best estimates of the Kt/V, while the Jindal-Goldstein equation overestimates the Kt/V. The need for frequent urea kinetic modelling is stressed. An online urea monitor for each dialysis would be the ideal solution.

It has been hypothesized that the protein catabolic rate (PCR) is dependent upon the amount [Kt/V (urea)] and the type of dialysis (synthetic vs. cellulosic membrane). In an ongoing multicenter study comparing short hour-high flux with conventional cellulosic dialysis, 49 patients have completed 6 months and serial urea kinetic data has been obtained. Of the 49, 28 were on AN69S membrane dialyzers, and 21 on cellulosic. The patients on AN69S received significantly less Kt/V than those on cellulosic dialyzers (0.97 +/- 0.3 vs. 1.20 +/- 0.2; p = 0.0016), yet attained similar PCRs (1.07 +/- 0.2 vs. 1.02 +/- 0.1, NS). Significant (p = 0.002) linear relationships between PCR and Kt/V (urea) were found, yet the line slopes were higher for AN69S (average 0.46) than cellulose (average 0.25). Patients on AN69S achieve the same PCR for less Kt/V than patients on cellulosic dialyzers, supporting the hypothesis.

The National Cooperative Dialysis Study (NCDS) suggested that the removal of small molecules controls the adequacy of the dialysis prescription, and it would seem appropriate that renal units regularly carry out formal urea kinetic modeling to ensure that the adequacy of dialysis is provided. Current methods of calculating Kt/V (urea) are complex and require the accurate measurement of dialyzer urea clearance and calculation of the volume of distribution of urea. This may be done by the direct measurement of total urea removed or by the use of computer programs that examine plasma urea and weight changes over time. Both methods have inherent problems, and this has stimulated the search for easier "bedside" formulas for the calculation of Kt/V. These newer formulas involve examination of the percentage reduction in blood urea concentration during hemodialysis. Two such formulas were examined and applied to 78 patients undergoing hemodialysis in two centers. One center routinely carried out formal urea kinetic modeling; the other did not. In the first center, it was found that the majority of patients were receiving more dialysis than necessary to achieve Kt/V (urea) = 1 when the latter was judged by those formulas. This suggested the possibility of time savings, with considerable implications for cost efficiency. In the second center, the majority of patients required more dialysis. It was concluded that intermittent formal urea kinetic modeling tends to overshoot the necessary prescription to allow for occasional "imperfect" dialyses and also that it is impossible to base dialysis prescriptions on routine pre-dialysis blood work and a "feel" for patients' needs.(ABSTRACT TRUNCATED AT 250 WORDS)

Urea kinetic modelling was performed serially, over 24 months, on 55 patients undergoing hemodialysis and eight patients receiving peritoneal dialysis. The data obtained, together with changes in therapy aimed at increasing or decreasing the normalized dose of dialysis [KT/V (urea)], suggested the dependence of dietary protein intake and protein catabolic rate (PCR; g/kg/d) on the KT/V (urea). The studies also indicated that the nature of this relationship may be dependent upon the dialysis treatment used; dialysis by AN69S membrane hemodialyzers required less KT/V (urea) than hemodialysis by cellulosic membranes to obtain a given PCR. This difference may be explained by the beneficial effect of removal of "middle molecular weight" uremic toxins by the AN69S membrane, which has a different solute clearance profile than the cellulosic membrane. The studies also indicated a similar relationship between PCR and KT/V (urea) for peritoneal dialysis. With this form of therapy, however, it is difficult to obtain a PCR greater than 1 g/kg/d without first achieving very high values for KT/V (urea). It is postulated that this is due to an independent adverse effect of peritoneal dialysate in suppressing appetite. The data presented suggest that the conclusions of the National Cooperative Dialysis Study may be reinterpreted by assigning a major role to the nutritional status of patients in morbidity, with satisfactory nutritional status attained only in patients receiving adequate dialysis which, in turn, ensures control of plasma urea levels. Studies to prove this hypothesis are indicated.