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Biomedical subjects

K D Nolph

Publications and source records attributed to K D Nolph.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Cross-sectional assessment of weekly urea and creatinine clearances in patients on continuous ambulatory peritoneal dialysis.

In 55 patients on continuous ambulatory peritoneal dialysis, the authors determined daily renal and dialysate clearances of urea nitrogen (CUN) and creatinine (CCr). Results are expressed as weekly CUN in liters (Kt) divided by liters of total body water determined from a nomogram (V). The authors calculated weekly CCr as the weekly dialysis clearance plus the average of renal CUN and CCr (to correct for creatinine secretion); they normalized total weekly CCr to 1.73 m2 body surface area. Mean weekly Kt/V and CCr were 2.1 and 65.2, respectively. Mean dietary protein intake by dietary survey was 0.85 g/kg body weight. Protein catabolic rate (PCR) calculated from urea kinetics was 0.94 g/kg standardized weight (V/0.58); PCR was significantly (p < 0.01) correlated with Kt/V (r = 0.53). The authors used linear regression to determine PCR, as follows: PCR = 0.80 [weekly Kt/V]/3 + 0.39. This slope is nearly 1.5 times that reported for the relationship of PCR to [weekly Kt/V]/3 in hemodialysis patients. Eighty-two percent of patients on continuous ambulatory peritoneal dialysis had more than the targeted minimum weekly Kt/V of 1.7, 71% had a weekly CCr more than the targeted minimum of 50, and 75% had a PCR > 0.8 g/kg/day. In support of the hypothesis that Kt/V requirements are related to peak concentration control rather than to time averaged blood urea nitrogen, patients on continuous ambulatory peritoneal dialysis have a higher PCR at given Kt/V values compared to hemodialysis patients. These patients are more likely to have a PCR > 0.8 if weekly Kt/V > 1.7.

Blood Urea Nitrogen↗
PubMedDate not supplied

Reproducibility of the peritoneal equilibration test in CAPD patients.

A study was undertaken to evaluate the short-term reproducibility of peritoneal equilibration test (PET) results. Nine patients with end-stage renal disease undergoing continuous ambulatory peritoneal dialysis underwent PETs under similar conditions on 2 consecutive days. Dialysate samples were obtained at 0 hours, midcycle, and at the end of exchange. There were no significant differences between the mean ratios at 4 hours for creatine, urea nitrogen, potassium and protein, and glucose between PET 1 and PET 2. A standard PET is highly reproducible when repeated under similar conditions. Reproducibility is better for ratios of creatinine, glucose, urea nitrogen, and potassium than for protein.

Aged↗
PubMedDate not supplied

Lean body mass estimation by creatinine kinetics, bioimpedance, and dual energy x-ray absorptiometry in patients on continuous ambulatory peritoneal dialysis.

Lean body mass (LBM), which is fat free body mass, can be used as an index of nutritional status. We evaluated three techniques for LBM estimation, including dual energy x-ray absorptiometry (DEXA), creatinine kinetics (CrKin), and bioimpedance (BI) in 10 patients on continuous ambulatory peritoneal dialysis (CAPD). Two different formulae were applied for BI LBM estimation, Segal (S) and Deurenberg (D). Mean values (+/- SEM) of LBM estimated were 48.2 +/- 3.6, 46.12 +/- 2.87, 43.32 +/- 3.87, and 41.27 +/- 4.26 by DEXA, BI-S, BI-D, and CrKin, respectively. LBM by CrKin was significantly lower than that by DEXA and BI-S values. There was no statistically significant difference between DEXA and BI-S values. Statistically significant correlations were found between LBM values by all methods. Particularly strong correlations were found between DEXA versus BI-S (r = 0.976) and BI-S versus BI-D (r = 0.98). Because clinical assessment of hydration status is inaccurate, and both BI and DEXA measure excess extracellular water in LBM, falling muscle mass may be missed by these techniques. The CrKin technique for estimating LBM at normal body fluid volumes (dry weight) may be a better index of nutritional status in patients on CAPD because this may truly reflect the dry LBM and changes in muscle mass. Both DEXA and BI include excess body water in LBM and may mask malnutrition in the presence of subclinical or clinical overhydration, which is common in patients on peritoneal dialysis.

Absorptiometry, Photon↗
PubMedDate not supplied

A new approach to optimizing urea clearances in hemodialysis and continuous ambulatory peritoneal dialysis.

Recent studies suggest that the relationship of the net normalized protein catabolic rate (which is the normalized protein equivalent of nitrogen appearance [nPNA]) to the weekly clearance of urea normalized to total body water (Kt/V urea) in patients on continuous ambulatory peritoneal dialysis (CAPD) is curvilinear, rather than linear, as has been thought. The authors have reexamined the relationship of nPNA to weekly Kt/V urea in a CAPD population by cross-sectional analysis to see if the curvilinear definition of the relationship is as good as or better than the usual linear description. They also examined this relationship in the hemodialysis populations at the Dialysis Clinics Inc. in Columbia, Missouri, and in the Renal Kidney Disease Program in Minneapolis, Minnesota. It seems obvious that there should be a plateau of nPNA in each therapy because extension of linear regressions would predict protein intakes of normal individuals exceeding 8 g/kg/body weight/day. The authors compared their findings to other published results. Intuitively and analytically, the curvilinear relationships seem likely. The authors observed that the nPNA plateau is achieved at lower Kt/V in patients on CAPD than in those on hemodialysis, which is compatible with the peak concentration hypothesis. Asymptotes for CAPD and hemodialysis are similar. Weekly Kt/V urea requirements to achieve nPNA values at 95% of the asymptote are greater than those usually delivered. However, such nearly complete elimination of uremic appetite suppression may not be practical or necessary for achieving acceptable nutritional status and long-term survival in most patients. Optimum therapy may be well above adequate therapy relative to minimizing appetite suppression by uremia.

Appetite↗
PubMedDate not supplied

A prospective study of the effect of noncompliance on small solute removal in continuous ambulatory peritoneal dialysis. Preliminary report.

In nine patients on continuous ambulatory peritoneal dialysis (CAPD) who were in stable condition, the authors measured the effects of an extra daily exchange on small solute removals and clearances and the measured/predicted creatinine production (M/P). The goal was to evaluate the sensitivity of M/P to single exchange noncompliance. Daily collections of urine and dialysate were performed on the usual prescribed program and on the next day with an extra exchange of usual exchange volume. The average increase in drain volume of 26% was associated with an average increase in M/P of 6%. The maximum M/P increase was 15%; the percentage increase in M/P correlated inversely with renal creatinine clearance. Daily total urea clearance normalized to total body water by dialysis and renal function increased 12%. Extrapolating these findings suggests that an average patient with a baseline M/P near 1.0 and renal creatinine clearance of 5 ml/min would require more than 50% drain volume noncompliance to yield a M/P of 1.24 on the complaint day. A 50% noncompliance may not yield a M/P greater than 1.0 on the first compliant day if baseline M/P is less than 0.94. The authors suggest monitoring daily urine and dialysis creatinine output because M/P creatinine is relatively insensitive to noncompliance (particularly in patients with residual renal function) and because there are questions about the accuracy of predictions in patients with renal failure using formulae established in different populations. The authors recommend simply monitoring total daily creatinine output and establishing patients as their own controls. The authors provide a table for the interpretation of changes in creatinine output in conjunction with changes in other routinely monitored parameters.

Blood Urea Nitrogen↗
PubMedDate not supplied

Has peritoneal dialysis peaked? The impact of the CANUSA study. The Canadian-USA Multicenter study.

We previously summarized evidence that an increase of dialysis dose is associated with better protein intake and better nutritional status. The CANUSA study suggests that higher dialysis doses are associated with better patient survival rates. It is imperative that we design prescriptions and techniques to provide greater dialysis doses compatible with a reasonable quality of existence. The reasons why U.S. dialysis patients may have higher mortality rates than in other countries for both hemodialysis and CPD may relate to factors other than dialysis adequacy and commonly appreciated morbidity factors; this needs further attention.

Adolescent↗
PubMedDate not supplied

Longitudinal evaluation of a renal Kt/V(urea) of 2.0 as a threshold for initiation of dialysis.

We (Perit Dial Int 17:426 and 497, 1997) and the Dialysis Outcomes Quality Initiative guidelines (Am J Kidney Dis 30:S69, 1997) have reported evidence that protein intake often is < 0.8 g/kg standard weight when renal weekly urea clearance (L) normalized to total body water (V, L) is less than 2.0, and that initiation of dialysis should be considered if nutritional status is decreasing. We have prospectively followed renal urea (C(urea)) and creatinine clearances (C(cr)) in 20 patients with chronic renal failure. Nine patients received dietary counseling, but we have previously shown this has minimal effects on protein intakes (Perit Dial Int 17:497, 1997). In 16 patients (group 1), glomerular filtration rate (GFR) estimated as (C(urea) + C(cr))/2 decreased from 14.6 +/- 1.5 (mean +/- SEM) to 9.8 +/- 0.9 (ml/min/1.73 m2 BSA) over a mean interval of 10.3 +/- 1.6 months; in the other 4 patients (group 2), mean GFR did not decrease and was initially 17.6 +/- 3.8 and 21.7 +/- 2.2 after 8.5 +/- 2.3 months. In group 1, Kt/V went from 2.5 +/- 0.3 to 1.7 +/- 0.2; in group 2, Kt/V went from 3.1 +/- 1.0 to 3.7 +/- 0.6. In group 1, protein intake as assessed from the normalized equivalent of protein nitrogen appearance calculated from urea nitrogen and protein losses in urine (nPNA; g/kg standard weight) went from 1.0 +/- 0.1 to 0.8 +/- 0.1. In group 2, mean nPNAs were 1.1 +/- 0.3 and 1.1 +/- 0.1. In all measurements with Kt/V less than 2.0 (n = 18), 10 (56%) were with nPNA less than 0.8. In all measurements of Kt/V > or = 2.0 (n = 22), only 3 (13.6%) were with an nPNA of less than 0.8. These percentage values were different (p < 0.0001) by chi-squared analysis. Changes in nPNA correlated directly (but insignificantly, probably because of a small n) with C(cr), GFR, and Kt/V. These prospective results provide additional evidence that protein intakes decrease to dangerously low levels (without intense dietary monitoring) in most patients when renal weekly Kt/V decreases to below 2.0, which is similar to findings in patients on continuous ambulatory peritoneal dialysis.

Adult↗
PubMedDate not supplied

Low protein diets are not needed in chronic renal failure.

Low protein diets have been used for a long time in the conservative management of chronic renal failure as they have a beneficial effect in preventing the appearance of symptoms. However, with the exception of the beneficial effect on hyperphosphatemia of the very low protein diets supplemented with ketoacids, they have no proven effects on the other aspects of the uremic syndrome. Moreover, the weight of the evidence suggests that the effect of these diets on preservation of GFR, if any, in patients with nondiabetic renal disease is small and of little clinical relevance. There is very little evidence in the literature of its role in patients with diabetes. The nutritional safety of these diets is still suspect. Patients with chronic renal failure have low energy intakes, which is further reduced when these diets are prescribed. Metabolic studies predict that these patients would be in negative nitrogen balance and in fact, even nutritionally sound, nondiabetic patients enrolled in the Modification of Diet in Renal Disease Study developed subclinical signs of malnutrition. It is possible that the nutritional decline may have been more pronounced on longer duration of follow-up. Finally, these diets are difficult to follow, leading to issues of compliance and exert a great toll on the time of the dietitians. Hence, we conclude that low protein diets are not necessary in chronic renal failure.

Diet, Protein-Restricted↗
PubMedDate not supplied

Polycation as an alternative osmotic agent and phosphate binder in peritoneal dialysis.

We have previously shown that polyanions can be utilized to achieve balanced removal of sodium and water during peritoneal dialysis. The excessive binding of potassium, calcium, and magnesium to anionic polymers proves undesirable. The present study was designed to demonstrate the reversibility of cation binding by using a polycation (polyethylenimine) as the osmotic agent, thus favoring the removal of undesirable excess phosphate anions via peritoneal dialysis. Polyethylenimine shows a measurable affinity for phosphorus when present as dialysate in an in vitro system simulating peritoneal dialysis. The polycation also stimulates ultrafiltration across the rat peritoneum when present in dialysate. The polymer is toxic to the rat and light microscopy reveals gross morphological tissue alterations of the visceral mesothelium and associated organs. We have demonstrated that a polycation can give ultrafiltration with enhanced removal of phosphate. Although the polymer we chose as a prototype is toxic to the rat, other polycations should be studied.

Animals↗
PubMedDate not supplied

Effects of dipyridamole on peritoneal clearances.

To see if oral dipyridamole increases peritoneal clearances in humans undergoing peritoneal dialysis, two types of double-blind clinical studies were undertaken. In a single-dose study, 7 patients were randomized to take dipyridamole or placebo early in a peritoneal dialysis with 2 L, hourly cycles; later in the same dialysis a crossover administration was studied. In a multidose study, 17 patients were randomized to take dipyridamole or placebo three times daily and clearance studies were performed on days 1, 4, and 8 during 2 L, hourly peritoneal dialysis cycles. Neither the single dose of dipyridamole or placebo significantly altered drainage volumes, clearances, or dialysate protein from control periods. In the multidose study, mean values on dipyridamole or placebo were not significantly changed from respective baseline predrug values. Mean values with dipyridamole and placebo usually were not significantly different. Dipyridamole did not appear to improve peritoneal clearances even with repeated ingestion.

Adult↗
PubMedDate not supplied

Advanced glycosylation end-products in diabetic rats on peritoneal dialysis using various solutions.

OBJECTIVE: To evaluate and compare the effects of glucose-based solutions to those of icodextrin with respect to peritoneal transport characteristics and advanced glycosylation end-product (AGE) formation in the peritoneal membrane in a diabetic rat model of peritoneal dialysis (PD). DESIGN: Thirty-three male Sprague-Dawley rats weighing between 275-300 g were divided into five groups: group C (n = 6), control rats implanted with a catheter but not dialyzed; group D (n = 5), diabetic rats implanted with a catheter but not dialyzed; group G (n = 7), diabetic rats implanted with a catheter and dialyzed with standard 2.5% glucose solution for daytime exchanges and 4.25% glucose solution for overnight exchanges; group H (n = 8), diabetic rats implanted with a catheter and dialyzed with standard 2.5% glucose solution for daytime exchanges and 7.5% icodextrin solution for overnight exchanges; group I (n = 7), diabetic rats implanted with a catheter and dialyzed with 7.5% icodextrin solution for all exchanges. Dialysis exchanges (25 mL per exchange) were performed three times daily for a period of 12 weeks. Tissue sections were stained using a monoclonal anti-AGE antibody. One-hour peritoneal equilibration tests (PET) were performed every 4 weeks for comparison of transport characteristics. RESULTS: The level of immunostaining was lowest in group C and highest in group G. Significant differences in immunostaining were seen between group C and group G (p < 0.001), group C and group H (p = 0.001), and group C and group I (p < 0.05). Significant differences were also found between group G and group D (p < 0.05), and between group G and group I (p < 0.05). Over time, the ratio of glucose concentration after 1 hour to glucose concentration at instillation (D/D0) decreased and the dialysate-to-plasma ratio (D/P) of urea increased. Significant differences in D/D0 glucose and D/P urea were found between group C and group H (D/D0: 0.40 +/- 0.01 vs 0.35 +/- 0.01, p < 0.05; D/P urea: 0.87 +/- 0.03 vs 0.97 +/- 0.02, p < 0.05). CONCLUSIONS: These results suggest that AGE formation is lower with the use of peritoneal dialysis solution containing icodextrin than with glucose-based solution. We conclude that use of icodextrin may help to slow the deterioration of the peritoneal membrane, prolonging its use for dialysis.

Animals↗
PubMedDate not supplied

What we have learned about uremia from peritoneal dialysis.

Weekly clearances of small solutes such as urea are relatively low on continuous ambulatory peritoneal dialysis (CAPD) compared to those of thrice weekly hemodialysis (HD); large solute clearances are more comparable. Some believe that good clinical outcomes with chronic peritoneal dialysis support the importance of larger molecular weight toxins. However, CAPD patients of large size or approaching an anephric state occasionally develop uremic symptoms that can be reversed with an increased exchange volume or an increased number of exchanges. Increasing exchange volume or the number of exchanges increases small solute clearances by an amount near the increase in drain volume, but clearances of larger molecular weight substances are minimally affected. Thus, peritoneal dialysis experiences initially focused attention on large molecules and now appear to confirm the importance of small solutes in uremic toxicity but at lower clearance requirements than needed in HD.

Dialysis Solutions↗
PubMedDate not supplied

Peritoneal transfer of carbon dioxide in the rat.

In the authors' previous rat studies (Kidney Int 39: 608-617, 1991), peritoneal clearances (Cp) representing near exclusively diffusive CO2 transfer were evaluated: for isosmotic (0.37% dextrose) and hyperosmotic (15% dextrose) solutions with pH 7.2-7.3, Cp CO2 were 1.20 +/- 0.08 and 1.84 +/- 0.04 ml/min, respectively. In the present studies peritoneal transfer parameters (D/B, Cp) of CO2 gas, HCO3-, and total CO2 (tCO2) in anesthetized rats have been compared (n = 22) using solutions with dextrose contents as mentioned above but with a pH of 6.5 or 7.6; how much Cp CO2 measurements obtained with solutions at these pH values differ from Cp shown earlier with solutions of pH 7.2-7.3 has also been evaluated. When the pH was the same, transfer parameters of CO2 gas, HCO3-, and tCO2 were significantly higher under hyperosmotic conditions. The use of solutions with a pH different from 7.2-7.3 resulted in higher Cp of CO2 gas: with isosmotic solutions at pH 6.5 and 7.6, mean increases were 25 and 75%, respectively; with hyperosmotic solutions respective increases were 45 and 134%. The authors conclude that dialysis solution pH, especially under hyperosmotic conditions, significantly changes parameters of diffusive CO2 transfer in the rat. For evaluation of peritoneal blood flow from diffusive transfer parameters of CO2 gas, smaller overestimation can be expected when dialysis solution pH is slightly under than overadjusted compared to blood pH.

Animals↗
PubMedDate not supplied

ASAIO presidential address.

ASAIO has a proud heritage and a list of many accomplishments. It has given birth to many highly specialized societies and meetings. These changes and new developments in other fields have diverted it from being mainly a kidney society to being more multidisciplinary than ever before. Although meeting attendance declined for a number of years, the productivity of the society did not. Now attendance is increasing, and the number of submitted abstracts has exceeded all past records. Increasing activity in ASAIO may reflect the awareness of the need for a multidisciplinary meeting in this explosive era of artificial organ development. ASAIO can and should play a major role in fostering artificial organ research and development in the years to come. I am confident that it has the strengths to accomplish many important goals. I am very proud to have served as President of this society with a marvelous past and a promising future.

Artificial Organs↗