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Biomedical subjects

K D Nolph

Publications and source records attributed to K D Nolph.

At least 163 records · Page 9Linked to original sources
PubMed1981

Hyperosmolality, acetate, and lactate: dilatory factors during peritoneal dialysis.

Factors that alter peritoneal blood flow may influence the clearance of solutes during peritoneal dialysis. Arteriolar vasodilation, for instance, could increase the delivery of solutes to the capillaries and venules leading to an increase in solute transport into the peritoneal cavity. This study was designed to identify the vasoactive effects of several major components of McGaw and Dianeal peritoneal dialysis solutions to understand how the composition of these solutions may alter in vivo blood flow in the peritoneum. Because the major differences between these solutions and Krebs solution are a high osmolality, a high dextrose concentrations, and an acetate or lactate buffer system, we investigated the effects of these components. Rats were anesthetized with the combination of urethane and chloralose. The cremaster muscles, with the nerve and blood supplies from the rat still intact, was placed in a specially designed tissue chamber that was filled with Krebs solutions. A port permitted microscopic observations of the blood vessels. In vivo television microscopy observations was used to quantitate changes in small arteriole diameters induced by changes in the composition of the solution bathing the cremaster or by the addition of nitroprusside. Hyperosmolality produced by the addition of dextrose, sucrose, or sodium chloride to the Krebs solution induced a submaximal dilation of the small arterioles of the cremaster. The rate of dilation differed depending on the substance used to increase osmolality. A normal osmolality acetate (74 mM) or lactate (45 mM) solution produced a slow, submaximal dilation of the cremaster arterioles. Hyperosmolar acetate (37 or 74 mM) or lactate (45 mM) solutions produced a rapid, maximal dilation of these vessels. Because the rate of dilation and maximal effect produced by the commercial dialysis solutions were similar to these same parameters produced by the high-osmolality acetate or lactate solutions, the dilatory effects of McGaw and Dianeal solutions appear to be due to the combinations of high osmolality and the buffer anion acetate or lactate.

Acetates↗
PubMed1981

An hypothesis to explain the ultrafiltration characteristics of peritoneal dialysis.

We present an hypothesis that could account for many characteristics of ultrafiltration and solute movement during peritoneal dialysis. The hypothesis describes transcapillary ultrafiltration and can account for (1) the osmotic effectiveness of rapidly absorbed glucose, (2) small solute sieving in a system permitting protein loss, (3) functional estimates of effective pore sizes as low as 11 A for urea and as high as 62 A for proteins from hydrodynamic analyses, (4) isolated loss of ultrafiltration without loss of clearance, (5) decreased ultrafiltration with decreased clearances, and (6) increased ultrafiltration with decreased clearances. Mechanisms for fluid movement from the peritoneal interstitium into the peritoneal cavity may involve both hydrostatic and osmotic pressure. Interstitial water pathway dimensions, interstitial gel surface charges, mesothelial cell surface charges, and transmesothelial-cell water movement might also account for sieving effects during peritoneal ultrafiltration.

Animals↗
PubMed1981

Total body potassium--a guide to nutritional health in patients undergoing continuous ambulatory peritoneal dialysis.

Nutritional status in patients undergoing continuous ambulatory peritoneal dialysis was estimated by serial simultaneous measurements (3 to 6 months) of total body potassium, weight, serum, albumin, total serum globulins and IgG, IgA, IgM, total iron binding capacity, and hematocrit. Correlations were performed between the changes per month in these measurements and with episodes of peritonitis per month. Changes per month in serum albumin and total iron binding capacity correlated with total body potassium. Serum immunoglobulins fell with time on continuous ambulatory peritoneal dialysis but there was no correlation with the other measurements. Changes in total body potassium per month correlated negatively with episodes of peritonitis per month. Of these measured parameters only the change in total body potassium per month reflected long-term clinical consequences of peritonitis. The studies suggest that lower rates of infection, hopefully now possible with solutions in plastic bags, will prevent catabolism.

Adult↗
PubMed1981

Continuous ambulatory peritoneal dialysis.

CAPD has stimulated much interest because of conceptual and practical developments over the last decade. The growth of CAPD also demonstrates that hemodialysis as practices at the present time is not completely satisfactory for many patients and CAPD helps to fill a need. CAPD may not be the ultimate favorite in most patients, but may continue to offer an alternate approach to special problems. Careful controlled studies of long-term experiences with CAPD are needed. The initiation of a CAPD program should be done with extensive planning and care. CAPD is still a technique that can only be offered by specialists experienced in all of the complicated aspects of medical care in dialysis patients. Because this technique is spreading so rapidly and yet is still in its infancy, I would strongly urge cooperative studies of new devices and solution modifications to truly establish their worth and to control the spread of expensive but unproven gadgets. Also, there is an important need for a national registry of CAPD. The unfortunate demise of the hemodialysis registry and the transplant registry in this country at least took place after some years of monitoring and maturation of these techniques. The national experiences with CAPD should be shared to nurture the maturation of this promising but still evolving technique.

Hernia↗
PubMed1981

A comparison of peritoneal transport in patients with psoriasis and uremia.

Peritoneal solute equilibration studies during prolonged intraperitoneal dwell were performed in patients with psoriasis and normal renal function, and compared to patients with renal failure undergoing peritoneal dialysis. Calcium, phosphorous, uric acid and protein equilibration were faster in uremics. No differences were observed for sodium and chloride. Mass transfer area coefficients (a measure of the mass transfer at infinite dialysate flow rates) were calculated for glucose, protein and uric acid and found to be complimentary to the results obtained by studies of solute equilibration. Possible reasons for the differences obtained are discussed.

Adult↗
PubMed1981

In vitro simulations of peritoneal dialysis: a systematic approach to demonstrating isonatric contraction with sodium dextran sulfate.

Two sodium dextran sulfates (DS) were investigated as possible osmotic agents for use in peritoneal dialysis using an in vitro model. Initial studies with a medium molecular weight DS (Mn = 4.000) showed that sodium clearances were higher than water clearances and that both are linear functions of the concentration of polymer. In another series of studies using a low molecular weight DS (Mn = 5,000), it was found that sodium clearances decrease linearly as sodium chloride (NaCL) is added to the initial dialysate solution with only a slight increase in ultrafiltration. By plotting sodium clearances and water clearances as functions of added NaCl at constant polymer concentration, the point at which sodium clearance and water clearances are equal can be determined and, at that point, isonatric contraction can be demonstrated in the vitro model.

Dextran Sulfate↗
PubMed1980

Peritonitis during continuous ambulatory peritoneal dialysis.

We initiated a therapeutic program of continuous ambulatory peritoneal dialysis for patients with chronic renal failure. Our program resulted in many episodes of peritonitis arising from contamination due to the technical aspects of the procedure. Microbiologic evaluation showed that 73% of 97 episodes were culture positive, with gram-positive organisms causing most of the cases, especially early in dialysis. Gram-negative rods tended to occur later. Gram stains of dialysate effluent resulted in a disappointingly low yield of only 9% positivity. Cell counts were a dependable indicator of the presence of peritoneal inflammation and also of therapeutic success. Most patients responded well to intraperitoneal cephalothin, 125 mg/L for 10 to 14 d. The occurrence of peritonitis resulted in 0.93 years of hospitalization during the total of 15.45 patient-years on dialysis, which essentially negated the financial advantages of this method of treatment of chronic renal failure. For this to be a successful mode of therapy, advances in the prevention of peritonitis must be made.

Adult↗
PubMed1980

Continuous ambulatory peritoneal dialysis: three-year experience at one center.

Three years of clinical experience with continuous ambulatory peritoneal dialysis are summarized. Serum urea nitrogen, creatinine, hematocrit, nerve conduction velocity, calcium, inorganic phosphorus, serum proteins, and electrolytes have been maintained in acceptable ranges. Peritonitis, although reduced in incidence because of solutions in plastic bags and a new adapter, is still a problem. Excessive carbohydrate absorption, obesity, and high serum triglyceride concentrations may be long-term problems in some patients.

Adolescent↗
PubMed1980

New directions in peritoneal dialysis concepts and applications.

A limited number of peritoneal capillaries involved in solute exchange during peritoneal dialysis and inaccessible stagnant fluid films within the peritoneal interstitium may account for most resistance to solute transport during peritoneal dialysis. The control of small solute concentrations in blood by intermittent peritoneal dialysis will probably always require 30 to 40 hr/week of treatment even with the most rapid cycling devices. Increased understanding of factors that effect the microcirculation of the peritoneum may allow manipulation of protein losses and optimization of the long-term health of the peritoneum but will probably have little impact on the efficiency of small solute transport. CAPD accepts peritoneal dialysis as a low-efficiency system in terms of small solute clearances and yet yields similar weekly clearances to hemodialysis for small solutes by utilizing continuous dialysis. Large solute clearances with CAPD markedly exceed weekly clearances with hemodialysis.

Ambulatory Care↗
PubMed1980

In vitro simulations of peritoneal dialysis. A technique for demonstrating limitations on solute clearances due to stagnant fluid films and poor mixing.

Stagnant fluid films in the peritoneal interstitium and peritoneal cavity may explain low clearances during peritoneal dialysis. Various peritoneal dialysis techniques may influence clearances by enhancing mixing. However, such techniques also may change fresh fluid replacement rates and/or after peritoneal membrane transport characteristics secondary to mechanically, osmotically, or chemically induced changes in the peritoneium and its vasculature. Various techniques were evaluated in an in vitro simulation of peritoneal dialysis where membrane transport characteristics would not change and the impact of better mixing alone could be assessed. Only very vigorous agitation of fluid appears to influence stagnant fluid film resistances under the conditions of these studies. In actual peritoneal dialysis, fluid film resistances are probably even less likely to be influenced by existing techniques.

Ascitic Fluid↗
PubMed1980

The status of continuous ambulatory peritoneal dialysis.

CAPD continues to show promise as a continuous internal portable dialysis technique. Although unknown long-term problems may develop, it would seem at this time to offer an acceptable form of chronic dialysis for many patients.

Ambulatory Care↗
PubMed1979

Microvascular and clinical effects of altered peritoneal dialysis solutions.

Blood flow in the peritoneum is one of the more important factors governing the efficiency of peritoneal dialysis. Yet there have been no previous studies which relate alterations and control of the peritoneal microcirculation to dialysis efficiency. Thus, we used closed-circuit television microscopy to quantitative the in vivo response (changes in diameter) to dialysis solutions of the small arteries on the mesothelial surface of the rat cecum and arterioles of the rat cremaster muscle. These responses were correlated wiht solute clearances from multiple peritoneal dialysis performed in humans. In the cremaster, a transient constriction was followed by a prolonged dilation. pH adjustments of the dialysis solution from 5.6 to 7.4 had no effect on the microvascular response and no effect on solute clearances during human peritoneal dialysis. In the cecum, dialysis solution caused a prolonged dilation which reached a maximum in about 10 min. Since dilation appears to be an important determinant of solute clearances during human peritoneal dialysis, the effects of a vasodilator, sodium nitroprusside, were determined. Sodium nitroprusside decreased the time to maximal dilation, which correlated clinically with an increased solute clearance during exchanges with this drug. Since nitroprusside increased clearances of the larger molecular weight solutes proportionally more than the smaller molecular weight solutes did, we hypothesize that nitroprusside increases solute clearances by both a vasodilatory effect and by an effect on vascular membrane permeability and area for solute exchange.

Animals↗