Hemodialysate composition and intradialytic metabolic, acid-base and potassium changes.

We compared the effects of dialysate composition on changes in intermediary metabolites, acid-base balance, and potassium removal during hemodialysis. Patients were dialyzed against dialysates containing acetate or bicarbonate, each with or without glucose, in a four-way cross-over study. Dialysates containing acetate were associated with significant perturbations in intermediary metabolism, including increases in blood citrate, acetoacetate and beta-hydroxybutyrate and a decrease in pyruvate. In contrast, bicarbonate-containing dialysates caused minimal perturbations in intermediary metabolism. Addition of glucose to the dialysate decreased the changes in intermediary metabolites; however, the magnitude of this effect was less than that observed for the change from acetate to bicarbonate. Use of acetate also resulted in lower post-dialysis blood-concentrations of base equivalents than obtained with bicarbonate; this difference was unaffected by the presence or absence of glucose. Although pre- and post-dialysis potassium concentrations were unaffected by the dialysate formulation, total potassium removal was significantly greater when glucose was omitted from the dialysate. Our results suggest that both bicarbonate and glucose should be included in the dialysate, particularly for those patients whose capacity for metabolism may be limited because of highly efficient dialysis, intercurrent illness, or starvation. However, addition of glucose to the dialysate may require a reduction in dialysate potassium to maintain proper potassium homeostasis.

Comparative metabolic effects of acetate and dichloroacetate infusion in the anesthetized dog.

The comparative effects of acetate (10 mmol/h/kg) and dichloroacetate (DCA) (1 mmol/h/kg and 10 mmol/h/kg) on acid-base and intermediary metabolism were assessed using the fasted anesthetized dog, undergoing controlled ventilation, as a metabolic model. Infusion of acetate resulted in a marked metabolic alkalemia and a decline in PaO2, while DCA had minimal effects on acid-base state and oxygen consumption. Serum glucose decreased with both DCA and acetate infusion, although only significantly with the latter. At infusion rates of 10 mmol/h/kg, acetate caused marked decreases, while DCA caused marked increases, in serum potassium and phosphorus. Acetate and DCA also had opposing effects on lactate and citrate levels, the former caused increases and the latter decreases in both metabolites. Pyruvate levels decreased similarly in response to both infusates. Acetoacetate and beta-hydroxybutyrate levels increased significantly with both acetate and DCA infusions; however, the increases were much greater with acetate than with DCA infusion. Blood alanine levels decreased significantly during the infusion of both acetate and DCA, whereas, free fatty acids tended to increase with acetate infusion, remained unchanged with low dose DCA and fell significantly with high dose DCA. Plasma insulin levels were sustained during acetate infusion, but fell abruptly with termination of infusion. In contrast, insulin levels fell markedly with DCA infusion and remained depressed throughout the infusion and recovery periods. Blood levels of acetate and DCA rose markedly during infusion; however, while acetate levels decreased nearly to control values during the recovery period, DCA levels remained elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetic gastroparesis: an abnormality of gastric emptying of solids.

Gastric emptying is delayed in subjects with gastroparesis diabeticorum. To ascertain whether solid or fluid gastric emptying is affected by visceral autonomic neuropathy, ten severe diabetics with gastroparesis and ten nondiabetic disease matched controls were studied. Subjects were screened to identify the presence or absence of autonomic neuropathy. The gastric emptying of fluids and solids was assessed by standard methodology utilizing a simultaneous dual radionuclide technique. If delayed gastric emptying was present on the initial study, metoclopramide (10mg IV bolus) was administered in a repeat study on a separate day. Screening modalities for autonomic neuropathy were markedly positive for the diabetic group, and were negative in the control group. The gastric emptying rate of fluids was normal in both groups and was not statistically different from previous standards developed using the same methodology (p = 0.53, analysis of covariance). The gastric emptying of solids was markedly delayed in the diabetic group in relation to the control group (p = .0035, analysis of covariance). Metoclopramide normalized delayed solid emptying rates without affecting fluid emptying rates.

Reactions during hemodialysis caused by allergy to ethylene oxide gas sterilization.

In patients receiving long-term hemodialysis (HD), we have examined the presence of IgE-dependent sensitization to ethylene oxide (EO) gas, which is used for sterilization of disposable medical products including dialyzers. Serum was obtained from 25 patients who experienced acute allergic reactions during HD, five patients receiving HD with isolated eosinophilia, and 37 unselected patients receiving HD. Sera from 22 of 25 of the allergic reaction group and from five of 35 of the unselected group were demonstrated to contain IgE antibodies with specificity for EO. Corresponding IgG antibodies were also present. No such antibodies were detected in serum from normal controls or ragweed-allergic patients. The serum from one patient with isolated eosinophilia had a borderline elevated IgE antibody level. These results demonstrate a close relationship between the presence of IgE antibodies to EO and HD-related allergic reactions in this patient population.

Initial experience with a new prosthetic angioaccess device.

Long-term vascular access has increased longevity for many patients with end-stage renal disease. Much of the hospitalization in this group of patients continues to be for maintenance of reliable vascular access. Thrombosis, infection, aneurysm, and stenosis lead to serious morbidity. The Hemasite angioaccess system has been introduced in an attempt to circumvent some of these problems. We reviewed our initial experience with 90 of these devices placed in 77 patients during the past 24 months. Thirty-five devices (39%) were placed under emergency conditions when the primary access site had failed, 34 (38%) were used as the initial access procedure, and simple patient convenience was the indication 21 times (23%). Twelve patients have died, with no deaths related to the device. Twenty-eight infections and 18 thromboses accounted for the failures. Fourteen thromboses were seen with the graftless device where collateral flow existed around it. One-year patency was 46% for all devices, 38% for 34 graftless devices placed in the upper arm, and 50% for the grafted model in the upper arm position. Overall patency is not comparable to other access methods yet patient acceptance is high. Placement in the upper arm offers the highest rate of success.

Intraoperative localization of parathyroid glands using methylthionine chloride / tetramethylthionine chloride in secondary hyperparathyroidism.

Over an 18 month interval at the University of Louisville Affiliated Hospitals, 40 patients were evaluated in a nonrandomized prospective study to determine the value of methylthionine chloride / tetramethylthionine chloride (methylene blue--MB) as an aid for the rapid intraoperative identification of parathyroid hyperplasia of end-stage renal disease (ESRD). Patients assigned to the MB infusion subgroup had infusion of 1 per cent MB (5.5 milligrams per kilogram) over a time interval of 25 to 60 minutes (mean of 43.9) prior to anesthetic induction. A total of 159 glands were identified in both the control and MB infusion groups (3.98 glands per patient) of which the predominant histopathologic diagnosis on frozen section was chief cell hyperplasia (78.3 per cent). Of 91 hyperplastic glands submitted for analysis after subtotal parathyroidectomy in those in the MB infusion group, 82 glands (90.1 per cent) were observed to have positive staining with identifiable differentiation from surrounding tissues. Analyses of the correlation of the serum calcium value and probability of MB staining or its relation to serum intact parathyroid hormone (intact-PTH) values were not statistically significant (p greater than 0.05, correlation coefficient equals 0.149). Furthermore, no relationship existed between the glandular size (millimeter to the third power) and probability of MB staining (chi-square equals 1.750, p greater than 0.05) or between hyperplastic size and serum intact-PTH value (correlation coefficient equals 0.068). Conversely, analysis of MB gland staining with regard to intact PTH concentration disclosed 59 of 59 glands stained intensely with MB when intact-PTH concentration was not less than 700 picograms per milliliter (p less than 0.01). Non-staining of hyperplastic parathyroid tissue was observed in 28.1 per cent of glands submitted for histopathologic analysis in which preoperative intact PTH values were more than 699 picograms per milliliter. Time of operation was reduced from 119.0 +/- 47.53 minutes (mean +/- S.E.M.) in control patients to 92.1 +/- 20.12 minutes (mean +/- S.E.M.) for the MB infusion group (V per cent equals 21.85, p less than 0.01). Furthermore, this technique appears to have value in the detection of ectopically located parathyroid tissue as demonstrated by the in vivo staining of seven ectopic glands in six patients of the infused group. Complications were restricted to the patients in the MB infusion group (21.7 per cent) and included: pseudo-cyanosis in three; pain in the infusion site in two, wound hematoma in one patient, pancreatitis in one and angina in one.(ABSTRACT TRUNCATED AT 400 WORDS)

Gastric emptying in patients with chronic renal failure receiving hemodialysis.

Patients with renal failure requiring hemodialysis often suffer from nausea and vomiting. Gastric emptying has not been studied in these patients. To determine whether an abnormality of gastric emptying might account for symptoms in these patients, two groups of ten patients each were selected, one group with symptoms of nausea and vomiting and another without symptoms. Autonomic function was assessed in all patients. Fluid and solid gastric emptying rates were quantified utilizing a dual radionuclide technique. Half-emptying times for fluid and solid test meals were not statistically different from previous standards derived using the same methods in a normal population. Patients with chronic renal failure receiving hemodialysis have no demonstrable abnormality in gastric emptying, whether symptomatic or not.

[Long-term effects of acid-base equilibrium of bicarbonate dialysis]. / Effets à long terme sur l'équilibre acido-basique de la dialyse au bicarbonate.

The acid-base effects of long-term bicarbonate hemodialysis (BDH) were evaluated in five patients previously stabilized on acetate hemodialysis (AHD). Following 12 weeks on BHD, the patients were studied an additional 6 weeks on return to AHD. Hydrogen ion generation rate (calculated from urea generation rate), and pre- and post-dialysis pH, and blood gases were measured every 2 weeks. The results of the study show that, while pre-dialysis blood bicarbonate and pH did not change significantly during the stabilization period, during BHD, and following return to AHD, hydrogen ion generation rate increased substantially on the average during BHD (+6 mmol/24 h) and fell precipitously on return to AHD (-9 mmol/24 h). Pre- to post-dialysis changes in blood bicarbonate, and pH were significantly greater during BDH than during AHD. We conclude that the increase in hydrogen ion generation rate during BDH indicates that the patients increased their intake of fixed acid. Because of extreme increases observed intra-dialytically in blood bicarbonate and pH during BHD, the ability to vary bicarbonate delivery to the patient may have to be an integral part of equipment used in BDH.

Utilization of bicarbonate for base repletion in hemodialysis.

Because of physiochemical considerations, acetate rather than bicarbonate has traditionally been used as the base repletion agent in dialysate. There are major differences in the mechanisms through which these agents neutralize the body's acid load in the circumstance of dialysis. Acetate dialysis relies on metabolism of acetate to generate bicarbonate. Loss of bicarbonate into the dialysate requires that acetate dialysis supply base far in excess of that required to buffer metabolic hydrogen ion generation alone. Consequently, net accrual of base is difficult to quantitate and may be inadequate to neutralize the excess hydrogen ion, leading to chronic buffer depletion. However, acute acid-base problems are usually avoided because of the indirect nature of base addition. In contrast, net base accrual with bicarbonate dialysis occurs in a direct and quantitative manner. While inadequate base repletion is avoided, the direct addition of base requires much tighter control if undesirable acute changes in blood pH are to be avoided.

Acid-base and metabolic responses to anion infusion in the anesthetized dog.

This study evaluated the acid-base and metabolic effects of several organic anions which might have application in the correction of metabolic acidosis during hemodialysis. Anesthetized dogs were infused intravenously with the sodium salts of either chloride, bicarbonate, acetate, lactate, or pyruvate. Acetate perturbated metabolism more than any of the other organic anions infused. These perturbations included hypoxemia, reductions in serum potassium and phosphorus, a decrease in plasma, glucose, and increases in intermediary metabolites such as lactate, acetoacetate and beta-hydroxybutyrate. Transferance of our findings to hemodialysis suggests that acetate would compromise the ability of dialysis to reduce body burdens of potassium and phosphorus and provide proper base repletion. Pyruvate would appear superior to acetate as a base substitute by virtue of its lesser effects on oxygen consumption and electrolyte distribution and its capacity to produce glucose. However, the significant production of lactate with pyruvate infusion, coupled with diffusive losses of bicarbonate during dialysis and the possible instability of pyruvate in solution, would still hinder proper base repletion. Bicarbonate generation with lactate infusion was too slow to provide a practical alternative for base repletion in hemodialysis. Bicarbonate infusion caused minimal alterations in intermediary metabolism. This, in conjunction with obviating diffusive losses, suggests the use of bicarbonate would allow more appropriate base repletion during hemodialysis.

Nephrotic syndrome.

The nephrotic syndrome appears to be an expression of a number of complex disease processes. The supportive, as well as the definitive, management of the nephrotic syndrome patient requires considerable knowledge of disease pathophysiology, drugs, and drug interactions. Therapy of any degree cannot be undertaken lightly for fear of further compromising the nephrotic syndrome patient.

The metabolic effects of hemodialysis with and without glucose in the dialysate.

The present study compares some of the metabolic effects of hemodialysis of fasting patients with and without glucose in the dialysate bath. Unlike glucose dialysis, glucose-free dialysis caused marked decreases in blood levels of glucose, insulin, lactate, and pyruvate along with profound increases in acetoacetate and beta-hydroxybutyrate. It is concluded that oxidation of fatty acids increases to meet energy demands and that the combined processes of glycogenolysis and gluconeogenesis serve to prevent critical hypoglycemia during glucose-free dialysis.