Adequacy Targets Can be Met in Anuric Patients by Automated Peritoneal Dialysis: Baseline Data from Eapos

♦ Objective

Conventional continuous ambulatory peritoneal dialysis (CAPD) in patients without residual renal function and with high solute transport is associated with worse clinical outcomes. Automated peritoneal dialysis (APD) has the potential to improve both solute clearance and ultrafiltration in these circumstances, but its efficacy as a treatment modality is unknown. The European Automated Peritoneal Dialysis Outcomes Study (EAPOS) is a 2-year, prospective, European multi-center study designed to determine APD feasibility and clinical outcomes in anuric patients. The present article describes the baseline data for patients recruited into the study.

♦ Design

All PD patients treated in the participating centers were screened for inclusion criteria [urinary output < 100 mL/24 h, or residual renal function (RRF) < 1 mL/min, or both]. After enrollment, changes were made to the dialysis prescription to achieve a weekly creatinine clearance above 60 L per 1.73 m2 and an ultrafiltration rate above 750 mL in 24 hours.

♦ Setting

The study is being conducted in 26 dialysis centers in 13 European countries.

♦ Baseline Data Collection

The information collected includes patient demographics, dialysis prescription, achieved weekly creatinine clearance, and 24-hour ultra-filtration (UF).

♦ Results

The study enrolled 177 anuric patients. Median dialysis duration before enrollment was 22.5 months (range: 0 – 285 months). Mean solute transport measured as the dialysate-to-plasma ratio of creatinine (D/PCr) was 0.74 ± 0.12. Patients received APD for a median of 9.0 hours overnight (range: 7 – 12 hours) using a median of 11.0 L of fluid (range: 6 – 28.75 L). Median daytime volume was 4.0 L (range: 0.0 – 9.0 L). Tidal dialysis was used in 26 patients, and icodextrin in 86 patients. At baseline, before treatment optimization, the weekly mean total creatinine clearance was 65.2 ± 14.4 L/1.73 m2, with 105 patients (60%) achieving the target of more than 60 L/1.73 m2. At baseline, 81% of patients with high transport, 69% with high-average transport, and 40% with low-average transport met the target. At baseline, 70% of patients with a body surface area (BSA) below 1.7 m2, 60% with a BSA of 1.7 – 2.0 m2, and 56% with a BSA above 2.0 m2 achieved 60 L/1.73 m2 weekly. Median UF was 1090 mL/24 h, and 75% of patients achieved the UF target of more than 750 mL/24 h.

♦ Conclusion

This baseline analysis of anuric patients recruited into the EAPOS study demonstrates that a high proportion of anuric patients on APD can achieve dialysis and ultrafiltration targets using a variety of regimes. This 2-year follow-up study aims to optimize APD prescription to reach predefined clearance and ultrafiltration targets, and to observe the resulting clinical outcomes.

BENEFIT Niere - Bedeutung eines Nephrologie-Screenings für Interventionsbeginn und Therapieerfolg

BACKGROUND AND OBJECTIVE

Early specialist care of patients with renal disease, including timely and planned onset of dialysis, determine the course of the disease, quality of life, hospitalization and life expectancy. A multi-centre enquiry by standardized questionnaire was undertaken to define and analyse medical care of newly dialysis-requiring patients.

PATIENTS AND METHODS

Data on 551 patients in five different regions of Germany who for the first time required renal replacement treatment were prospectively collected between July 2002 and March 2003. Documentation of history, clinical findings and biochemical tests was done on consecutive patients with a standardized questionnaire, until the desired number of cases was reached.

RESULTS

The mean age of the patients (55.4% males) was 64.8 years. 30.7% had diabetes mellitus, 22.3% arterial hypertension/nephrosclerosis and 16.9% glomerulonephritis/vasculitis. Early predominantly nephrological care had been undertaken in 38.7% of patients. 59.0% were cared for almost exclusively by their general practitioner until the time when dialysis was started. 229 patients (41.6%) were referred to specialist (nephrologists) only when dialysis had become necessary. The onset of dialysis was at the right time in only 50.5% of this group. Comparing the care given by nephrologists with that by general practitioners, elective (i.e. planned) dialysis was begun in 81.0% vs. 48.0% (p<0.05). Hospitalization in the two groups was 54.5% vs. 83.7% (p<0.05), the duration of hospital stay 11.4 vs. 17.4 days (p<0.05).

CONCLUSION

Fewer than 40% of patients with chronic renal disease in preterminal renal failure (stage IV) were under the care of nephrologists. The lower the degree of nephrological care the more frequent was there a delay in the onset of dialysis treatment. The incidence and the duration of hospital stay was longer. Structured treatment pathways and incentives need to be formulated to reduce the incidence of wrong or substandard treatment of patients with impaired renal function.

Proteinuria and plasma total homocysteine levels in chronic renal disease patients with a normal range serum creatinine: critical impact of true glomerular filtration rate

Conflicting data have been reported concerning the independent association between proteinuria and plasma total homocysteine (tHcy) levels, particularly among chronic renal disease (CRD) patients with a normal range serum creatinine. Studies of this potential relationship have been limited by failure to assess true GFR, failure to assess proteinuria in a quantitative manner, or arbitrary restriction of the range of proteinuria examined. We examined the potential independent relationship between plasma tHcy levels and a wide range of quantitatively determined proteinuria (i.e., 0.000-8.340 g/day), among 109 CRD patients with a normal range serum creatinine (range; 0.8-1.5 mg/dl; median=1.2 mg/dl). Glomerular filtration rate (GFR) was directly assessed by iohexol clearance, and plasma status of folate, pyridoxal 5'-phosphate, and B12, along with serum albumin, were also determined. Linear modeling with ANCOVA revealed that proteinuria was not independently associated with tHcy levels (partial R=0.127; P=0.201), after adjustment for potential confounding by GFR (partial R=0.408; P<0.001), age, sex, plasma B-vitamin status, and serum albumin. Moreover, descending across quartiles (Q) [from Q4 to Q1] of GFR, ANCOVA-adjusted (i.e., for age, sex, and folate status) geometric mean tHcy levels (micromol/l) were significantly increased: tHcy Q4 GFR=9.6; tHcy Q3 GFR=10.5; tHcy Q2 GFR=11.9; tHcy Q4 GFR=14.5; P<0.001 for overall Q difference. We conclude that across a broad spectrum of quantitatively determined proteinuria, after adjustment for true GFR, in particular, there is no independent relationship between proteinuria and tHcy levels among CRD patients with a normal range serum creatinine.

Evaluation of renal Kt/V as a marker of renal function in predialysis patients

BACKGROUND

The use of renal Kt/V (r-Kt/V) as an indicator for the need of dialysis initiation has been recommended in the NKF-DOQI guidelines. In analogy to clinical practice in peritoneal dialysis, a fall of r-Kt/V below a threshold of 2.0 per week may indicate inadequate renal toxin elimination. However, there are no studies linking r-Kt/V with other parameters of glomerular filtration rate (GFR) in predialysis patients, and the validity of r-Kt/V as parameter for timing of dialysis initiation is unknown.

METHODS

Renal function was assessed repeatedly in 125 patients (N = 465 measurements). In predialysis patients (r-Kt/V <2.5 per week) r-Kt/V was compared with creatinine [CCr], urea [CUr], averaged creatinine/urea clearance [CCr/Ur], Cockcroft-Gault formula [CCG], and MDRD prediction equation 6 (MDRD6-GFR). The diagnostic performance of r-Kt/V as a parameter for timing the initiation of dialysis was evaluated.

RESULTS

Renal Kt/V <2.5 was prevalent in 24.9% of cases (N = 116, mean 1.92 +/- 0.34). In this group mean CCr was 13.8 +/- 4.9, mean CUr 6.7 +/- 1.3, and CCr/Ur 10.2 +/- 2.9 mL/min/1.73 m2. There was no correlation of r-Kt/V with serum creatinine and MDRD6-GFR, but a significantly positive correlation with CCr/Ur (r2 = 0.3382, P < 0.001). Sensitivity of r-Kt/V to detect CCr/Ur < 10.5 mL/min/1.73 m2, defined as the threshold for dialysis initiation, was 73.6% with a specificity of 91.9%.

CONCLUSIONS

These results suggest that r-Kt/V is a parameter of acceptable specificity but poor sensitivity for the timing of dialysis initiation. Additional measures of renal function, such as the average of measured creatinine and urea clearance, also should be taken into consideration when deciding on the timing of dialysis initiation prior to the development of clinical signs of uremia and malnutrition.

Homocysteine, cystathionine, methylmalonic acid and B-vitamins in patients with renal disease

Moderate hyperhomocysteinemia is very frequent in renal patients. Aside from homocysteine (HCY) itself, the metabolites methylmalonic acid (MMA) and cystathionine (CYS) supply further information about disturbances in HCY metabolism. In two groups of renal patients, transplant and hemodialysis patients, we measured HCY, MMA and CYS and evaluated their diagnostic value for impaired HCY metabolism due to vitamin deficiency and renal insufficiency. We investigated serum samples from 63 transplant patients and 38 patients undergoing hemodialysis. HCY, MMA and CYS were assayed by gas chromatography-mass spectrometry, vitamin B6 by HPLC, B12 and folate by chemiluminescence immunoassay. The determination of HCY, MMA, and CYS in renal patients provides specific information about intracellular disturbances of HCY metabolism. The frequency of increased metabolite levels in renal patients was much higher than the frequency of lowered vitamin concentrations in serum. Furthermore, the metabolite levels in transplant patients were only moderately increased, whereas they were strongly increased in patients on hemodialysis (HCY 19.2 vs. 28.8 micromol/l, MMA 292 vs. 1025 nmol/l, CYS 733 vs. 2711 nmol/l). Our findings may support the use of MMA determination in the diagnosis of vitamin B12 deficiency in renal patients. Compared to vitamin B12 deficiency, renal dysfunction itself appears to cause only a modest elevation in serum MMA. Regression analysis revealed that the moderate elevation of HCY and CYS in transplant patients is mainly a consequence of impaired remethylation of HCY to methionine with activated transsulfuration, whereas the mildly elevated MMA level is attributable to renal dysfunction. In patients on hemodialysis, all three metabolites were markedly elevated, indicating a strongly disturbed HCY metabolism. Based on a backward regression, we discovered that the HCY metabolism was strongly disturbed by renal insufficiency and vitamin deficiency. The markedly elevated HCY level was mainly attributable to functional vitamin B12 deficiency indicated by high MMA, and the strong CYS elevation was due to renal dysfunction and inhibition of this pathway by low levels of vitamin B6. In conclusion, besides HCY, the determination of MMA and CYS levels supports an early diagnosis of B-vitamin deficiency in renal patients. MMA is a more sensitive indicator of intracellular vitamin B12 deficiency than vitamin B12 in serum.

Chronic renal transplantation: a model for the hyperhomocysteinemia of renal insufficiency

Renal transplant recipients (RTR) are considered representative of patients with chronic renal insufficiency (CRI) in general with respect to both reduced, progressively declining renal function, and increased risk for cardiovascular disease (CVD). In accord with this argument, we hypothesized that total (t) plasma concentrations of the putatively atherothrombotic amino acid homocysteine (Hcy) would be equivalent in RTR and CRI patients with comparable renal function. We determined plasma tHcy, folate, pyridoxal 5'-phosphate, and B12 concentrations, in addition to serum creatinine and albumin concentrations, in 86 chronic, stable RTR, and 238 patients with CRI. Within comparable ranges of serum creatinine (i.e. RTR=0.6-4.2 mg/dl; CRI=0.7-4.1 mg/dl), tHcy concentrations did not differ between the two groups (RTR=15.0 micromol/l; CRI=14.9 micromol/l, P=0.899). ANCOVA revealed that renal function, gauged as a simple creatinine measurement, was the major independent determinant of plasma tHcy concentrations, accounting for approximately 80-90% of the total variability in tHcy predicted by the full model (i.e. full model R(2)) containing, in addition to creatinine, the seven other potential explanatory variables. If controlled trials confirm that tHcy-lowering treatment reduces CVD events rates in RTR, these results should be applicable to CRI patients in general.

Prophylactic hemofiltration in severely traumatized patients: effects on post-traumatic organ dysfunction syndrome

OBJECTIVE

To evaluate the effects of prophylactic veno-venous hemofiltration (CVVH) in the absence of renal failure on multiple organ dysfunction syndrome after severe multiple trauma.

DESIGN

Prospective, randomized study.

SETTING

Intensive care unit (ICU) in a university hospital.

PATIENTS

Twenty-four patients with severe multiple trauma (injury severity score > or = 27), no renal failure on admission and no contraindication for moderate heparinization.

INTERVENTIONS

Twelve patients received conventional treatment while 12 patients were treated additionally with isovolemic CVVH for 5 days starting within 24 h following trauma. Signs of organ dysfunction were assessed daily including monitoring of systemic hemodynamic by means of pulmonary artery catheterization during the first 5 days after trauma.

MEASUREMENTS AND MAIN RESULTS

Prophylactic CVVH did not affect the overall severity of organ dysfunction as assessed by MOF or APACHE II scores. However, the pattern of impaired organ systems was influenced by CVVH: while the post-traumatic decrease in platelet count in patients subjected to CVVH was more pronounced than in controls (e.g. day 4: control: 115,080 +/- 15,087, CVVH: 57,383 +/- 4,201 microliters-1; p < 0.05) the development of hyperdynamic circulatory failure was simultaneously attenuated, as reflected by a limited increased in cardiac output and an attenuated decrease in systemic vascular resistance and oxygen extraction ratio (e.g. systemic vascular resistance on day 4: control: 624.3 +/- 46.17, CVVH: 842.7 +/- 79.24 dyn.s.cm-5; p < 0.005).

CONCLUSION

CVVH blunts the cardiovascular response to multiple trauma and increases tissue oxygen extraction. However, the concomitant decrease in platelet counts represents a limitation for the use of prophylactic CVVH in surgical patients.

Hepatotoxic substance(s) removed by high-flux membranes enhances the positive acute phase response

BACKGROUND

Acute phase proteins (APPs) are enhanced in end-stage renal disease patients (ESRD) requiring dialysis treatment. They are involved in a variety of pathologic processes like muscle proteolysis, cachexia, regulation of appetite, and atherosclerosis. They are predictive for mortality. APPs are not only makers but also active substances. They are mainly produced in liver cells and are primarily, but not exclusively, regulated by proinflammatory cytokines. To what extent hepatic APPs are influenced by uremic toxins is still unclear. Therefore, we investigated the effects of different ultrafiltrates (UFs) on the synthesis of alpha1-acid glycoprotein (AGP) in HepG2 cells.

METHODS

A cross-sectional as well as a crossover study with high-/low-flux membranes was conducted to investigate the impact of UFs on bioactivity of liver cell cultures. Metabolic activity (MTT test), cytotoxicity (lactate dehydrogenase release), and the positive APP AGP were measured in HepG2 cells.

RESULTS

Cultured hepatocytes treated with UFs from high-flux membranes exhibited a higher cytotoxicity (18.6 +/- 0.3% high-flux vs. 13.9 +/- 0.2% low-flux, P < 0.001) and a lower metabolic activity (29.3% high-flux vs. 50.3% low-flux, P < 0.001) in comparison with low-flux UFs. In addition, enhanced APP secretion could be observed under costimulatory conditions (high-flux 5.0 +/- 0.7 vs. low-flux 3.1 +/- 0.6 ng/microg protein, P < 0.05). The effects of high- and low-flux UFs were strongly expressed at the beginning and were still significantly different after 120 minutes of hemodialysis (HD) treatment. The crossover experiments confirmed that UFs collected during high-flux HD had a higher capacity to stimulate AGP synthesis in liver cells.

CONCLUSION

The effects of UFs from dialysis patients demonstrate that hepatotoxic substances can be removed by dialysis. Stimulating the acute phase response UF collected during high-flux HD had a higher impact on liver cells in comparison with low-flux UF. These substances are putative cofactors involved in cytokine regulation.

An increased serum level of free Apo(a) in renal patients is more striking than that of Lp(a) and is influenced by homocysteine

Lipoprotein(a) [Lp(a)] excess combined with hyperhomocysteinaemia and hyperfibrinogenaemia may contribute to the high incidence of vascular diseases in dialysis patients. This study is aimed at investigating the role of free apolipoprotein(a) [fapo(a)] in renal patients. We have been able to show that, as compared with controls (0.53 mg/l), the median serum concentrations of fapo(a) in patients with nephrotic syndrome (2.58 mg/l) and with peritoneal dialysis (3. 40 mg/l) were strongly elevated (5- to 7-fold), while the fapo(a) levels in patients undergoing haemodialyis (1.02 mg/l) and after renal transplantation (0.90 mg/l) were about doubled. The observed differences in fapo(a) levels indicate that several mechanisms may increase the level of fapo(a), i.e., reduced renal clearance, enhanced hepatic synthesis, or homocysteine releasing apolipoprotein(a) from Lp(a). In the study collective, the median total homocysteine levels were significantly elevated in all patient groups, stronger in patients on haemodialysis (31.4 micromol/l) and peritoneal dialysis (31.2 micromol/l) than in patients with nephrotic syndrome (19.7 micromol/l) and after renal transplantation (19.5 micromol/l). In transplant patients with adequate renal function and without other apolipoprotein(a)-increasing factors, fapo(a) was significantly increased when total homocysteine exceeded 22 micromol/l. In conclusion, our findings let us presume that an increased fapo(a) level in renal patients possibly could be one of the reasons contributing to the high incidence of vascular diseases in these patients, because fapo(a) not covalently linked with Lp(a) is even more easily able to inhibit the fibrinolytic system than the complete Lp(a). These preliminary results have to be confirmed by further investigations.

In vivo effects of dialysate flow rate on Kt/V in maintenance hemodialysis patients

It is generally assumed that hemodialysis adequacy is only minimally affected by increasing the dialysate flow rate (Qd). Recent in vitro studies showed that dialyzer urea clearance (Kd(urea)) may increase substantially more than expected in response to an increase in Qd. Because these studies implied that dialysis efficacy may benefit from greater Qds, we studied in vivo the effects of various Qds on the delivered dose of dialysis in 23 maintenance hemodialysis (MHD) patients. Hemodialysis was performed at Qds of 300, 500, and 800 mL/min for at least 3 weeks each, whereas specific dialysis prescriptions (treatment time, blood flow rate [Qb], ultrafiltration volume, and type and size of dialyzer) were kept constant. Delivered dose of dialysis, assessed by single-pool Kt/V (Kt/V(sp)) and double-pool Kt/V (Kt/ V(dp)), was measured at least three times for each Qd (218 measurements). Mean +/- SEM Kt/V(sp) was 1.19 +/- 0.03 at Qd of 300 mL/min, 1.32 +/- 0.04 at 500 mL/min, and 1.45 +/- 0.04 at 800 mL/min. The relative gains in Kt/V(sp) for increasing Qd from 300 to 500 mL/min and 500 to 800 mL/min were 11.7% +/- 8.7% and 9.9% +/- 5.1%, respectively. Kt/V(dp) increased at a similar percentage (11.2% +/- 8.9% and 10.3% +/- 5.1%, respectively). The observed gain in urea clearance by increasing Qd from 500 to 800 mL/min was significantly greater than the increase in Kd(urea) predicted from mathematical modeling (5.7% +/- 0.4%; P = 0.0008). Removal ratios for creatinine and the high-molecular-weight marker, beta(2)-microglobulin, were not affected by increasing Qd from 500 to 800 mL/min. The proportion of patients not achieving adequacy (Kt/V(sp) >/= 1.2) was reduced from 56% at Qd of 300 mL/min to 30% at 500 mL/min and further to 13% at 800 mL/min. It is concluded that increasing Qd from 500 to 800 mL/min is associated with a significant increase in Kt/V. Hemodialysis with Qd of 800 mL/min should be considered in selected patients not achieving adequacy despite extended treatment times and optimized Qbs.

Hepatoactive substances eliminated by continuous venovenous hemofiltration in acute renal failure patients

BACKGROUND

Acute renal failure (ARF) in critically ill patients is mostly part of a multi-organ failure. Therefore, the effects of renal replacement therapy on the liver are clinically important. We investigated the effects of ultrafiltrates of patients treated with continuous venovenous hemofiltration (CVVH) on liver cells in vitro.

METHODS

Patients with ARF were consecutively treated with CVVH using Multiflow60 (group I) or FH66 filters (group II). They were comparable with respect to diagnosis, age, sex, laboratory parameters, and renal replacement treatment, but were different in daily diuresis, serum levels, and blood flow. Ultrafiltrates were collected within the first 10 minutes after change of hemofilter. Proliferation (bromodeoxyuridine), vitality (lactate dehydrogenase), and acute-phase protein secretion of HepG2 cells were measured.

RESULTS

Ultrafiltrates changed liver cell function significantly compared with medium control. Proliferation (group I 29.8+/-5.2% vs. group II 48.4+/-6.6%, P < 0.05) and vitality (group I 78.7+/-2.0% vs. group II 87.6+/-1.7%, P < 0.01) of HepG2 cells were significantly different. On the one hand, the secretion of the negative acute-phase protein transferrin [group 13.1+/-0.2 (ng/microg protein) vs. group II 5.1+/-0.5 (ng/microg protein), P < 0.01] was significantly reduced by Multiflow60 ultrafiltrates. On the other hand, positive acute-phase protein alpha1-acid glycoprotein was significantly stimulated by Multiflow60 ultrafiltrates [group I 2.6+/-0.1 (ng/microg protein) vs. group II 1.7+/-0.1 (ng/microg protein), P < 0.001].

CONCLUSION

This study demonstrates hepatoactive mediators in the ultrafiltrates. They are hepatotoxic and influence acute-phase protein metabolism. Further studies have to elucidate the different effects in both groups and the analysis of the putative mediator(s). It remains a challenging task to consider therapeutic measures to optimize renal replacement therapy in critically ill patients.

Effects of acidosis on acute phase protein metabolism in liver cells

Metabolic acidosis has been shown to act as a causative factor in muscle protein breakdown and negative nitrogen balance, as well as in decreased albumin synthesis. Albumin and other acute phase proteins (APP) are mainly synthesized in the liver following induction by interleukins, hormones and other mediators. Acute phase proteins have been shown to be predictors of cardiovascular mortality in the general population and in patients with end stage renal disease (ESRD). Clinical investigation gives evidence that albumin is reduced by acidosis in ESRD patients. The aim of our study was to investigate the role of the liver in acidosis, i.e. the influence of acidosis on metabolic activity and secretion of APP by liver cells (HepG2). Cells were cultured in a medium containing different amounts of bicarbonate. Metabolic activity was significantly diminished when the bicarbonate concentration of the extracellular medium was reduced (86.13+/-1.90% (pH 7.0) vs. 99. 53+/-90% (pH 7.4); p<0.01). While cellular release of negative APP was significantly decreased (albumin: 4.6+/-0.41 (pH 7.0) vs. 7.54+/-0.62 (pH 7.4) [ng/microg protein], p<0.001, transferrin: (0. 78+/-0.08 (pH 7.0) vs. 1.07+/-0.07 (pH 7.4) [ng/microg protein], p<0. 05), no significant influence of acidosis (pH 7.0) on the positive APP, alpha(1)-acid glycoprotein (AGP) (1.69+/-0.25) (pH 7.0) vs. 1.62+/-0.23 (pH 7.4) [ng/microg protein]), could be shown. Our data indicate that acidosis results in inhibition of liver cell metabolic activity and in reduced secretion of the negative acute phase proteins albumin and transferrin. In contrast, secretion of the positive acute phase protein AGP seems to be unchanged at pH 7.0 as compared to pH 7.4. We conclude that negative and positive APP in liver cells (HepG2) appear to be differently regulated by acidosis.

Liver cell reactive components in peritoneal dialysis fluids

Metabolic changes in peritoneal dialysis (PD) patients are an important aspect concerning long-term outcome. Liver plays the main role in regulating metabolism. The effects of peritoneal dialysis fluids (PDF) on liver cell function are scarcely investigated. Therefore, we investigated the effects of PDF, different in some components, on liver cell metabolism in vitro. Metabolic activity (MTT), cell integrity (LDH release), proliferation (BrdU incorporation) and synthesis of albumin and transferrin are measured by incubating HepG2 cells for 3 h and 24 h with six different PDFs: (a) lactate-buffered, pH5.5: PDF I (1.5% gluc.); PDF II (4.5% gluc. ); (b) bicarbonate-buffered, pH7.4: PDF III (1.5% gluc.), PDF IV (4. 5% gluc.); (c) amino acid-based solutions, pH 7.4: PDF V (low AA level) and PDF VI (high AA level). Metabolic activity of bicarbonate-treated cells is greatly enhanced in comparison to lactate-buffered PDFs. These findings are confirmed by proliferation data. Synthesis of albumin and transferrin is significantly enhanced by amino acid-based solutions. Our data demonstrate, that lactate-buffered PDF impair liver cells much stronger than bicarbonate-buffered PDF. pH is the parameter which contributes to cytotoxicity and impaired metabolism to a major extent. In contrast to glucose-containing solutions, amino acid-based PDF stimulate protein synthesis in liver cells.

Gender-specific differences in dialysis quality (Kt/V): 'big men' are at risk of inadequate haemodialysis treatment

BACKGROUND

Inadequate dialysis dose is closely related to mortality and morbidity of maintenance haemodialysis (MHD) patients. According to the DOQI guidelines a minimum prescribed dialysis dose of single-pool Kt/V (Kt/Vsp)=1.3, equivalent to equilibrated double pool Kt/V (e-Kt/Vdp)=1.1, is recommended. Knowledge of patient-related risk factors for inadequate delivery of hacmodialysis would be helpful to select patient subgroups for intensive control ofdialysis adequacy.

METHODS

A retrospective survey was conducted to assess the prevalence of inadequate dialysis dose according to DOQI criteria during a 7-month period. A total of 320 e-Kt/Vdp measurements in 62 MHD patients were evaluated (mean effective dialysis time 222+/-32 min). Residual renal function (RRF) was expressed as renal weekly Kt/V (r-Kt/Vweek) and included into assessment of total weekly renal and dialytic Kt/V (t-Kt/Vweek).

RESULTS

Inadequacy (e-Kt/Vdp<1.10) was prevalent in 37.2% of all measurements and in 22/62 patients (35.5%). In 54% of underdialysed patients r-Kt/Vweek compensated for insufficient dialytic urea removal. Mean weekly Kt/V was inadequate (t-Kt/Vweek<3.30) in 12/62 patients (19.4%) of whom 91.7% (11/12) were male. Body-weight, urea distribution volume (UDV). and body-surface area (BSA) were significantly higher in inadequately is adequately dialysed males. UDV>42.0 litres or BSA>2.0 m2 and a lack of RRF (r-Kt/Vweek<0.3) put 'big men' at increased risk to receive an inadequate dose of dialysis.

CONCLUSION

Our data identify patients at risk for inadequate haemodialysis treatment. Special attention should be focused on 'big men' with UDV>42.0 litres or BSA>2.0 m2. In this subset of patients frequent measurements of t-Kt/Vweek and assessment of RRF should be mandatory.

[Therapeutic plasma exchange 1996]

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique to remove large molecular weight substances. Since the late seventies TPE was used in a variety of diseases in which humoral factors may play a part in the pathogenesis. Today, accepted indications only exist for a few entities in defined situations: Anti-glomerular basement membrane antibody mediated disease, TTP/HUS, Guillain-Barré-syndrome, hyperviscosity syndrome, chronic polyneuropathy associated with IgG and IgA gammopathy, chronic inflammatory demyelinating polyneuropathy and myasthenia gravis.

[Regression of retroperitoneal fibrosis by combination therapy with tamoxifen and steroids]

BACKGROUND

Idiopathic retroperitoneal fibrosis is characterised by proliferation and fibrosis of retroperitoneal tissue. It is complicated by obstruction and encasement of retroperitoneal structures.

CASE REPORT

We describe two female patients with idiopathic retroperitoneal fibrosis. Both had to undergo lateralization of the ureter because of ureteral obstruction. Also both patients developed thrombosis of the inferior vena cava resp. the common iliac vein. Because of the eventful course of the disease a combined tamoxifen and steroid therapy was started. Hereafter there was a marked regression of the retroperitoneal fibrotic masses and the previous inflammatory signs disappeared.

CONCLUSION

Tamoxifen seems to be effective in the treatment of idiopathic retroperitoneal fibrosis by inducing a regression of the fibrotic masses. Especially in patients with continuous activity of the disease we recommend an additional steroid therapy to prevent a regeneration of the fibrosis.

[What is reliable in prevention of contrast medium-induced nephropathy?]

Nephropathy is one of the most important side effects of radiocontrast in patients with impaired renal function. Incidence is reported from 20% to 100% depending on underlying disease. For prevention of radiocontrast nephropathy a large number of substances were investigated in experimental and clinical studies. Clinical relevance of this findings will be assessed by this article. In summary of these studies hydration is the most relevant and significant measure for prevention of radiocontrast nephropathy in patients at risk (i.e. serum creatinine > 1.5 mg/dl). 1 ml/kg body weight/h with 0.45% NaCl 12 h before and after administration of radiocontrast should be supplied. Hemodialysis is recommended if impaired renal function (serum creatinine > 3.5 mg/dl) is accompanied by additional risk factors, e.g. diabetes mellitus. The impact of dialysis therapy is not clarified by clinical studies.

Cardiac depressant factors in renal disease

Chronic (CRF) and acute renal failure (ARF) are accompanied by cardiac dysfunction, particularly if ARF is complicated by sepsis. Intermyocardiocytic fibrosis is described in CRF, but there is also evidence for functional cardiomyopathy. Acetate ion (present in the dialysate) and secondary hyperparathyroidism do not appear to be clinically relevant myocardial depressant factors in uremia. The role of carnitine deficiency is not clarified, because most of the data are evaluated in poorly controlled study trials. Multiple effects of serum fractions and ultrafiltrates obtained from CRF and ARF patients during dialysis suggest the existence of myocardial depressant factor(s). Beneficial effects of continuous hemofiltration in multiorgan failure give evidence for the pathogenetic role of this substance(s). One group of experiments suggests a molecular weight between 500 and 5,000 d; other experiments suggest activity at > 10,000 d. It is currently believed that myocardial depressant substance is a water-soluble molecule weighing 10,000-30,000 d. The data confirm the existence of "specific cardiomyopathy" caused by a functional defect related to filterable toxins. There are different myocardial depressant factors in CRF, ARF, and sepsis.

[Potential nephrotoxicity of 2nd generation cephalosporins: cefuroxime versus cefotiam]

Forty-one hospitalized patients were randomized to be treated with cefuroxime (4.05 g/die) or cefotiam (5.30 g/die). Several patients received additionally furosemide (0.5 mg/kg body weight) intravenously. Serum creatinine and creatinine clearance did not show significant differences during versus after treatment in any of the groups. Cefotiam or cefotiam/furosemide treated patients displayed higher proteinuria and higher urinary excretion of lysosomal enzymes (leucine aminopeptidase) than patients treated with cefuroxime or cefuroxime/furosemide. Our data indicate higher tubulotoxicity of cefotiam compared to cefuroxime.

Low dose methotrexate therapy for rheumatoid arthritis complicated by pancytopenia and Pneumocystis carinii pneumonia

In a patient with rheumatoid arthritis pancytopenia and Pneumocystis carinii pneumonia occurred during low dose methotrexate therapy. This case emphasizes the potential development of opportunistic infections even with low dose methotrexate. Pneumocystis carinii pneumonia resembles methotrexate induced pneumonitis. Therefore opportunistic infections should be considered before a definite diagnosis of methotrexate induced pneumonitis is made.

Successful therapy of meningococcal sepsis in acute disseminated lupus erythematosus with plasmapheresis, immunosuppression, and antibiotics

A 17-year-old female with a 5-year history of disseminated lupus erythematosus has remained without immunosuppressive therapy for the last 3 years. She was admitted to the hospital for acute abdominal pain, generalized edema, and rapidly developing dyspnea and somnolence. Although all symptoms were consistent with active SLE, septicemia was suspected because of leukocytosis (20,000/microliters), greatly elevated C-reactive protein (45 mg/dl), and normal complement values (C3 0.74 g/l, C4 0.21 g/l). Directly after bacterial blood cultures were prepared, a combined treatment was instituted consisting of plasmapheresis (3 x 2.1 l against fresh frozen plasma), antibiotics, prednisolone, and cyclophosphamide following the last plasmapheresis. Within three days cerebral function returned to normal, edema improved, and CRP fell to 0.5 mg/dl. The blood cultures and pericardial effusion displayed meningococcal colonies.

Differences in effects of isoflurane and enflurane on splanchnic oxygenation and hepatic metabolism in the pig

The effects of end-tidal concentrations of 1.45% isoflurane and 2.12% enflurane on splanchnic blood flow (electromagnetic flow probes), oxygen (O2) extraction and surface PO2 (Clark-type electrode), and hepatic metabolism (organic acids) were compared in an animal model relevant to humans. Eighteen laparotomized, ventilated pigs, anesthetized and paralyzed with ketamine/flunitrazepam and pancuronium, were studied. Enflurane caused significantly (P less than 0.05) greater decreases in mean arterial pressure, cardiac output, and superior mesenteric arterial, portal, and total hepatic blood flows. In addition, hepatic arterial blood flow decreased during enflurane administration but increased markedly (40%) during isoflurane administration. However, mean surface PO2 of liver and small intestine decreased to similar degrees (20%) during isoflurane and enflurane. Summary histograms of surface PO2 values were leftward shifted but did not show O2 values in the hypoxic range (0-5 mm Hg). Except for a decrease in hepatic lactate uptake during enflurane, there were no changes in either hepatic uptake or release of organic acids during anesthesia with either agent. These data show that splanchnic O2 supply is better maintained during isoflurane than during enflurane. Although this was not reflected in differences in tissue oxygenation and metabolism, decreased portal and hepatic venous O2 contents during enflurane indicate that an increase in preportal and hepatic oxygen extraction was necessary to preserve tissue oxygenation.

Effect of cyclosporin A, azathioprine, and prednisolone on carbohydrate metabolism of rat hepatocytes

The effect of different immunosuppressive drugs (prednisolone, azathioprine, cyclosporin A) on liver carbohydrate metabolism in the rat was investigated. Daily administration of prednisolone (3 mg/kg body weight) and azathioprine (2 mg/kg body weight) intraperitoneally for 2 weeks caused significantly lower liver glycogen content than that in NaCl-treated controls. Liver glucose and lactate content, as well as plasma glucose, glucagon, and serum insulin concentration of these animals, remained unchanged. There were no differences in any of these parameters between cyclosporin A (15 mg/kg body weight)-treated and vehicle (olive oil/ethanol)-treated animals. Prednisolone caused significantly lower glucose production in isolated rat hepatocytes using Na-pyruvate as the substrate, whereas glucose production was unchanged in hepatocytes of azathioprine-treated rats using pyruvate or L-serine as substrates. Glucose production from pyruvate or serine was significantly inhibited by cyclosporin A compared to the vehicle, but did not differ from the effects of azathioprine and prednisolone. Lactate production was significantly lower in cyclosporin-treated animals than in those given either the vehicle or azathioprine. Cyclosporin A completely reversed the inhibition of hepatocyte glycogen consumption caused by the vehicle. However, glycogen production in the presence of cyclosporin A was comparable to the effects of prednisolone and azathioprine. Finally, hepatocyte ketone body production using pyruvate as the substrate was higher in the presence of all immunosuppressive drugs. In the presence of serine, acetoacetate production increased in rats treated with 50 mg/kg body weight cyclosporin A, and beta-hydroxybutyrate production in animals receiving 15 and 50 mg/kg body weight cyclosporin A.

Normalization of enhanced hepatic gluconeogenesis by the antiglucocorticoid RU 38486 in acutely uraemic rats

Hepatic amino acid uptake, urea and glucose production are increased in acute uraemia. It has been shown that this metabolic pattern is mediated by glucocorticoids. Accordingly, the administration of the antiglucocorticoid RU 38486 to acutely uraemic rats resulted in a reduction of serum urea-N and glucose levels. To clarify whether this effect is due to a reduction in hepatic gluconeogenesis we examined the effect of the antiglucocorticoid RU 38486 on urea and glucose formation in isolated hepatocytes from sham-operated (SHAM) and bilaterally nephrectomized (BNX) rats receiving RU 38486 or the vehicle only. Hepatic glucose production in BNX rats was considerably increased from Na-pyruvate (+79%), alanine (+174%), glutamine (+158%), and serine (+87%) compared with SHAM animals. Concomitantly, hepatic urea formation was also enhanced from amino acid substrates in acutely uraemic rats. When uraemic animals were treated with RU 38486, glucose production from amino acids and Na-pyruvate was reduced to the range of SHAM animals or even lower. This effect could not be demonstrated in SHAM-operated controls. A comparable decrement in hepatic urea production was observed in BNX rats treated with the antiglucocorticoid. Thus, glucocorticoids appear to play a key role in the abnormal hepatic urea and glucose production of acutely uraemic rats.

Reduced protein catabolism by the antiglucocorticoid RU 38486 in acutely uremic rats

Protein breakdown in acute uremia is enhanced, as evidenced by an increment in amino acid release from skeletal muscle and an increased amino acid uptake and urea and glucose production by the liver. To study whether this metabolic pattern is mediated by glucocorticoids, we investigated the effect of the antiglucocorticoid RU 38486 on both muscle protein breakdown and urea and glucose production of isolated hepatocytes in acutely uremic rats. Animals were rendered uremic by bilateral nephrectomy (BNX). Forty-eight hours after BNX, the rats had markedly elevated serum levels of urea nitrogen, creatinine, potassium, and phosphorus. In uremic rats receiving RU 38486 comparable levels of serum creatinine were found, but the serum levels of urea nitrogen (221 +/- 4 vs. 259 +/- 5 mg/dl) and phosphorus (6.5 +/- 0.3 vs. 8.5 +/- 0.4 mmol/liter) were significantly decreased as compared to uremic animals without RU 38486. In comparison to sham operated rats, urea-N appearance (net urea production) was increased by 56% 48 hours after BNX. This increment was almost completely reversed in uremic animals receiving the antiglucocorticoid. In untreated uremic rats, plasma levels of Nt-methylhistidine were 10.3 +/- 0.9 micrograms/dl, whereas the administration of RU 38486 caused a significant decline in the levels of this amino acid (7.6 +/- 0.5 micrograms/dl). Hepatic glucose production in BNX rats was significantly increased from alanine (+174%), glutamine (+158%), and serine (+87%) as compared to sham-operated controls. Concomitantly, hepatic urea formation from amino acid substrates was also enhanced in BNX animals. With the administration of RU 38486 to acutely uremic rats, both hepatic glucose and urea production were normalized.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cyclosporin A on carbohydrate metabolism of isolated rat liver cells

Treatment with cyclosporin A may cause hyperglycemia. The mechanisms for this phenomenon are not entirely clear. The effect of cyclosporin A treatment on rat liver phosphoenolpyruvate-carboxykinase and hepatocyte glycogen synthetase and phosphorylase activity was therefore investigated. Glycogen synthetase (total enzyme activity and the active I-form) was elevated in hepatocytes of rats undergoing immunosuppressive treatment with cyclosporin A. Glycogen phosphorylase activity showed no difference compared to hepatocytes from control rats. Activity of phosphoenolpyruvate-carboxykinase in liver homogenates was significantly enhanced after cyclosporin A treatment. Thus, it appears that cyclosporin A treatment stimulates gluconeogenesis, and glucose is used as substrate for glycogen synthesis in vitro. Differences of in vitro and in vivo experiments might be explained by long-term induction of phosphoenolpyruvate-carboxykinase and the short-term effects of cyclosporin A on glycogen synthetase.

Endocrine and metabolic abnormalities following kidney transplantation

Various endocrine and metabolic disturbances associated with long standing uremia persist after kidney transplantation or arise from the use of immunosuppressive drugs. Hyperlipidemia for long time being implicated as the cause of corticosteroids is also observed in renal transplant recipients treated with cyclosporin A monotherapy. After conversion from cyclosporin to azathioprine serum cholesterol and triglyceride concentration fall, and elevation of LDL-cholesterol may also be reversed. There is a tendency for higher HDL-cholesterol in azathioprine and prednisolone treated transplant patients. Those patients who are at risk for clinically significant cholesterol elevations can be predicted by their pretransplant lipid levels, specifically the LDL-fraction. Risk-benefit ratio of conversion and of treatment with lipid-lowering drugs, especially with lovastatin, should be carefully examined, also in view of glucose intolerance. Higher incidence of diabetes mellitus requiring insulin therapy in cyclosporin treated transplant recipients has been reported. Cyclosporin may cause toxic effects on pancreatic beta-cells resulting in inhibition of insulin secretion. High doses of cyclosporin induce inhibition of glycogen synthesis in rat liver. Glucose intolerance is reversible after reduction of cyclosporin dose or conversion to azathioprine. Therefore glucose metabolism in kidney transplant recipients treated with cyclosporin should be carefully followed. Immunosuppressive therapy may affect reproductive function, arachidonate metabolism and renin-angiotensin-aldosterone system as well as posttransplant calcium and phosphate metabolism. Endocrine and metabolic abnormalities are associated with long standing uremia. After successful kidney transplantation several observations are normalized but further complications arise from the use of immunosuppressive drugs. The present paper reviews various endocrine and metabolic disturbances described following renal transplantation.

Effect of cyclosporin A on carbohydrate metabolism in the rat

Liver and kidney carbohydrate metabolism was investigated in rats treated with daily doses of 15 mg/kg body weight cyclosporin A (CyA) for 2 and 8 weeks or of 50 mg/kg body weight CyA for 2 weeks. The higher dosage caused significantly reduced liver glycogen and liver glycogen synthetase activity (of both active I-form and total enzyme activity), whereas the activity of the glycogen-degrading enzyme phosphorylase (active a-form and total activity) remained unchanged. Plasma glucose and glucagon levels, as well as blood ketone bodies of these animals, increased significantly and plasma insulin decreased. In contrast, kidney glycogen and glucose content were higher in rats treated with 50 mg CyA, probably due to enhanced ketone body utilization. Reduced liver glycogen synthetase activity was also found in rats treated with 15 mg CyA. Our data suggest that hypoinsulinemia, induced by CyA, might be a contributing factor to the hyperglycemia, which is mainly due to inhibition of liver glycogen synthesis.

Carnitine and carnitine esters in acute renal failure

Plasma concentrations of carnitine and carnitine esters were determined in patients with multiple forms of acute renal failure with and without sepsis, and also before and after haemodialysis therapy. Total carnitine, free carnitine, short-chain and long-chain acylcarnitine values of both groups of acute renal failure patients were markedly elevated compared with healthy subjects and chronically uraemic patients undergoing regular haemodialysis treatment. Carnitine and carnitine esters did not differ between septic and non-septic patients before and after haemodialysis with dialysers made of cuprophane or polysulphone. Animal experiments with acutely uraemic rats were performed in order to determine whether the liver or the kidney may be responsible for elevated carnitine and carnitine esters in acute renal failure. Plasma and liver total carnitine, free carnitine, short-chain acylcarnitine and long-chain acylcarnitine were significantly elevated in sham-operated animals, and further in ureter ligated and bilateral nephrectomised rats. Skeletal muscle and heart muscle carnitine and carnitine esters remained the same as in sham-operated controls. Our data demonstrate markedly increased liver carnitine synthesis and carnitine acylation in an acute uraemic rat model even after binephrectomy and 48-h food depletion and in the presence of elevated serum carnitine concentrations. Furthermore, from our clinical study we conclude that there is no need for carnitine supplementation in patients who developed acute renal failure in the postoperative and post-traumatic state under adequate nutrition even when requiring daily haemodialysis.

Reduction of degranulation of polymorphonuclear leukocytes by immunosuppression in patients following cadaveric renal transplantation

Plasma levels of main granulocyte components of patients after cadaveric renal transplantation were compared 9 days postoperative with the plasma levels of patients undergoing aortofemoral and iliacofemoral bypass operation or abdominal surgery. Lactoferrin values were significantly lower in patients under immunosuppression with cyclosporine and prednisolone, whereas plasma levels of myeloperoxidase were comparable in all 3 groups of patients. Plasma E-alpha 1 PI values were significantly lower in patients undergoing bypass operation compared to abdominal surgery but did not differ from patients undergoing cadaveric kidney transplantation. Within 22 days postoperatively, there was no difference in the plasma levels of main granulocyte components in patients after kidney transplantation with and without postoperative complications. In vitro incubation of heparinized whole blood and isolated granulocytes obtained from healthy subjects in the presence of CsA, azathioprine, or prednisolone were performed. Only CsA caused inhibition of spontaneous degranulation of polymorphonuclear neutrophils showing significant lower elastase and lactoferrin release. However, in vivo administration of CsA and prednisolone in transplant patients displayed no effect on in vitro degranulation of both whole blood samples and isolated granulocytes. Our data demonstrate that CsA after in vitro incubation inhibits spontaneous granulocyte degranulation but not after in vivo administration. However, in vivo administration of CsA and prednisolone reduces lactoferrin release under certain conditions, e.g., postoperative stress or during hemodialysis therapy.

Plasma levels of main granulocyte components during cardiopulmonary bypass

Plasma levels of granulocyte lactoferrin, myeloperoxidase, and elastase in alpha 1-proteinase inhibitor complex were compared with C3a and C5a levels in 10 patients undergoing cardiopulmonary bypass. At the end of the operation, plasma levels of lactoferrin increased from 97.0 +/- 22.8 to 1257 +/- 139.8 ng/ml, myeloperoxidase increased from 37.1 +/- 4.3 to 170.9 +/- 34.9 ng/ml, and elastase in alpha-proteinase inhibitor complex rose from 89.4 +/- 7.4 to 437.8 +/- 97.3 ng/ml. There was also a significant anaphylatoxin formation. To investigate the relationship between complement and granulocyte activation, patients undergoing cardiopulmonary bypass received the calcium channel blocker nifedipine (orally and intravenously) and the antiplatelet drug dipyridamole. The continuous infusion of nifedipine (5.91 +/- 0.53 micrograms/kg body weight per hour) caused significantly lower levels of elastase in alpha-proteinase inhibitor complex and lactoferrin but not anaphylatoxin. Dipyridamole was without effect on complement and granulocyte activation during cardiopulmonary bypass. Our data demonstrate inhibition of granulocyte activation during cardiopulmonary bypass by continuous infusion of nifedipine, even in the presence of complement activation.