Minimal change disease with acute renal failure: a case against the nephrosarca hypothesis

An unusual but well-documented presentation of minimal change disease is nephrotic proteinuria and acute renal failure. One pathophysiological mechanism proposed to explain this syndrome is nephrosarca, or severe oedema of the kidney. We describe a patient with minimal change disease who presented with heavy proteinuria and acute renal failure but had no evidence of renal interstitial oedema on biopsy. Aggressive fluid removal did not reverse the acute renal failure. Renal function slowly returned concomitant with resolution of the nephrotic syndrome following corticosteroid therapy. The time profile of the clinical events is not compatible with the nephrosarca hypothesis and suggests an alternative pathophysiological model for the diminished glomerular filtration rate seen in some cases of minimal change disease.

Combined twice-daily plasma exchange and continuous veno-venous hemodiafiltration for bridging severe acute liver failure

Aiming to remove the toxins produced during the course of severe hepatic failure, we combined hemodiafiltration and plasma exchange (patient plasma replaced by fresh frozen plasma in a twice-daily regimen) for treatment of five patients: two affected by primary nonfunction of a liver graft and three by fulminant hepatic failure. The simultaneous use of the two extracorporeal techniques allowed a rapid reduction in the administration of vasoactive drugs and a rapid, significant decrease in the indices of liver necrosis. Native liver functional recovery occurred in one case, and the wait for a second graft was made possible in the other four. Although it has been reported that the detoxifying efficacy of plasma exchange is optimal when the replaced volume of plasma is high, such a technique requires both long treatment times and high blood flows in the extracorporeal circuit, making it often hemodynamically intolerable. Our approach leads to replacement of smaller volumes, allowing lower blood flows that are better tolerated despite the often unstable hemodynamics of these patients. Liver transplantation and retransplantation remains the definite therapy for severe liver failure or primary nonfunction. However, the organ waiting time is unpredictable and often does not coincide with the patients' clinical needs. Thus alternative strategies must be developed until a suitable donor is found or there is spontaneous recovery. From this point of view, in our albeit limited experience, twice-daily plasma exchange combined with hemodiafiltration has proved to be an effective therapeutic approach.

Recommendations for the use of icodextrin in peritoneal dialysis patients

Icodextrin is a starch-derived, high molecular weight glucose polymer, which has been shown to promote sustained ultrafiltration equivalent to that achieved with hypertonic (3.86%/4.25%) glucose exchanges during prolonged intraperitoneal dwells (up to 16 h). Patients with impaired ultrafiltration, particularly in the settings of acute peritonitis, high transporter status and diabetes mellitus, appear to derive the greatest benefit from icodextrin with respect to augmentation of dialytic fluid removal, amelioration of symptomatic fluid retention and possible prolongation of technique survival. Glycaemic control is also improved by substituting icodextrin for hypertonic glucose exchanges in diabetic patients. Preliminary in vitro and ex vivo studies suggest that icodextrin demonstrates greater peritoneal membrane biocompatibility than glucose-based dialysates, but these findings need to be confirmed by long-term clinical studies. This paper reviews the available clinical evidence pertaining to the safety and efficacy of icodextrin and makes recommendations for its use in peritonal dialysis.

Phosphate addition to hemodiafiltration solutions during continuous renal replacement therapy

OBJECTIVE

Hypophosphatemia often occurs during continuous renal replacement therapy (CRRT). The addition of phosphate to dialysate and replacement solutions facilitates phosphate handling, but the risk of precipitation with calcium within these solutions has not been addressed.

DESIGN AND SETTING

Experimental study with a retrospective observational study in a medico-surgical intensive care unit.

METHODS AND PATIENTS

We tested the addition of phosphate to calcium-rich lactate- and bicarbonate-based solutions (Hemosol LG2 and Hemosol B0) used in CRRT to see whether precipitation occurs. Two milliliters of potassium phosphate added to 5-l bags gives a physiological phosphate concentration of 1.2 mmol/l. In addition, calcium and phosphate homeostasis was retrospectively evaluated in 20 consecutive CRRT patients where potassium phosphate had been added to these solutions.

MEASUREMENTS AND RESULTS

Total and ionized calcium, phosphate, pH, PCO(2) and bicarbonate remained essentially unchanged 5 h after the addition of 2 ml of potassium phosphate to 5-l Hemosol solutions. Visual inspection did not reveal any precipitate. Of the 20 patients studied, 14 received more than 24 h of phosphate supplementation to dialysate and replacement solutions. Phosphate remained stable throughout CRRT despite phosphate intake from nutrition in 11 cases. No adverse event was noted on potassium, calcium, pH and bicarbonate homeostasis.

CONCLUSIONS

The addition of phosphate to Hemosol solutions does not precipitate with the calcium within these solutions. This practical method effectively prevents hypophosphatemia in CRRT patients.

Amino acid clearance during acute metabolic decompensation in maple syrup urine disease treated with continuous venovenous hemodialysis with filtration

OBJECTIVE

Assessment of amino acid clearances by continuous venovenous hemodialysis with filtration in treatment of a metabolic decompensation in acute maple syrup urine disease.

DESIGN

Single patient assessment.

SETTING

Pediatric intensive care unit.

PATIENTS

A 10-yr-old male with known maple syrup urine disease (branched chain alpha-ketoacid dehydrogenase deficiency) with metabolic decompensation due to an acute viral illness, characterized by altered mental status, progressive obtundation, and severe acidosis.

INTERVENTIONS

Continuous venovenous hemodialysis with filtration.

MEASUREMENTS AND MAIN RESULTS

Continuous venovenous hemodialysis with filtration was instituted with both filtration (500 mL/m(2)/hr) and dialysis (1000 mL/m(2)/hr) utilized, allowing rapid correction of systemic ketoacidosis while providing amino acid clearance. Amino acid clearance was measured at initiation and at 24 hrs into therapy. The procedure was well tolerated, with near normal mental status within 12 hrs and resumption of enteral feedings. During the 24-hr period of continuous venovenous hemodialysis with filtration, serum leucine levels fell from 2352 to 381 micromoles/L, isoleucine fell from 626 to 164, and valine fell from 1117 to 228. Leucine, isoleucine, and valine clearance rates averaged 13.1, 12.8, and 13.2 mL/min, respectively, and were constant during the 24 hrs of treatment. Clearance of other amino acids during this period did not vary significantly between cationic, anionic, neutral, or hydrophobic amino acids.

CONCLUSIONS

Continuous venovenous hemodialysis with filtration provides an effective therapeutic alternative to intermittent hemodialysis during acute metabolic decompensation in maple syrup urine disease.

[The K/DOQI guidelines on diagnosis and treatment of aluminum bone disease in hemodialysis patients]

The presence of aluminum bone disease can be predicted by a rise in serum aluminum of > or = 50 microg/L following DFO challenge combined with plasma levels of intact PTH of < 150 pg/mL. However, the gold standard for the diagnosis of aluminum bone disease is a bone biopsy showing adynamic bone or osteomalacia. The dialysate concentration of aluminum should be maintained at < 10 microg/L and baseline levels of serum aluminum should be < 20 microg/L. In symptomatic patients with serum aluminum levels > 60 microg/L but < 200 microg/L or a rise of aluminum after DFO > 50 microg/L, DFO should be given to treat the aluminum overload.

The achievement of normal homocysteinemia in regular extracorporeal dialysis patients

BACKGROUND

High total homocysteinemia (tHcy) is a vascular risk factor in regular dialysis treatment (RDT) patients. A near normal tHcy has previously been achieved (from 33 +/- 11 to 13 +/- 5 micromol/L) in 23 patients on hemodiafiltration (HDF) by adjusting intravenous (i.v.) supplements of folinic acid, vitamin B12 and B6, gradually during a 2-yr follow-up. Thereafter, the same therapeutic schedule was used for all patients undergoing RDT in our unit to confirm its efficacy on a larger scale.

PATIENTS AND METHODS

Patients (n=63, F 34, age 66 +/- 14 yrs, dialytic age 60 +/- 53 months) underwent high UF post-dilutional on-line HDF for at least 6 months. They received i.v. folinic acid 3 mg, vitamin B12 50 microg and vitamin B6 450 mg/wkly. After 4 months, pre- and post-dialytic serum Hcy (n.v. 11 +/- 2 micromol/L), as well as pre-dialytic serum folate (sFA, n.v. 3-17 ng/mL) and vitamin B12 (sB12, n.v. 226-966 pg/mL) were determined.

RESULTS

The mean pre-dialytic tHcy fell to within the normal range (from 31 +/- 10 to 12.5 +/- 5 umol/L), it was slightly above the normal limits (19 +/- 2 umol/L) in only 11 patients (17%), whereas the post-dialytic value was normal in all patients (7 +/- 2.5 umol/L). The average values of sFA (25 +/- 10 ng/mL) and sB12 (1500 +/- 320 pg/mL) were approximately twice the normal limits.

CONCLUSION

Therefore, HDF appears to remove tHcy efficiently and tHcy is generally normalized by adjusting the dose of vitamin B12, vitamin B6 and folinic acid supplements.

Comparison between hemofiltration and hemodiafiltration in a long-term prospective cross-over study

BACKGROUND

The objective of the study was to compare the convective treatment modes, on-line hemofiltration (HF) and on-line hemodiafiltration (HDF), regarding cardiovascular tolerance and effects on blood pressure, when applied under similar conditions in stable dialysis patients.

METHODS

39 clinically stable dialysis patients were treated with HD for 6 months (run-in period), followed by HF and HDF in random order for 2x6 months. Similar biocompatibility (same membrane and fluid quality), similar treatment time and urea Kt/V were achieved using AK100/200 ULTRA machines, polyamide membranes in low-flux and high-flux versions and appropriate adjustment of blood flow rate (Qb) and dilution ratio (Qb/Qinf). Predilution was used for HDF (target dilution ratio = 2/1 ) as well as for HF (target dilution ratio = 1/1).

RESULTS

30 patients completed the study; 5 dropped out for non-study related reasons and 4 for non-compliance. Treatment with HF in comparison to HDF showed fewer hypotension episodes during the sessions per patient and month (HF: 0.5, HDF 1.1; p = 0.017), less plasma expander administration per patient and month (HF: 35.9 ml, HDF: 103.1 ml; p = 0.035), fewer episodes of intra-session headache (HF: 0.1, HDF: 0.4; p = 0.06), and higher pre-session MAP (HF: 98.4 mmHg, HDF: 93.8 mmHg; p = 0.037). No significant difference was found in inter-treatment weight gain, post-session MAP, or pre-session plasma sodium.

CONCLUSIONS

HF and HDF provide good control of intra-session symptoms and blood pressure in stable patients. Treatment with HF resulted in a significant reduction in intra-session hypotension and a slight but significant increase in pre-session MAP, caused by an increase in systolic BP without any effect on the prevalence of hypertension or the dose of antihypertensive drugs, all compared to HDF.