BackgroundThe safety and adequacy are established for the native percutaneous renal biopsy (PRB) but no prospective studies exist that directly compare these with transplant PRB.MethodsFrom 1995 to 2015, 1705 adults underwent percutaneous native [native renal biopsy (NRB)] or transplant renal biopsy (TRB) by the Nephrology service. Real-time ultrasound and automated biopsy needles (NRB, 14 or 16 gauge; TRB, 16 gauge) were used. Patients were observed for 24 h (NRB) or 8 h (TRB) post-procedure. Adequacy was defined as tissue required for diagnosis plus glomerular yield. Complications were defined as those resulting in the need for an intervention, such as surgery, interventional radiologic procedure, readmission, blood transfusion and death. Data were collected prospectively in all biopsies.ResultsAt the time of biopsy, NRB patients were younger (mean ± SD, 47 ± 17 versus 50 ± 14 years, P < 0.0001) and more often female (62 versus 48%, P < 0.0001) compared with TRB. A fellow supervised by an attending performed the procedure in 91% of NRB compared with 63% of TRB (P < 0.0001). TRB patients were more hypertensive [systolic blood pressure (SBP) 140 ± 22 versus 133 ± 18 mmHg, P < 0.0001] and had a higher serum creatinine (3.1 ± 1.8 versus 2.3 ± 2.2 mg/dL, P < 0.0001), activated partial thromboplastin time (28 ± 4.3 versus 27 ± 5 s, P < 0.0001) as well as lower hemoglobin (Hgb) (11.2 ± 1.8 versus 11.7 ± 2.1 g/dL, P < 0.0001) compared with NRB. Adequate tissue for diagnosis was obtained in > 99% of NRB and TRB (P = 0.71). Compared with TRB, NRB had a greater drop in Hgb after the biopsy (0.97 ± 1.1 versus 0.73 ± 1.3 g/dL, P < 0.0001), a higher complication rate (6.5 versus 3.9%, P = 0.02) and higher transfusion rate (5.2 versus 3.3%, P = 0.045). There was one death in each group attributed to the biopsy.ConclusionsAlthough death is equally rare, the complication rate is higher in NRB compared with TRB despite TRB having more of the traditional risk factors for bleeding. Differences in technique, operator (fellow or attending) or needle gauge may explain this variability.

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Therapeutic plasma exchange (TPE) has long been utilized to manage a variety of immune-mediated diseases. The basic principle relies on removal of circulating pathogenic substances from the bloodstream. Methods of plasma separation include centrifuge (cTPE) and membrane (mTPE). Although mTPE has existed for a few decades, recent advances in developing highly permeable filters that are compatible with currently existing dialysis machines has opened a new frontier. Published data in the area of technical and clinical experience with mTPE is lacking. We report our single center experience of 998 inpatient mTPE treatments performed in 237 patients at a large tertiary care academic center. The most common treatment indication was neurologic. We found a very low incidence of patient-reported complications. Filter clotting without the use of anticoagulation occurred in 7.7% of treatments. Laboratory parameters that significantly changed during the course of therapy included serum potassium, platelet count, and partial thromboplastin time. We found that mTPE can be safely and efficiently performed as an alternative to cTPE, and suggest an individualized approach when prescribing this therapy. K E Y W O R D Santicoagulation, complications, membrane, plasmapheresis, therapeutic plasma exchange

Therapeutic plasma exchange has long been utilized to manage a variety of immune-mediated diseases. The underlying principle is the removal of a circulating pathogenic substance from the plasma and substitution with a replacement fluid. Different methodologies of plasma separation include the use of centrifuge, which relies on the variation in the specific gravity of blood components, and membrane-based separation, which relies on particle size. With advancements in technology and clinical insight into disease pathophysiology, membrane technology has become more biocompatible, safer, and more adaptable to conventional hemodialysis and hemofiltration machines. As such, nephrologists, who are familiar with management of extracorporeal blood purification systems, are increasingly involved with membrane-based plasma separation. This review aims to highlight the technical aspects of membrane-based separation, review the prescription for therapy, and draw comparisons with the centrifuge-based technique when applicable.

BackgroundPercutaneous renal biopsy (PRB) of native kidneys (NKs) to better understand and treat acute kidney injury (AKI) is being advocated, but little is known about the risk of complications.MethodsWe performed a retrospective study of PRB of NKs in 955 adults from 1991 to 2015 at an academic medical center with real-time ultrasound and automated biopsy needles. Patients undergoing PRB for evaluation of AKI (n = 160) were compared with 795 patients biopsied for other reasons (not-AKI) for postbiopsy complications [need for transfusion of packed red blood cells (PRBCs), an interventional radiologic or surgical procedure, readmission or death].ResultsPatients biopsied for AKI were older (58 ± 16 versus 44 ± 16 years; P < 0.0001), with a higher serum creatinine (SCr) (4.5 ± 2.7 versus 1.8 ± 1.6 mg/dL; P < 0.0001) and lower hemoglobin (Hgb) (10.4 ± 1.7 versus 12.1 ± 2.1; P < 0.0001) and a greater proportion had an abnormal bleeding time (12.5% versus 7.4%, P 0.04), partial thromboplastin time (15.2% versus 5.3%, P < 0.0001) and/or prothrombin time (27.0% versus 12.8%; P < 0.0001) compared with not-AKI patients. Complications post-PRB were significantly greater in patients biopsied for AKI {11.3% versus 6.7%; P=0.04; odds ratio [OR] 1.78 [95% confidence interval (CI) 1.01–3.12]} with patients biopsied for AKI requiring more blood transfusions (10.0% versus 5.3%; P 0.02; OR 2.04 (95% CI 1.12–3.74)]. By multivariate analysis, baseline features predictive of a complication were increased SCr and decreased Hgb level, as well as female gender and increased systolic blood pressure.ConclusionPatients biopsied for evaluation of AKI are at greater risk of complications due to increased risk factors.

In patients who receive hemodialysis, most hypersensitivity reactions to components of the dialysis circuit are due to ethylene oxide or complement activating bio-incompatible membranes. We present a case of a 59 year-old female, with a 4-year history of uneventful hemodialysis using a cellulose based dialyzer membrane at her outpatient dialysis center, who developed repeated anaphylactic reactions associated with markers of an IgE mediated hypersensitivity reaction when a polysulfone based dialyzer membrane was used while she was hospitalized. Only when the patient's dialyzer was changed back to her usual cellulose based membrane, did these reactions cease. On the basis of her clinical course and laboratory findings, we concluded that the patient's symptoms were due to exposure to polysulfone. This case reminds us that "biocompatible" membranes are not free from dialyzer reactions, and can be especially severe if the mechanism is an IgE mediated anaphylactic hypersensitivity reaction.

Use of calcium antagonists is safe and necessary to achieve blood pressure goals in people with chronic kidney disease. While both subclasses are safe and necessary to achieve blood pressure goals, dihydropyridine calcium antagonists fail to significantly slow the progression of kidney disease among patients with established nephropathy and macroalbuminuria when compared to agents that block the renin-angiotensin system.

Background/Aims: In pre-dilution hemofiltration (HF), solute clearance is less than the HF rate. While the amount of this loss is predictable, it has not been validated in high-volume HF associated with high blood flow rates. Methods: Using isovolemic pre-dilution HF, we studied small solute clearances using combinations of blood flow (Q_B; 150, 250, 350, 450 ml/min) and replacement fluid (RF) flow (Q_RF; 2, 4, 6 l/h) to determine clearance losses we entitled ‘measured efficiency’ (E_M). E_M was compared to predicted efficiency (E_P) = (Q_B/Q_B + Q_RF). Results: Pre-dilution produced E_M values of 61–93%. Increases in Q_B for any Q_RF and decreases in Q_RF for any Q_B increased E_M over a wide range of Q_B and Q_RF. E_P was equivalent to E_M. Conclusion: In high-volume pre-dilution HF, E_P can be used to determine E_M across a broad range of Q_B and Q_RF values. Higher Q_RF requires higher Q_B to minimize the attenuating effects of pre-dilution on clearance.