Raphael M. Cohen

Acute renal failure due to indinavir crystalluria and nephrolithiasis: report of two cases.

Two patients with oliguric acute renal failure (ARF) attributed to crystalluria and nephrolithiasis with obstructive uropathy caused by the human immunodeficiency virus protease inhibitor indinavir are described. In both patients, ARF resolved with administration of intravenous fluids. One patient required urologic intervention to relieve bilateral ureteral obstruction.

Physical Examination versus Normalized Pressure Ratio for Predicting Outcomes of Hemodialysis Access Interventions

PURPOSE The ratio of intragraft venous limb pressure (VLP) to systemic pressure (S) has been proposed to help determine the endpoint of hemodialysis access interventions. It was hypothesized that physical examination of the access could be used in the same way and these techniques were compared as predictors of outcome. PATIENTS AND METHODS With use of a quality-assurance database, records from 117 hemodialysis access interventions were retrospectively reviewed. Only interventions in grafts were included. The database included physical examination (to establish thrill, thrill with slight pulsatility [TSP], pulse with slight thrill [PST], and pulse) at three locations along the graft (proximal, midportion, and distal), normalized pressure ratio calculated with S from a blood pressure cuff (S(cuff)) and S within the graft with outflow occluded (S(direct)), graft configuration and location, indication, operator, and time to next intervention (outcome of primary patency). Only procedures with complete follow-up data were included in the analysis (n = 97; declotting, n = 51; prophylactic percutaneous transluminal angioplasty [PTA], n = 46). Statistical analysis was performed with use of Cox proportional-hazards regression. RESULTS Graft configuration, location, side, VLP, S(direct), and S(cuff) did not affect outcomes. An operator effect was noted for two physicians and was adjusted for in all analyses. Pressure ratios were weak predictors of outcome (VLP/S(direct), P =.07; VLP/S(cuff), P =.08) and suggested that patency increased with increasing pressure ratio, contrary to earlier studies. Procedure type predicted outcome (declotting, median patency of 50 days; PTA, median patency of 105 days; P =.01). Thrill at distal physical examination was predictive of outcome (P =.04) and even more so when thrill and TSP combined were compared with PST and pulse combined (P =.03). Similar but less-pronounced effects were seen at midportion and proximal physical examinations. CONCLUSIONS The presence of a thrill or slightly pulsatile thrill at the distal (venous) end of a dialysis graft is the best predictor of outcome after percutaneous intervention. Based on the present study, the authors believe that physical examination of dialysis access should supplant pressure measurements as an endpoint of intervention and should serve as an essential component of quality assurance of access interventions.

Incidence and management of percutaneous transluminal angioplasty-induced venous rupture in the "fistula first" era.

PURPOSE Percutaneous transluminal angioplasty (PTA)-induced venous rupture is a common complication of hemodialysis access interventions. The authors sought to determine if venous rupture rates and management differed between grafts and fistulas, and in the fistula subset, between transposed and nontransposed fistulas. MATERIALS AND METHODS Patients experiencing venous rupture during hemodialysis PTA over a 5-year period were identified. Of 1,985 hemodialysis interventions, 75 ruptures occurred in 69 patients (46 women) with a mean age of 63 years (range, 31-88 y). Rupture rates, proportion of successful treatments, and treatment type and number (ie, balloon tamponade, stent, covered stent) were determined. RESULTS Rupture was more common in fistulas overall (5.6%, 39 of 693) compared with grafts (2.8%, 36 of 1,292; P = .002), in transposed (10.7%, 20 of 187) compared with nontransposed fistulas (3.8%, 19 of 506; P = .001), and in transposed fistulas compared with grafts (P = .0001). There was no significant difference between nontransposed fistulas and grafts. Treatment success (ie, resolution of extravasation) was the same among groups: 69% (27 of 39) in fistulas overall, 70% (14 of 20) in transposed fistulas, 68% (13 of 19) in nontransposed fistulas, and 72% (26 of 36) in grafts. There was a greater need for stents in grafts (38.9%, 14 of 36) compared with fistulas (12.8%, five of 39; P = .003). CONCLUSIONS PTA-induced rupture is more common in fistulas than grafts, and this effect seems nearly entirely driven by transposed fistulas. Although rupture treatment in fistulas of all types yielded similar success to grafts, and graft ruptures were more difficult to treat than fistula ruptures, the high rupture rates in transposed fistulas attest to the increased difficulty of treating this subset of fistulas.

Outcomes of Single‐Stage Compared to Two‐Stage Basilic Vein Transposition Fistulae

Basilic vein transposition (BVT) fistulae are increasing in prevalence in the United States. We examined outcomes of BVT fistulae created in a single stage compared to those created in two stages. Prospective QA databases identified a consecutive cohort of 144 patients with BVT fistulae. Of these, 42% were created in one stage and 58% in two stages. Fistula maturation rates, mean time to fistula use and intensity of percutaneous interventions were compared; patency rates were compared from time of first intervention. Maturation rates (including assisted maturation) were 90% among 1‐stage and 75% among 2‐stage BVT (p = 0.02). Mean time to initiation of fistula use was 142 days (1‐stage) and 146 days (2‐stage) (p = 0.92). Intensity of percutaneous interventions was 1.84/patient‐year of dialysis (PYD) (1‐stage) and 2.15/PYD (2‐stage) (p = 0.57). Secondary patency at 1, 2, 3, and 4 years for 1‐stage BVT was 86%, 75%, 69%, and 57%; secondary patency at 1, 2, 3, and 4 years for 2‐stage BVT was 76%, 71%, 49%, and 25%, respectively (p = 0.12). BVT creation in two stages confers only a modest reduction in maturation rates and secondary patency and therefore should be considered over a synthetic graft in patients with basilic veins deemed inadequate for 1‐stage BVT.

Use of electrotherapy to reverse expanding cutaneous gangrene in end-stage renal disease.

nal type used to augment the healing rate of pressure ulcers. The technique causes few or no adverse effects, based on prospective randomized clinical trials.1-5 In 1999, Ovington6 reviewed the Agency for Health Care Policy and Research (AHCPR) guidelines that were published in 1994 as the pressure ulcer standard of care. She recommended that the strength-of-evidence rating for electrotherapy (including HVPC) be upgraded from the second highest level (B) to the highest level (A), based on updated clinical research (ie, multiple prospective randomized controlled clinical trials). The salutary effects reported for HVPC have been attributed in part to increased blood flow to wounds.7-12 Because of the blood flow increase, it is clinically hypothesized that HVPC may augment healing of ischemic wounds (defined as periwound transcutaneous oximetry [TcPO 2 ] <20 mm Hg) and that healing is associated with the increase in microcirculation (wherein TcPO 2 returns to normal; TcPO 2 >40 mm Hg). This hypothesis was tested in an uncontrolled case series,13 retrospective controlled observational study,14 and phase I prospective randomized blinded trial15 with uniformly encouraging, significant findings. The present case report describes successful intervention with HVPC electrotherapy to reverse an especially rapid case of expanding ischemic cutaneous gangrene in a patient with endstage renal disease; this is usually a limb-threatening scenario. Despite a guarded prognosis, cutaneous gangrene eventually reperfused, granulated, and healed.

Bromfenac disposition in patients with impaired kidney function

To compare the pharmacokinetics of bromfenac among normal subjects and renally compromised patients and patients with end‐stage renal disease.

Accuracy of Acid-Base Diagnoses Using the Central Venous Blood Gas in the Medical Intensive Care Unit

Background: Acid-base disturbances are frequent in critically ill patients. Arterial blood gas (ABG) is the gold standard in the diagnosis of these disturbances, but it is invasive with potential hazards. For patients with a central venous catheter, venous blood gas (VBG) sampling may be an alternative, less-invasive diagnostic tool. However, the accuracy of a central VBG-based acid-base disorder diagnosis compared to an ABG is unknown. The primary objective of this study was to assess the accuracy of a central VBG-based acid-base disorder diagnosis compared to the “gold standard” ABG in critically ill patients. Methods: This was a study of adult patients in a medical intensive care unit that had simultaneously drawn ABG and central VBG samples. Expert acid-base diagnosticians, all nephrologists, diagnosed the acid-base disorder(s) in each blood gas sample. The central VBG diagnostic accuracy was assessed with percent agreement, sensitivity, and specificity compared to the ABG-based diagnosis. Results: The study involved 23 participants. Overall, the central VBG had 100% sensitivity for metabolic acidosis, metabolic alkalosis, and respiratory acidosis, and lower sensitivity (71%) for respiratory alkalosis, and high percent agreement, ranging from 75 to 94%. VBG-based diagnoses in vasopressor-dependent patients (n = 13, 56.5%) performed similarly to the entire sample. Conclusions: In critically ill adult patients, central VBG may be used to detect and diagnose acid-base disturbances with reasonable diagnostic accuracy, even in shock states, compared to the ABG. This study supports the use of central VBG for diagnosis of acid-base disturbances in critically ill patients.

Contrast Media in Dialysis Patients: Should We Be More Concerned?

End-stage renal disease (ESRD) patients frequently require intravascular iodinated contrast media administration for a variety of radiologic procedures such as cardiac catheterization or peripheral vascular arteriography. Since contrast media are eliminated primarily by glomerular filtration, their use in ESRD patients has the potential for causing adverse effects due to hyperosmolality-induced volume and potassium shifts, loss of residual renal function due to nephrotoxicity, as well as various other reactions resulting from prolonged exposure to high levels of contrast media. These potential risks raise clinical concerns as to the relative safety of intravascular contrast media administration in ESRD patients and, in light of the dialyzability of these agents, have stimulated varying opinions among nephrologists regarding the timing of hemodialysis following contrast media administration.