Faculty Bibliography

Central venous stenosis is a well-described sequel to the placement of hemodialysis catheters in the central venous system. The presence of an ipsilateral arteriovenous fistula or graft often leads to severe venous dilatation, arm edema and recurrent infections. Vascular access thrombosis, compromised blood flow and inadequate dialysis delivery are dreaded complications that eventually render the access unusable. We report the case of a 58-year-old male hemodialysis patient who developed symptomatic central venous stenosis to illustrate the problem and review the pertinent literature. This patient developed severe enlargement of upper extremity veins due to central venous stenosis. The symptoms were refractory to multiple endovascular interventions and eventually necessitated ligation of his arteriovenous fistula. Central venous stenosis remains a pervasive problem despite advances in our understanding of its etiology and recognition of the enormity of its consequences. Due to the lack of effective therapeutic options, prevention is better than cure.

BACKGROUND: In order to develop clinical reasoning, medical students must be able to integrate knowledge across traditional subject boundaries and multiple disciplines. At least two dimensions of integration have been identified: horizontal integration, bringing together different disciplines in considering a topic; and vertical integration, bridging basic science and clinical practice. Much attention has been focused on curriculum overhauls, but our approach is to facilitate horizontal and vertical integration on a smaller scale through an interdisciplinary case study discussion and then to assess its utility. METHODS: An interdisciplinary case study discussion about a critically ill patient was implemented at the end of an organ system-based, basic sciences module at New York University School of Medicine. Three clinical specialists-a cardiologist, a pulmonologist, and a nephrologist-jointly led a discussion about a complex patient in the intensive care unit with multiple medical problems secondary to septic shock. The discussion emphasized the physiologic underpinnings behind the patient's presentation and the physiologic considerations across the various systems in determining proper treatment. The discussion also highlighted the interdependence between the cardiovascular, respiratory, and renal systems, which were initially presented in separate units. After the session students were given a brief, anonymous three-question free-response questionnaire in which they were asked to evaluate and freely comment on the exercise. RESULTS: Students not only took away physiological principles but also gained an appreciation for various thematic lessons for bringing basic science to the bedside, especially horizontal and vertical integration. The response of the participants was overwhelmingly positive with many indicating that the exercise integrated the material across organ systems, and strengthened their appreciation of the role of physiology in understanding disease presentations and guiding appropriate therapy. CONCLUSIONS: Horizontal and vertical integration can be presented effectively through a single-session case study, with complex patient cases involving multiple organ systems providing students opportunities to integrate their knowledge across organ systems while emphasizing the importance of physiology in clinical reasoning. Furthermore, having several clinicians from different specialties discuss the case together can reinforce the matter of integration across multiple organ systems and disciplines in students' minds.

Accurate assessment of blood volume (BV) may be helpful for prescribing hemodialysis (HD) and for reducing complications related to hypovolemia and volume overload. Monitoring changes in relative BV (RBV) using hematocrit, e.g., Crit-Line Monitor (CLM-III), an indirect method, cannot be used to determine absolute BV. We report the first study of BV measurement for assessing volume status in HD patients using the indicator dilutional method. Ten adult HD patients were enrolled in this prospective observational study. BV measurement was performed before and after HD using BV analysis (BVA)-100 (Daxor Corporation, New York, NY, USA). BVA-100 calculates BV using radiolabeled albumin (Iodine-131) followed by serial measures of the radioisotope. Fluid loss from the extravascular space was calculated by subtracting the change in BV from total weight loss. Intradialytic changes in RBV were measured by CLM-III. Eight out of 10 cases had significant hypervolemia, two cases were normovolemic. The range of BV variation from predicted normal was 156 to 1990 mL. Significant inter-individual differences in extravascular space fluid loss ranged from 54% to 99% of total weight loss. Spearman correlation showed a good correlation in the measurement of RBV by BVA-100 and CLM-III in 8 out of 10 patients (r(2) = 0.64). BV measurement using BVA-100 is useful to determine absolute BV as well as changes in BV and correlates reasonably well with CLM-III measurements. Individual refilling ability can be determined as well. This may prove useful in prescribing and monitoring ultrafiltration rates, establishment of optimal BV in HD patients and reducing morbidity and mortality associated with chronic HD.

BACKGROUND: Patients with nephrolithiasis and hyperoxaluria generally are advised to follow a low-oxalate diet. However, most people do not eat isolated nutrients, but meals consisting of a variety of foods with complex combinations of nutrients. A more rational approach to nephrolithiasis prevention would be to base dietary advice on the cumulative effects of foods and different dietary patterns rather than single nutrients. STUDY DESIGN: Randomized controlled trial. SETTING & PARTICIPANTS: Recurrent stone formers with hyperoxaluria (urine oxalate > 40mg/d). INTERVENTION: The intervention group was asked to follow a calorie-controlled Dietary Approaches to Stop Hypertension (DASH)-style diet (a diet high in fruit, vegetables, whole grains, and low-fat dairy products and low in saturated fat, total fat, cholesterol, refined grains, sweets, and meat), whereas the control group was prescribed a low-oxalate diet. Study length was 8 weeks. OUTCOMES: Primary: change in urinary calcium oxalate supersaturation. SECONDARY: Changes in 24-hour urinary composition. RESULTS: 57 participants were randomly assigned (DASH group, 29; low-oxalate group, 28). 41 participants completed the trial (DASH group, 21; low-oxalate group, 20). As-treated analysis showed a trend for urinary oxalate excretion to increase in the DASH versus the low-oxalate group (point estimate of difference, 9.0mg/d; 95% CI, -1.1 to 19.1mg/d; P=0.08). However, there was a trend for calcium oxalate supersaturation to decrease in the DASH versus the low-oxalate group (point estimate of difference, -1.24; 95% CI, -2.80 to 0.32; P=0.08) in association with an increase in magnesium and citrate excretion and urine pH in the DASH versus low-oxalate group. LIMITATIONS: Limited sample size, as-treated analysis, nonsignificant results. CONCLUSIONS: The DASH diet might be an effective alternative to the low-oxalate diet in reducing calcium oxalate supersaturation and should be studied more.

Context. Ingestion of glyphosate-surfactant herbicides (GlySH) can result in acute kidney injury, electrolyte abnormalities, acidosis, cardiovascular collapse, and death. In severe toxicity, the use of hemodialysis is reported, but largely unsupported by kinetic analysis. We report the dialysis clearance of glyphosate following a suicidal ingestion of a glyphosate-containing herbicide. Case details. A 62-year-old man was brought to the emergency department (ED) 8.5 h after drinking a bottle of commercial herbicide containing a 41% solution of glyphosate isopropylamine, in polyoxyethyleneamine (POEA) surfactant and water. He was bradycardic and obtunded with respiratory depression necessitating intubation and mechanical ventilation. Initial laboratory results were significant for the following: pH, 7.11; PCO2, 64 mmHg; PO2, 48 mmHg; potassium, 7.8 mEq/L; Cr 3.3, mg/dL; bicarbonate, 22 mEq/L; anion gap, 18 mEq/L; and lactate, 7.5 mmol/L. Acidosis and hyperkalemia persisted despite ventilation and fluid resuscitation. The patient underwent hemodialysis 16 h post ingestion, after which he demonstrated resolution of acidosis and hyperkalemia, and improvement in clinical status. Serum glyphosate concentrations were drawn prior to, during, and after hemodialysis. The extraction ratio and hemodialysis clearance were calculated to be 91.8% and 97.5 mL/min, respectively. Discussion. We demonstrate the successful clearance of glyphosate using hemodialysis, with corresponding clinical improvement in a patient with several poor prognostic factors (advanced age, large volume ingested, and impaired consciousness). The effects of hemodialysis on the surfactant compound are unknown. Hemodialysis can be considered when severe acidosis and acute kidney injury complicate ingestion of glyphosate-containing products.

Cystinuria is a genetic cause of recurrent kidney stones which may be more recurrent and larger than more common non-cystine stones. They may have a greater impact on health-related quality of life (HRQoL). We measured this impact by surveying HRQoL in patients with stones, comparing non-cystine stone formers (NCSF) to cystine stone formers (CYSF) and both groups to normative values of the US population. We used SF-36v2 via an internet instrument. CYSF patients were recruited via cystinuria-related websites, two patient advocacy groups, and an active endourology practice. NCSF patients were recruited from the same practice and by email. Total n surveyed with scorable data: 214 CYSF and 81 NCSF. The participants included 128 men and 161 women. The group of CYSF were significantly younger (39 vs. 54 years) and suffered longer from kidney stones (255 vs. 136 months). CYSF patients had significantly more episodes of stones than NCSF patients in the last year (N = 108 CYSF, N = 20 NCSF). More frequent stones in the last year and mental comorbidities most often predicted worse scores in the individual HRQoL domains. However, cystine stone composition was a significant predictor of worse scores only for role emotional. Better scores in all SF-36 domains were associated with greater time since the last kidney stone event. Although kidney stones are often transient, kidney stone formers, regardless of stone composition, have a worse HRQoL than the standard US population, which has a normative score of 50, such as general health (41.2 +/- 12.8), bodily pain (46.5 +/- 11.8) and mental health (45.1 +/- 12.6). CYSF are more frequent and severe stone formers compared with NCSF with a resulting greater, direct impact on the HRQoL of CYSF patients. Whether preventive strategies for cystinuria are being properly utilized by practitioners, and which strategies are most effective, should be established.

There is emerging evidence that mild chronic hyponatremia (MCH), highly prevalent in the elderly and once considered asymptomatic, is a major independent risk factor for falls, fall-related fractures (independent of osteoporosis, age, and sex), impaired attention and gait, reductions in bone mineral density (BMD), and even death. Although research on MCH and bone health is emerging and ongoing, it has not been recognized in orthopedics. Orthopedic surgeons must be educated regarding the impact of hyponatremia on bone, as osteoporotic fractures have enormous socioeconomic consequences, and the problem will worsen. Orthopedic surgeons should also be included in research, in education, and in the establishment of diagnostic and treatment protocols. In this article, we review the current concepts of MCH and its impacts on the skeletal system.

Introduction. Minimal Change Disease (MCD) is the most common cause of nephrotic syndrome in children, while IgA nephropathy is the most common cause of glomerulonephritis worldwide. MCD is responsive to glucocorticoids, while the role of steroids in IgA nephropathy remains unclear. We describe a case of two distinct clinical and pathological findings, raising the question of whether MCD and IgA nephropathy are separate entities or if there is a common pathophysiology. Case Report. A 19-year old man with no medical history presented to the Emergency Department with a 20-day history of anasarca and frothy urine, BUN 68 mg/dL, Cr 2.3 mg/dL, urinalysis 3+ RBCs, 3+ protein, and urine protein : creatinine ratio 6.4. Renal biopsy revealed hypertrophic podocytes on light microscopy, podocyte foot process effacement on electron microscopy, and immunofluorescent mesangial staining for IgA. The patient was started on prednisone and exhibited dramatic improvement. Discussion. MCD typically has an overwhelming improvement with glucocorticoids, while the resolution of IgA nephropathy is rare. Our patient presented with MCD with the uncharacteristic finding of hematuria. Given the improvement with glucocorticoids, we raise the question of whether there is a shared pathophysiologic component of these two distinct clinical diseases that represents a clinical variant.

Tubulocystic renal cell carcinoma (TC-RCC) is a rare renal tumor composed of well-differentiated tubules and cysts lined by neoplastic cells with eosinophilic cytoplasm and prominent nucleoli. The origin of the tumor cells is still controversial. TC-RCC typically arises unilaterally. Involvement of both kidneys by multifocal TC-RCC has not been reported. In this study we report the first case of bilateral and multifocal TC-RCC. Immunohistochemical, cytogenetic and ultrastructural studies suggest TC-RCC is closely related to papillary RCC.