Implications of Medicare procedure volumes on resident education.

BACKGROUND: Preparation of future general surgeons requires the ongoing assessment of projected case experience. METHODS: Surgical procedures (2005-2008) were abstracted from the Centers for Medicare and Medicaid Services inpatient National Claims History Part A 100% Nearline File for all general surgeons. The most frequent Medicare surgical procedures and physician caseloads were compared by practice population. RESULTS: Over 5 million procedures were evaluated, with procedures decreasing over time in urban and large rural areas. A total of 15 procedures comprised the top 10 for all population/year categories. The most frequent surgical procedures were similar in rural and urban areas. Rural surgeons' caseloads consisted of a higher proportion of endoscopic procedures. CONCLUSIONS: The most common Medicare general surgery procedures are similar across population areas and are required experience for residents. Separate surgical educational programs for urban and rural general surgeons may not be necessary to provide adequate care to rural patients.

Differential IL-7 responses in developing human thymocytes.

Interleukin (IL)-7 is a factor essential for mouse and human thymopoiesis. Mouse thymocytes have altered sensitivities to IL-7 at different developmental stages. CD4/CD8 double positive (DP) mouse thymocytes are shielded from the influence of IL-7 because of loss of CD127 (IL-7Ralpha). In this study, we assessed IL-7 receptor expression and IL-7 signaling in human thymocytes. We found human DP cells to be severely limited in their ability to phosphorylate STAT-5 in response to IL-7. The relative expression levels of the IL-7-inducible proteins Bcl-2 and Mcl-1 were also lower in human DP cells, consistent with a stage-specific decrease in IL-7 responsiveness. IL-7 responses were restored in a subset of cells that matured past the DP stage. Unlike the regulation of IL-7 signaling in mouse thymocytes, loss of IL-7 signaling in human DP cells was not due to absence of CD127, but instead correlated with downregulation of CD132 (common gamma chain).

Brachial vein transposition arteriovenous fistulas for hemodialysis access.

BACKGROUND: An arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis, offering lower morbidity, mortality, and cost compared with grafts or catheters. Patients with a difficult access extremity have often lost all superficial veins, and even basilic veins may be obliterated. We have used brachial vein transposition AVFs (BVT-AVFs) in these challenging patients and review our experience in this report. METHODS: The study reviewed consecutive patients in whom BVT-AVFs were created from September 2006 to March 2009. Most BVT-AVFs were created in staged procedures, with the second-stage transposition operations completed 4 to 6 weeks after the first-stage AVF operation. A single-stage BVT-AVF was created when the brachial vein diameter was > or =6 mm. RESULTS: We identified 58 BVT-AVF procedures, comprising 41 women (71.0%), 28 diabetic patients (48.3%), and 29 (50.0%) had previous access surgery. The operation was completed in two stages in 45 operations (77.6%) and was a primary transposition in 13 patients. However, five of these were secondary AVFs with previous distal AV grafts or AVFs placed elsewhere; effectively, late staged procedures. Follow-up was a mean of 11 months (range, 2.0-31.7 months). Primary patency, primary-assisted patency, and cumulative (secondary) patency were 52.0%, 84.9%, and 92.4% at 12 months and 46.2%, 75.5%, and 92.4% at 24 months, respectively. Harvesting the brachial vein was tedious and more difficult than harvesting other superficial veins. No prosthetic grafts were used. CONCLUSION: BVT-AVFs provide a suitable option for autogenous access when the basilic vein is absent in patients with difficult access extremities. Most patients required intervention for access maturation or maintenance. Most BVT-AVFs were created with staged procedures. Cumulative (secondary) patency was 92.4% at 24 months.

Creating radiocephalic arteriovenous fistulas: technical and functional success.

BACKGROUND: The radiocephalic arteriovenous fistula (RC-AVF) at the wrist is the recommended first choice for hemodialysis access. Several authors have reported early thrombosis or failure of RC-AVFs to mature in up to 20% to 57% of patients. We report a consecutive series of individuals in whom physical and ultrasonography (US) examinations predicted success with RC-AVFs. STUDY DESIGN: Records of all patients who underwent vascular access operations by the communicating author from June 2003 through June 2008 were reviewed to identify those individuals with RC-AVF procedures. Physical examination and US screening criteria for creating a RC-AVF included a continuous and uninterrupted outflow vein diameter > or = 2.5 mm and a normal radial artery inflow examination with vessel diameter > or = 2.0 mm. A venous branching point at the wrist was identified to create a broad patch for the RC-AVF anastomosis. RESULTS: We reviewed 796 consecutive vascular access operations, identifying 75 RC-AVFs created in 74 patients. Patient ages were 20 to 82 years (mean 57 years). Eighteen were women and 42 were diabetic. Mean followup was 14.5 months. Primary, primary-assisted, and cumulative (secondary) patency were 58.3%, 96.2%, and 100%, respectively, at 12 months and 48.1%, 91.5%, and 95.7%, respectively, at 24 months. CONCLUSIONS: RC-AVF at the wrist remains our first choice for vascular access in the subset of patients meeting specific preoperative criteria by physical and United States examinations. Cumulative patency was 100% at 12 months and 95.7% at 24 months. Although RC-AVF construction technique is important, careful patient selection is believed to be the critical element in creating functional and durable RC-AVFs.

Effects of hepatic zonal oxygen levels on hepatocyte stress responses.

BACKGROUND: Hepatocytes spend their lifetimes in a gradient of oxygen, hormones, and enzymes. We used a three-dimensional Matrigel model to determine whether hepatocytes cultured at perivenous (zone 3) oxygen levels differed in susceptibility to anoxia-induced cell injury compared with hepatocytes cultured at periportal (zone 1) oxygen levels. MATERIALS AND METHODS: Hepatocytes were harvested from Sprague Dawley rats and cultured at 9% oxygen (hepatic zone 1) or 5% oxygen (hepatic zone 3) and stressed at 0% oxygen. Microscopy, real-time reverse transcriptase-polymerase chain reaction, and enzyme-linked immunosorbent assay were used to assess cell viability, mitochondrial potential, acute phase responses, and membrane blebbing. RESULTS: Hepatocytes cultured in Matrigel with HepatoZyme medium at zone 1 and zone 3 oxygen conditions were viable for 1 wk and showed acute phase responses as measured by interleukin-6-induced fibrinogen production. In response to 3 h anoxia, cells maintained at the perivenous oxygen level showed increased membrane blebbing and increased loss of mitochondrial membrane potential in comparison to the periportal oxygen cultured cells. Cells at perivenous oxygen also showed a reduced ability to recover following reoxygenation. CONCLUSIONS: Hepatocytes can remain viable and functional for extended periods in culture at low oxygen levels that mimic the hepatic perivenous environment, yet these cells are more susceptible to anoxia-induced damage than hepatocytes cultured at the periportal oxygen level. The small population of perivenous hepatocytes may be critical in determining the fate of the liver during ischemia/reperfusion since hepatocytes cultured at that concentration appear to be more labile in response to anoxia.

Spontaneous hepatic hemorrhage in older women.

Spontaneous liver hemorrhage in older women is not well described. We report an experience with five postmenopausal women who spontaneously bled from the liver. All five patients presented with acute bleeding. Four were treated nonoperatively. No tumor was identified in any patient. Four patients acutely were discharged alive and well, but one died after operation to control bleeding. Spontaneous liver hemorrhage can occur in a variety of clinical settings, but an association with older women taking hormone replacement and anticoagulation has not been reported.

Primary breast lymphoma: the role of mastectomy and the importance of lymph node status.

OBJECTIVE: To construct and analyze a database comprised of all reported cases of primary breast lymphoma (PBL) that include treatment and follow-up information published during the last 3 decades. SUMMARY BACKGROUND DATA: PBL accounts for 0.4% of breast malignancies and 2% of extranodal lymphomas. Surgical therapy has varied from biopsy to radical mastectomy. Chemotherapy and radiation therapy have been used as adjuvant or primary therapy. A standard consensus treatment of PBL is not available. METHODS: We reviewed all published PBL reports from June 1972 to March 2005. A database was compiled by abstracting individual patient information, limiting our study to those reports that contained specific treatment and outcome data. Patient demographics such as survival, recurrence, and time to follow-up were recorded, in addition to surgical, radiation, and/or chemotherapy treatment(s). RESULTS: We found 465 acceptable patients reported in 92 publications. Age range was 17 to 95 years (mean, 54 years). Mean tumor size was 3.5 cm. Diffuse large cell (B) lymphoma was the most common histologic diagnosis (53%). Disease-free survival was 44.5% overall. Follow-up ranged from one to 288 months (mean, 48 months). Treatment by mastectomy offered no survival benefit or protection from recurrence. Treatment that included radiation therapy in stage I patients (node negative) showed benefit in both survival and recurrence rates. Treatment that included chemotherapy in stage II patients (node positive) showed benefit in both survival and recurrence rates. Histologic tumor grade predicted survival. CONCLUSIONS: Mastectomy offers no benefit in the treatment of PBL. Nodal status predicts outcome and guides optimal use of radiation and chemotherapy.

Vascular ultrasonography prior to dialysis access surgery.

BACKGROUND: Native arterial venous fistulas (NAVF) are generally considered preferable to synthetic grafts for chronic dialysis access. As increasing numbers of diabetic and elderly patients are treated, adequate NAVFs become more difficult to establish. Vascular ultrasonography (US) prior to NAVF surgery has received little attention. METHODS: Patients with questionable venous or arterial status underwent 47 US evaluations by the operating surgeon prior to AV fistula surgery. Veins were evaluated for compressibility, size and distensibility. Arterial and venous occlusive lesions were identified. RESULTS: In all, 74.5% of patients were diabetic. More than half the patients had at least one previous access operation. Ultrasonography examination detected venous occlusions, stenoses, or fibrotic segments in addition to atheromatous disease in the radial artery. CONCLUSIONS: The use of the origin of the radial artery for anastomotic inflow was frequently helpful. Only once in 47 procedures was placement of a prosthetic graft required. One patient had early thrombosis. There were no infections or ischemic complications. The use of preoperative US by the operating surgeon aids in selection of site and feasibility for NAVFs. Almost all patients can have a NAVF created and avoid the problems associated with synthetic graft material.

Choledochal Cystic Diseases.

Cystic disease of the intrahepatic and extrahepatic bile ducts results in rare malformations with a variable presentation. The majority of patients present during childhood with symptoms of abdominal pain, cholangitis, and an abdominal mass. A palpable mass is unusual in adults, and adult patients tend to present with recurrent cholangitis, pancreatitis, or rarely portal hypertension. The cause of this disorder also is debated, with both congenital and acquired origins postulated. The gold standard for the treatment of choledochal cysts is complete excision with the establishment of biliary flow into the gastrointestinal tract. The well described malignant potential of the cyst and the high rate of recurrent cholangitis with internal drainage procedures mandate cyst excision when possible. In the event of extensive scarring or malignant changes of the cyst, the posterior wall of the cyst may be left in situ to avoid endangering the portal vessels, which are found posteriorly. Alternatively, various endoscopic or percutaneous interventions may provide symptomatic relief. However, every effort should be directed towards complete resection of the cyst and the re-establishment of biliary-enteric continuity.