Deborah A. Andris

Treatment of Hickman Catheter Sepsis Using Antibiotic Lock Technique

Antibiotic lock therapy, an alternative treatment for Hickman catheter sepsis, was evaluated in six recipients of prolonged outpatient intravenous therapy. Twenty-two episodes of catheter sepsis were identified, involving coagulase-negative staphylococci (11), gram-negative bacilli (3), gram-positive bacilli (1), yeast (4), and mixed bacteria or fungi (3). In a select group of patients, treatment was successful 92% of the time.

Anemia After Bariatric Surgery: More Than Just Iron Deficiency

Bariatric surgery for morbid obesity is rapidly gaining popularity. Restrictive and/or malabsorptive surgical interventions result in dramatic weight loss with significantly decreased obesity-related morbidity and mortality. Anemia, which may affect as many as two-thirds of these patients, is of concern and generally thought to be caused by iron deficiency. Although iron deficiency in this population may be frequent given pouch hypoacidity, defunctionalized small bowel, and red meat intolerance, it may not account for all anemias seen. First, there is increasing evidence that obesity creates a state of chronic inflammation. Both iron deficiency anemia and anemia of chronic inflammation present with low serum iron levels. Most studies reporting anemia after bariatric surgery lack serum ferritin determinations so that the relative contribution of inflammation to anemia cannot be assessed. Second, a significant number of anemias after bariatric surgery remain unexplained and may be attributable to less frequently seen micronutrient deficiencies such as copper, fatsoluble vitamins A and E, or an imbalance in zinc intake. Third, although deficiencies of folate and vitamin B(12) are infrequent, study observation periods may be too short to detect anemia attributable to vitamin B(12) deficiency because vitamin B(12) storage depletion takes many years. This review is intended to increase awareness of the mechanisms of anemia above and beyond iron deficiency in the bariatric patient and provide healthcare providers with tools for a more thoughtful approach to anemia in this patient population.

Pinch-Off Syndrome: A Rare Etiology for Central Venous Catheter Occlusion

BACKGROUND Catheter pinch-off syndrome is a rare and often misdiagnosed complication of tunneled Silastic central venous catheters. Pinch-off syndrome occurs when the catheter is compressed between the first rib and the clavicle, causing an intermittent mechanical occlusion for both infusion and withdrawal. We report its incidence in a large series of catheter insertions and describe the clinical presentation, radiographic findings, and recommended treatment. METHODS A total of 1457 tunneled Silastic central venous catheters that were inserted using the percutaneous subclavian approach were prospectively studied. Indications for catheter placement included bone marrow transplant, continuous or intermittent chemotherapy, long-term antibiotics, and parenteral nutrition. Catheters were evaluated for clinical presentation of an occlusion relieved by postural changes and radiographic findings of luminal narrowing. RESULTS Pinch-off syndrome was identified in 16 (1.1%) catheters. Radiographic findings were present in all catheters; clinical findings were present in 15 catheters. Clinical symptoms presented within a median of 2 days after placement (range, 0 to 167 days). Partial or complete catheter transection, a serious sequela of catheter pinch-off syndrome, occurred in 19% of the identified catheters. CONCLUSIONS (1) Catheter pinch-off syndrome presents clinically as a catheter occlusion related to postural changes; (2) clinical symptomatology should be confirmed radiographically; and (3) catheter removal with a more lateral replacement in the subclavian vein or in the internal jugular vein will avoid a recurrent complication.

Elimination of Intraluminal Colonization by Antibiotic Lock in Silicone Vascular Catheters

An in vitro model was designed to evaluate the efficacy of instilled antimicrobials to reduce or eliminate intraluminal microbial colonization. Minimal inhibitory concentration and minimal bactericidal concentration activity of appropriate test anti-infectives were determined using standard methodology against clinically derived and reference test strains commonly associated with catheter-related infection. Drug activity was validated by bioassay for the test anti-infectives. Reference and clinical test strains were inoculated to the intraluminal surface of silicone catheter segments and incubated for 30 min, after which the inoculum was replaced with total parenteral nutrition (TPN) solution and reincubated for 12 h. For 7 d, instillation of antibiotic and TPN solution was alternated every 12 h to simulate clinical conditions. On days 1, 4, and 7, catheter segments were rinsed, bisected, and sonicated for quantitative plate count to determine mean microbial counts per centimeter of catheter surface. Catheter segments were also prepared for scanning electron microscopy. A significant decrease in staphylococcal intraluminal colonization after instillation of nafcillin, ceftriaxone, gentamicin, and vancomycin was demonstrated (P < 0.001). Aztreonam, ceftriaxone, and gentamicin completely eliminated gram-negative catheter colonization (P < 0.001). Yeast was eradicated from the internal catheter surface after treatment with amphoteracin B, and fluconazole significantly decreased intraluminal colonization (P < 0.001). Results show a significant decrease in staphylococcal, gram-negative, and fungal intraluminal colonization after instillation of appropriate antimicrobial. In vitro results support early clinical success using this technique. Future studies are warranted to identify optimal drug concentrations and dosing intervals.

Anemia after bariatric surgery cannot be explained by iron deficiency alone: results of a large cohort study.

BACKGROUND We sought to identify the frequency and mechanisms of anemia after bariatric surgery in a bariatric surgery program at the Medical College of Wisconsin, (Milwaukee, WI). Anemia after bariatric surgery has often been attributed to iron deficiency, although an inflammatory component might be present, making the anemia after surgery mechanistically complex. METHODS The body mass index and hemoglobin (Hb), vitamin B(12), folate, iron, and ferritin levels were extracted from the records of 1125 patients for ≤4 years after Roux-en-Y gastric bypass. Anemia was defined using the World Health Organization criteria. RESULTS The mean body mass index, Hb, and ferritin decreased after surgery. The body mass index decreased from 50.1 kg/m(2) (95% confidence interval [CI] 49.6-50.6) at baseline to 33.0 kg/m(2) (95% CI 32.3-33.6) at 12 months and remained unchanged thereafter. The Hb level decreased from 13.4 g/dL (95% CI 13.3-13.5) to 12.8 (95% CI 12.6-13.1) and ferritin from 87.5 ng/mL (95% CI 75.2-99.7) to 55.4 (95% CI 42.9-68.0) at 24-48 months, and serum iron increased from 68.4 μg/dL (95% CI 66.8-70.0) to 82.8 (95% CI 76.4-88.7); all P values were <.01. Anemia was present in 12% (95% CI 10-14%) of patients at baseline and had increased to 23% (95% CI 16-30%) at 24-48 months. The changes in ferritin, Hb, and the percentage of patients with anemia were most pronounced in premenopausal women. Vitamin B(12) and folate levels were unaffected. CONCLUSION The baseline incidence of anemia was greater than expected and increased significantly after surgery. The percentage of those with anemia and low ferritin was most significant in premenopausal women; however, the overall iron bioavailability improved significantly with pronounced weight loss, suggesting a reduction in inflammation. These findings indicate that anemia after bariatric surgery cannot be explained on the basis of iron availability and suggest that other mechanisms, currently undefined, contribute to the development of anemia in these patients.

Glucose response to abrupt initiation and discontinuation of total parenteral nutrition.

Plasma glucose was studied during the initiation of total parenteral nutrition (TPN) and the discontinuation of TPN without a tapering schedule. Blood was sampled every 5 minutes for 2 hours after the start of TPN and 1 week later as TPN was discontinued. A total of 14 initiations and 14 discontinuations were studied in 18 patients. Severity of illness in patients ranged from stable condition postoperatively to multiple-system failure; six patients had diabetes mellitus. The TPN solution was a 3:1 admixture that provided a caloric intake equal to 1.2 times the resting energy expenditure, with 40% fat and 60% carbohydrate calories. An average of 1963 kcal was provided per day (340 g of glucose, 79 g of fat). During the initiation phase, the mean increase in plasma glucose was 60 mg/dL. The increase for diabetic patients was 79 +/- 14 mg/dL compared with 52 +/- 23 mg/dL for the nondiabetics. During the discontinuation phase, the mean plasma glucose decreased 40 +/- 20 mg/dL; two patients with high concentrations of regular insulin (50 and 100 units) showed an increase in plasma glucose when the TPN was stopped. Plasma glucose returned to the preinfusion baseline after discontinuation. During both initiation and discontinuation, plasma glucose showed little change after the first 60 minutes. No clinical symptoms of hypoglycemia were observed. In conclusion, TPN as a 3:1 admixture can be safely started as full nutrition support and stopped abruptly without a tapering schedule. Plasma glucose response is rapid, predictable, and mostly complete within 60 minutes.

The Malfunctioning Silastic Catheter—Radiologic Assessment and Treatment

Occlusion of silastic catheters is attributed to several documented causes. One factor not yet adequately documented is fibrin sleeve formation. In this instance, the catheter functions for infusion purposes, but blood withdrawal is no longer feasible. This is a troublesome occurrence when encountered in the clinical setting. This report reviews the assessment of fibrin sleeve formation, the use of catheter phlebography and treatment with low-dose streptokinase. Seventeen instances of the inability to aspirate blood from silastic catheters are evaluated with restoration of full catheter function in all cases after streptokinase administration.

Hepatic Gene Networks in Morbidly Obese Patients With Nonalcoholic Fatty Liver Disease

BackgroundGenetic factors alter the risk for nonalcoholic fatty liver disease (NAFLD). We sought to identify NAFLD-associated genes and elucidate gene networks and pathways involved in the pathogenesis of NAFLD.MethodsQuantitative global hepatic gene expression analysis was performed on 53 morbidly obese Caucasian subjects undergoing bariatric surgery (27 with NAFLD and 26 controls). After standardization of data, gene expression profiles were compared between patients with NAFLD and controls. The set of genes that significantly correlated with NAFLD was further analyzed by hierarchical clustering and ingenuity pathways analyses.ResultsThere were 25,643 quantitative transcripts, of which 108 were significantly associated with NAFLD (p < 0.001). Canonical pathway analysis in the NAFLD-associated gene clusters showed that the hepatic fibrosis signaling was the most significant pathway in the up-regulated NAFLD gene cluster containing three (COL1A1, IL10, IGFBP3) significantly altered genes, whereas the endoplasmic reticulum stress and protein ubiquitination pathways were the most significant pathways in the down-regulated NAFLD gene cluster, with the first pathway containing one (HSPA5) and the second containing two (HSPA5, USP25) significantly altered genes. The four primary gene networks associated with NAFLD were involved in cell death, immunological disease, cellular movement, and lipid metabolism with several significantly altered “hub” genes in these networks.ConclusionsThis study reveals the canonical pathways and gene networks associated with NAFLD in morbidly obese Caucasians. The application of gene network analysis highlights the transcriptional relationships among NAFLD-associated genes and allows identification of hub genes that may represent high-priority candidates for NAFLD.

Catheter Infections: Diagnosis, Etiology, Treatment, and Prevention

Infection remains the leading complication that is associated with intravascular access devices. Despite continuous research efforts and advances in technology, the rate of central venous catheter infections has remained relatively constant over the past decade. This article focuses on four pertinent aspects of central venous access infection: microbial etiology and pathogenesis, diagnosis, prevention, and treatment. An update of the scientific literature in this area will aid clinicians in their patient care practices and serve to identify unanswered questions.

Twenty-five Years of Advances in Vascular Access: Bridging Research to Clinical Practice

Vascular access has become a key component for a multitude of IV therapies, including parenteral nutrition. Access of the central venous system has been long recognized for its associated complications of infection, thrombosis, and occlusion. Over the past 25 years, clinical practice based on research and innovation has attempted to decrease complication rates and therefore improve the safety of vascular access. This article highlights the research and its influence on catheter care procedures, technology, and education that has led to advances in vascular access. An improved understanding of the pathophysiology associated with catheter-related complications and an ongoing evaluation of new treatment modalities has provided clinicians today with new options for improved patient care and the ability to preserve vascular access options for patients.