Prediction of fracture load at different skeletal sites by geometric properties of the cortical shell.

Quantitative bone assessment today is primarily based on the analysis of bone mineral density (BMD). The geometric properties of bone, which are an important parameter for skeletal strength, are generally not considered in the routine clinical assessment of osteoporosis. This study combined the geometric properties and the BMD values determined by peripheral quantitative computed tomography (pQCT) at the distal radius and at the femoral neck to predict fracture loads of the radius, femur, and lumbar vertebrae of 20 cadavers. Generalized osteopenia reduced the fracture loads at all three sites (p < 0.001). The strength of the radius and the femoral neck could best be predicted by considering either the second moment of inertia and trabecular BMD (R = 0.93) or the moment of inertia and the cortical BMD (R = 0.91). The geometric properties at the distal radius were highly correlated with the fracture load at the same skeletal site (R = 0.89) and were also used to estimate the fracture risk at the lumbar vertebrae (R = 0.75) and at the femoral neck (R = 0.87). We conclude that both geometry and density contribute substantially to the strength of the skeleton. The screening for osteoporosis and the prediction of fracture risk can be improved, therefore, by an additional consideration of the geometric properties of the cortex.

Complications of central venous catheters in pediatric patients with acquired immunodeficiency syndrome.

Medical records of 18 pediatric acquired immunodeficiency syndrome patients with 24 central venous catheters (CVCs) were reviewed to determine the rates and types of CVC complications and to evaluate the influence of selected social factors, absolute granulocyte counts and CD4+ T cell counts on the rate of CVC infections. CVCs were in place for a total of 4233 days. CVCs were used for blood sampling, administration of blood products and infusions of intravenous immune globulin, parenteral nutrition and medications. Complications included catheter-related infections (8 episodes; with a rate of 1.9/1000 CVC days), occlusions (15 episodes) and unplanned catheter removals (9 episodes). Reduced CD4+ T cell counts were not predictive of CVC infection. The CVC infection rate in our pediatric acquired immunodeficiency syndrome patients was similar to rates reported in children with cancer and adults with cancer and acquired immunodeficiency syndrome.

Management of cutaneous reactions and mechanical complications of central venous access devices in pediatric patients with cancer: algorithms for decision making.

Surgically placed central venous catheters (CVCs) facilitate the delivery of medication and nutrition support for patients with malignant disease. There is little information regarding allergic reactions to materials used for standard CVC care or about mechanical complications associated with CVC use. This study describes allergic and mechanical complications that occurred in a series of 288 CVCs implanted in 238 pediatric patients with malignant disease. There were 20 episodes of cutaneous reactions to standard central line dressing care (alcohol/povidone-iodine/TegadermTM), 13 incidents of catheter exit site infections, and 14 experiences of mechanical breakage in external CVCs. Complications were managed from algorithms that provided a systematic sequence of nursing interventions for alternative catheter dressing techniques and line repair. Only two CVCs were removed because of progressive infection, and one catheter was removed because of occlusion after repair.

Diagnosis of central venous access device occlusion. Implications for nursing practice.

Central venous catheters provide reliable access to patients requiring prolonged parenteral therapies. An occluded catheter can impede treatment and hinder medical management of the patient. Early recognition and treatment of a malfunctioning line are paramount for catheter preservation. An understanding of the causes of catheter occlusion and methods to diagnose and treat obstructions will assist the nurse in developing appropriate nursing interventions for catheter treatment. This article reviews causes of central venous catheter obstruction and describes methods for diagnosis and treatment.