Altered regulation of in-vivo coagulation in orthopedic patients prior to knee or hip replacement surgery.

Up to 20% of patients develop venographically proven deep-vein thrombosis after elective orthopedic surgery even under the cover of heparin or low molecular weight heparin. The extent to which the chronic inflammation of osteoarthritis requiring elective orthopedic surgery alters in-vivo coagulation and whether any specific alteration influences the development of postoperative thrombosis are unknown. This study compared the concentrations of activated factor VII (FVIIa), tissue factor pathway inhibitor (TFPI), activated factor X (FXa)-TFPI, thrombin-antithrombin, and prothrombin fragment 1+2 (F1+2) in plasmas of 535 healthy individuals (ages 17-76) with those in the preoperative plasmas of 306 arthritis patients (ages 30-92) scheduled for elective knee or hip replacement surgery. C-reactive protein was also measured in the plasmas of approximately 15% of the participants. Age-adjusted concentrations of FVIIa, F1+2, and C-reactive protein were higher in patients than controls, while the concentrations of thrombin-antithrombin, TFPI and FXa-TFPI were similar. Chronic inflammation in the patients was thus associated with increased coagulation in vivo. Without compensatory increases in the concentrations of TFPI (natural inhibitor of prothrombinase), the elevated concentrations of FVIIa in the preoperative plasmas and the trauma associated with surgery may enhance the risk for developing postoperative deep-vein thrombosis.     

Nosocomial infection in adult patients with sickle cell anemia

Although the vulnerability of patients with sickle cell disease to infection with encapsulated organisms is well recognized, nosocomial transmission of infection has not been studied in this population. We describe eight serious, nosocomially transmitted infections in four adult patients hospitalized for complications of sickle cell disease, which led to death in one patient and prolonged hospital stays in three others. Although we have not surveyed all patients with sickle cell disease for rates of nosocomial infection, the cases presented suggest that these patients may be at increased risk. Risk can be reduced if health care workers are especially vigilant in adhering to handwashing and other infection control measures when caring for these patients. Additionally, we recommend that a patient with sickle cell disease not share a room with a patient known to have or suspected of having a nosocomial or community-acquired infectious disease.     

Proximal femoral focal deficiency: radiologic analysis of 49 cases

Proximal femoral focal deficiency, an uncommon congenital anomaly, necessitates early radiologic classification for surgical planning and treatment. Objective radiographic criteria, including femoral length index, acetabular depth index, acetabular angle index, and shape of the proximal femur were determined in 49 patients before cartilaginous ossification of the femoral capital epiphysis; final classification was based on follow-up radiographs or findings at arthrography or surgery. These parameters were analyzed to determine the accuracy and contributions of each in classification. Correct classification into one of three groups was possible in 86% of cases with use of three of the parameters: femoral length index, acetabular depth index, and shape of the proximal femur. The acetabular angle was found to contribute insignificantly to classification. Magnetic resonance imaging, used in only one case, depicted the nonossified cartilaginous femoral capital epiphysis, thus obviating the need for invasive diagnostic procedures and facilitating early classification.     

Personal exposure to house dust mite allergen in bed: nasal air sampling and reservoir allergen levels

BACKGROUND: Assessment of personal exposure to dust mite allergen has relied on proxy measures. Only recently has a means to directly measure inhaled allergen particle number become available (the intra-nasal air sampler). OBJECTIVE: To quantify inspired dust mite group 1 and group 2 allergen-bearing particles in bed in undisturbed conditions prior to sleep by nasal air sampling and to investigate the relationship between inhaled particles and reservoir allergen levels. METHODS: Twelve volunteers wore nasal samplers in bed for 6 evenings, nose-breathing in undisturbed conditions. Allergen-bearing particles ('halos') were detected by immunostaining for Der p 1, Der p 2, or Der p 1 and Der p 2 together, and counted by light microscopy. Count data were square root transformed for analysis of variance. Mattress dust samples were assayed for Der p 1 and Der p 2 concentrations. RESULTS: Square root detransformed mean particle counts per 30-min sample were: Der p 1, 4.22; Der p 2, 5.9; Der p 1 + Der p 2, 4.87; and for all samples, 5.01, with no difference between the groups. With replicate samples, halo number correlated significantly with mattress allergen concentrations (Der p 1 r = 0.80, P < 0.01; Der p 2 r = 0.68, P < 0.02). CONCLUSION: Nasal air sampling can be used to quantify nocturnal Der p exposure in undisturbed conditions in an area with moderate exposure to mite allergen and can provide a direct measure of inhaled mite allergen. The choice of either Der p 1 or Der p 2 is appropriate for this purpose.     

Postprandial triglyceridemia and carotid atherosclerosis in middle-aged subjects.

BACKGROUND AND PURPOSE: It has been suggested that a postprandial accumulation of triglyceride-rich lipoproteins promotes the development of atherosclerosis. This study was designed to test the hypothesis that postprandial lipemia is independently associated with intima-media thickening of the extracranial carotid arteries. METHODS: Forty-seven middle-aged, moderately hypercholesterolemic individuals were recruited for a 1-day study of the lipemic response to a standard high-fat test meal. The formula was fed at a dose of 65 g fat/m2 body surface area, after a 14-hour fast, and blood was obtained for triglyceride analysis hourly for 8 hours. A baseline lipid profile was obtained. Each subject underwent a carotid ultrasound examination. The extent of alimentary lipemia (peak triglyceride response) was correlated with the carotid artery wall thickness as measured by B-mode ultrasound. RESULTS: Univariate analyses indicated an inverse correlation between peak triglyceride response and high density lipoprotein cholesterol concentration and a direct correlation with male sex, baseline triglyceride concentration, background fat intake, and waist-to-hip ratio. Of these, the only variable that showed a univariate correlation with B-mode score was peak triglyceride response. Age and cigarette smoking were also correlated with B-mode score in univariate analyses. The correlation coefficient (r = 0.52) between peak triglyceride response to a fat-rich meal and B-mode score was significant (p less than 0.002) and remained so in multivariate analysis. Forward-selection stepwise regression resulted in the inclusion of only peak triglyceride response (p = 0.001) and smoking history (p = 0.005) as important predictors of carotid wall thickness in a linear model. CONCLUSIONS: The association between lipemic response and carotid wall thickness suggests that prolonged exposure of arterial wall cells to triglyceride-rich chylomicron remnants enhances the atherogenic process.     

A high fidelity tissue-based cardiac surgical simulator.

OBJECTIVE: Issues concerning the training and certification of surgical specialists have taken on great significance in the last decade. A realistic computer-assisted, tissue-based simulator developed for use in the training of cardiac surgical residents in the conduct of a variety of cardiac surgical procedures in a low-volume cardiothoracic surgery unit of a typical developing country is described. The simulator can also be used to demonstrate the function of technology specific to cardiac surgical procedures in a way that previously has only been possible via the conduct of a procedure on a live animal or human being. METHODS: A porcine heart in a novel simulated operating theatre environment with real-time simulated haemodynamic monitoring and coronary blood flow, in arrested and beating-heart modes, is used as a training tool for surgical residents. RESULTS: Standard and beating-heart coronary arterial bypass, aortic valve replacement, aortic homograft replacement and pulmonary autograft procedures can be simulated with high degrees of realism and with the superimposition of adverse clinical scenarios requiring valid decision making and clinical judgments to be made by the trainees. CONCLUSIONS: The cardiac surgical simulation preparation described here would appear to be able to contribute positively to the training of residents in low-volume centres, as well as having the potential for application in other settings as a training tool or clinical skills assessment or accreditation device. Collaboration with larger centres is recommended in order to accurately assess the utility of this preparation as an adjunctive cardiothoracic surgical training aid.