Imaging evaluation of suspected pulmonary embolism.

Venous thromboembolism (VTE) is a common disorder that is difficult to diagnose clinically but carries significant morbidity and mortality if untreated. Additionally, although demonstrated to be of benefit in cases of proven deep vein thrombosis (DVT) and pulmonary embolism (PE), anticoagulation therapy is not without risk. Because the clinical exam is known to be unreliable for the detection of both DVT and PE, many imaging modalities have been used in the diagnostic imaging algorithm for the detection of VTE, including chest radiography, ventilation/perfusion (V/Q) scintigraphy, pulmonary angiography, and recently, spiral computed tomography (CT) and magnetic resonance imaging (MRI). Chest radiographic findings in acute PE include focal oligemia, vascular enlargement, atelectasis, pleural effusions, and air space opacities representing pulmonary hemorrhage or infarction. The chest radiograph can occasionally be suggestive of PE but is more often nonspecifically abnormal. The main use of the chest radiograph in the evaluation of suspected PE is to exclude entities that may simulate PE and to assist in the interpretation of V/Q scintigraphy. Lower extremity venous compression ultrasonography (CU) is both sensitive and specific for the diagnosis of femoropopliteal DVT, and the value of negative CU results has been established in outcomes studies. However, the reliability of CU for the detection of isolated calf vein thrombosis is not well established, and the clinical significance of such thrombi is debatable. Additional methods such as color and spectral Doppler analysis are also useful in the diagnostic evaluation of DVT but are best considered as adjuncts to the conventional CU examination rather than as primary diagnostic modalities themselves. Compression ultrasonography and Doppler techniques are useful in the evaluation of suspected upper extremity DVT; spectral Doppler waveform analysis is particularly useful to assess for the patency of veins that cannot be directly visualized and compressed with conventional gray-scale sonography. V/Q scintigraphy has been the initial modality obtained in patients suspected of PE for a number of years. Although many studies have investigated the role of V/Q scintigraphy in the evaluation of VTE, the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study has provided the most useful information regarding the utility of V/Q scintigraphy in this setting. A high probability scan interpretation is sufficient justification to institute anticoagulation, and a normal perfusion scan effectively excludes the diagnosis of PE. A normal/near normal scan interpretation also carries a sufficiently low prevalence of angiographically proven PE to withhold anticoagulation. Although the prevalence of PE in the setting of low probability scan interpretations is low and several outcomes studies have demonstrated a benign course in untreated patients with low probability scan results, patients with inadequate cardiopulmonary reserve do not necessarily have good outcomes. Such patients deserve more aggressive evaluation. Patients with intermediate probability scan results have a 20% to 40% prevalence of angiographically proven PE and thus require further investigation. The radionuclide investigation of DVT includes such techniques as radionuclide venography and thrombus-avid scintigraphy. Although these methods have not been as thoroughly evaluated as CU, studies thus far have indicated encouraging results, and further investigations are warranted. Pulmonary angiography has been the gold standard for the diagnosis of PE for decades. Studies have indicated that angiography has probably been underutilized by referring physicians for the evaluation of suspected PE, likely because of the perception of significant morbidity and mortality associated with the procedure. (ABSTRACT TRUNCATED)     

Laparoscopic versus open splenectomy in the pediatric population: a contemporary single-center experience

The purpose of this study was to compare a recent contemporaneous experience between laparoscopic (LS) and open (OS) splenectomy in children. All splenectomy cases between 1994 and 1999 at our institution were reviewed. The study included open and laparoscopic cases performed according to surgeon preference. Emergency splenectomies for trauma were excluded. The patient record was reviewed for the diagnosis, indications, postoperative length of stay, operative technique, postoperative complications, blood loss/blood transfusion, total amount of parenteral narcotics, and time to resumption of oral intake. Chi-square and t tests were used to compare measured differences for statistical significance. Between May 1994 and December 1999, 52 splenectomies were performed at Vanderbilt Children's Hospital. Of these, 45 were elective operations with 29 open and 16 laparoscopic procedures. During four OS and five LS operations a concomitant cholecystectomy was performed. The median patient age was 9.2 years (range 0.5 to 17.3). There was no statistical difference between the two groups in terms of age, weight, American Society of Anesthesiologists class, or estimated blood loss. There were no immediate postoperative complications in either group. There were no conversions from LS to OS. The mean duration of surgery was 264 minutes (LS) versus 169 minutes (OS) (P < 0.05). The average time to first oral intake was shorter in patients undergoing LS (1.1 vs 1.6 days, P < 0.05) and the mean postoperative length of stay was also shorter in the LS group (1.3 vs 3.1 days, P < 0.05). The use of postoperative intravenous narcotics (in morphine-equivalent doses) was significantly less in LS patients than in OS patients (7.5 mg or 0.15 mg/kg vs 46.9 mg or 1.5 mg/kg, P < 0.001), as was the need for PCA pump analgesia (90% in the OS group vs 25% in LS group, P < 0.01). Overall the average hospital charge (anesthesia fee, narcotics charge, and hospital room charge) was $5400 (range $4240-6250) in the OS group and $4950 (range $4450-6240) in the LS group (P < 0.05). Among the nine patients undergoing splenectomy with cholecystectomy, findings between the OS and LS groups were similar except for one late complication consisting of a diaphragmatic hernia in an LS patient. Both LS and OS with or without a concomitant procedure can be accomplished safely in children. LS appears to result in longer operative times but shorter lengths of stay, earlier first oral intake, and significantly fewer requirements for intravenous narcotics; all of these contribute to a reduction in hospital charges compared with the open operation.     

Effects of Combination of Calcium and Aspirin on Azoxymethane-Induced Aberrant Crypt Foci Formation in the Colons of Mice and Rats

Human intervention studies have suggested an exciting synergistic action between calcium supplementation and aspirin intake in reducing the risk of colorectal cancer. The aim of this study was to determine whether such a synergy can be demonstrated on azoxymethane (AOM)-induced colon aberrant crypt foci (ACF) formation in mice and rats. Female CF-1 mice and male F344 rats were injected subcutaneously with AOM and then received diet treatments for 8 wk. The basal control diet contained high fat (20% mixed lipids by weight) and low calcium (1.4 mg/g diet) to mimic the average Western diet. The treatment diets contained enriched calcium (5.2 mg calcium/g diet), aspirin (0.2 mg aspirin/g diet), or calcium plus aspirin (5.2 mg calcium plus 0.2 mg aspirin/g diet). Treatment with calcium, aspirin, or their combination significantly decreased the number of total ACF and aberrant crypt per mouse (by 43–59%) or rat (by 23–38%), but statistically significant differences among the 3 groups were not observed. A hint of additivity between calcium and aspirin was observed in mice but not in rats. These results indicate that the combination of calcium and aspirin did not produce a synergistic effect on the ACF formation in AOM-treated mice and rats.     

Editorial

The present study was conducted to determine whether older adults can learn and retain information on asthma and play a role as community health workers to teach children about asthma. A total of 36 older adults and 28 students in grades K-6 participated. Pre-tests and post-tests were administered to participants. Improvement in older adult scores after training was significant (p =. 001), and improvement persisted through the conclusion of teaching sessions (p = 0.001). The increase in lower student scores was significant (p = 0.050). Results suggest that older adults can learn and retain asthma information and schoolchildren can learn asthma-related information taught by older adults.     

Numerical simulation for a wind dust event in the US/Mexico border region

Soil-derived dust represents one of the major components of the natural atmospheric aerosols. Arid and semiarid areas with unpaved and non-vegetated land cover are particularly vulnerable to windblown dust, which results in high particulate matter pollution. To understand, predict, and mitigate the impact of dust aerosol on air quality and climate, it is necessary to parameterize the emission rate of dust particles from the wind erosion processes accurately. However, windblown dust emission is poorly represented in existing air quality models. In this paper, a windblown dust emission model has been developed based on a parameterization of threshold wind friction velocity depending on the roughness of surface, vegetation type, soil type, soil moisture content, and on the size distribution of aerosols. The proposed dust model incorporates into a region air quality modeling system to simulate a North American dust storm episode occurring near the border of southwestern USA and northwestern region of Mexico on 23 February 2007. It is shown that the implementation of a windblown dust model in an air quality model can significantly improve the model capability for capturing the dust episode. The simulation of the model is in good agreement with the evolution of dust distribution. The modeled dust spatial patterns matched dust cloud patterns appearing on satellite images. Implementation of the windblown dust model successfully captured the time of peak particulate matter (PM) concentrations for both PM₁₀ and PM_2.5, as well as the peak value of the PM_2.5 concentration. The modeled results clearly demonstrate an improved ability to predict PM events by applying the windblown dust emission scheme.     

MR findings in iatrogenic Gerbode defect

Congenital or acquired communication between left ventricle and right atrium is rare and can be easily overlooked as an eccentric tricuspid regurgitation jet. MRI is the ideal modality for accurate diagnosis, providing details for surgical planning about the location and size of the defect.     

Phase Diagrams Map the Properties of Antiviral Agents Directed against Hepatitis B Virus Core Assembly

Assembly effectors are small molecules that induce inappropriate virus capsid assembly to antiviral effect. To identify attributes of hepatitis B virus (HBV) assembly effectors, assembly reaction products (normal capsid, noncapsid polymer, intermediates, and free dimeric core protein) were quantified in the presence of three experimental effectors: HAP12, HAP13, and AT-130. Effectors bound stoichiometrically to capsid protein polymers, but not free protein. Thermodynamic and kinetic effects, not aberrant assembly, correlate with maximal antiviral activity.