Real-time risk stratification of patients with acute pulmonary embolism by grading the reflux of contrast into the inferior vena cava on computerized tomographic pulmonary angiography.

OBJECTIVE: To investigate whether fast grading of reflux of contrast to the inferior vena cava (IVC) on computerized tomographic pulmonary angiography (CTPA) is a potential biomarker for real-time risk stratification. METHODS: We retrospectively identified 343 patients investigated for possible pulmonary embolism (PE) by CTPA at our medical center between September 2004 and March 2006. A total of 145 consecutive patients with PE (age 67 +/- 19 years) and 168 consecutive ones with negative CTPAs (age 64 +/- 20 years) fulfilled entry criteria. CTPAs were evaluated for retrograde reflux of contrast to the IVC by fast visual grading from 1 to 6 using the original axial images. Pulmonary obstruction index, the diameters of right and left ventricles and pulmonary artery, and patient survival data were recorded as well. RESULTS: Twenty-nine (20.0%) patients with positive CTs and 23 (13.7%) patients with negative CTs had substantial degrees (>or=4) of reflux of contrast to the IVC (P = 0.14). The Kaplan-Meier 30-day survival curves demonstrated significant reduction in survival in individuals with PE and grade >or=4 reflux of contrast to the IVC compared with lower grades (P = 0.008), but not in patients with grade >or=4 and no PE on CTPA (P = 0.26). The other cardiovascular parameters showed no significant correlation with survival in patients with and without PE. CONCLUSION: Substantial grades of reflux of contrast to the IVC during CTPA could predict early mortality in patients with acute PE. Rapid grading of reflux of contrast from the original axial CTPA images can be used for real-time risk stratification in patients with acute PE.

Rheological consequences of acute infections: the rheodifference between viral and bacterial infections.

The aim of the present study was to explore the difference between viral and bacterial infections regarding the intensity of erythrocyte aggregation in the peripheral venous blood. Although a rheodifference in terms of erythrocyte aggregation between viral and bacterial infections has been shown by us in the past, the time from onset of disease was not included. We have presently included the time from the onset of disease in a group of 133 patients with an acute bacterial infection who showed a significantly enhanced erythrocyte aggregation as opposed to a group of 23 with viral ones and no increased erythrocyte aggregation despite of there being no significant difference in the time from onset of disease (55.7+/-55.6 hours in the bacterial group versus 50+/-35.2 in the viral one). In addition, we could match 22 patients with viral infections who presented the same fibrinogen concentrations (338+/-78 mg/dl) as those with acute bacterial ones (338+/-79 mg/dl). Although of borderline (p=0.06) significance, patients with an acute bacterial infection presented enhanced (vacuum radius=12.6+/-6.4 microns) erythrocyte aggregation as opposed to their isofibrinogenemic counterparts (vacuum radius=9.4+/-6.5 microns). Again, both groups presented no difference regarding the time from onset of disease. We conclude therefore that patients with acute bacterial infections present higher levels of erythrocyte aggregation. This is not a result of a shorter time interval from disease onset of the viral group. The known detrimental effects of increased erythrocyte aggregation regarding capillary slow flow, endothelial dysfunction and reduced tissue oxygenation might be therefore relevant in the context of patients with an acute infection, especially the bacterial ones.

Serum lipids as minor determinants of the degree of erythrocyte adhesiveness/aggregation in the peripheral blood of individuals with low grade inflammation and moderately increased serum lipids.

Both lipids and inflammation sensitive proteins have been reported to affect the aggregation of red blood cells yet their relative importance in this regard have not been determined. We have included high sensitive C-reactive protein, erythrocyte sedimentation, fibrinogen concentrations as well as various serum lipid concentrations and the degree of erythrocyte adhesiveness/aggregation in the peripheral blood in a linear regression analysis. Partial Pearson correlation coefficients were included as well. In a group of 674 individuals with various atherosclerotic risk factors, low grade inflammation and moderately increased serum lipids, a relatively low correlation was noted between red blood cell adhesiveness/aggregation and triglycerides concentrations. A negative correlation was noted for HDL cholesterol. None of the lipid variables turned significant in the regression analysis. In a group of individuals with atherosclerotic risk factors, low grade inflammation and moderately increased serum lipids, the degree of erythrocyte adhesiveness/aggregation in the peripheral blood correlates much better with the presence of inflammation sensitive proteins than with the presence of increased lipid concentrations.

Airborne polarized lidar detection of scattering layers in the ocean.

A polarized lidar technique based on measurements of waveforms of the two orthogonal-polarized components of the backscattered light pulse is proposed to retrieve vertical profiles of the seawater scattering coefficient. The physical rationale for the polarized technique is that depolarization of backscattered light originating from a linearly polarized laser beam is caused largely by multiple small-angle scattering from particulate matter in seawater. The magnitude of the small-angle scattering is determined by the scattering coefficient. Therefore information on the vertical distribution of the scattering coefficient can be derived potentially from measurements of the time-depth dependence of depolarization in the backscattered laser pulse. The polarized technique was verified by field measurements conducted in the Middle Atlantic Bight of the western North Atlantic Ocean that were supported by in situ measurements of the beam attenuation coefficient. The airborne polarized lidar measured the time-depth dependence of the backscattered laser pulse in two orthogonal-polarized components. Vertical profiles of the scattering coefficient retrieved from the time-depth depolarization of the backscattered laser pulse were compared with measured profiles of the beam attenuation coefficient. The comparison showed that retrieved profiles of the scattering coefficient clearly reproduce the main features of the measured profiles of the beam attenuation coefficient. Underwater scattering layers were detected at depths of 20-25 m in turbid coastal waters. The improvement in dynamic range afforded by the polarized lidar technique offers a strong potential benefit for airborne lidar bathymetric applications.