A retrospective review of chest radiographs from 205 patients with blunt chest trauma who also underwent aortography was performed. Forty-one of the 205 had aortographically proved aortic rupture. Discriminant analysis of 16 radiographic signs indicated that the most discriminating signs were loss of the aorticopulmonary window, abnormality of the aortic arch, rightward tracheal shift, and widening of the left paraspinal line without associated fracture. No single or combination of radiographic signs demonstrated sufficient sensitivity to indicate all cases of traumatic aortic rupture on plain chest radiographs without the performance of a large number of aortographically negative studies. The bedside anteroposterior "erect" view of the chest proved far more valuable than the supine view in detecting true-negative studies. Despite significant reader variability in the interpretation of the various radiographic signs, in general the analysis confirmed the role of chest radiography in this clinical situation, but suggests that its most beneficial use is in excluding the diagnosis and eliminating unwarranted aortography rather than in predicting aortic rupture.
Widening of the retropharyngeal soft tissue space (RSTS) has been interpreted as a sign of cervical spine trauma. Widely differing measurements are reported in the literature. However it is clear that, using the currently acceptable limits of normal, a large number of patients without spinal injury are subjected to further tests. The RSTS on lateral cervical spine radiographs of 318 patients with a history of cervical spine trauma were measured at the C2-C4 level. The values for patients found to be normal or with fractures/dislocations were evaluated. Statistical analysis of the results demonstrates a considerable overlap in the RSTS of normal and abnormal patients. Therefore we suggest that RSTS measurements are of limited diagnostic value. Using the statistical probability of abnormality, guidelines that indicate which patients may require additional study are suggested.
In a two-compartment scintillation vial, suspensions of bacteria were cultured with 1 µCi of [U-14C] glucose and the released 14CO2 was measured continuosly, cumulatively, and automatically in a liquid-scintillation counter modified to maintain sample temprature at 37 °C. We could follow the metabolism of bacterial populations through their early phase of exponential growth with good precision. The data were obtained conveniently, with use of conventional regents, glassware, and counting equipment. From analysis of the exponential portion of the curves for cumulative activity vs. time, we could measure cell replication rate precisely in units of time. The resulting values were demonstrably independent of some common experimental variables, including the number of bacteria in the inoculum and counting system sensitivity. Sensitivity of the bacteria to antibiotics was measured to within a few percent by noting the relative prolongation of replication time in the presence of those inhibitors. The digital data from the scintillation counter are susceptible to on- or off-line computer analysis, thus providing the prospect for a totaly-automated analytical system. The method shows promise for the mechanized quantitative analysis of bacterial growth, and its inhibition.
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