The non-invasive diagnosis of pulmonary embolus

Increased diagnosis of pulmonary embolism without a corresponding decline in mortality during the CT era

AIM

To determine the association between the increasing computed tomography (CT) use for suspected pulmonary embolism (PE) on the annual rates of PE diagnosis and mortality, using time as a surrogate for CT use.

MATERIALS AND METHODS

New York State's (NYS) Statewide Planning and Research Cooperative System (SPARCS) database was used to determine the rate of PE diagnosis and mortality between 1 January 1994 and 31 December 2004. Risk factors for PE were investigated. Bivariate and multivariate analyses were performed to determine the relationships between variables.

RESULTS

The study population consisted of 24,871,131 NYS patients. The number of patients with a primary diagnosis of PE nearly doubled over the study period, from 2590 in 1994 to 4920 in 2004, while total admissions remained stable. PE deaths did not vary significantly over time, from 157 in 1994 to 159 in 2004 and did not vary with the diagnoses of PE. Age-adjusted multivariate analysis did not reveal a significant association between the rates of PE diagnosis or mortality and corresponding risk factors.

CONCLUSION

This study suggests that the increased use of CT in patients with suspected PE has led to an increase in the diagnosis of PE without a corresponding decline in mortality. Further evidence, using data on individual patients, is needed to determine the appropriate role of CT in evaluating patients with suspected PE.

Pulmonary embolism as a complication of major depressive disorder with catatonic features: a case report

Catatonia in the setting of a mood disorder, an organic process, or a psychotic disorder presents significant risk to the patient's well-being, as well as an additional barrier to treating the underlying disorder. The signs and symptoms of catatonia interfere severely with essential activities of daily living; they also at times compromise the ability of caregivers to evaluate and treat the patient's primary disorder driving the catatonia. This interference often leads to medical emergencies, such as marked dehydration and pressure ulcers. Another life-threatening complication of the immobility commonly seen in catatonic patients is the development of deep vein thromboses (DVT) and pulmonary emboli. As with all patients, it is critical to provide preventative measures where possible to minimize risk of complications. Routine anticoagulation perhaps deserves more consideration in the case of catatonia, such as the one presented in this case report.

Diagnosis of pulmonary embolism: ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.

The role of Bayesian Networks in the diagnosis of pulmonary embolism

Pulmonary embolism (PE) is a life-threatening condition and, despite advances in diagnostic technology, it remains an elusive diagnosis. The rich variety of possible clinical presentations make it particularly difficult to represent the diagnostic process as a 'decision tree'. However, Bayesian networks offer the opportunity of a compact representation of the domain underlying the decision process: once the network portrays the natural history of the disease, the utility of investigations can be quantitatively evaluated. We developed a network for the diagnosis of PE, including 72 variables to represent both the risk factors and the pathophysiological consequences of the disease. Its structure has been specified by discussing which causal relationships explain the manifestations of the disease. The quantitative measures of associations were retrieved from the medical literature, through a critical review of available studies and agreement on the assumptions made to cope with the lack of published information. Six examples are presented to illustrate the appropriateness of 'entropy reduction' as a measure of the utility of investigation, once the set of examinations to be evaluated is bounded on the grounds of their cost and the patient's current risk. The network, which has been given the acronym 'BayPAD' (Bayesian network for Pulmonary embolism Assisted Diagnosis), appears to be able to detect which observations make others irrelevant, so that decisions can be tailored to single cases.