Comparison of a basic lung scanning protocol against formally reported chest x-ray in the diagnosis of pulmonary oedema.

Introduction: Brief lung scan protocols have been recommended as a useful adjunct to identify pulmonary oedema in the breathless elderly patient. Some papers quote diagnostic accuracies above that of chest x-ray. Method: We recruited a prospective convenience sample of patients over sixty years of age reporting any breathlessness on presentation to the emergency department. Those who received both bedside lung scan and chest x-ray later had their case notes audited by an expert cardiologist for the cause of their breathlessness at presentation. Admission diagnosis was also extracted. Results: 204 comparative data sets were collected. Compared with cardiologist chart review, delayed expert radiology report had a diagnostic accuracy of 92.2% (95%CI 87.6 to 95.1). Bedside interpretation of lung scan protocol had a diagnostic accuracy of 85.3% (95%CI 79.8 to 89.5). The difference of 6.9% between the two accuracy measures was significant (95%CI 0.69 to 13.1). Admission diagnosis accuracy, which encompasses inexpert x-ray interpretation was 70.2%(95%CI 62.9 to 76.6), significantly less than either lung scan or expert chest x-ray report. Conclusion: For identifying heart failure in breathless patients, urgent chest x-ray with delayed formal report has not been shown to be redundant. Basic lung scan protocols should not yet replace chest x-ray, but may be more reliable in the interim than inexpert clinician interpretation of chest x-rays.