Discussion: This well done prospective observational study adds to a growing body of evidence questioning the utility of routine blood cultures on all patients hospitalized with CAP. The argument traditionally has been made that blood cultures allow clinicians to narrow or broaden antibiotics based on sensitivities. Yet, empiric therapy was broadened in response to bacteremia in only a small fraction of patients (1%) and in only 11 of 19 patients was therapy appropriately narrowed based on the blood cultures. The study did not measure the impact of blood cultures on clinical outcomes, but these striking results reveal that routine blood cultures rarely alter our management of hospitalized patients with CAP.
Further, many have argued obtaining routine blood cultures in CAP can have negative consequences. Blood cultures are relatively costly and time intensive, contaminated blood cultures can lead to repeated testing and increased length of stay, and delays in obtaining blood cultures can delay antibiotic administration, another important quality marker in CAP. For now, it remains the standard of care to obtain blood cultures in these patients, but hospitalists should be aware of the limitations of this practice and consider focusing on other clinical interventions and quality measures in CAP.
A Review Study: A Dyspneic Emergency Patient
Wang CS, FitzGerald JM, Schulzer M, et al. Does this dyspneic patient in the emergency department have congestive heart failure? JAMA. 2005 Oct 19;294:944-1956.
Background: Distinguishing CHF from non-cardiac causes of dyspnea is a major challenge for hospitalists and emergency physicians, particularly in patients with a prior history of cardiac disease. Traditionally, clinicians have relied on the history, physical examination, and basic tests (chest X-ray and electrocardiogram) to diagnose CHF, but rapid B-type natriuretic peptide (BNP) testing is now widely incorporated as well.
A previous article in the Rational Clinical Examination series (Can the clinical examination diagnose left-sided heart failure in adults? JAMA. 1997;277(21):1712-1719) found that systolic dysfunction was moderately well predicted by an abnormal apical impulse on physical examination, radiographic cardiomegaly or venous redistribution, or electrocardiographic q waves or left bundle branch block.
Methods: In this review, the authors update and extend previous findings by also assessing the utility of serum BNP testing. The authors identified articles evaluating the diagnostic accuracy of the clinical exam and laboratory testing in diagnosing CHF in patients presenting to the emergency department with undifferentiated dyspnea. The “gold standard” was a clinical diagnosis of CHF made by the treating clinicians after an appropriate diagnostic workup. Summary likelihood ratios (LRs) were calculated using meta-analytic methodology.
Results/discussion: The authors determined that several findings increase the probability of CHF. A prior history of CHF (LR 5.8, CI 4.1-8.0) or myocardial infarction (LR 3.1, 95% CI 2.0-4.9), symptoms of paroxysmal nocturnal dyspnea (LR 2.6, 95% CI 1.5-4.5) and orthopnea (LR 2.2, 95% CI 1.2-3.9) were the most predictive historical factors. On physical examination, the presence of an S3 (LR 11, 95% CI 4.9-25), jugular venous distension (5.1, 95% CI 3.2-7.9), lung rales (LR 2.8, 95% CI 1.9-4.1), and peripheral edema (2.3, 95% CI 1.5-3.7) increased the probability of CHF. In interpreting these results, it is helpful to remember that a likelihood ratio of 2 increases the post-test probability by about 15%, and an LR of 5 increases the post-test probability by about 30%. Thus, a prior history of CHF and presence of an S3 or jugular venous distension are the most useful findings. Interestingly, clinician’s gestalt was equally predictive (LR 4.4, 95% CI 1.8-10.0.)