[Usefulness of B-type natriuretic peptide in emergency medicine].
OBJECTIVES: Acute dyspnea is frequent in emergency medicine. The B-type natriuretic peptide is a polypeptide, released by ventricular myocytes directly proportional to wall tension, for lowering renin-angiotensin-aldosterone activation. Conversely, NT-proBNP has no physiological activity. BNP and NT-proBNP concentration closely correlate to various indicators of heart failure. CURRENT KNOWLEDGE AND KEY POINTS: Numerous studies have demonstrated high usefulness of BNP and NT-proBNP to diagnose heart failure, which is the main cause of acute dyspnea in emergency medicine. The diagnostic accuracy of BNP and NT-proBNP seems similar, and is higher than that of the emergency physician. Bedside dosages are now available, with high sensibility and specificity for the diagnosis of heart failure. For BNP, threshold value is ranging from 100 to 300 pg/ml in patients aged over 65 years; for NT-proBNP the threshold value is 1000 to 2000 pg/ml in elderly patients. Briefly, heart failure is unlikely when BNP is below 100 pg/ml (NT-proBNP<500 pg/ml), and very likely when BNP is higher than 400 pg/ml (or NT-proBNP>2000 pg/ml). FUTURE PROJECTS: Early rapid measurement of BNP could improved the evaluation and treatment of patients with acute dyspnea and reduce the total cost of treatment.