Sonographic chest B-lines anticipate elevated B-type natriuretic peptide level, irrespective of ejection fraction

Echocardiography and the N-terminal pro-brain-type natriuretic peptide (NT-proBNP) level are important tests for assessing left ventricular function in patients presenting to the emergency department with acute dyspnea. Chest ultrasound is becoming an important tool in diagnosing acute pulmonary edema.

To assess the diagnostic accuracy of chest ultrasound examination using echocardiography and a curvilinear probe for detecting B-lines in patients presenting with acute pulmonary edema compared with assessment using NT-proBNP.

This paper reports a prospective observational study of 61 consecutive patients presenting with symptoms and signs of pulmonary edema and B-profile detected by echocardiography with a 5 MHz curvilinear probe. The emergency department physicians ordered NT-proBNP levels, and critical care physicians trained in ultrasound examination performed echocardiography and chest ultrasounds. The findings of the chest ultrasound were reviewed by another senior physician.

Sixty-one participants were enrolled over a period of 6 months (49.2 % male, with a mean age 66.8). Forty-seven of the 61 patients had a B-profile. The median NT-proBNP level in the patients with B-profile was 6200, compared with the mean level in the patients with an A-profile of 180 (CI 0.33-0.82). The distributions in the two groups differed significantly (p = 0.034). Based on a threshold level of NT-proBNP in relation to age, the sensitivity and specificity (including the 95 % confidence interval) were determined; the sensitivity of finding B-profile on ultrasound was 92.0 %, and the specificity was 91.0 %. The positive predictive value of the B-profile was 97.0 %, and the negative predictive value was 71.0 %. The systolic function in the subjects with a B-profile was below 50 in 84.3 % of the subjects and normal in 15.7 % of the subjects. An A-profile was present in all of the subjects with systolic function >55 %. In the subjects with a B-profile, 94 % had a Framingham score of CHF >4; the subjects with all A-profile had scores <4, p < 0.0001. There was an NHANES score of >3 in 96 % of the subjects with a B-profile, and all of the subjects with an A-profile had scores <3 (p < 0.0001).

Detecting the B-profile with an echocardiography probe (curvilinear 5 MHz) in lung ultrasound is highly sensitive and specific for elevated NT-proBNP helping in diagnosing pulmonary edema, although of resolution inferior to micro convex probes.