Table 1 Summary of studies assessing the utility of B-line estimation in emergency medicine and cardiology

Lichtenstein and Meziere [34]

Acutely dyspnoeic patients (n = 66)

3.0 MHz cardiac transducer Anterior - area bound by clavicle to diaphragm and sternum to AAL Lateral - area bound by armpit to diaphragm and AAL to PAL

Clinical, radiological, Echo

B-line artefact was seen in 100% of patients with pulmonary oedema and absent in 92% patients with COPD and 98.75% patients with normal lungs

Lichtenstein and Meziere [41]

Acutely dyspnoeic patients (n = 260)

5 MHz microconvex transducer 6 sites in each hemithorax divided in anterior, lateral and posterolateral

NA

Lung ultrasound can reliably distinguish asthma, COPD, oedema, pulmonary embolism, pneumothorax and consolidation

Jambrik et al. [26]

Cardiology/ pneumonology (n = 121)

2.5 to 3.5 MHz cardiac transducer 2nd to 4th ICS in left hemithorax (to 5th ICS on the right) at parasternal, midclavicular, AAL, PAL

Chest X-ray

Strong co-relation between B-line count and radiological lung water score (r = 0.78, P < 0.01)

Agricola et al. [37]

Cardiology (n = 72)

1.8 to 3.6 MHz transducer 2nd to 4th ICS in left hemithorax (to 5th ICS on the right) at parasternal, midclavicular, AAL, PAL

Echo (LV systolic function, PCWP, PAP)

Positive linear correlations between baseline B-line count and baseline ejection fraction, sPAP and estimated PCWP. A similar co-relation of the difference between post-exercise and baseline B-line count with indices of LV systolic and diastolic dysfunction

Frassi et al. [39]

Cardiology (n = 290)

2.5 to 3.5 MHz transducer 2nd to 4th ICS in left hemithorax (to 5th ICS on the right) at parasternal, midclavicular, AAL, PAL

Echo

Absence or presence of B-line predicted event-free survival (70% versus 19%, P < 0.0007)

Frassi et al. [38]

Chest pain/dyspnoea patients (n = 340)

2.5 to 3.5 MHz transducer 2nd to 4th ICS in left hemithorax (to 5th ICS on the right) at parasternal, midclavicular, AAL, PAL

Echo

B-lines associated with acute cardiac failure, response to treatment, EDV, LA dimension, MR, TR (P < 0.0001). In multivariate analysis NYHA functional class, EF and diastolic dysfunction predicted the presence of B-line

Gargani et al. [40]

Dyspnoea patients (n = 149)

2.5 to 3.5 MHz transducer 2nd to 4th ICS in left hemithorax (to 5th ICS on the right) at parasternal, midclavicular, AAL, PAL

NT pro-BNP

B-line co-related to NT pro-BNP (r = 0.69, P < 0.0001). High accuracy for B-line to predict aetiology of dyspnoea as of cardiac origin (AUC 0.893)

Volpicelli [42]

Unselected acute emergency medicine admissions (n = 300)

3.5 MHz convex transducer 8 areas in total Anterior - from the sternum to the AAL Lateral - from the AAL to PAL Each zone was divided into upper and lower halves

Chest X-ray

Diffuse B lines had sensitivity of 85.7% and a specificity of 97.7% for diagnosing radiologic interstitial oedema and a sensitivity of 85.3% and a specificity of 96.8% for diagnosing

a clinical disease with diffuse interstitial oedema

Volpicelli et al. [43]

Acute cardiac failure (n = 81)

3.5 MHz convex transducer 11 areas - 3 anterior and 3 lateral on right side and 2 anterior and 3 lateral on left side

Chest X-ray NT pro-BNP

Significant resolution of B lines after treatment (P < 0.001). Significant co-relation between B-line and clinical score (r = 0.87; P < 0.001), and radiological score (r = 0.62; P < 0.001) and BNP levels (r = 0.44; P < 0.05)

Prosen et al. [52]

Acutely dyspnoeic patients (n = 218)

8 areas in total Anterior - from the sternum to the AAL Lateral - from the AAL to PAL Each zone was divided into upper and lower halves

NT pro-BNP Clinical score

B-line was the strongest predictor of acute heart failure with 100% sensitivity, 95% specificity, 96% PPV and 100% negative NPV to diagnose cardiac failure. B-line can reliably exclude pulmonary related dyspnoea in patients with elevated BNP and a history of cardiac failure

Liteplo et al. [53]

Acutely dyspnoeic patients (n = 100)

2-5 MHz transducer 8 areas in total Anterior - from the sternum to the AAL Lateral - from the AAL to PAL Each zone was divided into upper and lower halves

NT pro-BNP Clinical review

The presence of a completely positive test gave an infinite likelihood ratio for diagnosing congestive cardiac failure and a completely negative test gave a likelihood ratio of 0.22 (CI 0.06 to 0.8).