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Lung

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Pneumothorax

EXTRAVASCULAR LUNG WATER

An increase in interstitial fluid or alveolar interstitial syndrome (AIS) gives rise to B lines. The Ddx for AIS is wide ranging from infective to ARDs to fluid overload. Examining the integrity of the pleura, looking for associated features like consolidation and effusions and determining the distribution of B lines will help narrow the differential (1). 

B lines are vertical laser like lines which extend to the bottom of the screen without fading 

CAUSES OF B LINE ACCORDING TO PLEURAL APPEARANCE

THIN REGULAR PLEURA

CCF

Fluid overload

THIN IRREGULAR PLEURA

Pulmonary contusion

Early infective process

Infarction

Malignancy

THICK IRREGULAR PLEURA

Infective (viral, early bacterial)

Inflammatory

Pulmonary fibrosis

ARDs

Pleural disease

    thin pleura and B lines: more likely with CCF

    Thickened pleura and B lines in a Covid positive patient

    LEFT: Thick pleura and B lines -  RIGHT: thin pleura and B lines

    B line distribution and pleural abnormalities give clues to the cause of B lines

    COMMON CAUSES OF B LINES ACCORDING TO LOCATION

    UNILATERAL

    Infective

    Contusion

    Infarction

    BILATERAL LOWER ZONES

    CCF

    Interstitial disease eg pulmonary fibrosis affecting lower lobes

    Viral pneumonia eg COVID19

    Miliary TB (2)

    Diffuse mets

    BILATERAL UPPER ZONES

    CCF

    interstitial disease eg pulmonary fibrosis affecting upper lobes 

    ARDs

    diffuse mets

    There is still debate about the best way to visualise and quantify B lines. Horizontal transducer orientation leads to a wider field of view than the vertical orientation we have described and may allow a more uniform assessment of the B lines in that area (3); however, most guidelines still recommend vertical orientation of the transducer.

    In the following pages we will describe common conditions presenting as B lines on lung US. 

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    CCF

    REFERENCES

    1. Volpicelli, G., Elbarbary, M., Blaivas, M. et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med 38, 577-591 (2012). https://doi.org/10.1007/s00134-012-2513-4

    2. Hunter L, Bélard S, Janssen S, van Hoving DJ, Heller T. Miliary tuberculosis: sonographic pattern in chest ultrasound. Infection. 2016 Apr;44(2):243-6. doi: 10.1007/s15010-015-0865-8. Epub 2015 Dec 11. PMID: 26661658.

    3. Mongodi S, Bouhemad B, Orlando A, et al. Modified Lung Ultrasound Score for Assessing and Monitoring Pulmonary Aeration. Modifizierter Lungen-US-Score zur Bewertung und Überwachung der Belüftung der Lunge. Ultraschall Med. 2017;38(5):530-537.