HG U/S Course Prep #2: Lung Ultrasound Dr. Caroline Walker March 23, 2018

Practice Changing

Intro to lung ultrasound How to get started Pneumothorax Pulmonary edema Pleural effusion

Why do lung ultrasound? Technically easy Superior diagnostic tool to CXR in majority of instances Integrate with other ultrasound skills (IVC/echo/FAST) to systematically evaluate undifferentiated sick patients Target resuscitation Save lives! Let your x-ray tech sleep…

Probes of choice: Pros and Cons Phased Array Small footprint = Visualize in rib space (matters more for cardiac views) Low Hx; Deep penetration ideal for lung artefact Curvilinear Array Low Hz; Deep penetration Easy transition from FAST to e-FAST and advantage of single probe Linear Array Higher Hz = better near field resolution Good for assessing pleura

Non-Anatomic Images

Lung ultrasound = mostly artifact In a healthy lung you do not see the anatomy due to air scatter “A” lines - normal horizontal lines that represent reverberation artifact from the pleural line “A” lines = air filled lung

Technique Probe in long axis Indicator to patient head Perpendicular to chest wall Pleural lines will be as close to near field as possible Will see either A line or B line pattern

Pneumothorax POCUS Better test than a chest x-ray! Comparing POCUS vs supine CXR in traumatic pneumothorax Sensitivity for u/s: 98% (CXR: 28-75%) Specificity for u/s: 99-100% (CXR: 100%)

Primary Question: Is there lung sliding? If there is lung sliding there is no pneumothorax at that location Excellent RULE OUT test NO lung sliding can mean: Pneumothorax COPD blebs Pleurodesis/other pleural conditions Post pneumonectomy Mainstem intubation Dense pneumonia (consolidated lung not inflating) Apnea Technique: Check most non-dependent areas (air rises)

The “sea shore” sign = lung sliding present

The “stratosphere” or “bar code” sign = lung sliding absent

The Lung Point = Pathognomonic for PTX

Pneumothorax

Lung point = Rule IN PTX (100% specific)

Be sure you are looking at the pleural line! Subcutaneous emphysema - Irregular (not like pleural line) - Too superficial to be pleural line

B-lines A fluid-air artifact ’B’ lines = Something going on in the alveoli and interstitium (edema, fibrosis)

B-line Characteristics Arises from the pleural line Well defined and laser-like Hyperechoic Long, spreading out without fading to the edge of the screen Erases the A-lines Moves with lung-sliding (if present)

Technique Phased or curvilinear array Increase depth to 15 cm Probe perpendicular to chest wall Scan in 4 regions (supine patient)

All about the B-lines Originates from fluid/fibrosis of interlobular septae Isolated B-lines in dependent area is normal finding 3 or more B-lines in one lung region is abnormal Distribution helps your diagnosis RULES OUT pneumothorax in that area

B-line pattern: stuff in the alveoli/interlobular septae Diffuse B-lines Pulmonary edema Pulmonary fibrosis Focal B-lines Pneumonia ARDS Pulmonary contusion Pulmonary hemorrhage

B-lines to guide resuscitation Undifferentiated hypotensive patient, can use lung US to guide resus A line pattern: no pulmonary edema, consider more fluid Correlates with low pulmonary artery wedge pressure B line pattern: be cautious about more fluid, consider transition to pressors

Pleural Effusion POCUS Much more sensitive than CXR, as good as CT Assists thoracentesis (much safer!) RUQ and LUQ FAST scan locations then move superiorly Generally see hypoechoic fluid (obvious); not always (clot, pus) May cause compressive atelectasis “The Spine Sign” – fluid transmits sound, will generate image of vertebrae through the lung (not normal)

“Jellyfish sign”

Integration: BLUE Protocol (Lichtenstein) Acute Dyspnea NYD

Summary A-lines: normal parenchyma B-lines: stuff in the interstitium Lung sliding: Rule OUT pneumothorax, Lung point rule IN Pleural effusion: Spine sign Can guide Dx and resuscitation THANK YOU!