Lung Ultrasound Part 1 Drew Sheldon, MD

Objectives Know the basic principles of lung ultrasound Learn the steps of how to perform a bedside lung ultrasound Learn the 2 images of a normal lung ultrasound scan

Lung Ultrasound Principles Why use lung ultrasound? Quick Reproducible Safe Effective Easy to learn Faster than a CXR Findings can be re-demonstrated in real time No radiation or harm to the patient Able to differentiate between multiple diagnoses Only 5 artifacts to know Effectiveness: Using Bedside Lung Ultrasound in Emergency (BLUE) protocol (Lichtenstein 2008) yielded dx in 90.5% of cases of acute respiratory distress PTX: CXR Sn 27-82%, Sp 89-100% vs US Sn 85-89%, Sp 99-100%, LR+ 36-153 Pleural Effusions: US Sn 84%, Sp 100%, accuracy 94% Alveolar Consolidation: US Sn & Sp >90%

Lung Ultrasound Principles Unlike other ultrasound scans, lung ultrasound relies on artifacts Air refracts ultrasound which makes it bright white (hyperechoic) on scans Fluid conducts ultrasound easily which makes it black (hypoechoic) on scans Specific interactions of air and fluid create reproducible artifacts Gravity influences the location of these artifacts Remember US is refracted by air (or bounces off of it and does not go through it) = white or “hyperechoic” US goes through water and fluids easily = black or “hypoechoic” Artifacts in lung ultrasound are helpful unlike other scans; eg: cardiac US, abdominal US, FAST scan https://annalsofintensivecare.springeropen.com/articles/10.1186/2110-5820-4-1 Lichtenstein. Lung ultrasound in the critically ill. Annals of Intensive Care 2014 4:1

Lung Ultrasound Principles All artifacts and signs arise from the pleural line Almost all lung pathology meets the pleural line Therefore patterns of artifacts can be applied to clinical decision making Remember US is refracted by air (or bounces off of it and does not go through it) = white or “hyperechoic” US goes through water and fluids easily = black or “hypoechoic” Artifacts in lung ultrasound are helpful unlike other scans; eg: cardiac US, abdominal US, FAST scan https://annalsofintensivecare.springeropen.com/articles/10.1186/2110-5820-4-1 Lichtenstein. Lung ultrasound in the critically ill. Annals of Intensive Care 2014 4:1

Performing a Lung Ultrasound Probe Choice #1 Phased Array: better depth, able to visualize all artifacts #2 Linear Transducer: sacrifices depth for resolution, used to clarify lung sliding #2 #1 http://used-medicalequipmentblog.blogspot.com/2011/02/what-are-ultrasound-probes-used-for.html

Performing a Lung Ultrasound Probe in sagittal or vertical axis 3 Standard Zones Anterior Zone Indicator to head (Make sure dot is on the left side of the screen) Lateral Zone Posterior Zone or PLAPS Point Anatomical Spots: (for reference, but don’t need to know specifics) Anterior Zone: Mid-Clavicular Line 2nd-3rd Intercostal Space Lateral Zone: Lateral-Clavicular Line 4-5th Intercostal Space Posterior Zone or PLAPS Point (Posterior-Lateral Alveolar/Pleural Syndrome)* Right Mid-Axillary Line 9-10th Intercostal Space Left Posterior Axillary Line 7-8th Intercostal Space *From the BLUE (Basic Lung Ultrasonography in Emergency) protocol, coined by Dr. Lichtenstein in 2008 (CHEST 2008; 134:117–125) http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1933931 (Posterior Lateral Alveolar Pleural Syndrome)

Performing a Lung Ultrasound Anterior Zone PLAPS Point Lateral Zone Another way to determine probe positions (redundant) https://link.springer.com/article/10.1007/s13089-011-0066-3 Anterior and Lateral Zones Posterior Zone or PLAPS Point

Normal Lung Ultrasound Images Anterior and Lateral Zones Normal lung with air refraction Both zones should look the same Posterior Zone or “PLAPS” Point Should see air refraction from normal lung hiding the liver or spleen on inspiration Lung Liver (or spleen) Lung Diaphragm

Normal Lung Ultrasound Images Anterior Zone Rib Lateral Zone Lung http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1933931 (probe) https://ultrasound-store.com/products/8r-reck-z955?variant=883949899

Normal Lung Ultrasound Images PLAPS Point Lung (Make sure dot is on the left side of the screen) Liver (or spleen) (left decubitus) http://knowledge.statpearls.com/chapter/nbde%20part%20i-anatomy/24092 (probe) https://www.lynnmedultrasound.com/product/ge-6s-d-phased-array-probe/ Diaphragm

Summary Lung ultrasound is a quick, safe, and effective imaging modality Lung ultrasound relies on artifacts which are generated by air, fluid, and their interactions; these can be used to guide clinical management There are three standard scanning zones in bedside lung ultrasound: Anterior Zone, Lateral Zone, and Posterior Zone or PLAPS Point There are 2 basic images to know in a normal lung ultrasound scan