Written by: Morgan McCarthy, MD (NUEM ‘24) Edited by: Jon Hung, MD (NUEM ‘21) Expert Commentary by: John Bailitz, MD & Shawn Luo, MD (NUEM ‘22)
SonoPro Tips and Tricks
Welcome to the NUEM Sono Pro Tips and Tricks Series where Sono Experts team up to take you scanning from good to great for a problem or procedure! For those new to the probe, we recommend first reviewing the basics in the incredible FOAMed Introduction to Bedside Ultrasound Book and 5 Minute Sono. Once you’ve got the basics beat, then read on to learn how to start scanning like a Pro!
Did you know that Lung Ultrasound (LUS) has a higher sensitivity than the traditional upright anteroposterior chest X-ray for the detection of a pneumothorax? (LUS has a reported 90.9 for sensitivity and 98.2 for specificity. CXR were 50.2 for sensitivity and 99.4 for specificity). Busy trauma bay? Ultrasound is faster than calling for X-ray. Critically ill patient? Small pneumothoraces are less likely to be missed with ultrasound. To take your Sono Skills to the next level, read on:
Beyond the classic trauma patient during your E-Fast Exam, who else does the Sono-Pros scan?
Primary spontaneous pneumothorax: the classic scenario is a tall, young adult, with symptoms such as breathlessness, along with potentially those with risk factors of pneumothoraxes such as smoking, male sex, family history of pneumothorax
Secondary spontaneous pneumothorax: those with underlying lung disease including but not limited to COPD, tuberculosis, necrotizing pneumonia, pneumonocystis carini, lung cancer, sarcoma involving the lung, sarcoidosis, endometriosis, cystic fibrosis, acute severe asthma, idiopathic pulmonary fibrosis
Of course, traumatic pneumothorax, especially in penetrating trauma or blunt trauma with broken ribs
Don’t forget iatrogenic causes of pneumothorax including transthoracic needle aspiration, subclavian vessel puncture, thoracentesis, pleural biopsy, and mechanical ventilation
SonoPro Tips - How to scan like a Pro
The key is to have the patient completely supine - air rises! - with the probe in the anterior field in sagittal orientation pointing towards the patient's head.
It is commonly taught to start at the second intercostal space, midclavicular line, and scan down a few lung spaces to at least the 4th intercostal space, however, keep in mind some studies show that trauma supine trauma patients had pneumothoraces seen more commonly in the 5-8 rib spaces.
Important Landmarks
Green = Subcutaneous tissue. Red = Pleural space. Blue = A - lines.
4. Look for lung sliding, improve your image by turning down gain and decrease depth to have lung sliding become clearer
What to Look For:
To Rule-Out a pneumothorax
Lung Sliding - Lung sliding has a negative predictive value of 100% for ruling out a pneumothorax, however only at that interspace
Additional Findings: B-lines and Z lines also help to rule out pneumothorax!
2. To Rule-In a pneumothorax
Lung point - the interface between where lung sliding is happening and where the absence of lung sliding is happening has been shown to have 100% specificity for pneumothorax.
Keep in mind the border of where the heart and lung come in contact and the border where the diaphragm and lung come in contact can cause a false lung point.
The lung point may be hard to find in a larger pneumothorax, and impossible to find in a completely collapsed lung.
3. Next turn on M-mode:
Sandy Beach Shore = Lung sliding (left). Barcode Sign = No lung sliding (right)
What to do next:
Lung sliding = sensitive, Lung point = specific
If you see lung sliding, there is no pneumothorax
If you do not see lung sliding it does not rule in a pneumothorax -> look for a lung point, the interface between where lung sliding is happening and where the absence of lung sliding is happening to rule it in
Always keep in mind other causes that result in lack of lung sliding before management decisions take place!: atelectasis, main-stem intubation, adhesions, contusions, and arrest or apnea. Check out this great table from 5 - Min Sono.
4. If your patient is apneic or has a mainstem intubation look for lung pulse, when the heart beats if the parietal and visceral pleura are touching (no pneumothorax) it will show a pulse at the interfaces of the pleura
5. Sub-Q emphysema - Always look for E - lines. When there is subcutaneous air above the pleural line it creates a false pleural line above the actual pleural. You may also see B-lines obscuring the actual pleural line. This is most likely subcutaneous air and you can not interpret it for a pneumothorax.
SonoPro Tips - Where to Learn More
American College of Emergency Physicians. Emergency ultrasound imaging criteria compendium. Ann Emerg Med. 2006;48(4):487-510.
Ma, John, et al. Ma and Mateer's Emergency Ultrasound. McGraw-Hill Education, 2020.
Macias, Micheal. TPA, The Pocus Atlas.
Availa, Jacob. 5 minute Sono.
Alrajhi K, Woo MY, Vaillancourt C. Test characteristics of ultrasonography for the detection of pneumothorax: a systematic review and meta-analysis. Chest. 2012;141(3):703-708.
Expert Commentary
Morgan went “beyond lung sliding” and dove deep into how to increase your sensitivity & specificity for PTX with POCUS. Supine is ideal to make PTX visible against the anterior chest wall, but if the patient cannot tolerate lying flat, look at the apical pleural superior to the clavicles. First, identify the true pleural line--it should be the bright line just deep to the ribs in your view. SQ emphysema may obscure the view or even mimic the pleura, although its outline is usually more hazy & irregular, a little pressure helps to move the SQ air out of the way can be helpful. Sliding? Great, PTX ruled out. But absent sliding does not automatically mean PTX. Make sure there is no B-line or “lung pulse”, as sometimes pleural adhesion or poor ventilation can cause absent sliding too. Most of the time you don’t need M-mode unless the movement is very subtle and you want to be extra sure. The lung point is pathognomonic for PTX, but don’t waste time digging around for it if the patient is unstable with a good clinical story for PTX > decompress instead!
John Bailitz, MD
Vice Chair for Academics, Department of Emergency Medicine
Professor of Emergency Medicine, Feinberg School of Medicine
Northwestern Memorial Hospital
Shawn Luo, MD
PGY4 Resident Physician
Northwestern University Emergency Medicine
How To Cite This Post:
[Peer-Reviewed, Web Publication] McCarthy, M. Hung J. (2021 Sept 20). SonoPro Tips and Tricks for Pneumothorax. [NUEM Blog. Expert Commentary by Bailitz, J. Shawn, L.]. Retrieved from http://www.nuemblog.com/blog/sonopro-tips-and-tricks-for-pneumothorax
