patients and, like a well-orchestrated dance, the “running” of the traumas commences. All six require emergent intubations to protect their airways, and two are receiving bilateral chest tubes for pulseless electrical activity. The patient your resident is managing, who seemed quasi-stable to start with, suddenly starts dropping her O2 sats and her blood pressure. The respiratory therapist takes her
off the vent and starts bagging her manually, while your nurses crank up the Level 1 infuser. The patient’s O2 sats are hovering around 90% as your senior resident calls for a STAT chest X-ray and reaches for two 14-gauge needles for bilateral needle decompression. Before your resident can
pop the lid off the Betadine bottle, you’ve already scanned the patient’s left hemithorax and clearly identified signs like lung-sliding and comet tails that lead you to believe that a pneumothorax is not present on that side (Stay tuned for future articles on Ultrasound Detection of Pneumothoraces). Sweeping your ultrasound probe in an oblique angle at the level of T10 on the left side gives you
the image below (left).
- The traditional four-view FAST exam can be expanded to evaluate the pleural space just cephalad to the bright hyperechoic hemidiaphragm.
- Because trauma patients are often lying supine strapped to a backboard in cervical spine precautions, portable chest radiographs may not detect small hemothoraces. Bedside ultrasound can be used to quickly assess for the presence of a hemothorax, and is often better than chest radiography in detecting small amounts of pleural fluid (sensitivity 94.6–97% and specificity 99–100%).
- Use the curved array 2.5 to 3.5 MHz transducer or phased array transducer on most patients. Lower frequency probes provide greater penetration in patient’s with an obese body habitus.
- Ensure consistent image directionality by orienting the external identification dot of the transducer towards the patient’s right or towards the patient’s head. The indicator dot on the screen should be to the right of the ultrasound image.
- Position the probe in an oblique angle in the mid-axillary line >>Normal lung tissue in the dependent areas of the thorax will share approximately the same echogenicity as a normal liver on ultrasound. Free fluid in the pleural space will appear as a dark anechoic stripe just cephalad to the diaphragm.
- Observe the pleural space through a full respiratory cycle to monitor changes and characteristics of the fluid with diaphragm movement. Use the sonographic images to help localize the ideal interspace for chest tube insertion.
- Remember that blood will appear less anechoic and more hypoechoic (gray rather than black) as it clots. Don’t mistake clotting blood in the pleural space for normal lung tissue. Scan cephalad above the clot to search for the more hyperechoic lung tissue floating within the hemothorax between the 8th and 11th ribs. Once you identify the hyperechoic bright white diaphragm, angle the ultrasound beam more cephalad to evaluate the pleural space just above the diaphragm.
Brady Pregerson, MD, oversees QI for ED Ultrasound at Cedars-Sinai Medical Center in Los Angeles. Check out more from Dr. Pregerson at www.ERPocketBooks.com. Teresa Wu, MD, a clinical assistant professor in EM at Florida State University, completed her ultrasound fellowship at Stanford University Medical Center.