1. Correct Answer: B. Right mainstem bronchial intubation

Rationale: Any pathophysiologic condition in which the visceral and parietal pleura no longer slide against each other will result in an absence of lung sliding (and therefore the barcode sign on M-mode) on thoracic ultrasound. Other differential diagnoses include bullous pulmonary disease, over-distension from mechanical ventilation, or adhesions. The single most specific ultrasound finding for pneumothorax is the lung point sign, the point of transition between presence and absence of lung sliding, but lack of a lung point does not rule out a pneumothorax. Lung pulse is perceptible cardiac motion observed through the pleural line, usually in the absence of sliding. This sign is equivalent to lung sliding since the “pulse” is created by movement between the two pleurae. The presence of lung pulse, lung sliding, or short vertical artifacts has a high negative predictive value for pneumothorax. Right upper lobe obstruction may create a lack of lung sliding at the apex but not at the base.

1. Ahn, JH, Kwon E, Lee SY, Hahm TS, Jeong JS. Ultrasound-guided lung sliding sign to confirm optimal depth of tracheal tube insertion in young children. Br J Anaesth. 2019 Sep;123(3):309-315.

2. Alrajab S, Youssef AM, Akkus NI, Caldito G. Pleural ultrasonography versus chest radiography for the diagnosis of pneumothorax: review of the literature and meta-analysis. Crit Care. 2013 Sep 23;17(5):R208.

3. Goffi A, Kruisselbrink R, Volpicelli G. The sound of air: point-of-care lung ultrasound in preoperative medicine. Can J Anaesth. 2018 Apr;65(4):399-416.

4. Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670.

5. Volpicelli G, Elbarbary M, Blaivas M, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012 Apr;38(4):577-591.

2. Correct Answer: A. Motion extending through the upper (“sea”) portion of the M-mode image

Rationale: Motion of the probe or hand will translate throughout the entire M-mode image back to the probe and will not behave differently at the interface between visceral and parietal pleura, as indicated by the arrowhead in Figure 47.6. A true lung point will demonstrate transition between “sea” and “beach” patterns only below the pleural line. B-lines are visible in 2D ultrasound and represent an interstitial syndrome when present in excess in most clinical scenarios. When superior and inferior ribs are difficult to identify and artifacts do not originate from the pleural line, subcutaneous emphysema is often present.

1. Volpicelli G, Elbarbary M, Blaivas M, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012 Apr;38(4):577-591.

3. Correct Answer: D. Coalescent B-lines correspond to ground-glass opacities on computed tomography (CT) scans.

Rationale: B-lines that are coalescent or too numerous to count, the so-called “B2” pattern, correspond to areas of ground-glass appearance on chest CT. The number and density of B-lines correlate with the clinical severity of the patient’s pulmonary interstitial syndrome, as well as right heart pressures; however, in the absence of left heart failure, it does not correlate with pulmonary capillary wedge pressures. B-lines can be used to anticipate progression of hypoxemic respiratory failure, as they typically precede the onset of significant symptomatic disease. More than three B-lines per rib space is considered abnormal and is correlated to the degree of extravascular lung water.

1. Gargani L. Lung ultrasound: a new tool for the cardiologist. Cardiovasc Ultrasound. 2011 Feb 27;9:6.

2. Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670.

3. Noble VE, Murray AF, Capp R, Sylvia-Reardon MH, Steele DJR, Liteplo A. Ultrasound assessment for extravascular lung water in patients undergoing hemodialysis. Time course for resolution. Chest. 2009 Jun;135(6):1433-1439.

4. Platz E, Lattanzi A, Agbo C, et al. Utility of lung ultrasound in predicting pulmonary and cardiac pressures. Eur J Heart Fail. 2012 Sep;14:1276-1284.

5. Volpicelli G, Elbarbary M, Blaivas M, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012 Apr;38(4):577-591.

4. Correct Answer: B. Thoracic spine sign

Rationale: In a normal patient, the aerated lung causes near-complete reflection of the ultrasound beam above the diaphragm. Visualization of the vertebral bodies—the “thoracic spine sign”—occurs because ultrasound waves are transmitted through a pleural effusion and allows for visualization of the vertebral bodies. B-lines, also called lung rockets or comet-tail artifacts, are laser-like vertical reverberation artifacts originating from the pleural line, extending to the bottom of Figure 47.1, and moving synchronously with lung sliding. They represent interlobar septal thickening, often due to extravascular lung water. A curtain sign is observed in normal lungs when, at full inspiration, the descent of lung and diaphragm obscures the liver or spleen. The bar code or stratosphere sign is an M-mode finding in the absence of pleural sliding.

1. Dickman E, Terentiev V, Likourezos A, Derman A, Haines L. Extension of the thoracic spine sign: a new sonographic marker of pleural effusion. J Ultrasound Med. 2015 Sep;34(9):1555-1561.

2. Goffi A, Kruisselbrink R, Volpicelli G. The sound of air: point-of-care lung ultrasound in preoperative medicine. Can J Anaesth. 2018 Apr;65(4):399-416.

3. Volpicelli G, Elbarbary M, Blaivas M, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012 Apr;38(4):577-591.

5. Correct Answer: A. Obtain CT angiogram

Rationale: This patient has a normal pulmonary ultrasound examination. Hypoxemia in the setting of a normal pulmonary examination should lead to a venous ultrasound to evaluate for the presence of deep venous thrombosis. In the setting of symptoms consistent with pulmonary embolism, as in this case, a CT angiogram is appropriate. Right heart strain on cardiac ultrasound may also support this diagnosis. Initiation of anticoagulation or thrombolysis may also be appropriate, subject to clinical course and clinician judgment. Acute decompensated heart failure requiring nitroglycerin drip will typically manifest with diffuse bilateral B-lines. Unilateral B-lines, hyperechoic areas, or dense consolidations of the visualized lung segments may suggest pneumonia and support use of antibiotics. The absence of lung sliding in the setting of hypotension would be expected with tension pneumothorax and a lung point may not be visualized due to the size of the pneumothorax.

1. Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670.

2. Staub, LJ, Mazzali Biscaro RR, Kaszubowski E, Maurici R. Lung ultrasound for the emergency diagnosis of pneumonia, acute heart failure, and exacerbations of chronic obstructive pulmonary disease/asthma in adults: a systematic review and meta-analysis. J Emerg Med. 2019 Jan;56(1):53-69.

6. Correct Answer: B. Broad-spectrum intravenous antibiotics

Rationale: Figure 47.2 and Video 47.1 demonstrate dense consolidation of the lung with hyperechoic areas, which correspond to air bronchograms on chest X-ray. Figure 47.2 and Video 47.1 also show an irregular inferior border between normally aerated and abnormally aerated lung segments (the shred sign). These findings support the diagnosis of pneumonia, and antibiotics would be indicated. Needle thoracostomy is performed in the setting of a tension pneumothorax, but there is no ultrasound evidence of a pneumothorax on Figure 47.2. Pulmonary edema requiring diuretics and NIPPV will typically demonstrate diffuse, bilateral B-lines, which are not seen here. CT angiography is used to diagnose a pulmonary embolism, but the ultrasound findings and the clinical scenario are not consistent with pulmonary edema.

1. Copetti R, Soldati G, Copetti P. Chest sonography: a useful tool to differentiate acute cardiogenic pulmonary edema from acute respiratory distress syndrome. Cardiovasc Ultrasound. 2008 Apr 29;6:16.

2. Goffi A, Kruisselbrink R, Volpicelli G. The sound of air: point-of-care lung ultrasound in preoperative medicine. Can J Anaesth. 2018 Apr;65(4):399-416.

3. Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670.

7. Correct Answer: B. Large-bore chest tube placement

Rationale: Hypoxemia after blunt chest trauma may be due to pneumothorax, hemothorax, hypoventilation due to pain (splinting), pulmonary contusion, or mechanical inefficiency (flail chest). The ultrasound (Figure 47.3) demonstrates a large volume of pleural fluid, consistent with hemothorax and compressive atelectasis of the adjacent lung segments. Mobile particles or septa are also highly suggestive of exudate or hemothorax. Figure 47.3 is also notable for the thoracic spine sign, in which the thoracic vertebrae are visible. Traumatic hemothorax should be drained as part of the initial resuscitation. Needle thoracostomy would be indicated for decompression in tension pneumothorax, but not tension hemothorax. Thoracentesis is indicated for draining simple rather than hemorrhagic or purulent fluid and would not be performed acutely during a trauma resuscitation. Antibiotics may be indicated, but they will not address the patient’s acute hypoxemia.

1. Copetti R, Soldati G, Copetti P. Chest sonography: a useful tool to differentiate acute cardiogenic pulmonary edema from acute respiratory distress syndrome. Cardiovasc Ultrasound. 2008 Apr 29;6:16.

2. Lichtenstein DA. BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill. Chest. 2015 Jun;147(6):1659-1670.

3. Yang PC, Luh KT, Chang DB, Wu HD, Yu CJ, Kuo SH. Value of sonography in determining the nature of pleural effusion: analysis of 320 cases. AJR Am J Roentgenol. 1992 Jul;159(1):29-33.

8. Correct Answer: C. Extubate and then reintubate the patient