1. Correct Answer: D. Distributive shock

Rationale: Video 44.1 and Figure 44.1 show a normal heart and no pericardial effusion. Video 44.2 and Figure 44.2 show an A-profile in the lung field. According to the Fluid Administration Limited by Lung Sonography (FALLS) protocol, obstructive shock is ruled out using a subcostal four-chamber view, demonstrating the absence of pericardial effusion and acute right ventricular (RV) enlargement, and lung views all showing lung sliding. Because lung views demonstrate A-profile at the time of evaluation, cardiogenic shock is ruled out and the assumption is made that pulmonary artery occlusion pressure is lower than or equal to 18 mm Hg (threshold for forming pulmonary edema). At this time the assumption is made that the patient is fluid tolerant (FALLS-responder), not bleeding based on clinical examination and laboratory value of hemoglobin, and receives intravenous fluids until lung A-profile switches to B-profile ( Video 44.3; Figure 44.3), consistent with interstitial pulmonary edema. Now the patient reaches FALLS-endpoint and intravenous fluid therapy is discontinued. Distributive shock is the only diagnosis as other types of shock are either ruled out (obstructive and cardiogenic) or corrected (hypovolemic), and the patient should receive an infusion of vasoactive medication.

1. Lichtenstein D. FALLS-protocol: lung ultrasound in hemodynamic assessment of shock. Heart Lung Vessel. 2013;5(3):142-147.

2. Correct Answer: B. Withdraw endotracheal tube

Rationale: Video 44.4 and Figure 44.4 show both lung pulse and lung sliding with isolated B-lines. Video 44.5 and Figure 44.5 reveal only lung pulse with isolated B-lines. This patient developed opioid-induced respiratory depression which in the setting of preexisting obstructive sleep apnea led to severe hypercapnia and respiratory arrest, requiring endotracheal intubation. Auscultation in general, and particularly in this patient, with morbid obesity (this patient’s body mass index is 55.5 kg/m²) is not as accurate as lung ultrasound to confirm tracheal versus bronchial positioning of endotracheal tube. When evaluating patients with respiratory failure, a systematic approach is advocated, with Bedside Lung Ultrasound in Emergency (BLUE) protocol being commonly accepted clinically. In this patient, ultrasound demonstrated both lung pulse and lung sliding on the right and only lung pulse on the left, which ruled out pneumothorax and was consistent with endobronchial intubation, requiring withdrawal of the endotracheal tube until lung sliding could be appreciated on both sides of the chest. The presence of isolated B-lines is not consistent with pulmonary edema, which requires the presence of at least three B-lines in each lung view.

1. Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest. 2008;134(1):117-125.

2. Ramsingh D, Frank E, Haughton R, et al. Auscultation versus point-of-care ultrasound to determine endotracheal versus bronchial intubation: a diagnostic accuracy study. Anesthesiology. 2016;124(5):1012-1020.

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

3. Correct Answer: C. Consider cessation of resuscitative efforts

Rationale: Video 44.6 shows cardiac standstill. Figure 44.6 shows absence of cardiac tamponade. In patients with pulseless electrical activity (PEA), two goals of resuscitative efforts include high-quality CPR and identifying reversible causes of cardiac arrest. Cardiac causes of PEA include acute RV failure, tamponade, left ventricular failure, and hypovolemia. While cardiac ultrasound can establish prognosis by identifying lack of cardiac motion and identify reversible causes of cardiac arrest, it may prolong pauses between cycles of CPR. Training is required to incorporate cardiac ultrasound safely into the workflow of ACLS protocols, and is the basis of Focused Echocardiographic Evaluation in Resuscitation (FEER) management. In this case, after prolonged CPR, the patient demonstrates no observable cardiac motion during two separate pauses, highly suggestive of irreversible arrest, and cessation of resuscitative effort should be considered. There is no evidence of pulmonary embolism as the right ventricle is not dilated. Left heart catheterization is not indicated in a patient without cardiac activity. There is no pericardial effusion and no evidence of tamponade to warrant pericardiocentesis.

1. Breitkreutz R, Walcher F, Seeger FH. Focused echocardiographic evaluation in resuscitation management: concept of an advanced life support-conformed algorithm. Crit Care Med. 2007;35(suppl 5):S150-S161.

4. Correct Answer: C. Ultrasound of the hepatorenal recess

Rationale: Video 44.7 and Figure 44.7 show subcostal view with a small pericardial effusion without evidence of tamponade. Video 44.8 and Figure 44.8 show a subcostal view of inferior vena cava (IVC) with IVC diameter less than 1 cm. Initial assessment of the hypotensive trauma patient should include an evaluation for intraperitoneal free fluid, which is an important factor determining operating room triage. Historically, diagnostic peritoneal lavage (DPL) was used to assess for intraperitoneal fluid, despite a high associated complication rate. The Focused Assessment with Sonography for Trauma (FAST) examination evolved as an ultrasound-guided protocol for the evaluation of intraperitoneal fluid and was first adopted in North America in the 1990s. With a relatively high sensitivity and specificity for detecting hemoperitoneum, and the ability to rapidly evaluate a trauma patient at the bedside, the FAST examination revolutionized the assessment of the traumatically injured patient. The views obtained in the FAST examination include the right upper quadrant, left upper quadrant, pelvic, and subxiphoid/subcostal. The FAST examination was later modified to the extended FAST examination (eFAST) to include lung views evaluating for pneumothorax. The hepatorenal recess (also known as Morison pouch), imaged in the right upper quadrant, is the most dependent portion of the peritoneal cavity in a supine patient and is the view with the highest likelihood of detecting hemoperitoneum. Pericardiocentesis is not indicated as there is no evidence of tamponade. This patient is unstable and if there is evidence of hemoperitoneum on FAST examination, this patient should proceed directly to the operating room, not the computed tomography scanner.