Cardiogenic Pulmonary Edema, Noncardiogenic Pulmonary Edema (ARDS), Diffuse Parenchymal Lung Disease (Interstitial Pneumonitis)

Cardiogenic Pulmonary Edema, Noncardiogenic Pulmonary Edema (ARDS), Diffuse Parenchymal Lung Disease (Interstitial Pneumonitis)

Christopher N. Parkhurst

1. A 75-year-old man with a medical history that includes heart failure with reduced ejection fraction and atrial fibrillation presents to the Emergency Department with 4 months of worsening shortness of breath with ambulation. He has a 45 pack-year smoking history and is a current every-day smoker. His atrial fibrillation is treated with amiodarone. Vital signs are notable for an SpO2 of 85% at rest and are otherwise unremarkable. His physical examination is notable for moderate lower extremity edema with evidence of chronic venous stasis and fine rales in the lower and midlung fields. A focused lung ultrasound examination demonstrates the following finding in multiple fields in the anterior, posterior, and midaxillary lines (Figure 53.1 and image Video 53.1).

Given the above finding, the least likely etiology of this patient’s shortness of breath is:

A. Chronic obstructive pulmonary disease (COPD)

B. Idiopathic pulmonary fibrosis (IPF)

C. Amiodarone toxicity

D. Decompensated heart failure

View Answer

1. Correct Answer: A. Chronic obstructive pulmonary disease (COPD)

Rationale: The presence of B-lines is a nonspecific finding that signifies the presence of an interstitial syndrome. The pathologies that underlie this finding are numerous and include pulmonary edema (both cardiogenic and noncardiogenic), drug-induced lung injury, and tissue fibrosis. This older man with a significant smoking history (both risk factors for IPF), heart failure, amiodarone use (risk for pulmonary drug toxicity), and reduced left ventricular function has multiple possible etiologies for his breathlessness. The presence of B-lines does not rule out any of these processes except for COPD, which should demonstrate a normal A-line profile. Note that the B-line profile seen in this patient does not rule out the presence of underlying COPD, as it is possible to have pulmonary edema on top of obstructive lung disease.

Selected References

1. Hasan AA, Makhlouf HA. B-lines: transthoracic chest ultrasound signs useful in assessment of interstitial lung diseases. Ann Thorac Med. 2014;9(2):99-103. doi:10.4103/1817-1737.128856.

2. Soldati G, Copetti R, Sher S. Sonographic interstitial syndrome: the sound of lung water. J Ultrasound Med. 2009;28(2):163-174. doi:10.7863/jum.2009.28.2.163.

2. A 65-year-old man with a past medical history of heart failure with preserved ejection fraction is brought to the Emergency Department by ambulance with 3 days of worsening dyspnea. He is emergently intubated due to respiratory distress and brought to the intensive care unit (ICU). Over the next 24 hours, he develops worsening hypoxemia, and increasing inspiratory pressures are required to maintain an adequate minute ventilation. Nasopharyngeal polymerase chain reaction (PCR)-based testing is positive for influenza A virus. The estimated central venous pressure (CVP) derived from an internal jugular central venous catheter is normal. Bilateral breath sounds are heard on lung auscultation. The lung ultrasound findings that would be most consistent with the cause of this patient’s worsening oxygenation and compliance are:

A. Large unilateral pleural effusion

B. Bilateral B-line profile

C. Interspersed areas of B-lines and normal lung

D. Absence of A-lines

View Answer

2. Correct Answer: C. Interspersed areas of B-lines and normal lung

Rationale: This case involves differentiating the cause of worsening hypoxia and lung compliance in a patient presenting with acute respiratory failure. Although his underlying cardiac dysfunction, specifically a stiff left ventricle, puts him at risk for cardiogenic pulmonary edema (CPE), the low CVP makes this a less likely etiology. Given the presence of an influenza viral infection, worsening oxygenation, and decreasing lung compliance, ARDS is the most likely diagnosis in the patient. Because the pattern of lung injury seen in ARDS is typically nonuniform, lung ultrasound often demonstrates a patchy distribution of B-lines alternating with areas of normal lung, whereas fulminant pulmonary edema more typically shows B-lines in multiple imaging fields.

Selected Reference

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;6:16. doi:10.1186/1476-7120-6-16.

3. The finding most specific for a diagnosis of interstitial lung disease (ILD) is:

A. A thickened and fragmented pleural line

B. Absence of lung sliding

C. Diffuse bilateral B-lines

D. Bilateral A-line profile

View Answer

3. Correct Answer: A. A thickened and fragmented pleural line

Rationale: The ILDs are a heterogeneous group of pulmonary diseases affecting the lung parenchyma that ultimately progress to lung fibrosis and include idiopathic pulmonary fibrosis, connective tissue disease-related ILD, and hypersensitivity pneumonitis. In a lung ultrasound study of patients with ILD, the most common finding present in ILD vs. healthy control patients was irregularity and thickening of the pleural line (see Figure 53.9 for example images).

Selected Reference

1. Reissig A, Kroegel C. Transthoracic sonography of diffuse parenchymal lung disease: the role of comet tail artifacts. J Ultrasound Med. 2003;22(2):173-180. doi:10.7863/jum.2003.22.2.173.

4. A 50-year-old woman with metastatic breast cancer is admitted to the hospital with approximately 1 week of worsening dyspnea on exertion and is found to have a large right-sided pleural effusion. Thoracentesis is performed using local anesthesia with 1% lidocaine, and 2.5 L of clear yellow fluid is removed without any obvious complication. Immediately after the procedure, the patient experiences relief of her dyspnea; however, over the next 2 hours, she becomes increasingly short of breath and develops respiratory distress. Focused ultrasound of the lungs is performed with the patient in the supine position and the following findings over the right anterior and lateral hemithorax are demonstrated in Figure 53.2 and image Videos 53.2, 53.3, 53.4.

The most likely etiology of this patient’s postprocedural dyspnea is:

A. Pneumothorax

B. Hemothorax

C. Lidocaine toxicity

D. Reexpansion pulmonary edema

View Answer

4. Correct Answer: D. Reexpansion pulmonary edema

Rationale/Critique: A number of complications are associated with common bedside pleural procedures. These include hemothorax from injury to intercostal vessels, pneumothorax due to inadvertent interruption of the pleura, and reexpansion pulmonary edema. This type of non-CPE (NCPE) occurs after the removal of air or pleural fluid from the pleural space, typically within several hours of the procedure. Here the presence of lung sliding and absence of fluid in the pleural space rule out pneumothorax and hemothorax, respectively. Although the mechanism is incompletely understood, reexpansion pulmonary edema appears as an interstitial syndrome with ultrasound, and therefore creates a diffuse B-line profile. Although these findings are typically seen ipsilateral to the procedure, it is important to note that in rare cases reexpansion pulmonary edema can occur in the lung contralateral to the procedure, and so—as with all lung ultrasound—both lungs should be examined.

Selected References

1. Gomes R, Rocha B, Morais R, Araujo I. Acute non-cardiogenic pulmonary oedema due to contralateral pulmonary re-expansion after thoracentesis: an uncommon complication. BMJ Case Rep. 2018. doi:10.1136/bcr-2018-224903.

2. Mahfood S, Hix WR, Aaron BL, Blaes P, Watson DC. Reexpansion pulmonary edema. Ann Thorac Surg. 1988;45(3):340-345. doi: 10.1016/s0003-4975(10)62480-0.

5. A 70-year-old man is admitted to the ICU for the treatment of septic shock. He is intubated and mechanically ventilated, and is being treated with antibiotics, a vasopressor infusion, and crystalloid infusions due to persistent hypotension. On his third day in the ICU, it is noted that both his FiO2 and inspiratory pressure requirements have increased to maintain adequate oxygenation and ventilation. A member of the ICU team suspects pulmonary edema due to iatrogenic volume overload and begins a focused lung ultrasound examination. Which of the following findings would most likely suggest that pulmonary edema is not the etiology for the patient’s change in oxygenation and lung compliance?

A. The absence of B-lines in the anterior lung fields

B. The absence of a pleural effusion

C. The absence of multiple B-lines in the posterior lung fields

D. Normal bilateral lung sliding

View Answer

5. Correct Answer: C. The absence of multiple B-lines in the posterior lung fields

Rationale: The patient in the scenario has a suspected interstitial syndrome due to iatrogenic volume overload, a commonly-encountered situation in the postresuscitation setting. The presence of multiple B-lines on lung ultrasound can help to confirm this diagnosis; however, it is important to remember that fluid accumulation is gravity-dependent. Unlike a patient with acute respiratory failure from flash pulmonary edema, B-lines may be most prominent in the lateral or posterior fields, and it is important to scan all lung fields. This is especially relevant in a typical ICU population, in which many patients may be lying in the supine position for extended periods of time due to sedation/ventilation requirements.

Selected Reference

1. Lichtenstein D, Meziere G, Biderman P, Gepner A, Barre O. The comet-tail artifact. An ultrasound sign of alveolar-interstitial syndrome. Am J Respir Crit Care Med. 1997;156(5):1640-1646. doi:10.1164/ajrccm.156.5.96-07096.

6. The greatest number of B-line artifacts that may be seen within a single intercostal space in a healthy adult patient is:

A. 1

B. 2

C. 3

D. 5

View Answer

6. Correct Answer: B. 2

Rationale: Although the presence of a B-line profile may indicate an interstitial syndrome, it is important to remember that up to two of these artifacts may be seen in a given intercostal space in a healthy adult patient and that isolated B-lines in the otherwise asymptomatic patient should not necessarily be considered a pathologic finding.

Selected Reference

1. Chiesa AM, Ciccarese F, Gardelli G, et al. Sonography of the normal lung: comparison between young and elderly subjects. J Clin Ultrasound. 2015;43(4):230-234. doi:10.1002/jcu.22225.

7. A 65-year-old woman with a medical history of chronic hypersensitivity pneumonitis (cHP, a form of ILD) and heart failure with reduced ejection fraction is brought to the Emergency Department with several days of progressive dyspnea and worsening lower extremity edema. Her oxygen saturation by pulse oximetry on arrival is noted to be 83% on 6 L of supplemental oxygen (she does not normally use supplemental oxygen at home), and her breathing is mildly labored. Ultrasound examination of her lungs demonstrates a diffuse B-line pattern in all lung fields examined. The lung ultrasound findings observed in this patient indicate that her dyspnea and hypoxia are most likely due to which of the following?

A. Exacerbation of congestive heart failure

B. Exacerbation of cHP

C. Pulmonary embolism

D. The etiology cannot be determined from this data

View Answer

7. Correct Answer: D. The etiology cannot be determined from this data.

Rationale: The patient in the vignette carries two diagnoses that may be contributing to her worsening respiratory status, one an intrinsic lung process (cHP) and the other cardiogenic (congestive heart failure [CHF]). Although it is tempting to use lung ultrasound to aid in differentiating between these two processes, the presence of an ILD makes interpretation of B-lines more challenging, if not impossible, given that diffuse B-lines are present in a significant percentage of ILD patients, regardless of the degree of extravascular lung water. In this patient, focused echocardiography may be of more utility in determining the etiology of her acute respiratory failure.

Selected Reference

1. Lichtenstein DA, Meziere GA, Lagoueyte JF, Biderman P, Goldstein I, Gepner A. A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill. Chest. 2009;136(4):1014-1020. doi:10.1378/chest.09-0001.

8. Which of the following scenarios is the least likely to produce B-lines?

A. Transfusion-related acute lung injury (TRALI)

B. Asthma exacerbation

C. Subarachnoid hemorrhage

D. Endotracheal tube obstruction

View Answer

8. Correct Answer: B. Asthma exacerbation

Rationale: B-lines are hyperechoic, streak-like artifacts that arise from and move with the pleural surface, projecting in a perpendicular manner to the deepest point in the image. They are the result of a reverberation artifact that occurs when the normally aerated subpleural alveoli are altered by the presence of fluid or fibrotic lung tissue. To correctly interpret the meaning of these artifacts, it is important to remember that B-lines represent an alveolar-interstitial syndrome. Any process that leads to this syndrome, rather than a single disease process, is therefore able to produce B-lines. TRALI is an acute inflammatory reaction within the lung due to allogenic blood products that result in leakage of plasma proteins into the alveolar space. Subarachnoid hemorrhage and other traumatic brain injuries can lead to non-cardiogenic pulmonary edema (NCPE) through neurovascular activation. Large negative pressure efforts made against a closed glottis or obstructed endotracheal tube can lead to negative pressure pulmonary edema. All three of these conditions can certainly lead to the presence of B-lines. Asthma, a disease that may involve a significant degree of air trapping, does not typically result in an interstitial syndrome and would not be expected to result in the formation of B-lines.

Selected Reference

1. Lichtenstein DA, Meziere GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest. 2008;134(1):117-125. doi:10.1378/chest.07-2800.

9. A 67-year-old man with a long-standing history of poorly controlled hypertension is brought to the Emergency Department from home with several days of fever and increasing lethargy. He is found to be hypotensive and tachycardic and has a serum lactate level of 7 mmol/L. He is admitted to the ICU and treated with broad-spectrum antibiotics, crystalloid fluid resuscitation, and vasopressors. Despite this early therapy, his condition declines and he is intubated. Overnight, his oxygen requirements increase, and by the following day his P:F ratio is 150. He has received a total of 8 L of intravenous fluid since admission for ongoing hypotension. A portable chest X-ray is obtained and shows diffuse bilateral infiltrates and no evidence of a pneumothorax. Ultrasound is performed and shows numerous and diffuse B-lines bilaterally, in addition to the finding shown in image Video 53.5. The most likely etiology for this patient’s hypoxemia is:

A. Cardiogenic pulmonary edema (CPE)

B. Pneumothorax

C. Acute respiratory distress syndrome (ARDS)

D. Ventilator-associated pneumonia

View Answer

9. Correct Answer: C. Acute respiratory distress syndrome (ARDS)

Rationale/Critique: Differentiating CPE from ARDS remains a significant challenge due to multiple shared diagnostic features. The patient in the above vignette typifies this challenge: he has received multiple liters of intravenous crystalloid fluids in the setting of sepsis and likely has an increased left ventricular end-diastolic pressure (LVEDP) due to long-standing uncontrolled hypertension, making CPE likely. However, his rapidly worsening P:F ratio in the setting of sepsis would also be consistent with ARDS. Although the total number of patients was low (58 total patients), Copetti, et al. found that 100% of patients with a final diagnosis of ARDS demonstrated reduced or absent lung sliding in at least one examined lung zone compared to 0% of patients with a final diagnosis of CPE. This finding is demonstrated in image Video 53.5 (the slight movement of the pleura is a lung pulse—the movement induced by the beat of the heart, not by pleural sliding during respiration). Of course, pneumothorax must also be considered in this patient population given the typically poor lung compliance and high inspiratory pressures required to maintain adequate ventilation, but the presence of the lung pulse excludes pneumothorax at this location. Additional findings from this study are summarized in Table 53.1.

Selected Reference

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;6:16. doi:10.1186/1476-7120-6-16.

10. A patient undergoes an ultrasound examination of the lung, which demonstrates a normal-appearing pleural line, normal lung sliding, no B-lines, and a loss of A-lines in all lung fields examined. What are these findings most consistent with?

A. Idiopathic pulmonary fibrosis

B. Pneumothorax

C. Chronic obstructive lung disease

D. Normal lung tissue with advanced age

View Answer

10. Correct Answer: D. Normal lung tissue with advanced age

Rationale: Although A-lines are present in nearly 100% of healthy persons <65 years of age, they are often absent in the elderly population. Although the etiology of the loss of A-lines is unclear, it may be in part due to subtle subpleural fibrosis that frequently occurs in the senile lung. In a healthy patient, this finding should not be considered pathologic.

Selected References

1. Chiesa AM, Ciccarese F, Gardelli G, et al. Sonography of the normal lung: comparison between young and elderly subjects. J Clin Ultrasound. 2015;43(4):230-234. doi:10.1002/jcu.22225.

2. Copley SJ, Wells AU, Hawtin KE, et al. Lung morphology in the elderly: comparative CT study of subjects over 75 years old versus those under 55 years old. Radiology. 2009;251(2):566-573. doi:10.1148/radiol.2512081242.

11. A 65-year-old man is evaluated in the Emergency Department with several weeks of worsening dyspnea. He has no known history of pulmonary disease. He is noted to be hypoxemic with SpO2 of 85% on room air. The pleural ultrasound images (Figure 53.3, image Video 53.6, image Video 53.7) are obtained in multiple lung regions bilaterally. Cardiac ultrasound examination demonstrates grossly normal left and right ventricular size and function, and Doppler ultrasonography indicates normal diastolic pressures within the left ventricle.

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Jun 9, 2022 | Posted by in CARDIOLOGY | Comments Off on Cardiogenic Pulmonary Edema, Noncardiogenic Pulmonary Edema (ARDS), Diffuse Parenchymal Lung Disease (Interstitial Pneumonitis)
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