Tag: lung

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Case 49: ARDS

Kayhon Rabbani

A 22 year old male who has no past medical history presented with a 3 day history of viral URI-like symptoms with sore throat, dry cough, shortness of breath, and dyspnea on exertion. The patient was an active marine recruit with many other members in his company being sick during this time. Shortly prior to arrival, the patient became unable to walk short flights of steps without becoming short of breath. The patient otherwise had no respiratory or cardiac history. He had no family history of sudden cardiac death or early MI. The patient denied fevers, chills, chest pain, pleuritic chest pain, positional chest pain, abdominal pain, flank pain, dysuria, hematuria, diarrhea, or any other associated symptoms.

Vitals: BP 87/56 | Pulse 96  | Temp 98.6 °F (37 °C)  | Resp 28 | SpO2 92%

On physical examination, the patient was alert and in acute distress. Patient presented with tachycardia, hypotension, hypoxia, and tachypnea. Mucous membranes were dry. Respiratory exam revealed decreased air movement, breath sounds, and faint crackles in the right lower lung field.

A bedside echocardiogram was performed.

Figure 1: POCUS echocardiogram in 4 chamber apical view demonstrating a small pericardial effusion.

Figure 2: POCUS lung exam revealed bilateral B lines anterosuperior aspects of the lungs.

Figure 3: Lung consolidation and pleural effusion demonstrating positive "spine sign."

The patient was initially stable but desaturated upon position change. The patient was persistently hypoxic with significant work of breathing on BiPAP before escalating to intubation, remaining persistently hypoxic in the mid 80s post intubation on a ventilator.

Discussion

Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure characterized by rapid onset of widespread inflammation in the lungs. It is defined by the Berlin criteria, which include acute onset within one week of a known clinical insult, bilateral opacities on chest imaging not fully explained by cardiac failure or fluid overload, and severe hypoxemia with a PaO2/FiO2 ratio of less than 300 mmHg.[1-3]

Common differential diagnoses for ARDS include cardiogenic pulmonary edema, pneumonia, and pulmonary embolism. Cardiogenic pulmonary edema can be differentiated by the presence of signs of fluid overload and cardiac dysfunction, often confirmed by echocardiography. Pneumonia may present with localized infiltrates and clinical signs of infection, while pulmonary embolism typically presents with sudden onset dyspnea, pleuritic chest pain, and may be confirmed by imaging studies such as CT pulmonary angiography.[1][4-5]

On physical examination, patients with ARDS often present with tachypnea, dyspnea, and diffuse crackles on auscultation. Hypoxemia is a hallmark, and patients may exhibit signs of respiratory distress such as use of accessory muscles and cyanosis. Imaging studies, particularly chest radiography, typically reveal bilateral alveolar infiltrates. Computed tomography (CT) scans can provide more detailed images, showing patchy or diffuse ground-glass opacities and consolidations.[1-2][6]

Point-of-care ultrasound (POCUS) is a valuable tool in the diagnosis and management of ARDS. Lung ultrasound findings in ARDS include the presence of multiple B-lines (indicating interstitial syndrome), spared areas, pleural line thickening, and subpleural consolidations. Cardiac ultrasound can help differentiate ARDS from cardiogenic pulmonary edema by assessing left ventricular function and the presence of pleural effusions.[7] Combining lung and cardiac ultrasound can enhance diagnostic accuracy and guide management decisions in critically ill patients with acute hypoxemic respiratory failure.[7]

References

  1. Saguil, A., & Fargo, M. V. (2020). Acute Respiratory Distress Syndrome: Diagnosis and Management. American family physician, 101(12), 730–738.
  2. Meyer, N. J., Gattinoni, L., & Calfee, C. S. (2021). Acute respiratory distress syndrome. Lancet (London, England), 398(10300), 622–637. https://doi.org/10.1016/S0140-6736(21)00439-6
  3. Matthay, M. A., Zemans, R. L., Zimmerman, G. A., Arabi, Y. M., Beitler, J. R., Mercat, A., Herridge, M., Randolph, A. G., & Calfee, C. S. (2019). Acute respiratory distress syndrome. Nature reviews. Disease primers, 5(1), 18. https://doi.org/10.1038/s41572-019-0069-0
  4. Papazian, L., Calfee, C. S., Chiumello, D., Luyt, C. E., Meyer, N. J., Sekiguchi, H., Matthay, M. A., & Meduri, G. U. (2016). Diagnostic workup for ARDS patients. Intensive care medicine, 42(5), 674–685. https://doi.org/10.1007/s00134-016-4324-5
  5. Sekiguchi, H., Schenck, L. A., Horie, R., Suzuki, J., Lee, E. H., McMenomy, B. P., Chen, T. E., Lekah, A., Mankad, S. V., & Gajic, O. (2015). Critical care ultrasonography differentiates ARDS, pulmonary edema, and other causes in the early course of acute hypoxemic respiratory failure. Chest, 148(4), 912–918. https://doi.org/10.1378/chest.15-0341
  6. Zompatori, M., Ciccarese, F., & Fasano, L. (2014). Overview of current lung imaging in acute respiratory distress syndrome. European respiratory review : an official journal of the European Respiratory Society, 23(134), 519–530. https://doi.org/10.1183/09059180.00001314
  7. Corradi, F., Brusasco, C., & Pelosi, P. (2014). Chest ultrasound in acute respiratory distress syndrome. Current opinion in critical care, 20(1), 98–103. https://doi.org/10.1097/MCC.0000000000000042
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Case 43: Shortness of Breath

Molly Chou

An 83-year-old male presented to our emergency department with shortness of breath. He woke up that morning with symptoms and called EMS. On arrival, the patient was alert and oriented with SpO2 90% on room air. The patient had a recent admission for right middle and lower lobe pneumonia. He also reported a history of heart failure with mildly reduced ejection fraction, coronary artery disease, and chronic kidney disease.

Vitals: BP 122/71, HR 92, RR 30, T 98.8F, spO2 90% on room air, 99% on 4LNC

Exam: Normal heart sounds, tachypnea, rhonchi in bilateral lower lobes, non-tender abdomen, >4mm pitting lower extremity edema

Labs: Cr 2.23 (from 1.98), BNPP 34,591 (from 19,366), WBC 31

EKG: new left bundle branch block

CXR: pulmonary edema, bilateral pleural effusions, and opacities that may represent atelectasis, though cannot rule out pneumonia or aspiration.

A bedside ultrasound was performed:

Figure 1: Right-sided pleural effusion, atelectasis, and pneumonia in seen right lower lobe

Figure 2A: During exhalation. Left-sided pleural effusion, atelectasis. 2B: During inhalation. Pneumonia becomes more visible as air fills alveoli adjacent to consolidated lung tissue (also known as “dynamic air bronchogram”)

Discussion: Bedside ultrasound demonstrated persistent pneumonia as a likely contributor to his shortness of breath. While other clinical indicators directed the diagnosis toward acute on chronic heart failure, POCUS was instrumental in also identifying persistent pneumonia. The patient was ultimately started on antibiotics and admitted to Cardiology for pneumonia and diuresis.

Learning points:

  • Pneumonia is among the leading causes of hospitalization, and it can be detected on ultrasound if the pleural line is involved, which is in about 99% of cases.
  • Ultrasound can detect inflammation and lung-tissue thickening of lobar pneumonias and consolidations. Interstitial pneumonias more often manifest as B-lines or white lung areas. Complications such as empyema and lung abscess can also be detected [1].
  • POCUS is highly sensitive (estimated around 93%) and specific (estimated around 98%) for pneumonia, particularly if done by a skilled sonographer [2,3].
  • Classic ultrasound findings:
    • “Hepatization” of lung parenchyma, when multiple hypoechoic areas give the tissue a “liver-like” or “spleen-like” appearance.
    • “Shred sign” (Figure 1), when a clear margin can be detected separating a consolidation with aerated parenchyma.
    • Air bronchograms (hyperechoic, linear punctate spots) can be detected within a consolidation in over 90% of pneumonia patients, though they are non-specific, as they may indicate any form of airway obstruction [1].
      • However, “dynamic air bronchograms” (Figure 2) where air-filled bronchograms move with respiration, are highly specific (94%) to pneumonia and have a high positive predictive value (97%) when seen [4]. An example can be seen below [5]:

References:

  1. Boccatonda A, Cocco G, D'Ardes D, et al. Infectious Pneumonia and Lung Ultrasound: A Review. J Clin Med. 2023;12(4):1402. Published 2023 Feb 10. doi:10.3390/jcm12041402
  2. Reissig A, Copetti R, Mathis G, et al. Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: a prospective, multicenter, diagnostic accuracy study. Chest. 2012;142(4):965-972. doi:10.1378/chest.12-0364
  3. Chavez MA, Shams N, Ellington LE, et al. Lung ultrasound for the diagnosis of pneumonia in adults: a systematic review and meta-analysis. Respir Res. 2014;15(1):50. Published 2014 Apr 23. doi:10.1186/1465-9921-15-50
  4. Lichtenstein D, Meziere G, Seitz J. The Dynamic Air Bronchogram: A Lung Ultrasound Sign of Alveolar Consolidation Ruling Out Atelectasis. Chest. 2009;135(6):1421-1425. Published 2009 Jan 8. doi:10.1378/chest.08-2281
  5. Hailey Hobbs, MD. Dynamic Air Bronchograms. NephroPOCUS. Published 2019 Jul 1. Accessed 2024 Dec 13.
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