Medical Image of the Month: Giant Bulla

Figure 1. A chest radiograph demonstrates marked oligemia of the left lung with displacement of the cardiomediastinal silhouette to the right. Subtle, linear lung parenchymal markings are noted in the base of the left lung hinting at extensive bullous disease and not a pneumothorax (red arrows).

Figure 2. A CT of the chest with contrast in lung windows demonstrates a giant bulla centered in the left upper lobe. Adjacent bullous disease is also present.

Clinical Background: A 49-year-old gentleman with an extensive smoking history who was transferred from an outside hospital for higher level of care for management of his acute hypoxemic respiratory failure. His outside chest radiograph (Figure 1) demonstrated marked oligemia of the left lung with displacement of the cardiomediastinal silhouette to the right. Subtle linear parenchymal markings are noted in the lower lobe suggesting bullous disease. There is extensive airspace disease of the right lung. A CT of the chest (Figure 2) demonstrated extensive bullous disease with a giant bulla noted in the left upper lobe. The patient was transferred to the MICU for further management of his hypoxemic respiratory failure. A CT surgery consult was obtained, and he was deemed not to be a surgical candidate given his tenuous clinical status.

Discussion: A bulla is defined as an air-containing space measuring greater than 1 cm in diameter and surrounded by a thin wall which is less than 1 mm thick. Bulla are usually located in a subpleural location and can be seen with emphysema - both paraseptal and centrilobular types. A giant bulla is defined as a bulla occupying at least 30% of a hemithorax. In this case, the patient had a giant bulla centered in the left upper lobe.

Giant bullae typically develop because of long-term cigarette smoking, which is the most likely cause in this case. Bullous lung disease has also been associated with HIV infection and intravenous use of methadone, methylphenidate, or talc-containing drugs.

In asymptomatic patients, smoking cessation is recommended to prevent further progression. In dyspneic patients with COPD, medical therapy with bronchodilators, inhaled corticosteroids, supplemental oxygen, and pulmonary rehab are recommended. In patients who have dyspnea despite medical optimization or who have issues with a spontaneous, secondary pneumothorax, a bullectomy may be beneficial. Contraindications to a bullectomy include ongoing cigarette smoking, significant comorbid disease, poorly-defined bullae on chest imaging, pulmonary hypertension, and other comorbid conditions that make surgery high risk.

Leslie Littlefield MD and Mohammed Fayed MD

UCSF Fresno

Fresno, CA USA

References

1. Rosado-de-Christenson M, Abbott GF. Diagnostic Chest Imaging. 2^nd edition. Canada: Amirsys; 2012; Section 1, p 15.
2. Diaz PT, Clanton TL, Pacht ER. Emphysema-like pulmonary disease associated with human immunodeficiency virus infection. Ann Intern Med. 1992 Jan 15;116(2):124-8. [CrossRef] [PubMed]
3. Palla A, Desideri M, Rossi G, Bardi G, Mazzantini D, Mussi A, Giuntini C. Elective surgery for giant bullous emphysema: a 5-year clinical and functional follow-up. Chest. 2005 Oct;128(4):2043-50. [CrossRef] [PubMed]

Cite as: Littlefield L, Fayed M. Medical image of the month: giant bulla. Southwest J Pulm Crit Care. 2019;19(4):125-6. doi: https://doi.org/10.13175/swjpcc040-19 PDF

Medical Image of the Month: Air Bronchogram Sign

Figure 1. Chest radiograph showing bilateral dense airspace disease with air bronchograms. Veno-venous ECMO catheter is visible tracking from the right internal jugular vein to the inferior vena cava.

Figure 2. Chest radiograph on day 5 of ECMO after 4 days of induction chemotherapy demonstrating marked improvement of his airspace disease.

An 18-year-old man without any known past medical history presented with a one-day history of progressive shortness of breath. He reported a sudden onset of symptoms the morning of presentation, and an accompanying sensation of confusion with difficulty concentrating. Initial laboratory evaluation was significant for leukocytosis over 60 K/mm³. Due to his increased work of breathing and worsening lethargy, the patient was intubated and sedated for airway protection and ventilatory support. The patient was admitted to the ICU, and his initial chest radiograph was concerning for acute respiratory distress syndrome. Subsequent hematologic analyses from his admission CBC were consistent with a new diagnosis of acute myelogenous leukemia.

Despite aggressive alveolar recruitment maneuvers and maximum ventilator support, the patient’s oxygen saturation remained poor and his respiratory reserve continued to decline. The decision was made to place the patient on veno-venous extracorporeal membrane oxygenation (ECMO) prior to initiating therapy with doxorubicin and cytarabine (7+3 induction protocol). A dual-lumen ECMO catheter was placed in the right internal jugular vein. His initial chest radiograph demonstrated complete bilateral air bronchograms (Figure 1). The patient was started on chemotherapy while on ECMO and was successfully decannulated after five days on the circuit. His chest radiograph on day 5 of ECMO was significant for marked improvement in bilateral airspace disease (Figure 2).

In patients with hematologic malignancy, an inflammatory response can be generated by either the malignant cells themselves, or more commonly as a reaction to subsequent infection. This inflammation often results in protein-rich fluid infiltrating the alveoli. When this process becomes severe enough to cause hypoxic respiratory failure, it can progress to acute respiratory distress syndrome (ARDS) (1). The chest radiograph demonstrates dense airspace disease which developed in this patient. The fluid-filled alveoli in this extreme example of ARDS created a volume of uniform opacities throughout his lung parenchyma which make the conducting airways stand out clearly (2). Segmental air bronchograms can be seen in localized airspace disease, such as atelectasis or pneumonia, but a full-pulmonary air bronchogram of this clarity can only be seen on a patient undergoing ECMO as there are effectively no functional alveoli to participate in gas exchange.

Eric Brucks, MD and Richard Young, MD

Department of Internal Medicine

Banner University Medical Center

University of Arizona

Tucson, AZ USA

References

1. Papazian L, Calfee CS, Chiumello D, Luyt CE, Meyer NJ, Sekiguchi H, Matthay MA, Meduri GU. Diagnostic workup for ARDS patients. Intensive Care Med. 2016 May;42(5):674-85. [CrossRef] [PubMed]
2. Natt B, Raz Y. Air Bronchogram. N Engl J Med. 2015 Dec 31;373(27):2663. [CrossRef] [PubMed]

Cite as: Brucks E, Young R. Medical image of the month: air bronchogram sign. Southwest J Pulm Crit Care. 2019;19(4):119-20. doi: https://doi.org/10.13175/swjpcc036-19 PDF