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