Systemic air embolism following percutaneous lung biopsy: A rare case report

A 52-year-old diabetic and hypertensive gentleman with a history of dyspnoea came to department of diagnostic & interventional radiology for CT-guided biopsy from a newly diagnosed left lung lesion. Following the informed written consent patient was placed prone position in 128 slice CT scanner machine as his preoperative lab (Platelets count, PT/INR) were within normal limits. Under local anaesthesia & all aseptic precaution, a coaxial biopsy system with a 17-gauge introducer needle and an 18-gauge core biopsy needle (length16 cm, Semiautomatic Core Biopsy Instrument) was selected for this procedure. Once the introducer needle had reached the lesion, the internal stylet was removed along with flow of NS (to avoid passage of atmospheric air) and the core biopsy needle was inserted to procure specimen. After the second core of specimen (HPE: non-small cell carcinoma-squamous cell carcinoma), minimal air was seen in the left ventricle & descending thoracic aorta (Possible mechanism: via transient Broncho-venous fistula or other communication between air containing spaces and pulmonary veins) hence procedure was halted & patient was placed in Trendelenburg position with 100% oxygen. The last scan (after 10 min) showed the resolution of the air (dissolution via blood air mixing.). The patient did not have any symptoms; vitals were normal, no neurological changes were noted. He was observed for 24hrs then discharged in stable conditions.

 CT Thorax shows 

• Pre-procedure: Heterogeneously enhancing diffuse nodular pleural thickening involving the apical, mediastinal, costal, and diaphragmatic pleura on the left side, maximum thickness ~ 1.1cm in costal pleura along left upper lobe. Associated multiloculated pleural effusion with the largest measuring ~ 50x27mm along the posterior segment of the left upper lobe.
• Postprocedure (Immediate): Multiple air foci are seen in the left ventricle & descending thoracic aorta. The largest measuring ~ 4.5 x 1.5 x 0.5 cm (CC X TR X AP) in descending thoracic aorta corresponding to T5-T7 vertebrae. An area of a hemorrhagic contusion in the left lower lobe.

Postprocedure (Late CECT): No evident air focus or filling defect or active extravasation of contrast.

Background

CT-guided percutaneous lung biopsy is commonly used for the diagnosis of pulmonary lesions. Though systemic air embolism is rare & often self-limiting but can lead to disastrous, even fatal complications when the embolus reaches the brain or coronary arteries. (2) 

Clinical Perspective

Systemic air embolism is described in 0.02-0.07% of CT-guided percutaneous lung biopsies. (3) These signs and symptoms may occur either immediately or several minutes after the biopsy while the under-recognized proportion is asymptomatic. The manifestations are mainly related to air embolism in the coronary or brain circulation and include neurologic alterations and manifestations related to heart ischemia. (2) 

Air enters systemic circulation via pulmonary vein via 

• A fistula tract (bronchoalveolar-pulmonary venous) connecting an air-containing space to a pulmonary vein when alveolar pressure is high (e.g., during coughing),

• Direct exposure of pulmonary vein to air through the needle and 

• Air penetration from the pulmonary arterial circulation to the pulmonary vein. (2)

Imaging Perspective

 CT improves the diagnosis of systemic air embolism, providing vital information regarding the exact size and location of air embolus & help the clinicians/radiologist in the management of patients. If air embolism is detected, another delayed CT scan is recommended to follow the air’s course. If this delayed CT scan does not demonstrate air emboli in the coronary artery, left heart, or thoracic aorta, either no air entry occurred, or the coronary artery has recanalized. However, if the air embolism persists or progresses, the patient should be intensively monitored.

Outcome

• Possible prevention strategies include avoiding coughing and straining during the procedure and ventilation with positive pressure. No specific treatment has been established yet other than supplying 100% hyperbaric oxygen, immediately halting the procedure & placing the patient in the Trendelenburg position. (1, 2) In the event of an “air lock” in the RVOT & in the setting of “hypotension and cardiovascular collapse”, aspiration can be encouraged. The patient has to be strictly monitored for potentially life-threatening complications & may require repetition of a chest-brain CT scan.

Teaching Points

Even if uncommon, systemic air embolism after percutaneous biopsy must always be considered and rapidly handled. Thus an early post-biopsy CT scan is crucial for its early detection as delay in detection and management may result in significant morbidity and mortality. 

Written informed patient consent for publication has been obtained.