Type: Response Essays
Sample donated: Antonia Bush
Last updated: May 26, 2019
Introduction: Transthoracic lung biopsy is acommon diagnostic procedure that is known to be associated with variouscomplications.
Most commonly encountered complications are such as pneumothoraxand hemorrhage. Systemic air embolism however is a known but rare occurrence.We report a fatal case of air embolism to the left ventricle of the heart andthe aorta, confirmed by a CT thorax, followed by a review of the differentmechanisms that may have lead to the event. Case Report: A 72 year old man wasadmitted to the hospital for bilateral chronic limb ischaemia. His medicalhistory was also significant for right sided heart failure with Type 2respiratory failure. His workup included a chest radiograph and a CT scan whichincidentally revealed a solitary left lung nodule at the apicoposterior segmentof the left upper lobe measuring 1.2 x 1.
8cm. It was then decided for a CT guided biopsy to establish a diagnosis. Patient was placed in prone position and an 18G biopsyneedle, 15c in length was inserted into the nodule under CT guidance. As theneedle was passing through, patient coughed slightly.
Despite this shortcoming,an adequate tissue sample was obtained. Immediately afterward, a CT scan was performed. A review of the CT scan demonstrated airentering the left pulmonary vein and advancing to the left ventricle andeventually leaving the aorta. Followingthis, the patient became unresponsive and pulseless. Resuscitative efforts werecommenced immediately and code blue was activated.Patient was intubated and after 15 mins ofcardiopulmonary resuscitation, cardiac monitor showed sinus rhythm.
Subsequently patient was transferred to ICU and placed on high FiO2 settingin order to facilitate reabsorption of the embolised air. Hyperbaricoxygen therapy was contemplated. However due to the patient’s hemodynamicallyunstable condition, he was deemed not safe for transfer. Patient died shortlyafter. Transthoracic lung biopsy is a frequently performedprocedure that has been has been widely accepted as a standard method for thediagnosis of pulmonary lesions. Ofnote, Bou-Assaly et al stated that the most frequent complications arepneumothorax (27%), pulmonary bleeding (11%) and hemoptysis (7%). Systemic air emboli are extremely rare with a published incidence of0.
02% from a lung biopsy survey in the United Kingdom.However it is to be noted that the incidence rateand mortality of air embolism is believed to have been underestimated due toundiagnosed asymptomatic casesThe risk ofcomplications appears to be greatest in smokers, older patients (>60 years),patients with chronic obstructive pulmonary disease or emphysema, and possiblyin those with ground glass nodules. Reportedly, there are threelikely manners air can be introduced in the systemic circulation duringneedle biopsy of the lung. First, when the needle tip is placed within thepulmonary vein and the stylet has been removed, it can create a directcommunication between the atmosphere and the pulmonary vein. Second, acommunicating fistula can be created between the pulmonary vein and lungparenchyma as the needle passes through the lung parenchyma. Intra-alveolar, intrabronchial, cavity or air cyst, and a nearby pulmonary veinair can get introduced into the pulmonary venous circulation through thefistula. A Valsalva maneuver, coughing, or positive-pressure ventilation mayincrease air introduction by causing an elevation in the intra-alveolarpressures.
Finally, air may be introduced in the pulmonary arterial circulationand later reach the pulmonary venous circulation by traversing the pulmonarymicrovasculature. Inthis case, we are to believe that as patient coughed after the passing of thecore biopsy needle, it is likely that a fleeting communication between thepulmonary vein and the biopsy tract may have been present at that time,resulting in alveolar or bronchial air passing into the pulmonary vein, whichresulted from an increased intrapulmonary pressure induced by the coughing. Theair thereafter passed into the left atrium and then into the left ventricle.The subsequent clinical events arose as a result of antegrade propulsion of theair bubbles into the major branches of the aorta. The immediate response to an air embolism is theadministration of 100% oxygen and placing the patient in the left lateraldecubitus position with lowering of the head. Hyperbaric oxygen therapy is considered thefirst-line therapy for systemic air embolism by reducing bubble volume andimproving tissue oxygenation. The size of a gas bubble is inverselyproportional to ambient pressure at constant temperature. Breathing100% oxygen at a pressure above that of the atmosphere decreases the size.
Hyperoxia produces diffusion of oxygeninto the bubble and nitrogen out and also allows a large quantity of oxygen todissolve in the plasma and increases oxygen diffusion in tissues. Although immediate treatment isrecommended, delayed hyperbaric oxygen therapy may also increase survival anddecrease the neurologic deficit, even many hours after the incidence becauseair bubbles have been demonstrated at 48 h after initial events. Inour case, hyperbaric oxygen was considered to be ineffective, as patient wasnot fit for transfer. Severalconsiderations have been recommended to reduce the risk of air embolism. One of it being avoiding biopsy through acystic, cavitating lesion or bullous lung parenchyma. The use of a stylet andkeeping an occluded hollow at all times may also be considered.
We should also request the patient to holdtheir breath when manipulating the biopsy kit and to restrain from coughing andstraining. Lastly, we should be sure to penetrate the least amount ofparenchyma to reach the lesion to avoid entrapment of air within thevasculature. Despitethe rarity of this dangerous and possible fatal complication, interventionalradiologists should be aware of the complication that is systemic air embolismafter lung biopsy and should be ready to provide emergent management for thetreatment of the patient. Although several recommendations and precautions havebeen proposed to reduce the risk of this complication, it may be inevitable andcan occur despite long experience and meticulous care.