Case 10857 Iatrogenic venous air embolism La Pietra P, Sommario M, Marchini N, Venturi P Ospedale Bentivoglio, Asl Bologna, Dipartimento servizi; Via Marconi 40121 Bentivoglio, Italy; Email:plapietra@tin.it Ospedale Bentivoglio Section: Chest Imaging Published: 2013, Jun. 12 Patient: 73 year(s), male Clinical History A 73-year-old man underwent a contrast-enhanced CT scan for colorectal cancer follow-up. Imaging Findings Two gas bubbles of 15 mm in size, with air-fluid levels, were detected in the main pulmonary artery, during the preliminary evaluation of the thoracic images (Fig. 1 a). Other smaller gas bubbles were observed in right subclavian vein and in the brachiocephalic vein a triradiated image was present, due to a motion artefact from pulsation of intravascular gas bubbles (dynamic mercedes-benz sign) (Fig. 1 b, c, d). These findings were characteristic of iatrogenic venous air embolism. The patient was asymptomatic but was kept prudently in observation for 24 hours; since there were no complications during this period he returned home the day after the incident. Discussion
Venous air embolism (VAE) is a condition resulting from the presence of gas bubbles inside the venous bloodstream. Generally this is an iatrogenic complication that can occur during venous access procedures, caused by the incidental introduction of atmospheric gas into the venous blood flow [1-2]. During contrast media injection for computed tomography (CECT) small amounts of air can be discovered in about 23% of patients [3]. This gas can arise from the inadequate removal of the air from the syringe, from the pressure tubing or from microbubbles present within the contrast medium. Generally the patients are asymptomatic; however, a bigger amount of air can be a potentially lethal process, because a large bubble of gas is able to stop blood flow to the lungs. The risk of morbidity or mortality not only is affected by the amount of air but also by the speed of introduction; for this reason the most serious accidents are linked by to use of injectors pump [4-5]. The more common symptoms are: sudden dyspnoea, chest pain, cough, tachyarrhythmias or bradycardias, hypotension, circulatory shock or cardiovascular collapse, feeling of impending doom. VAE appears on CT as gas bubbles, within the veins enhanced by contrast medium, variable in size by less than 1 cm to 1-3 cm in diameter; generally located in the main pulmonary artery, superior vena cava, right side of heart, subclavian or brachiocephalic vein. Several patients can have multiple emboli in different sites [1]. In some cases, for the preexistence of anatomical anomalies such as patent foramen ovale or pulmonary shunts, the gas from venous system can go in the arterial system with the possibility of arterial air embolism. Typically gas bubbles can have a triradiate aspect (dynamic mercedes-benz sign) due to motion artefact. For preventing or minimizing the risk of VAE, before initiating the injection, it is essential to remove the air from the syringe and from pressure tubing and orientate the syringe downward. At the onset of the slightest symptoms, because of this potentially life-threatening condition, it is suggested to put the patient immediately in the left lateral decubitus position with the head down (Durant's maneuver), then give oxygen with high flow rates in order to reverse ischaemia and reduce the air bubble size. In severe cases haemodynamic support and hyperbaric oxygen therapy is required. Final Diagnosis Iatrogenic venous air embolism Differential Diagnosis List Pulmonary embolism, Arterial embolism Figures Figure 1 CECT scan
CECT (axial view) shows, in the main pulmonary artery, two gas bubbles of 15 mm of size with air-fluid levels. (arrowheads) CECT (Axial view) shows: triradiate image due to pulsation artefact (circle) caused by intravascular air bubble (dynamic Mercedes Benz sign) in the brachiocephalic vein.
Special Focus: Artefact; CECT (axial view) shows gas bubbles in right subclavian vein (red arrow). CECT (MPR coronal view) shows gas bubbles in right subclavian vein (red arrow).
MeSH Iatrogenic Disease [C23.550.291.875] Any adverse condition in a patient occurring as the result of treatment by a physician, surgeon, or other health professional, especially infections acquired by the patient during the course of treatment. Arterial Occlusive Diseases [C14.907.137] Diseases in which arterial vessels are partially or completely obstructed or in which the blood flow through the vessels is impeded. References [1] Pham KL, Cohen AJ. (2003) Iatrogenic venous air embolism during contrast enhanced computed tomography: a report of two cases. Emerg Radiol. Dec;10(3):147-51 [2] Cook LS. (2013) Infusion-related air embolism. J Infus Nurs. Jul-Aug;22(4):269-71. [3] Ie SR, Rozans MH, Szerlip HM (1999) Air embolism after intravenous injection of contrast material South Med J. Sep;92(9):930-3. [4] Imai S, Tamada T, Gyoten M, Yamashita T, Kajihara Y. (2004) atrogenic venous air embolism caused by CT injector--from a risk management point of view. Radiat Med. Jul-Aug;22(4):269-71. [5] Roman Kleynberg, MD; Berj Demirjian, MD; Nader Kamangar, MD (2011) Massive Fatal Iatrogenic Venous Air Embolism During Contrast Enhanced Computed Tomography Chest October 2011, Vol 140, No. 4 Citation La Pietra P, Sommario M, Marchini N, Venturi P Ospedale Bentivoglio, Asl Bologna, Dipartimento servizi; Via Marconi 40121 Bentivoglio, Italy; Email:plapietra@tin.it (2013, Jun. 12) Iatrogenic venous air embolism {Online} URL: http://www.eurorad.org/case.php?id=10857