Orbital Air Embolism After Intravenous Injection

An asymptomatic air embolism in the right superior ophthalmic vein was discovered incidentally during a cerebral computed tomography, most likely due to a preceding intravenous fluid bolus. This case illustrates the potential risk of air emboli being propagated to the cerebral venous circulation during routine injections and fluid resuscitation.

Photo Essay Section Editor: Timothy J. McCulley, MD Orbital Air Embolism After Intravenous Injection Michael Rossiter-Thornton, FRANZCO, Aditya Varma, FRANZCR, Nitin Verma, FRANZCO, MD, Alex W. Hewitt, FRANZCO, PhD FIG. 1. Air embolus (arrow) in right superior ophthalmic vein (A), which resolved 7 days later (B). Abstract: An asymptomatic air embolism in the right superior ophthalmic vein was discovered incidentally during a cerebral computed tomography, most likely due to a preceding intravenous fluid bolus. This case illustrates the potential risk of air emboli being propagated to the cerebral venous circulation during routine injections and fluid resuscitation. Journal of Neuro-Ophthalmology 2018;38:486-487 doi: 10.1097/WNO.0000000000000686 © 2018 by North American Neuro-Ophthalmology Society A n 83-year-old woman, being treated for pneumonia and mild delirium after collapsing at home, was found to have a 0.17-mL air embolus in the superior ophthalmic vein on a contrast-enhanced brain computed tomography (CT) performed on the day of admission (Fig. 1A). She had not sustained skull fracture from the fall and did not have sinusitis. Apart from age-related cerebral changes, there were no other abnormalities on CT. The patient had received multiple intravenous injections through a peripheral intravenous line in the Departments of Ophthalmology (MR-T, NV, AWH) and Radiology (AV), Royal Hobart Hospital, Hobart, Australia; and Menzies Research Institute (NV, AWH), Hobart, Australia. The authors report no conflicts of interest. Address correspondence to Michael Rossiter-Thornton, FRANZCO, Department of Ophthalmology, Concord Repatriation General Hospital, Hospital Road, Concord, Sydney, NSW 2139, Australia; E-mail: [e-mail] 486 hours leading up to the scan, and a fluid bolus had been administered 30 minutes before the CT. She had openangle glaucoma and was using latanoprost drops and atrial fibrillation treated with warfarin. Visual acuity was 20/30 in each eye. Pupillary reactions, ocular motility, and external examination were normal. Slitlamp biomicroscopy showed intraocular lenses to be in good position, and intraocular pressures were 15 mg Hg in the right eye and 14 mm Hg in the left eye. Funduscopy revealed symmetric glaucomatous optic disc cupping and mild pigmentary change in each macula. The patient's delirium and pneumonia resolved over the course of a week-long admission, and repeat CT scan performed 7 days after admission demonstrated complete resolution of the air embolus (Fig. 1B). Air embolization into the dense and richly interconnected cerebral and faciocervical venous networks, including the superior ophthalmic vein, after peripheral intravenous injection has been described previously in retrospective radiology audits (1,2). They tend to be noted incidentally on brain CT scans. Other causes include mechanisms by which air of sufficient volume can enter the venous system, such as basilar skull fracture (2), central venous cannulation or manipulation (3), or intervention of the pulmonary circulation (4). An air bubble can ascend through the superior vena cava into the dense venous networks of the head and neck if the thorax and head are erect at the time of injection, occurring in a manner determined by the buoyancy of the bubble vs. the flow of venous blood in the opposite direction (5). Two Rossiter-Thornton et al: J Neuro-Ophthalmol 2018; 38: 486-487 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay additional factors that may have contributed to air embolism in our patient were venous stasis in the atria due to atrial fibrillation and breath holding (and consequent increase in intrathoracic pressure) that is requested at the moment of contrast injection during CT. In most instances, cerebral venous air emboli are asymptomatic and resolve without clinical sequelae. However, any air embolus of sufficient volume can cause cardiorespiratory arrest or venous sinus infarction. Our case serves as a reminder of the care that should be exercised with peripheral intravenous injections, considering the ease with which air emboli can be propagated to the cerebral venous circulation. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: M. Rossiter-Thornton, A. Varma, N. Verma, and A. Hewitt; b. Acquisition of data: M. Rossiter-Thornton and A. Varma; c. Analysis and interpretation of data: M. RossiterThornton, A. Varma, N. Verma, and A. Hewitt. Category 2: a. Drafting Rossiter-Thornton et al: J Neuro-Ophthalmol 2018; 38: 486-487 the manuscript; M. Rossiter-Thornton and A. Hewitt; b. Revising it for intellectual content: M. Rossiter-Thornton, A. Varma, N. Verma, and A. Hewitt. Category 3: a. Final approval of the completed manuscript; M. Rossiter-Thornton, A. Varma, N. Verma, and A. Hewitt. REFERENCES 1. Rubinstein D, Dangleis K, Damiano TR. Venous air emboli identified on head and neck CT scans. J Comput Assist Tomogr. 1996;20:559-562. 2. Rubinstein D, Symonds D. Gas in the cavernous sinus. Am J Neuroradiol. 1994;15:561-566. 3. Schlimp C, Loimer T, Schmidts M, Rieger M, Lederer W. Venous air embolism through central venous access. BMJ Case Rep. 2009;2009:bcr04.2009.1786. 4. El-Ali W, Browne T, Jones R. A case of cranial air embolism after transthoracic lung biopsy. Am J Resp Crit Care Med. 2012;186:1193-1195. 5. Schlimp C, Loimer T, Tieger M, Lederer W, Schmidts M. The potential of venous air embolism ascending retrograde to the brain. J Forensic Sci. 2005;50:1-4. 487 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.