Background Ophthalmic eye blocks, such as retrobulbar, peribulbar and sub-Tenon’s, are traditionally conducted “blind”. Complications are rare but potentially devastating. Life-threatening complications include brain stem anesthesia and local anesthetic toxicity, whereas sight-threatening complications include globe perforation, optic nerve damage and ocular muscle damage. Ultrasound permits a view of orbital structures and can be used to guide needle placement. The ultrasound appearances of unintended local anesthetic injection into vital orbital structures have not been documented. This study aimed to record the ultrasound appearances of unintended injection locations.
Methods The spherical shape of the eyeballs of three soft-fix Thiel embalmed human cadavers were restored using glycerol. Iatrogenic injury in peribulbar block was then simulated through injection of printers’ ink mixed with Thiel embalming fluid. Ultrasound was used to guide the needles and the tips were redirected to lie within the globe, lateral rectus and optic nerve. Ultrasound images were recorded during injection. The orbital cavities were then dissected via a superior approach to record the location and extent of injectate spread.
Results Real-time globe rupture, ocular muscle injection and optic nerve injection were visible using ultrasound. Characteristic appearances were identified in each case. Dissection confirmed needle and injection placement.
Conclusions The ultrasound appearance of block complications is important to document and should be an integral part of regional anesthesia training. This study is the first to provide such images for ophthalmic nerve blocks. It offers ophthalmic anesthetists and ophthalmologists the potential to diagnose severe complications rapidly and accurately with a potential impact on patient safety.
- head and neck
- nerve injury
- regional anesthesia
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Presented at Previously presented in poster form at the Annual Scientific Meeting of Regional Anaesthesia UK, Swansea, 2018.
Contributors AS and GM: conducted study and wrote paper. PGM: designed study and contributed to paper. TW: supervized study, provided facilities, contributed to paper.
Funding Permission was granted by Tracey Wilkinson at CAHID as Licenced Anatomist at the University of Dundee for the research session to be completed. The embalmed cadavers used in the research project were obtained and used in accordance with all applicable laws and regulations including, without limitation, the Anatomy Act 1984 (as amended) and the Human Tissue (Scotland) Act 2006. In compliance with these acts, fully informed consent was received from all donors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.