Ultrasound detection of iatrogenic injury during peribulbar eye block: a cadaveric study

Abstract

BackgroundOphthalmic 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.MethodsThe 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.ResultsReal-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.ConclusionsThe 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.

Globe penetration during loco-regional anesthesia: prevalence and review of cases

“…Some authors describe that ultrasound guidance can be used to conduct locoregional anesthesia. Ultrasound can be used to guide needle placement [36][37] , to minimize the volume of local anesthetic by using the globe axial length measurement [38] and to train young anesthesiologists or ophthalmologists [39] . Some features of the administration technique of the anaesthetic drugs such as the use of sharp long needles and the use of multiple injections have also been described as risk factors for ocular penetration.…”

Brainstem anesthesia during awake craniotomy: illustrative case

“…Brainstem anesthesia is commonly observed in ophthalmic surgery and is caused by unexpected intrathecal injection. 4 Brainstem anesthesia in ophthalmic surgery has an incidence of 0.79% 5 and can lead to relatively long-term (usually a few hours) brainstem suppression such as disturbance of consciousness, respiratory depression, arrhythmia, and even cardiac arrest. 6 In this case, the patient returned to spontaneous breath shortly after removal of the cotton pledgets.…”

The Development of a Virtual Simulator for a Novel Design Non-Permanent Magnetic Needle Based Eye Anesthesia Training System

“…The system calculates the needle tip position as the state ( − → x k ) at frame k in a term of the cartesian coordinate system, where the direction of unit vector − → d refers to the direction in x and y axis, while the output of ( 8), (9), and (10) denotes the coordinates in − → d and z with the orientation of the needle (θ 0 ). The transfer function in (11) also applies to the covariance of sensing data (ϵ k i ) to calculate the covariance of needle tip position (σ)…”

“…In general, the type of practice for eye anesthesia is a cadaveric training system [8]- [10]. After the fresh cadaver is acquired, the expert physicians supervise the trainees in the practice procedures, focusing on their postures and the remaining needle length [9], [10]. This information will allow the experienced inspectors to prognosticate the needle tip position in the cadaver.…”