Death potentially secondary to sub‐Tenon's block

Abstract

SummaryAn 82-year-old ASA 2 patient underwent routine sub-Tenon's block for cataract surgery. One minute after injection of the local anaesthetic, the patient had a generalised tonic-clonic seizure and developed refractory ventricular fibrillation; subsequent resuscitation was unsuccessful. With no evidence for intravascular injection, the lack of structural brain abnormalities, and the most striking feature on post mortem examination being severe triple vessel coronary artery disease, it was concluded that this was primarily cardiac in origin; however, the possibility of brainstem anaesthesia should also be considered. The use of sub-Tenon's block for cataract surgery is becoming increasingly popular in the UK and it is felt to be a safer alternative to other anaesthetic techniques, despite the lack of a randomised double-blind study to validate conclusions regarding its relative safety [1]. 'Brainstem anaesthesia' is a complex phenomenon which may result from local anaesthesia entering the central nervous system, and it is a recognised complication of ophthalmic regional blocks, with various postulated and debated mechanisms and variable presentation [2]. To date there have been no reported deaths in connection with a sub-Tenon's block. The following is a case report of a death potentially secondary to inadvertent subarachnoid injection. Case historyAn 82-year-old female presented for an elective cataract operation. On a routine pre-operative visit she was found to be a known hypertensive on 2.5 mg bendrofluazide once daily. She denied having any history of myocardial infarction, angina, epilepsy or allergic reactions. Her blood pressure was 178 ⁄ 94 mmHg and her pulse rate 76 beats.min . She had undergone general anaesthesia previously, but she had not had cataract surgery. Her left axial globe length was 25.83 mm. No pre-operative ECG was performed.In the anaesthetic room she was calm and was happy to proceed with the sub-Tenon's block.She was monitored using pulse oximetry and electrocardiography, and following venous cannulation with a 22G cannula in her left hand, 1% amethocaine was instilled followed by 5% povidine eye drops.A 19G 25-mm (1-inch) sub-Tenon's metal cannula was used to perform a left sub-Tenon's block in the inferior nasal quadrant. After a negative aspiration, 3 ml of the injectate, which contained 750 IU hyalase in a 50 : 50 mix of 2% lidocaine and 0.5% bupivacaine, was injected over 3-4 min. She complained of a little discomfort, but no change in heart rate was noted.Within 1 min of performing the sub-Tenon's block, in mid sentence, the patient stopped talking and had a generalised tonic-clonic seizure.She was immediately turned to her right, ventilated with 100% oxygen via a Bain's circuit and given 2 mg midazolam intravenously. She was then discovered to have no pulse and to be in ventricular fibrillation.Adrenaline 1 mg was administered intravenously whilst the paddles of the defibrillator were attached, and three stacked shocks were administered: 200 J, 200 J, 360 J. She remained in ...

Sub-Tenon's anesthesia: an update

“…Also, accidental perforation of the optic nerve sheath due to excessively deep dissection with the Westcott scissors is theoretically possible. There have been two cases of transient loss of consciousness17 and one death possibly caused by central spread of local anesthetic to the brain stem following STB 50. It must be borne in mind that this complication is much rarer than with a retrobulbar block.…”

Sub-Tenon's anaesthesia: complications and their prevention

“…Unintentional perforation of the Tenon's capsule during injection, subsequent deposition of local anaesthetic into the intraconal space and spread to the central nervous system through an orbital foramen is another possibility. 30 Symptoms 46 described a patient who developed a generalized tonicclonic seizure and refractory ventricular fibrillation one minute after sub-Tenon's block injection. Subsequent resuscitation was unsuccessful.…”

Management of emergence agitation

“…We read with interest the report by Hatzakorzian et al describing the successful treatment of emergence agitation with droperidol [1]. In our institution a smaller dose of droperidol is used for prophylaxis and treatment of postoperative nausea and vomiting.…”