Biomedical subjects
Publications and source records attributed to Chandra M Kumar.
The sub-Tenon's anesthesia block was reintroduced into clinical practice in the early 1990s as a simple, effective, and safe alternative to needle blocks. The technique has remained simple and effective but has evolved. Although still very unusual, both sight- and life-threatening complications have occurred. To safely perform the block, detailed knowledge of anatomy and methods for administering anesthesia are essential.
PURPOSE: To describe the visual sensations experienced by patients during glaucoma filtration surgery under peribulbar anesthesia and to determine possible risk factors that may affect the visual sensations experienced. SETTING: King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. METHODS: In this prospective questionnaire study, 75 consecutive adult patients listed for glaucoma filtration surgery (trabeculectomy or Ahmed tube implantation) under peribulbar anesthesia were interviewed postoperatively about the visual sensations experienced in their operated eye during the surgery. RESULTS: The mean age of the 75 patients was 59.7 years (range, 27 to 83, SD +/-12.1). Sixty-five patients (86.7%) perceived light perception during the surgery and the overall light intensity fluctuated in 45 patients (60.0%). The mean age of the patients who retained light perception intraoperatively was significantly lower compared with those who lost light perception (58.3 y vs. 68.8 y; P=0.009). Forty-six patients (61.3%) were able to perceive colors, 32 patients (42.7%) perceived movement, 31 patients (41.3%) saw surgical instruments, and 33 patients (44.0%) reported seeing the surgeon's hands or fingers. The severity of glaucoma did not affect the proportion of patients who perceived the various visual sensations. One patient (1.3%) was frightened by his intraoperative visual experience. Of the remaining patients, 53 (70.7%) said the visual sensations did not affect them, whereas 21 (28.0%) found them unpleasant. CONCLUSIONS: The majority of patients undergoing glaucoma filtration surgery retained light perception intraoperatively and many also experienced various visual sensations. Only 1.3% of patients were frightened by their visual experience.
Complications following ophthalmic regional anaesthesia are rare but are reported during both needle (intraconal and extraconal blocks) and blunt cannula (sub-Tenon's block) techniques. At present there is no perfect technique of ophthalmic regional anaesthesia. This article reports on the complications, treatment and prevention of commonly used ophthalmic regional blocks. Thorough knowledge of the measures required to deal with complications when they occur are of paramount importance for safe clinical practice.
Cataract surgery is the commonest ophthalmic surgical procedure and a local anaesthetic technique is usually preferred but the provision of anaesthesia in terms of skills and resources varies worldwide. Intraconal and extraconal blocks using needles are commonly used. The techniques are generally safe but although rare, serious sight- and life-threatening complications have occurred following the inappropriate placement of needles. Sub-Tenon's block was introduced as a safe alternative to needle techniques but complications have arisen following this block as well. Currently, there is no absolutely safe ophthalmic regional block. It is essential that those who are involved in the care of these patients have a thorough knowledge of the techniques used. This review article outlines the relevant anatomy, commonly used techniques and their safe performance and perioperative care.
INTRODUCTION: A case is presented of a patient with severe and chronic pain in the orbital region, which was relieved by retrobulbar injection of absolute alcohol. The management of chronic pain in the orbital region has received little attention and the literature is reviewed. CLINICAL PICTURE: A 52-year-old man with adenoid cystic carcinoma of the maxillary sinus was suffering from severe pain, especially in the left orbital region. There was also pain from ocular exposure and compression caused by the tumour. Magnetic resonance imaging (MRI) revealed spread of tumour to both orbits, particularly on the left. Multiple debulking surgery and various treatment modalities offered no relief from his pain. TREATMENT: A single retrobulbar injection of 2 mL of absolute alcohol, was placed into the putative orbital apex. OUTCOME: As a consequence of the injection, he had complete resolution of his pain in the 6 months prior to his death. DISCUSSION: Retrobulbar injection of alcohol offers effective pain relief in certain specific conditions characterised by chronic orbital pain when other treatments do not help. CONCLUSION: We have demonstrated that the retrobulbar technique still has a place in our armamentarium.
Recently published literature shows that most patients experience a variety of visual sensations during cataract surgery under local anaesthesia. Most patients (80-100%) retain at least some light perception in the operated eye and many also experience a variety of other visual sensations during cataract surgery under regional ophthalmic anaesthesia (retrobulbar, peribulbar and sub-Tenon's blocks) or topical anaesthesia. The visual sensations experienced include perception of movements, flashes, colours, changes in brightness, or the sight of surgical instruments, the surgeon's hands or fingers, or even the surgeon. These findings are clinically significant because 3-16.2% of patients who had cataract surgery under either regional or topical anaesthesia were frightened by their intraoperative visual experience. Fear and anxiety may cause some patients to become uncooperative during the surgery and may also induce a sympathetic stress response that might cause hypertension, tachycardia with myocardial ischaemia, hyperventilation or an acute panic attack. These effects are especially undesirable as the majority of cataract patients are elderly and have concurrent medical problems. Besides increasing the risk of intraoperative complications, a frightening visual experience may decrease patient satisfaction. Appropriate preoperative counselling has been shown to be effective in reducing the patients' fear. As most patients retain some visual function during cataract surgery under local anaesthesia, anaesthesia providers should be mindful of this phenomenon and offer appropriate preoperative information and counselling to their patients.
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PURPOSE: To evaluate the effectiveness and safety of an orbital block using an ultrashort, wide-bore blunt metal cannula to inject local anesthetic agents into the anterior sub-Tenon's space. SETTING: Department of Ophthalmology, North Riding Infirmary, Middlesbrough, United Kingdom. METHODS: Fifty-nine consecutive patients having routine phacoemulsification with intraocular lens implantation were studied. Five milliliters of lidocaine 2% with adrenaline 1:200000 and hyaluronidase 150 units was injected into the anterior sub-Tenon's space in the inferonasal quadrant via a 16-gauge, short (0.6 cm), blunt metal cannula. Horizontal and vertical movements were assessed before injection and 2, 4, and 6 minutes after injection (also at 8 and 10 minutes if akinesia was inadequate). The movements were scored from 0 (no movement) to 3 (full movement). Incyclotorsion and lid movements were assessed at the same intervals. In the first 15 patients, B-scan ultrasonography was performed before, during, and 2 minutes after the injection. If the aggregate akinesia score was higher than 4 at 6 minutes, a supplementary injection was given. Pain during the injection and surgery was assessed using a 10-point verbal rating score. The incidence, severity, and quadrant of chemosis and conjunctival hemorrhage were noted. RESULTS: Forty-eight patients (81.35%) had an aggregate akinesia score lower than 4 at 2 minutes and 58 (98.30%) at 4 minutes. One patient had an akinesia score higher than 4 at 6 minutes and required supplementary injection. Incyclotorsion was present in 42 patients (72.88%) at 2 minutes and in 19 (32.20%) at 4 minutes. Lid opening (levator function) was present in 33 patients (55.93%) at 2 minutes and in 19 (32.20%) at 4 minutes. Lid closure (orbicularis function) was present in 34 patients (57.62%) at 2 minutes and in 18 (30.50%) at 4 minutes. One patient required a supplementary injection at 10 minutes. Ultrasonography showed the injection caused rapid opening of sub-Tenon's space, with fluid spreading around the optic nerve. No pain on injection occurred in 67.79% of patients; 17 (28.81%) had a verbal rating score of 1, 1 (1.69%) had a score of 3, and 1 had a score of 5. No patient reported pain during surgery. A minor degree of chemosis and conjunctival hemorrhage occurred in 43 patients and 37 patients, respectively. Moderate chemosis occurred in 15 cases and severe chemosis in 1 case. CONCLUSIONS: Effective and predictable ocular anesthesia can be achieved using a blunt, ultrashort cannula for sub-Tenon's block. The technique greatly reduces the risks for globe perforation, muscle damage, and other serious complications.
OBJECTIVE: This case report describes convulsions and hemiparesis after retrobulbar injection with good outcome in a patient undergoing outpatient cryocoagulation of his right eye. CASE REPORT: We report a young man in which localized convulsions of the ipsilateral face occurred 9 minutes after retrobulbar injection followed shortly by convulsions of the contralateral arm and leg. After the convulsions, the patient experienced left-sided hemiparesis resolving approximately 1 hour after the injection. There was no hemodynamic instability during this period. It was difficult to determine the exact cause of convulsions and hemiparesis. CONCLUSIONS: We believe these complications occurred because of unintentional injection of local anesthetic agent into the subarachnoid space without affecting the brainstem. Possible mechanisms of spread of local anesthetic agent into the central nervous system after retrobulbar block are discussed.
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