Regional Anesthesia for Pediatric Ophthalmic Surgery: A Review of the Literature

Abstract

Ophthalmic pediatric regional anesthesia has been widely described, but infrequently used. This review summarizes the available evidence supporting the use of conduction anesthesia in pediatric ophthalmic surgery. Key anatomic differences in axial length, intraocular pressure, and available orbital space between young children and adults impact conduct of ophthalmic regional anesthesia. The eye is near adult size at birth and completes its growth rapidly while the orbit does not. This results in significantly diminished extraocular orbital volumes for local anesthetic deposition. Needle-based blocks are categorized by relation of the needle to the extraocular muscle cone (ie, intraconal or extraconal) and in the cannula-based block, by description of the potential space deep to the Tenon capsule. In children, blocks are placed after induction of anesthesia by a pediatric anesthesiologist or ophthalmologist, via anatomic landmarks or under ultrasonography. Ocular conduction anesthesia confers several advantages for eye surgery including analgesia, akinesia, ablation of the oculocardiac reflex, and reduction of postoperative nausea and vomiting. Short (16 mm), blunt-tip needles are preferred because of altered globe-to-orbit ratios in children. Soft-tip cannulae of varying length have been demonstrated as safe in sub-Tenon blockade. Ultrasound technology facilitates direct, real-time visualization of needle position and local anesthetic spread and reduces inadvertent intraconal needle placement. The developing eye is vulnerable to thermal and mechanical insults, so ocular-rated transducers are mandated. The adjuvant hyaluronidase improves ocular akinesia, decreases local anesthetic dosage requirements, and improves initial block success; meanwhile, dexmedetomidine increases local anesthetic potency and prolongs duration of analgesia without an increase in adverse events. Intraconal blockade is a relative contraindication in neonates and infants, retinoblastoma surgery, and in the presence of posterior staphylomas and buphthalmos. Specific considerations include pertinent pediatric ophthalmologic topics, block placement in the syndromic child, and potential adverse effects associated with each technique. Recommendations based on our experience at a busy academic ophthalmologic tertiary referral center are provided.

The Oculocardiac Reflex: A Review

“… 125 From initial OCR 86±16 (percent of baseline HR induced by 10-second, 200 gram square wave tension) to second EOM 66±25% with dexmedetomidine 0.5 µ/Kg IV between in 33 young patients was a significant augmentation compared to a non-opioid control group of 842 age-matched patients with first EOM 75±25% and second EOM 77±22% with no sedative in between. 131 Jean et al reviewed regional anesthesia for eyes suggesting that dexmedetomidine “increases local anesthetic potency and prolongs duration of analgesia without an increase in adverse events.” 132 In a retrospective study of strabismus surgery in children, the 34 who received pre-induction IV midazolam were 3.6 times less likely to have 20% OCR than the 52 who did not get it. 85 …”

“…In one study, peribulbar block failed to abolish OCR 46 contrary to a recent review of the topic. 132 Indeed, many have found orbital block very effective in reducing or preventing OCR. 34 , 48 , 52 , 56 , 140 , 141 Peribulbar block reduced OCR and PONV during vitreoretinal surgery in children.…”

“… 149 Periocular and even sub-tenon’s block is more challenging in young children due to the relatively larger size of the globe. 150 Bupivicaine injected into an eyelid before chalazion surgery caused asystole. 151 …”

Anesthesia Management of Oculocardiac Reflex in Strabismus Surgery: A Case Study

“…This should be avoided in vitreoretinal surgery in which p-ISSN 2337-7909; e-ISSN 2338-8463; http:// intraocular gas bubbles of sulfur hexachloride or perfluoropropane are inserted into the eye to compress the dislodged surface. 2,3,5,6 Oculocardiac reflex is triggered by pressure on the globe and by traction on the extraocular muscles as well as on the conjunctiva or the orbital structures. this reflex is a part of the trigeminocardiac reflex, which is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve.…”

Local anaesthetic systemic toxicity in paediatric patient: Tips to prevent

“…also suggested weight-based submaximal dosing of LA in paediatric patients. [ 3 ] American society of regional anaesthesia guideline for neuraxial block advocates the use of the lowest concentration of local anaesthetics to prevent LAST. This principle can be applied to other peripheral nerve blocks.…”