Sub-Tenon's injection versus paracetamol in pediatric strabismus surgery

Efficacy of the subtenon block in children undergoing strabismus surgery: A systematic review and meta-analysis

PURPOSE

To investigate the efficacy of the subtenon block in preventing postoperative complications in children undergoing strabismus surgery.

DESIGN

Systematic review and meta-analysis METHODS: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, Web of Science, and clinicaltrials.gov. All randomized controlled trials (RCTs) investigating the efficacy of the subtenon block in children undergoing strabismus surgery were included. Outcomes included severity of pain after surgery, number of children requiring postoperative opioid and non-opioid analgesia, and the incidences of postoperative nausea and vomiting, oculocardiac events, and block-related complications. We pooled continuous outcomes using a random-effects model to calculate the mean difference (MD) and/or standardized mean difference and corresponding 95% confidence intervals (CI). Dichotomous outcomes were pooled using a random-effect model to calculate the relative risk (RR) and corresponding 95% CI. Risk of bias was assessed using the Cochrane Risk of Bias instrument and quality of evidence was assessed using a Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Nine RCTs (607 participants) were included. We found evidence for an effect of the subtenon block in reducing pain at 20-40 min after surgery (MD -1.9, 95% CI -2.2 to -1.5; high-quality evidence) and on admission to PACU (MD -1.8, 95% CI -2.2 to -1.4; moderate-quality evidence); however, there was no difference in pain scores at 6 h after surgery. In addition, evidence was found that the subtenon block decreased the number of children requiring postoperative opioid (RR 0.59, 95% CI 0.37 to 0.92; high-quality evidence) and non-opioid (RR 0.52, 95% CI 0.27 to 0.98; moderate-quality evidence) analgesia, and the incidences of postoperative vomiting (RR 0.31, 95% CI 0.12 to 0.7; high-quality evidence) and intraoperative oculocardiac events (RR 0.40, 95% CI 0.26 to 0.60; high-quality evidence). Other secondary outcomes had low or moderate-quality evidence. Risk of bias was low in six trials and high in three. There were no reports of block-related complications.

CONCLUSION

Our findings suggest that the subtenon block reduces the severity of early postoperative pain and the incidences of postoperative vomiting and intraoperative oculocardiac events compared with controls in children undergoing strabismus surgery.

REVIEW REGISTRATION

PROSPERO (CRD42015025443).

Sub-Tenon's bupivacaine injection is superior to placebo for pediatric strabismus surgery: A meta-analysis

BACKGROUND

The effect of post-operation sub-Tenon's bupivacaine injection for pediatric strabismus surgery is controversial. The objective of this meta-analysis is to compare the outcome of sub-Tenon injection of bupivacaine and placebo duringstrabismus surgery.

METHODS

We searched the databases (Pubmed, Cochrane library and EMBASE) and reference lists systematically. Randomized controlled trials (RCTs) comparing sub-Tenon's bupivacaine and placebo injection for pediatric strabismus surgery were included. The methodological quality was evaluated by the Cochrane risk of bias (ROB) tool. Outcome measurements were pain score, oculocardiac reflex (OCR), additional drug consumption and related complications. RevMan 5.4 was used for the statistical analysis and graph preparation. For the outcomes that are not suitable for statistical analysis, descriptive analysis was performed.

RESULTS

A total of 5 RCTs with 217 patients were finally identified and analyzed. Sub-Tenon's bupivacaine injection showed pain relief within 30 min after operation. But with the extension of time, the analgesic effect gradually disappeared at 1 h. It can reduce the incidence of OCR, vomiting and supplementary drug requirements. However, in terms of nausea, there is no difference between the two groups.

CONCLUSION

Sub-Tenon's bupivacaine injection can relieve short-term postoperative pain, reduce the incidence of OCR and vomiting, and reduce the use of supplementary drugs in strabismus surgery.

The Oculocardiac Reflex: A Review

BACKGROUND

A typical oculocardiac reflex (OCR) is a moderate trigemino-vagal bradycardia elicited by tension on an extraocular muscle (EOM) during strabismus surgery; however, many other orbital stimuli can elicit cardiac slowing including retinopathy of prematurity examination.

METHODS

World literature related to trigeminovagal and oculocardiac reflex covering over 15,000 patients including 51 randomized clinical trials and case reports are analyzed and reviewed. Under an ongoing observational trial in Alaska, anesthetic, patient and surgical influences on routine strabismus surgery using prospective, uniform EOM tension are compared seeking sufficient sample size to characterize this individually widely variable cardiac response.

RESULTS

With adequate sample size, and emphasizing clinical studies controlling type of EOM, muscle tension amount and duration, anticholinergic and opioid medications, the following augment OCR; rapid-acting opioids and dexmedetomidine while OCR is reduced in older patients, the right eye, less EOM tension, deeper inhaled agents, hypocarbia, anticholinergic medications and orbital block. In re-operations, the former are relatively poor predictors of subsequent OCR.

CONCLUSION

Profound bradycardia can occur in almost 10% of strabismus surgery cases without anticholinergic preventive measures, but reliable prediction of OCR remains elusive. With foreknowledge and careful anesthetic monitoring of the patient before EOM manipulation, residual adverse sequelae from OCR are fortunately very rare. Despite well over a century of experience, the teleology for this occasionally dramatic cardiac response to eye surgery is still not known.

Anaesthetic considerations for strabismus surgery in children and adults

Strabismus correction surgery is the most common eye operation in children. Adults have approximately a 4% lifetime risk of developing strabismus. Current treatment options include pharmacological injection of botulinum toxin or bupivacaine, conventional corrective surgery, adjustable suture surgery and minimally invasive surgery. Repeated surgery is common as each operation has a 60%-80% chance of successful correction. The benefits of early surgical correction in large-angle strabismus in children outweigh the risks of anaesthesia. General anaesthesia is suitable for patients of all age groups, for complicated or repeated surgery, and bilateral eye procedures. Regional ophthalmic block reduces the incidence of oculocardiac reflex and emergence agitation, and provides postoperative analgesia, but requires a cooperative patient as many experience discomfort. Topical anaesthesia has been used in pharmacological injection, minimally invasive surgery, uncomplicated conventional strabismus surgery and some adjustable suture strabismus surgery. Its use, however, is only limited to cooperative adult patients. Prophylactic antiemesis with both ondansetron and dexamethasone is recommended, especially for children. A multimodal analgesia approach, including paracetamol, intravenous non-steroidal anti-inflammatory drugs, topical local anaesthetic and minimal opioid usage, is recommended for postoperative analgesia, while a supplementary regional ophthalmic block is at the discretion of the team.

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

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.

Does Topical Proparacaine Improve Postoperative Comfort After Strabismus Surgery?

Background

Strabismus surgery is often performed on children and adults as a quick-turnover, outpatient procedure under general anesthesia. Ideal methods to reduce post-operative pain and nausea are not yet perfected. We postulated that a simple topical anesthetic drop after surgery might help.

Methods

In a prospective study of oculocardiac reflex (OCR) and strabismus surgery, a cohort of ongoing patients either received proparacaine immediately post-op, or none. Co-variables were Intraoperative opioid and OCR, patient age, type of surgery. Several post-operative recovery outcome variables were prospectively monitored.

Results

Sixty strabismus surgery patients (age 15±22 years) received proparacaine 1% while another 80 (16.5±22 years) received none; both received topical antibiotic-steroid ointment. Pain and nausea (Likert scale) were not impacted by covariables complexity of case, age less than 3.5, OCR >33% drop, intraoperative opioid or neuro-status. Immediate post-op heart rate was lower if OCR >33% and if opioids used. Time until discharge was shorter in younger patients. Proparacaine did not impact outcome variables, except in patients younger than 3.5 years when post-op pain was worse.

Conclusion

Post-op topical anesthetic either produced no difference, or worsened post-op pain and recovery. This prospective study does not support the use of topical anesthetic drop to reduce post-strabismus pain and nausea.

Clinical trials registration

NCT03672435, Strabismus Recovery With Proparacaine and Oculocardiac Reflex (OCRprop).

Efficacy of horizontal muscle augmentation combined inferior oblique muscle shortening for pediatric strabismus: Study Protocol

BACKGROUND

This study will explore the efficacy and safety of horizontal muscle augmentation (HMA) combined inferior oblique muscle shortening (IOMS) for the treatment of pediatric strabismus (PS).

METHODS

Literature search for studies will be carried out in the following databases: Cochrane Library, MEDILINE, EMBASE, CINAHL, Web of Science, PsycINFO, CBM, and CNKI. We will search all these databases without language and publication status restrictions. Two independent authors will perform selection of studies, data collection and management, risk of bias evaluation. A third author will be consulted with the help of discrepancies.

RESULTS

This study will provide a synthesis of existed evidence for HMA combined IOMS for the treatment of PS.

CONCLUSION

The results of this study will provide evidence to evaluate the efficacy and safety of HMA combined IOMS for the treatment of PS, which can help to guide clinical decision-making.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019149716.

Reduction of oculocardiac reflex with Tetracaine eye drop in strabismus surgery

INTRODUCTION

Recently, to reduce the incidence of oculocardiac reflex (OCR) in strabismus surgery, retrobulbar block and anticholinergic drugs or local anesthesia are also used. The present study evaluated the effects of Tetracaine eye drop as a topical nerve blocker on OCR during strabismus surgery.

METHODS AND MATERIALS

In this randomized trial, 70 strabismus surgery candidates were randomly divided into placebo or synthetic teardrop (E) and Tetracaine eye drop (T) groups, so 3 drops of each solution were dropped in four directions of patients' eye immediately after applying anesthesia and before surgery. The incidence and severity of OCR during the stages of muscle release and incision (cutting), hemodynamic changes, the required time for OCR recovery and atropine dose were assessed.

RESULTS

OCR was more seen in release phase compared to cutting phase. There were no significant differences between two group regarding the incidence and severity of OCR in the release phase (p > 0.05), but the incidence and severity of OCR in the cutting phase was more in group E than group T (p = 0.02, for both). The duration of OCR improvement (p-value = 0.74) and Atropine consumption (p-value = 0.92) did not differ between the groups.

CONCLUSION

Tetracaine eye drop only reduces the incidence and severity of OCR during the incision stage of strabismus surgery.

Prospective evaluation of anesthetic protocols during pediatric ophthalmic surgery

PURPOSE

To date, no protocol of anesthesia for pediatric ophthalmic surgery is unanimously recognized. The primary anesthetic risks are associated with strabismus surgery, including oculocardiac reflex, postoperative nausea and vomiting, and postoperative pain.

METHODS

This was a prospective, monocentric, observational study conducted in a tertiary pediatric ophthalmic unit. Our anesthetic protocol for strabismus surgery included postoperative nausea and vomiting prevention using dexamethasone and ondansetron. No drug-based prevention of oculocardiac reflex or local/locoregional anesthesia was employed.

RESULTS

A total of 106 pediatric ophthalmic surgeries completed between November 2015 and May 2016 were analyzed. The mean patient age was 4.4 (range: 0.2-7.3, standard deviation: 2.4) years. Ambulatory rate was 90%. Oculocardiac reflex incidence was 65% during strabismus surgery (34/52), 50% during congenital cataract surgery (4/8), 33% during intramuscular injection of botulinum toxin (1/3), and 0% during other procedures. No asystole occurred. Postoperative nausea and vomiting incidence was 9.6% after strabismus surgery (5/52) and 0% following the other procedures. One child was hospitalized for one night because of persistent postoperative nausea and vomiting. Postoperative pain generally occurred early on in the recovery room and was quickly controlled. Its incidence was higher in patients who underwent strabismus surgery (27%) than in those who underwent other procedures (9%).

CONCLUSION

Morbidity associated with ophthalmic pediatric surgery is low and predominantly associated with strabismus surgery. The benefit-risk ratio and cost-effectiveness of oculocardiac reflex prevention should be questioned. Our postoperative nausea and vomiting rate is low, thanks to the use of a well-managed multimodal strategy. Early postoperative pain is usually well-treated but could probably be more effectively prevented.