Attenuation of the oculocardiac reflex after topically applied lignocaine during surgery for strabismus in children

Surgical and anesthetic influences of the oculocardiac reflex in adults and children during strabismus surgery

One of the most common untoward occurrences during strabismus surgery at all ages is the oculocardiac reflex. Although typically easily treated, the sudden bradycardia or cardiac arrest may add a few gray hairs to ophthalmologists and anesthesiologists alike as it can be potentially fatal. This updated review of the literature and novel detailed treatment algorithm may prevent patient morbidity and mortality through proper recognition of at-risk patients and rapid treatment through proper communication between surgical and anesthesia physicians/providers.

Adverse Events during Vitreoretinal Surgery under Adequacy of Anesthesia Guidance—Risk Factor Analysis

Vitreoretinal surgeries require the administration of general anesthesia (GA) in selected groups of patients. The administration of intraoperative rescue narcotic analgesia (IRNA) during GA poses the risk of postoperative nausea and vomiting (PONV). The surgical pleth index (SPI), a crucial component of the adequacy of anesthesia (AoA) guidance of GA, optimizes the intraoperative titration of IRNA. The current analysis evaluated the risk factors for the occurrence of PONV and the oculo-cardiac reflex (OCR) in patients undergoing pars plana vitrectomy (PPV) under AoA guidance. In total, 175 patients undergoing PPV were randomly allocated to receive either GA with SPI-guided IRNA administration using fentanyl alone or in addition to different preoperative analgesia techniques. Any incidence of PONV or OCR was recorded. Obesity, overweight, smoking status, motion sickness, postoperative intolerable pain perception, female gender, fluid challenge and arterial hypertension did not correlate with an increased incidence of PONV or OCR under AoA guidance. Diabetes mellitus, regardless of insulin dependence, was found to correlate with the increased incidence of PONV. The AoA regimen including SPI guidance of IRNA presumably created similar conditions for individual subjects, so no risk factors of the occurrence of PONV or OCR were found, except for diabetes mellitus. We recommend using AoA guidance for GA administration to reduce OCR and PONV rates.

Adverse Events during Vitrectomy under Adequacy of Anesthesia-An Additional Report

The intraprocedural immobilization of selected subsets of patients undergoing pars plana vitrectomy (PPV) requires the performance of general anesthesia (GA), which entails the intraoperative use of hypnotics and titration of opioids. The Adequacy of Anesthesia (AoA) concept of GA guidance optimizes the intraoperative dosage of hypnotics and opioids. Pre-emptive analgesia (PA) is added to GA to minimize intraoperative opioid (IO) usage. The current additional analysis evaluated the advantages of PA using either COX-3 inhibitors or regional techniques when added to AoA-guided GA on the rate of presence of postoperative nausea and vomiting (PONV), oculo-emetic (OER), and oculo-cardiac reflex (OCR) in patients undergoing PPV. A total of 176 patients undergoing PPV were randomly allocated into 5 groups: (1) Group GA, including patients who received general anesthesia alone; (2) Group T, including patients who received preventive topical analgesia by triple instillation of 2% proparacaine 15 min before induction of GA; (3) Group PBB, including patients who received PBB; (4) Group M, including patients who received PA using a single dose of 1 g of metamizole; (5) Group P, including patients who received PA using a single dose of 1 g of acetaminophen. The incidence rates of PONV, OCR, and OER were studied as a secondary outcome. Despite the group allocation, intraoperative AoA-guided GA resulted in an overall incidence of PONV in 9%, OCR in 12%, and OER in none of the patients. No statistically significant differences were found between groups regarding the incidence of OCR. PA using COX-3 inhibitors, as compared to that of the T group, resulted in less overall PONV (p < 0.05). Conclusions: PA using regional techniques in patients undergoing PPV proved to have no advantage when AoA-guided GA was utilised. We recommend using intraoperative AoA-guided GA to reduce the presence of OCR, and the addition of PA using COX-3 inhibitors to reduce the rate of PONV.

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.

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.

A randomised comparison of lidocaine 2% gel and proparacaine 0.5% eye drops in paediatric squint surgery

We conducted a randomised trial comparing lidocaine 2% gel with proparacaine 0.5% eye drops in children having elective squint surgery. One hundred and forty children aged between 3 and 14 years were recruited. The requirement for intra-operative fentanyl and postoperative ibuprofen was significantly less in the lidocaine group compared with the proparacaine group (1 (1.7%) vs 12 (18.5%), p=0.002 and 16 (27.6%) 38 (58.5%), p=0.001, respectively). The incidence of postoperative nausea and vomiting was significantly less in the lidocaine group compared with the proparacaine group (6 (10.3%) vs 16 (24.6%), p=0.04). There were no differences between the groups in terms of incidence and severity of the oculocardiac reflex. We conclude that, compared with proparacaine 0.5% eye drops, a single application of lidocaine 2% gel improves peri-operative analgesia and reduces the incidence of postoperative nausea and vomiting in elective paediatric squint surgery.

Adjustment in patients with asystole during strabismus surgery

PURPOSE

To investigate whether patients who developed asystole during strabismus surgery under general anesthesia also develop asystole during adjustment, and whether adjustment can safely be performed under topical anesthesia in these patients.

DESIGN

Retrospective, noncomparative interventional case series.

METHODS

Adjustment was performed with topical anesthesia in four patients aged 28, 32, 50, and 53 years who exhibited asystole during strabismus surgery under general anesthesia. Blood pressure and electrocardiogram were monitored during the adjustment.

RESULTS

Adjustment was successfully completed in all patients without asystole. Two patients showed oculocardiac reflex (OCR), with a reduction in heart rate (HR) >20% of the baseline value. One of these patients exhibited severe OCR that developed when the patient's posture was changed from the supine to the sitting position for measurement of the angle of strabismus after adjustment, and again during conjunctival manipulation after conjunctival closure. No patient required atropine.

CONCLUSIONS

Adjustment can safely be performed under topical anesthesia in patients who developed asystole during strabismus surgery under general anesthesia.

Single bolus of intravenous ketamine for anesthetic induction decreases oculocardiac reflex in children undergoing strabismus surgery

BACKGROUND

Oculocardiac reflex (OCR) is a major complication of pediatric strabismus surgery. The aim of the present study was to determine whether a single bolus of intravenous (i.v.) ketamine for anesthetic induction can decrease OCR in children undergoing strabismus surgery.

METHODS

One hundred and twenty healthy children undergoing strabismus surgery were allocated to three groups using double-blind randomization. Anesthesia was induced with propofol 3 mg/kg in Group P, ketamine 1 mg/kg in Group K1, or ketamine 2 mg/kg in Group K2. Anesthesia was maintained with 3% sevoflurane in 50% N(2)O/O(2) in all patients. The baseline heart rate was obtained 30 s prior to the first traction of the extraocular muscle (EOM). OCR was defined as a development of arrhythmia or a decrease of more than 20% of the baseline heart rate during EOM traction.

RESULTS

The incidence of OCR was significantly lower in the ketamine groups (4/40 and 1/40 in Group K1 and K2, respectively) compared with the propofol group (14/40).

CONCLUSION

A single bolus of i.v. ketamine 1 or 2 mg/kg for anesthetic induction results in a lower incidence of OCR than propofol when combined with sevoflurane for maintenance in children undergoing strabismus surgery.

Association of oculocardiac reflex and postoperative nausea and vomiting in strabismus surgery in children anesthetized with halothane and nitrous oxide

BACKGROUND

Postoperative nausea and vomiting (PONV) occurs frequently after strabismus surgery. The controversy still exists regarding the association of PONV and the oculocardiac reflex (OCR). A recent study has proven that rocuronium attenuates OCR. If these two occurrences are dependent, it is expected that with the diminution of OCR, occurrence of PONV will also be reduced. The goal of this randomized, controlled study was to prove an association between OCR and PONV by attenuating OCR with 0.4 mg x kg(-1) of rocuronium and subsequently diminishing PONV if these occurrences are associated.

METHODS

A total of 119 ASA 1 children, aged between 3 and 10, undergoing surgery of the medial rectus muscle, were randomly assigned to two groups. In group R (n = 59), 0.4 mg x kg(-1) of rocuronium was administered i.v. before intubation. Group C (controls, n = 60) received no muscle relaxant. The anesthesia was induced and maintained with halothane and N(2)O/O(2) (50/50%). Chi-squared test, Fisher's exact test, t-test, and anova were used for statistical analysis; P-value <0.05 was considered statistically significant.

RESULTS

There were no differences between groups regarding patients' characteristics as well as endtidal halothane and duration of surgery and anesthesia. The occurrence of OCR was different between groups (R: 16/59, 27.1%, C: 28/60, 46.7%; P = 0.027), but not the occurrence of PONV (R: 27/59, 45.8%, C: 28/60, 46.7%; P = 0.921). There was an equal number of patients with PONV and bradycardias in both groups (R: 4/27 vs C: 4/28; P = 0.858), whereas there was different, but statistically insignificant distribution of patients (R: 3/27 vs C: 10/28; P = 0.086) with PONV and arrhythmias other than bradycardia. However, simultaneous occurrence of total OCR and PONV in the 24-h period was not different between the two groups (P = 0.964).

CONCLUSIONS

Rocuronium (0.4 mg x kg(-1)) attenuates the occurrence of OCR, but with the reduced occurrence of OCR we were not able to attenuate the occurrence of PONV, therefore the association of OCR and PONV in strabismus surgery in children anesthetized with halothane and nitrous oxide remains unclear, and if there is a link between the two, it could be related to arrhythmias and not bradycardia.

Strabismus surgery under augmented topical anesthesia

PURPOSE

Recently, topical lidocaine 2% jelly had been used in phacoemulsification and trabeculectomy surgeries. The purpose of this study is to evaluate the efficacy and stability of one-stage adjustable suture using topical lidocaine jelly 2% in combination with intravenous nalbuphine (Nubain).

METHODS

Forty adult patients aged 16 to 46 years (median, 24 years) underwent adjustable rectus muscle surgery under topical lidocaine jelly 2% and intravenous 10 mg nalbuphine given 10 minutes before surgery. Adjustment was performed on the operating table before conjunctival closure. The stability of adjustment was studied by comparing the postadjustment deviation to that at 1 day, 1 week, and 3 weeks postoperatively. Success was defined as alignment within 10 prism diopters on distant fixation. Analgesia was assessed using Verbal Description Scale. Changes in vital signs were recorded during surgery to evaluate the oculocardiac reflex.

RESULTS

Forty rectus muscles were recessed, 22 muscles were resected, 3 muscles were tucked, and 2 muscles were retrieved. During the operation, 35 patients expressed no pain, 3 patients complained of discomfort, and 2 patients complained of distressing pain and required an additional 10 mg of intravenous nalbuphine. Thirty-eight patients (95%) were successfully aligned during the first postoperative day, 37 patients (92.5%) after 1 week, and 36 patients (90%) after 3 weeks. Intraoperative cardiac monitoring did not record positive oculocardiac reflex in any patient.

CONCLUSION

Lidocaine jelly in combination with intravenous nalbuphine is an effective topical anesthesia strategy that provides for the patient's comfort and the surgeon's ability to fine-tune ocular alignment on the operating table.