Effects of atracurium and pancuronium on the oculocardiac reflex in children

Restrictive strabismus and gaze-evoked oculocardiac reflex following pterygium repair with fibrin glue

Oculocardiac reflex is a phenomenon caused by traction applied to the extraocular muscles, or pressure on the globes. The afferent stimulus travels via the ophthalmic branch of cranial nerve V, and the efferent stimulus travels via cranial nerve X, which can cause severe bradycardia and potentially hypotension, atrioventricular block, ventricular ectopy, and rarely asystole. Oculocardiac reflex is different from vasovagal syncope which has another pathway, and is triggered by pain or emotional upset, that results in failure of autoregulation of blood pressure. Ophthalmologists often observe oculocardiac reflex intraoperatively upon manipulation of extraocular muscles during strabismus surgeries. We report a case with a previously undescribed complication following pterygium autograft with fibrin glue stimulating oculocardiac reflex resulting in episodes of sudden bradycardia associated with light headedness and nausea.

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.

Anesthetic Impacts on the Oculocardiac Reflex: Evidence from a Large, Observational Study

Background

The oculocardiac reflex (OCR) is a sudden vagal bradycardia that can be elicited by traction on an extraocular muscle. Bradycardia is highly variable from case to case necessitating a large sample size to observe small to moderate impact on OCR. While the surgeon’s tissue manipulation has immediate impact on OCR and individual patients may have some proclivity to OCR, we sought to characterize the impact on OCR by the anesthesiologist.

Methods

From 1992 to 2019, during routine, community outpatient general anesthetic strabismus surgery, oculocardiac reflex was prospectively observed utilizing a uniform 10-second, 200 gram square wave tension on each extraocular muscle. Anesthetic parameters were recorded and analyzed with double-cohort design and non-parametric statistics and correlations. We define %OCR as the maximally tension-altered heart rate and a percent of stable pre-tension heart rate.

Results

The median (IQR) confidence intervals OCR for 2527 initial cases was 89% (67% to 97%) without anticholinergic, and 99% (95% to 100%) in 165 patients with anticholinergic. OCR was 81% (62% to 96%) in 1034 with opioids and to 75% (60% to 95%) in 59 with dexmedetomidine and in 189 with IV dexamethasone to 72% (56% to 92%) There was a significant (p<0.01 Kruskal–Wallis) impact on OCR by various opioids, muscle relaxants and inhalational agents. Linear regression showed significant inhibitory impact on OCR by increased inhalational agent depth and by lower exhaled CO₂.

Conclusion

The anesthesiologist can block OCR with sufficient anticholinergics, deeper inhalational agents and robust ventilation, and can augment OCR with opioids, dexmedetomidine and apparently also with dexamethasone.

Clinical Trials Registry

NCT04353960.

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Incidence and ramifications of the oculocardiac reflex during the orbitozygomatic approach: a prospective assessment

OBJECTIVE

The oculocardiac reflex (OCR) is a sudden decrease in heart rate resulting from mechanical manipulation of the orbit, especially due to traction on the orbital contents. The purpose of this study was to determine the incidence and clinical ramifications of OCR elicitation by the orbitozygomatic (OZ) approach.

METHODS

Electrocardiographic strips were collected prospectively from 104 patients undergoing OZ approaches. Recording was started at the commencement of the craniotomy cuts and was stopped after completion of the OZ osteotomy. Each recording was divided into stage 1, which encompassed the time between the start of the craniotomy cuts to the commencement of the osteotomy cuts, and stage 2, which encompassed the time from commencement of osteotomy cuts until completion of all bone work and dural tacking Orbital manipulation occurred exclusively during stage 2. A decrease in heart rate of 10 bpm or more between stage 1 and stage 2 was recorded as an OCR event.

RESULTS

In our 104 patients we detected OCR events 31.7% of the time. There was no significant difference in rate of OCR occurrence found in analysis of the covariates of hypertension, hyperlidemia, diabetes mellitus, hypothyroidism/hyperthyroidism, β-blocker use, calcium channel blocker use, or tobacco use. In each case, transient cessation of orbital manipulation was sufficient to normalize heart rate. No patients required anticholinergic intervention as a result of OCR, and there were no postoperative ramifications of the OCR.

CONCLUSIONS

OCR occurs in nearly one-third of patients who undergo the OZ approach. However, simple cessation of orbital manipulation is sufficient to normalize the patient's heart rate. Rarely is medical management required or does there appear to be any significant postoperative ramifications.

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.

Rocuronium attenuates oculocardiac reflex during squint surgery in children anesthetized with halothane and nitrous oxide

BACKGROUND

The oculocardiac reflex (OCR) may be activated during squint surgery. The aim of this study was to test whether rocuronium 0.4 mg kg(-1) could reduce the frequency of OCR, and also whether a single dose of succinylcholine 1 mg kg(-1) could affect the frequency of OCR during anesthesia with halothane in a nitrous oxide/oxygen mixture.

METHODS

A total of 161 ASA I children, 3-10 years old, undergoing elective surgery of the medial rectus muscle (MRM) were randomly assigned to three groups. Group R (n = 51), received 0.4 mg kg(-1) of rocuronium intravenously before endotracheal intubation. Group S (n = 58) received 1 mg kg(-1) of succinylcholine. Group C (controls, n = 52) received no relaxant. Oculocardiac reflex was defined as a reduction in heart rate (HR) > or = 15% and/or the appearance of any other arrhythmias, during manipulation of the MRM. Analysis of variance (anova), chi-squared, Kruskal-Wallis, and Student's t-tests were used for statistical analysis; P< 0.05 was considered statistically significant.

RESULTS

In group R, OCR occurred in 15/51 (29%) of children, in group S in 31/58 (53%), and in group C in 23/52 (44%) (chi2 = 6.46, P = 0.049). In group R, the incidence of arrhythmias such as nodal rhythms, supraventricular and ventricular premature beats was 6%, compared with 22% in group S and 19% in group C (chi2 = 6.01, P = 0.040). However, there was no reduction in the occurrence of bradycardia (chi2 = 0.16, P = 0.924).

CONCLUSION

Rocuronium reduced the frequency of OCR, mainly by reducing the incidence of supraventricular and ventricular premature beats.

A comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children

We examined changes in the cardiorespiratory system of small children during surgical correction of strabismus with a laryngeal mask airway and spontaneous respiration with sevoflurane or halothane inhaled anesthesia. Fifty-one children, 1-7 yr old, having outpatient strabismus correction were randomized to sevoflurane (S) or halothane (H) in 66% nitrous oxide at 1.3 minimum alveolar concentration. Children breathed spontaneously through a laryngeal mask airway and were not pretreated with anticholinergics. The oculocardiac reflex (OCR), defined as a 20% decrease in heart rate (HR) from baseline, dysrhythmias, or sinoatrial arrest concomitant with ocular muscle traction occurred less frequently with sevoflurane than with halothane (S 38%, H79%, P = 0.009). The baseline HR was higher with sevoflurane (S 114 +/- 13 bpm, H 101 +/- 15 bpm, P = 0.002). The lowest HR occurred with halothane (S 95 +/- 22 bpm, H 73 +/- 19 bpm, P = 0.001). The incidence of dysrhythmias was higher in the halothane group (S 4%, H 42%, P = 0.004). Reductions in minute ventilation and PETCO(2) accompanied OCRs. Airway irritability was present with halothane only (S 0, H 3). Eleven children, of whom the majority had received halothane, required measures to correct SpO(2) < 95% or PETCO(2) > 60 mm Hg during maintenance anesthesia (S 11%, H 32%). Sevoflurane may be a more suitable anesthetic than halothane for operations involving traction on the ocular muscles with spontaneous respiration in children because of reduced incidence of OCR, airway irritability, and ventilatory disturbances.

IMPLICATIONS

Some children experience a sudden slowing of the heart and impaired breathing when the surgeon pulls on the eye muscles during squint operations under anesthesia. Sevoflurane, a recently developed anesthetic vapor, may reduce this problem when compared with the established vapor halothane.

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

The effect of topical lignocaine applied to the eye muscles, on the incidence of the oculocardiac reflex during squint surgery of the medial rectus was investigated in 56 healthy children aged between 3-14 years. Three groups were studied. One (n = 16): stimulation of the reflex without lignocaine; 2 (n = 10): stimulation of the reflex after topical administration of 1 mg kg-1 lignocaine 2% to the medial part of the eye after induction of anaesthesia; 3 (n = 30): stimulation of the oculocardiac reflex without, and after a 5 min interval under the influence of lignocaine. Topical administered lignocaine significantly attenuated the OCR (105 vs. 68 bpm group II vs. group 1:82 vs. 63 bpm in group III). Severe bradycardiac rhythm disturbances, in particular cardiac stand-still, were not observed after lignocaine had been applied. Systemic side effects of lignocaine were not seen.