Surgical factors affecting oculocardiac reflex during strabismus surgery

The role of surgical factors eliciting oculocardiac reflex of patients undergoing orbital tumor surgery: a retrospective study

PURPOSE

Orbital tumors are an interdisciplinary disease, and surgery is one of the main treatment methods. The oculocardiac reflex (OCR) is a condition of surgery for orbital tumors. The aim of this study was to investigate whether there is an association between many surgical factors and the incidence of OCR in orbital tumor surgery.

METHODS

Comparisons were made between patients with and without OCR using the Mann-Whitney test, Fisher's exact test, and Chi-square test. When comparing multiple groups (groups > 2), to explain which two groups had differences, post hoc testing was used for analysis, and the differences between groups were judged according to the adjusted standardized residuals.

RESULTS

The results showed that the incidence of intraoperative OCR was different based on the different exposed operative field locations (p = 0.021). The OCR incidence in those with lesions involving the orbital apex and lesions adhering to extraocular muscles was higher than that of others (p < 0.001 and p = 0.003). In addition, multivariate logistic regression analysis revealed that orbital apex involvement and extraocular muscle adhesion were highly associated with a higher incidence of OCR (p < 0.001 and p = 0.013), while the operative field located in the lateral-superior orbit was highly associated with a lower incidence of OCR (p = 0.029).

CONCLUSION

In orbital tumor surgery under general anesthesia, lesions involving the orbital apex and lesion adhesion to the extraocular muscles were independent risk factors for OCR, and an operative field located in the lateral-superior orbit was a protective factor for OCR.

Post-operative vomiting after pediatric strabismus surgery: A comparison of propofol versus sevoflurane anaesthesia

Background and Aims

Squint surgery is a risk factor for postoperative vomiting (POV) in children. This study was designed to compare the incidence of POV in children undergoing strabismus surgery under balanced anesthesia with sevoflurane versus intravenous anesthesia with propofol.

Material and Methods

In this prospective randomized controlled study conducted in a tertiary care ophthalmology hospital, 70 ASA I-II children aged 1-12 years undergoing strabismus surgery were randomized to two groups -Group S (sevoflurane-based anesthesia) and Group P (propofol-based anesthesia) for maintenance. The surgical details, intraoperative hemodynamic parameters, recovery characteristics, and emergence delirium were recorded. Any episode of postoperative vomiting in the 0-2 hours, 2-6 hours, and 6-24 hours period was noted. Rescue antiemetic was administered if there was more than one episode of vomiting.

Results

Both the groups were similar with respect to demographic and surgical details. The average duration of surgery was 118.2 ± 41.88 min in group S and 137.32 ± 39.09 min in group P (P = .05). Four children in group S (11.4%) and one child in group P (2.9%) had POV in the first 24 hours but this was not statistically significant (P = .36). The median time to discharge from post anesthesia care unit was significantly less (P = .02) in the P group (50 min) than in the S group (60 min).

Conclusion

Propofol-based anesthesia does not offer advantage over sevoflurane, in reducing POV after squint surgery, when dual prophylaxis with dexamethasone and ondansetron is administered. It, however, reduces the duration of stay in the post anesthesia care unit.

Comparing Effectiveness and Safety of Intravenous Atropine with Topical Tetracaine in Preventing and Relieving Oculocardiac Reflex in Patients Undergoing Strabismus Surgery: A Randomized Clinical Trial

Background

Oculocardiac reflex (OCR) is one of the serious complications following surgical therapeutic procedures for strabismus. Various medications have been tested to prevent or mitigate this complication. We aimed to compare the effect of intravenous atropine and topical tetracaine on the incidence and severity of OCR in strabismus surgery.

Materials and Methods

In this triple-blind randomized clinical trial study, 120 patients who were candidates for strabismus surgery were randomly assigned to receive intravenous atropine, topical tetracaine, or artificial tears as the control. The incidence of OCR and its severity along with the changes in hemodynamic conditions were compared across the groups.

Results

The incidence rate of OCR in the groups receiving atropine, tetracaine, and the control was found to be 17.5%, 25.0%, and 32.5% in the releasing phase without any difference, respectively (P = 0.303); however, it was 2.5%, 7.5%, and 25.0%, respectively, in the cutting phase, indicating a lower rate in the group receiving tetracaine (P = 0.004). Similarly, there was no difference in the severity of OCR across the three study groups in the releasing phase (P = 0.666); however, in the cutting phase, OCR was revealed to be milder in the group receiving atropine as compared to other groups (P = 0.033). Prescribing atropine led to higher mean systolic blood pressure and mean arterial pressure during surgery.

Conclusion

The injection of atropine can effectively reduce the incidence of OCR during strabismus surgery and reduce its severity if this reflex occurs.

Smooth Emergence from General Anesthesia after Deep Extubation in a Pediatric Patient Diagnosed with Catecholaminergic Polymorphic Ventricular Tachycardia: A Case Report

Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare genetic disorder where catecholamine causes bidirectional ventricular tachycardia, potentially leading to cardiac arrest. In patients undergoing surgery, sympathetic responses can be triggered in situations associated with surgical stimulations as well as high anxiety before the surgery, anesthetic maneuvers such as endotracheal intubation and extubation, and postoperative pain. Therefore, planning for surgery demands meticulous attention to anesthesia during the perioperative period in order to prevent potentially life-threatening arrhythmias. Case: We discuss a case of an 11-year-old male pediatric patient with known CPVT who required elective strabismus surgery for exotropia involving both eyes. After thorough planning of general anesthesia to minimize catecholamine response, sufficient anesthesia and analgesia were achieved to blunt the stressful response during intubation and maintained throughout the surgical procedure. Complete emergence was achieved after deep extubation, and the patient did not complain of pain or postoperative nausea and vomiting. Conclusions: Anesthesiologists should not only be able to plan and manage the catecholamine response during surgery but also anticipate and be prepared for situations that may lead to arrhythmias before and after the procedure. In certain cases, deep extubation can be beneficial as it reduces hemodynamic changes during the extubation process.

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.

Effect of Ice Slush on Reducing the Oculocardiac Reflex During Strabismus Surgery

BACKGROUND

The aim of this study was to explore whether ice slush (IS) causing local hypothermia can effectively inhibit the oculocardiac reflex (OCR) during strabismus surgery.

METHODS

This prospective, randomized, double-blind study included 58 patients with concomitant strabismus scheduled for lateral rectus (LR) recession under general anesthesia. Patients were randomly allocated to receive IS (IS group) or standard treatment (control group) with sterile saline at room temperature before surgery. OCR was defined as a sudden decrease in heart rate (HR) of >15% from baseline. If one incidence of the OCR was found in 1 patient in any stage (0/I/II/III), the patient was defined as an OCR responder, and the incidence of overall OCR was the incidence of OCR responders. The primary outcome was the incidence of overall OCR during all stages of the surgery, which was analyzed by the Z test and computed based on the absolute risk difference with 2-sided 95% confidence intervals (CIs) using the Newcombe method.

RESULTS

The overall OCR occurred in 19 of 29 patients (62.5% [95% CI, 45.7-82.1]) in the IS group and 28 of 29 patients (96.6% [95% CI, 82.2-99.9]) in the control group (absolute risk difference, -31.0% [95% CI, -49.4 to -11.0]; Z test, P < .001), which demonstrated that the incidence of overall OCR in IS group was significantly lower than that in the control group.

CONCLUSIONS

IS on the ocular surface causing local hypothermia is a promising and easily accessible method to reduce the overall OCR, which can improve the safety of strabismus surgery.

Prediction of the Occurrence of the Oculocardiac Reflex Based on the Assessment of Heart Rate Variability. An Observational Study

Introduction

Ophthalmic surgery is assumed to be safe, but some operations require general anaesthesia which is associated with a number of potential complications. In addition, adverse cardiovascular symptoms, such as severe slowing of the heart rate and, in some cases, cardiac arrest may occur due to the surgical technique. The aim of this study was to determine whether it is possible to predict the occurrence of oculocardiac reflex (OCR) based on heart rate variability (HRV) analysis for autonomic nervous system (ANS) activity assessment measured prior to the induction of anaesthesia and immediately before eyeball traction.

Methods

Fifty-two adults of both sexes (age range 18–65 years) with American Society of Anesthesiologists (ASA) physical status class 1 and 2 were enrolled in this study. All patients had underwent episcleral buckling under general anaesthesia. High-frequency (HF) changes in HRV are thought to reflect parasympathetic impulse transmission, whereas low-frequency (LF) changes reflect both sympathetic and parasympathetic activity. However, in practice, LF changes can be considered to reflect sympathetic changes. Thus, the LF/HF ratio reflects the actual balance between sympathetic and parasympathetic activity. Based on that, frequency domain HRV parameters from 5-min Holter electrocardiogram recordings before anaesthesia induction and before eyeball traction were used for the analysis. The statistical analysis also included patient age, sex, ASA status and preanaesthesia and premanoeuvre heart rate and blood pressure.

Results

Data from 42 patients were analysed. Oculocardiac reflex was observed in 32 patients (76.2%). No difference was found in the analysed parameters between patients with and without oculocardiac reflex. There was no relationship between the incidence of the OCR and the analysed parameters.

Conclusion

The prediction of OCR based on initial ANS tone was not possible, and the initial heart rate, blood pressure, age, sex, and ASA status were not helpful for the identification of patients at risk of this reflex.

Trial registration

ClinicalTrials.gov identifier no.: NCT01714362

Hydroxyzine Dihydrochloride Premedication Is a Necessity for Pediatric Patients Undergoing Strabismus Surgery: An Observational Prospective Clinical Trial

Objective

In this single-blind, observational prospective clinical trial, we aimed to determine and compare the effects of premedication with hydroxyzine plus midazolam and midazolam alone on the incidence of oculocardiac reflex (OCR).

Methods

Forty-five patients were divided into three groups. Group M received 0.5 mg/kg midazolam alone, Group H received 0.5 mg/kg hydroxyzine plus 0.5 mg/kg midazolam, and Group HM received 1 mg/kg hydroxyzine plus 0.5 mg/kg midazolam. The Ramsay Sedation Scale (RSS), the heart rates (HR1: after induction of anesthesia; HR2: before retraction of orbital muscle; and HR3: right after retraction of orbital muscle), the muscles with OCR, and the incidence of OCR (20% decrease of the HR right after the traction) were recorded and compared between the three groups.

Results

The mean HR1, HR2, and HR3 values were significantly increased (p=0.002, p < 0.001, p < 0.001) and the incidence of OCR (p=0.004) was significantly decreased in Group H and in Group HM (for all, p < 0.01) compared to Group M. The most common orbital muscle in which OCR occurred was the rectus medialis.

Conclusion

Premedication with a combination of 0.5 or 1 mg hydroxyzine with 0.5 mg midazolam significantly reduced the incidence of OCR compared to premedication with midazolam alone. This study was registered on https://clinicaltrials.gov/ with number NCT03806270.

The association between surgical technique and oculocardiac reflex in pediatric strabismus surgery: an observational study

Background and objectives

The most common cause of oculocardiac reflex (OCR) is traction of the extraocular muscles. Therefore, strabismus surgery is highly risk for the development of this complication. This study aimed to investigate whether an association exists between the occurrence of OCR and the type of extraocular muscle manipulated during strabismus in a pediatric population.

Methods

A total of 53 pediatric patients who were operated for strabismus under sevoflurane anesthesia were enrolled in this prospective study. The association between surgical techniques and the occurrence of OCR was investigated.

Results

This study included 30 (56.6%) males and 23 (43.4%) females, with a mean age of 8.4 years. Overall, 83 eyes with 93 extraocular muscles were operated. Surgery was performed most frequently on the medial (44.6%) and lateral (36.1%) recti. OCR occurred in 33 (62.3%) patients. OCR was found to be significantly higher in the first operated muscle compared with the second muscle, regardless of muscle type, as identified in the statistical analysis based on the sequence of the operated muscles.

Conclusions

The manipulation of the first extraocular muscle has a higher risk of OCR in the pediatric population undergoing two-muscle surgery for strabismus.

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.

Oculocardiac reflex and oculorespiratory reflex during strabismus surgery under general anesthesia using the laryngeal mask airway with maintenance of spontaneous respiration: A retrospective study

Objective

To determine (1) how the specific muscle undergoing surgical treatment affects the occurrence of the oculocardiac reflex (OCR) and oculorespiratory reflex (ORR) and (2) whether the depth of anesthesia influences the occurrence of the OCR and ORR in patients undergoing strabismus surgery with a laryngeal mask airway with maintenance of spontaneous respiration.

Methods

The medical records of patients who underwent strabismus surgery on the lateral rectus (LR) and medial rectus (MR) muscles from January 2017 to December 2017 were retrospectively reviewed.

Results

The incidence of the OCR was not significantly different between LR and MR operations in either pediatric or adult patients. The incidence of the ORR as indexed by the tidal volume (TV) was significantly higher during MR than LR surgery in pediatric patients (29.3% vs. 10.1%, respectively). The change in TV during muscle traction and the bispectral index were significantly correlated in both pediatric and adult patients (r² = 0.034 and 0.058, respectively).

Conclusions

The OCR was not influenced by the specific muscle undergoing surgery or the depth of anesthesia. The incidence of the ORR as indexed by the TV was higher during MR surgery in pediatric patients and was positively correlated with the depth of anesthesia.

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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Penehyclidine mitigates postoperative nausea and vomiting and intraoperative oculocardiac reflex in patients undergoing strabismus surgery: a prospective, randomized, double-blind comparison

Background

Postoperative nausea and vomiting (PONV) is one of the most frequent complications following strabismus surgery. Penehyclidine, an anticholinergic agent, is widely used as premedication. This study investigated the effect of preoperative penehyclidine on PONV in patients undergoing strabismus surgery.

Methods

In this prospective, randomized, double-blind study, patients scheduled for strabismus surgery under general anesthesia were randomly assigned to either penehyclidine (n = 114) or normal saline (n = 104) group. Penehyclidine was administrated immediately after anesthesia induction, and normal saline was substituted as control. PONV was investigated from 0 to 48 h after surgery. Intraoperative oculocardiac reflex (OCR) was also recorded.

Results

Compared with normal saline, penehyclidine significantly reduced PONV incidence (30.7% vs. 54.8%, P < 0.01) and mitigated PONV severity as indicated by severity scoring (P < 0.01). Compared with normal saline, penehyclidine also significantly reduced OCR incidence (57.9% vs. 77.9%, P < 0.01) and mitigated OCR severity, as indicated by the requirement for atropine rescue (77.3% vs. 90.1%, P < 0.05) and the maximum decrease of heart rate during OCR (23.1 ± 9.4 bpm vs. 27.3 ± 12.4 bpm, P < 0.05). The recovery course did not differ between groups.

Conclusions

Penehyclidine administrated after anesthesia induction significantly reduced the incidence of PONV and alleviated intraoperative OCR in patients undergoing strabismus surgery.

Trial registration

ClinicalTrials.gov (NCT04054479). Retrospectively registered August 13, 2019.

Oculocardiac Reflex During ROP Exams

PURPOSE

Reducing physiologic stress including bradycardia during staging eye exams for retinopathy of prematurity (ROP) is desirable. We observed heart rate change during routine retinopathy of prematurity eye examinations and compared the response with our ongoing study of oculocardiac reflex (OCR) elicited by uniform EOM tension during strabismus surgery.

PATIENTS AND METHODS

Electrocardiograph was prospectively monitored during ROP exams featuring indirect ophthalmoscopy with Alfonso lid speculum and see-through scleral depressor without topical anesthesia. Clinical data were retrieved from ROP-Check software. OCR was defined as maximally changed heart rate (HR) as a percent of baseline. Strabismus surgery patients under general anesthesia served as controls.

RESULTS

From 10/2017 to 9/2020, 281 infants had ROP exams, and the median OCR was 55.9% of baseline HR (IQR 41.4% to 72.6%), the kurtosis 0.93 and skewness 1.01 representing a drop from HR 169 ± 16 bpm to 102 ± 39 bpm. In comparison, 1493 adult and pediatric strabismus surgery patients had less OCR median bradycardia 87.8% (IQR 72-98%), kurtosis 1.60 and skewness -1.18. ROP %OCR correlated with birth gestational age (%OCR = 2.5 (GA) - 11, r(279)=0.33, p<0.01) and with birthweight (%OCR = 0.02 (BW) + 38, r(279) =0.35, p<0.01). The duration of bradycardia induced by ROP exam averaged 92 ± 34 seconds (range 34-240 seconds).

CONCLUSION

Bradycardia is common during eye exams in the smallest premature infants with greater degree, more rapid onset and longer duration than OCR during strabismus surgery.

The Impact of Re-Operation, Relatives and Race on the Oculocardiac Reflex During Strabismus Surgery

Purpose

The oculocardiac reflex (OCR) is a trigeminovagal bradycardia elicited by tension on an extraocular muscle (EOM). Using three decades of observational data, we investigated whether or not individual strabismus patients are prone to oculocardiac reflex.

Patients and Methods

All patients undergoing strabismus surgery from 1992 to 2019 had deliberate 10-second, 200-gram square-wave tension on extraocular rectus muscles with anesthetic variables recorded. OCR was defined as the maximally tension-altered heart rate as a percent of stable baseline heart rate.

Results

OCR was compared in 2532 original cases with 323 re-operations. The 169 cases that used anticholinergics (99% OCR) were excluded from the analysis. The median OCR, a 15% drop, was found to be 85% (95% CI 39%, 102%,; range 5–151%). Factors that showed a significant effect on the OCR were the type of EOM with lateral rectus least (Kruskal–Wallis X²(3)=8, p<0.05), and adults had less OCR compared to the children (X²(2)=105, p<0.01). Factors that showed an augmenting effect on the OCR were peri-operative opioids (X²(6)=62, p<0.01) and Caucasian race (X²(4)=12, p<0.02). Gender and iris color were not found to have an impact on OCR. Re-operations and first-degree relatives did not differ from age-matched controls, but EOM- and opioid-adjusted re-operations correlated with their initial cases (r=0.37).

Conclusion

We confirmed the previously published blocking effect of atropine, augmenting impact of opioids, and an inverse relationship of age on OCR. There was a weak proclivity for individuals to be prone to OCR. We found an impact of race with Caucasians having more OCR.

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Oculocardiac Reflex During Intravitreal Injection

Oculocardiac reflex (OCR) has been described to occur with mechanical manipulation of the eye, eyelids or orbit. There are no reports in the literature of OCR during intravitreal injection (IVI). This may be due to the fact that heart rate is not monitored during the procedure. We aimed to evaluate OCR during IVI. A total of 532 patients were enrolled in the study at Asociacion para Evitar la Ceguera en Mexico. Mexico City, Mexico. IVI was performed on one eye in every patient with diabetic retinopathy (DR), age related macular degeneration (AMD) or choroidal neovascularization (CNV) secondary to pathological myopia. Heart rate was monitored with a pulse oximeter before, during and after injection. OCR was defined as a 20% decrease or more of basal heart rate. The population enrolled included 270 females and 262 males with mean age of 63.8 years. A decrease in heart rate of 20% or more occurred in 18 patients during IVI (3.3%; 95% confidence interval 1.85% and 4.92%). OCR was asymptomatic in these patients. OCR occurred in 3.3% of our patients during IVI. Hence, OCR must be considered when performing IVI.