Reduction of oculocardiac reflex with Tetracaine eye drop in strabismus surgery

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.

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.

Efficacy of tetracaine eye drops in strabismus surgery: a systematic review and meta-analysis of randomized controlled trials

AIM

To comprehensively evaluate the efficacy and safety profile of tetracaine eye drops as a local anesthetic agent among pediatric patients undergoing for strabismus surgery.

METHODS

We systemically searched four electronic databases (PubMed, Scopus, Web of Science, and Cochrane Library) from inception until April 2023. We included randomized controlled trials (RCTs) comparing tetracaine and placebo or no intervention for intraoperative and postoperative outcomes in strabismus surgery patients. We used the Cochrane risk of bias-2 tool for the risk of bias assessment. Continuous variables were pooled as mean difference (MD) or standardized mean difference (SMD), and categorical variables were pooled as risk ratio (RR) with a 95% confidence interval (CI).

RESULTS

Six RCTs were included in the meta-analysis, with a total of 326 patients. There was no significant difference between the tetracaine and the control groups regarding the mean operative time (MD = -0.10 minutes, 95% CI [-3.79, 3.59], p = .96), the mean time to first analgesia (MD = -0.87 minutes, 95% CI [-11.15, 9.40], P = .87), the mean behavior score (SMD = -S0.48, 95% CI [-1.24, 0.28], p = .22), the rate of postoperative vomiting (RR = 1.27, 95% CI [0.62, 2.61], p = .52), or the number of additional analgesia (RR = 0.55, 95% CI [0.27, 1.13], p = .10).

CONCLUSION

Our systematic review and meta-analysis found no significant differences in the safety and efficacy of tetracaine eye drops for strabismus surgery when compared to placebo or no intervention. Further investigation is needed to establish the best local anesthetic for 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 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.

The Oculocardiac Reflex: Its Evolution and Management

INTRODUCTION

The oculocardiac reflex is initiated by a pressure stimulus to the orbit or periorbital structures causing in bradycardia transmitted via the trigeminal-vagus nerve reflex arc. While this most frequently occurs with ophthalmologic surgeries, trauma to the orbit and periorbital structures can result in bradycardia and even in some cases, asystole. The aim of this case report and review of the literature is to identify and examine recent studies of the oculocardiac reflex related to facial trauma and to identify associated patient age, symptoms, and fracture patterns.

METHODS

A literature search was performed using the database within PubMed.gov using the term "oculocardiac." Results were reviewed for case reports or series related to facial trauma from the year 2000 to 2019. Studies were then evaluated for fracture pattern, presence of entrapment, patient symptoms, and age.

RESULTS

The initial search resulted in 109 articles. A total of 22 articles were case reports or series of trauma patients. Twenty articles met inclusion criteria. Median age was 22 years. Eleven patients sustained orbital floor fractures. Four patients sustained medial wall fractures. Three patients had concomitant orbital floor and zygomatic fractures, and 4 with concomitant orbital floor and medial wall fractures. The most common extracardiac symptom experienced was nausea and vomiting (15/23) followed by diplopia (10/23). Status of entrapment was available in 20 patients of which entrapment was reported in fourteen (14/20).

CLINICAL REPORT

A 26-year old male presents after blunt trauma to the face resulting in a left orbital floor, rim, and maxillary fractures. Extraocular movements were initially intact and the patient had no diplopia. He developed bradycardia to 30 to 40 bpm just prior to induction of anesthesia. He was found to have developed entrapment of the inferior rectus muscle. The orbital floor and rim were repaired with complete resolution of bradycardia.

CONCLUSION

Patients who sustain maxillofacial trauma involving the orbit are at risk of developing the oculocardiac reflex. Patients tend to be younger. The orbital floor is more commonly the site of traumatic injury. Nausea and vomiting are common encountered symptoms. The oculocardiac reflex, clinicians must recognize, is not static but may evolve over a patient's clinical course as seen in our patient.