Is there a cholinergic and an adrenergic phase of the 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.

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.

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.

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.

Surgical factors affecting oculocardiac reflex during strabismus surgery

Background

To investigate surgical factors associated with the occurrence of oculocardiac reflex (OCR) and changes in heart rate (HR) during strabismus surgery.

Methods

Patients who underwent strabismus surgery under general anesthesia were enrolled in this study. The HR during surgery was measured at baseline, and at the following points during surgery: traction of the muscle, maximal increase after traction (adrenergic phase), and the cutting of the muscle. OCR was defined as an HR reduction of more than 20% at traction of the muscle, when compared to baseline HR. The HR at each stage during the surgery was compared between patients with and without OCR.

Results

A total of 162 operated muscles from 99 patients were enrolled. The incidence of OCR was 65% in patients. In patients with two muscle surgeries, there were significantly more OCRs in the first operated muscle than in the second operated muscle (p < 0.01). The difference in the decrease in HR in patients with OCR was significantly lower than that in patients without OCR at traction of the muscle, the adrenergic phase, and the cutting of the muscle (all, p < 0.01). The first operated muscle was a significant risk factor associated with the occurrence of OCR (OR = 3.95, p < 0.01).

Conclusion

The first operated muscle in patients with two muscle surgeries was a significant risk factor for OCR. Decreased HR at the traction of the muscle during surgery did not fully recover in patients with OCR.

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

BACKGROUND

Emergence agitation, vomiting, and oculocardiac reflex (OCR) in children undergoing strabismus surgery under general anesthesia are common problems. The purpose of this study was to determine whether the effect of analgesia can reduce the incidence of these problems. We compared the effects of sub-Tenon's injection versus intravenous (IV) and rectal paracetamol in this surgery.

METHODS

In a prospective, randomized, double-blind study, ninety patients ranging in age from 4 to 8 years scheduled for extraocular muscle surgery for strabismus were included in this study. After induction of anesthesia, just before the surgery, children were divided into three groups (n = 30 for each group) Group A received sub-Tenon's anesthesia with 2.5% bupivacaine (0.08 ml/kg). Group B received IV paracetamol (20 mg/kg). Group C received paracetamol rectal suppository (40 mg/kg). The occurrence of oculocardiac reflex (OCR) intraoperatively was recorded. Then, in the Postanesthesia Care Unit, patients were assessed for their emergence behaviors. Vomiting was also noticed.

RESULTS

The OCR developed in few patients, and there was no significant difference between the groups. The highest number of patients with agitation was in Group C followed by Group B then Group A. Vomiting was significantly low in Group A followed by Group B then Group C.

CONCLUSION

Sub-Tenon block in strabismus surgery in children decreased the incidence of postoperative agitation and vomiting compared with IV paracetamol then rectal paracetamol. There was no difference between sub-Tenon block and paracetamol in the incidence of oculocardiac reflex.

Low-dose dexmedetomidine reduces emergence agitation after desflurane anaesthesia in children undergoing strabismus surgery

PURPOSE

Emergence agitation (EA) is frequently observed in children undergoing general anaesthesia. This study tested whether the addition of an intra-operative low-dose infusion of dexmedetomidine to fentanyl treatment reduced the incidence of emergence delirium following desflurane anesthesia in children undergoing strabismus surgery.

MATERIALS AND METHODS

A total of 96 children (1-5 years old) undergoing strabismus surgery were enrolled. Anaesthesia was induced with propofol and maintained with desflurane. After induction, fentanyl (1 μg/kg) was administered to all children. During surgery, patients were infused with 0.2 μg/(kg·h)⁻¹ dexmedetomidine (Group FD, n=47) or normal saline (Group F, n=47). Postoperative objective pain score (OPS), Paediatric Agitation and Emergence Delirium (PAED) score, and EA score were documented every 10 minutes in the post-anaesthesia care unit.

RESULTS

There were no significant differences between the two groups in demographic characteristics and haemodynamic changes. The mean values of maximum EA, maximum PAED, and maximum OPS score were significantly lower in Group FD than in Group F at 0, 10, and 20 minutes after arrival at the post-anaesthesia care unit (p<0.001). The frequency of fentanyl rescue was lower in Group FD than in Group F (p<0.001). The incidence of severe EA was significantly lower in Group FD than in Group F (12.8% vs. 74.5%, p<0.001).

CONCLUSION

Intra-operative low-dose infusion of dexmedetomidine in addition to fentanyl reduces EA following desflurane anaesthesia in children undergoing strabismus surgeries.

Effect of ketamine and midazolam on oculocardiac reflex in pediatric strabismus surgery

Background

The oculocardiac reflex (OCR) can be elicited during manipulation of the orbital structures in the strabismus correction surgery. A sinus bradycardia is the most common manifestation of OCR; and cardiac dysrhythmia and asystole may also occur. Various efforts to reduce OCR have been attempted, but without coherent outcome results.

Methods

Sixty one children, undergoing elective strabismus surgery, were randomly allocated into 2 groups: Group K received ketamine 1.0 mg/kg; and Group M received midazolam 0.15 mg/kg for induction of anesthesia. Anesthesia was maintained with 1-1.3 MAC of sevoflurane with 50% N₂O in O₂. Heart rate and blood pressure were measured 30 seconds before extraocular muscle (EOM) traction and immediately after traction. The OCR was defined as a decrease in heart rate more than 20% of the baseline heart rate, following manipulating EOM. Postoperative nausea and vomiting (PONV) and emergence agitation (EA) were assessed in postanesthetic care unit (PACU).

Results

Blood pressure before tightening EOM in Group K was higher than that in Group M (P < 0.05). However Δ HR (2.7 ± 15% vs. - 0.9 ± 16%) and incidence of OCR (10.0% vs. 19.4%) after traction an EOM were not different between the two groups. The occurrence of PONV (6.7 vs. 9.7%) and EA (30.0% vs. 22.6%) were similar.

Conclusions

Ketamine does not reduce the incidence of OCR compared with midazolam in pediatric strabismus surgery. In addition, ketamine does not increase the incidence of PONV and EA. In conclusion, it is reliable to use ketamine in pediatric strabismus surgery.

Effect of different anesthetic agents on oculocardiac reflex in pediatric strabismus surgery

PURPOSE

The oculocardiac reflex (OCR) occurs frequently during pediatric strabismus surgery. The aim of this study was to assess the effects of various anesthetic regimens on the incidence of OCR during the surgery.

METHODS

Two hundred and eighty children, 1 to 9 years old, undergoing elective strabismus surgery, were randomly assigned to eight groups; ketamine-sevoflurane (KS), ketamine-desflurane (KD), ketamine-propofol (KP), ketamine-remifentanil (KR), midazolam-sevoflurane (MS), midazolam-desflurane (MD), midazolam-propofol (MP), and midazolam-remifentanil (MR). No premedication was given. Anesthesia was induced using ketamine 1 mg kg(-1) or midazolam 0.15 mg kg(-1) with 66% N(2)O in O(2). Laryngeal mask airways (LMAs) were placed with rocuronium 0.5 mg kg(-1). Anesthesia was maintained with sevoflurane 2-3 vol. %, desflurane 5-6 vol. %, propofol 7-8 mg kg(-1) h(-1), or remifentanil 0.75 microg kg(-1) over 1 min, followed by a continuous infusion of remifentanil 0.5 microg kg(-1) min(-1) with 66% N(2)O in O(2). Heart rate (HR) was recorded during extraocular muscle (EOM) manipulation. OCR was defined as a reduction in HR of more than 20% induced by the traction of an EOM.

RESULTS

In patients given ketamine, OCR occurred more frequently in the KP (65.7%) and KR (62.9%) groups than in the KD (29.4%) and KS (37.1%) groups (P < 0.05). In patients given midazolam, OCR occurred more frequently in the MP (54.3%) and MR (60.6%) groups than in the MD (36.4%) and MS (31.4%) groups (P < 0.05).

CONCLUSION

Propofol or remifentanil anesthesia was associated with a higher incidence of OCR during pediatric strabismus surgery than sevoflurane and desflurane anesthesia, when either ketamine or midazolam was used as an induction agent.

Comparison of desflurane with sevoflurane for the incidence of oculocardiac reflex in children undergoing strabismus surgery

BACKGROUND

The oculocardiac reflex (OCR) is frequently observed during strabismus surgery. This study was designed to evaluate and compare the effect of sevoflurane and desflurane on the incidence of OCR.

METHODS

After obtaining Institutional Review Board approval and informed consent from parents, we enrolled 237 paediatric patients, aged 2-10 yr, undergoing strabismus surgery. No premedication was given. Anaesthesia was induced with thiopental and rocuronium. Patients were randomly allocated to one of the two anaesthetic regimens. Group S (n = 123) received sevoflurane and Group D (n = 114) received desflurane, both with 60% N2O/O2 for maintenance of anaesthesia. The OCR was defined as a > or = 20% decrease in heart rate (HR) from baseline values obtained immediately before muscle manipulation. If the HR did not increase after release of muscle tension, atropine 0.01 mg kg(-1) was administered.

RESULTS

There were no significant differences between the two groups in age, sex, body weight, and the number of muscles operated upon. The mean values of baseline HR were 123 (16) min(-1) in Group S and 121 (18) in Group D (NS). The minimum HR was 106 (22) min(-1) in Group S and 103 (21) in Group D (NS). There was no difference in the incidence of OCR between sevoflurane (26.0%) and desflurane (28.0%) anaesthesia.

CONCLUSIONS

Both agents can be used safely during strabismus surgery in paediatric patients.

[Standardized oculocardiac reflex in ex-premature near full term (93 cases)]

The aim of the study was to present data investigating vagal reactivity in a population of premature infants reaching term, using the oculo-cardiac reflex.

PATIENTS AND METHODS

Ninety three premature infants, free of any disease, near full term at the moment of testing, were prospectively investigated at a time close to discharge from neonatal unit. After an all-night polygraphic recording, a standardized oculo-cardiac reflex test was performed during quiet sleep. Data were classified in relation to both chronological and postconceptional ages. Simple liner regression analyses were performed on the selected variables.

RESULTS

The results showed heterogeneity of the vagal response in this population: longest asystole (1049 ms +/- 540; 95th percentile = 1894 ms); maximal percentage of deviation between two successive RR intervals (88% +/- 90; 95th percentile = 200%); and duration between the beginning of decrease in heart rate and return to mean heart rate (14 s +/- 10; 95th percentile = 30 s).

CONCLUSION

Our healthy premature infants at time of discharge exhibited a wider range of vagal reactivity than previously reported for the full term newborns. Considering our findings, we recommend caution before proceeding with treatment of vagal bradycardia in a similar premature infant population.

Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery

The oculocardiac reflex (OCR) is induced by mechanical stimulation and therefore is frequently encountered during strabismus surgery. This study was designed to determine how various anaesthetic regimes modulate the haemodynamic effects of the OCR during paediatric strabismus surgery. Thirty-nine patients (4-14 years, ASA I) were randomized to one of four anaesthetic regimes: group P: propofol (12 mg.kg(-1).h(-1)) and alfentanil (0.04 mg.kg(-1).h(-1)); group S: sevoflurane 1-1.2 MAC in 30% O(2)/70% N(2)O; group K: ketamine racemate (10-12 mg. kg(-1).h(-1)) and midazolam (0.3-0.6 mg.kg(-1).h(-1); group H: halothane 1-1. 2 MAC in 30% O(2)/70% N(2)O. Electrocardiogram (ECG), beat-to-beat heart rate (HR) and blood pressure (BP) changes were measured during and after a standardized traction was applied to an external eye muscle (4-6 Newton, 90 s). OCR was defined as a 10% change in HR induced by traction. OCR occurred in 77% of patients. Whereas virtually all patients in the P, H and S groups developed OCR, only 22% developed it in group K. Median HR change in group P (-37 bpm) was significantly greater (P < 0.05) than in group H (-17 bpm) or group K (-7 bpm). Median BP change in group K (+10 mmHg) was significantly different (P < 0.05) from group H (-5 mmHg), group S (-3 mmHg) and group P (-8 mmHg). Atrioventricular rhythm disorders were significantly more frequent in group P compared with group K (P < 0.02). Respiration-induced sinus dysrhythmia was significantly less frequent (P < 0.001) in group K (0%), compared with group P (100%), group H (56%) and group S (55%). Of the anaesthetic techniques studied, ketamine anaesthesia is associated with the least haemodynamic changes induced by OCR during strabismus surgery in paediatric patients.

Oculocardiac reflex in sedated patients having laser in situ keratomileusis

PURPOSE

To eliminate stress as a variable in assessing the frequency of the oculocardiac reflex during laser in situ keratomileusis (LASIK).

SETTING

Merida Ophthalmological Hospital and Oftalmedica, Mexico City, Mexico.

METHODS

A pulse oximeter registered the heart rate of 30 sedated patients having LASIK. Sedation was accomplished with a combination of midazolam and fentanyl. The heart rate was noted before and during suction. The results in 1 eye of each patient were recorded. Oculocardiac reflex was defined as a decrease of 10% or more of the basal heart rate.

RESULTS

Fourteen patients (46.7%) had a 10% or more decrease in heart rate when suction was applied. Ten of the 14 had a decrease in heart rate between 10% and 19%, 3 between 20% and 29%, and 1 of more than 30%. Two patients (6.6%) had an increase in the basal heart rate of more than 10%.

CONCLUSIONS

The findings suggest that the oculocardiac reflex occurs more frequently in sedated patients than in nonsedated patients.

Orbital mass in a child causing somnolence, nausea and bradycardia

PURPOSE

To highlight the need for referral and prompt intervention when signs of increased intraorbital pressure are present.

CLINICAL FEATURES

A four year old child presented to hospital with orbital swelling of recent onset, nausea and somnolence. Computed tomography and brain scan demonstrated a normal brain with a mass in the left orbit. She was referred for ophthalmic surgery the following day, when she had lost responsiveness of her left pupil to light. Anaesthetic management was highlighted by the presence of preoperative signs and symptoms of increased intraocular pressure--somnolence, nausea and vomiting, and bradycardia. These signs and symptoms were alleviated postoperatively.

CONCLUSION

Rapid onset of orbital swelling with physiological signs of increased orbital pressure necessitate urgent surgical intervention. It is possible that early referral and surgery could have preserved some functional vision in a situation where the light reflex remained in the affected eye. Alleviation of preoperative nausea and vomiting, bradycardia, and somnolence indicates that the preoperative symptomatology was related to vagal stimulation from increased intraocular pressure, usually identified as an oculocardiac reflex.

Perianesthesia care of adult and pediatric strabismus surgery patients

Strabismus procedures on children and adults are frequently performed in an outpatient setting. Perianesthesia care of patients having strabismus procedures may be optimized by recognizing the characteristics of strabismus patients, the frequently associated diagnoses that may affect perioperative care, and the specific surgical techniques used to treat strabismus. Complications including postoperative nausea, pain, prolonged PACU stay, and unplanned postoperative admissions can be minimized and treatment facilitated by preparing patients with preoperative instructions, careful choice of anesthetic agents and postoperative medications, and appropriate perioperative care. This report will provide a brief review of surgical strabismus, including current techniques, and present guidelines for perioperative care of pediatric and adult strabismus patients.

Profound bradycardia related to long bone fracture manipulation

A 69-year-old male presented to the Emergency Department (ED) with a left comminuted femur fracture. Manipulation of the fractured leg resulted in profound bradycardia, necessitating cessation of the procedure in the ED. Various causes of sinus bradycardia, including vagal-mediated responses, as well as management of vagal-mediated bradycardia are discussed.

Regional ophthalmic anesthesia: safe techniques and avoidance of complications

In the last decade, anesthesiologists have become increasingly involved in administering regional eye blocks, while providing care for patients undergoing ophthalmic surgery. This article describes the two major approaches to regional eye block, namely retrobulbar and peribulbar, with special consideration given to relevant orbital anatomy and technical guidelines. Potential complications, ocular and systemic, with their risk factors, are reviewed. Anesthesiologists wishing to acquire skill in administering safe regional blockade are encouraged to familiarize themselves with regional anatomy and specific guidelines suggested herein.