Prolonged oculocardiac reflex during strabismus surgery under topical anesthesia

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.

Subtenon lidocaine vs topical proparacaine in adult strabismus surgery

Intraoperative subtenon 2% lidocaine and topical 0.5% proparacaine in patients undergoing strabismus surgery were compared. No additional systemic analgesics and sedatives were used. Mean and total pain scores intraoperatively and postoperatively were not different. Each anesthetic agent provides good intraoperative anesthesia and postoperative analgesia. Topical 0.5% proparacaine may be preferred because of its easy administration and fewer side effects, lack of hospital admission, and immediate and predictable alignment of the eyes.

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.

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.

Single-stage adjustable strabismus surgery for restrictive strabismus

PURPOSE

To evaluate the feasibility and stability of ocular alignment of single-stage adjustable strabismus surgery (SSASS) in restrictive strabismus.

METHODS

This was an observational case series comprising 12 patients with restrictive strabismus (mean age, 54.8 years) who were treated with SSASS using intravenous midazolam, fentanyl, and topical anesthesia. All were studied in a retrospective institutional manner. The refractive strabismus in 7 patients was caused by dysthyroid orbitopathy. Five patients had undergone previous ocular surgery, and 4 had undergone previous strabismus surgery. SSASS typically involved the vertical rectus muscles. Horizontal rectus muscles were adjusted when necessary. Silicon-treated polyester suture material (Ti-cron; United States Surgical, Norwalk, CT no longer available), 6-0, were used for inferior rectus recessions. Ocular alignment was set at ortho at the end of surgery and evaluated at 2 days, 6 weeks, and 3 months after surgery. The typical hang-back procedure was to lock the suture at the middle and edges of the tendon or muscle at the intended disinsertion point. The tendon was then disinserted and hung back from the original insertion with adjustments until the desired position (ortho) and single vision were attained.

RESULTS

All patients remained comfortable throughout surgery and had no significant postoperative discomfort. All patients except 2 (16.6%) maintained satisfactory vertical alignment (<2 prism diopters). These 2 patients with dysthyroid orbitopathy had progressive overcorrection after inferior rectus recession.

CONCLUSIONS

SSASS, using intravenous midazolam, fentanyl, and topical anesthesia, is a safe and precise alternative treatment for patients with restrictive strabismus including those with dysthyroid orbitopathy.

Comparison of lidocaine 2% gel versus amethocaine as the sole anesthetic agent for strabismus surgery

PURPOSE

To compare the efficacy of lidocaine 2% gel with amethocaine 1% eyedrops as the sole anesthetic agent for one-stage adjustable suture strabismus surgery.

DESIGN

Prospective, double-masked randomized trial.

PARTICIPANTS

Fourteen consecutive patients scheduled to undergo bilateral and symmetrical strabismus surgery under topical anesthesia in one institution.

METHODS

Each patient was randomized to receive lidocaine 2% gel in one eye and amethocaine 1% eyedrops in the other eye as the sole anesthetic agent for surgery. Masking of the patient and surgeon was ensured by administration of a placebo gel and eyedrop as part of the regimen. Pain and discomfort were assessed via a 10-cm visual analog scale.

MAIN OUTCOME MEASURES

Subjective pain and discomfort perceived during surgery were assessed separately by the patient and the surgeon, and the need for any additional anesthesia was recorded.

RESULTS

A total of 14 subjects indicated mean pain and discomfort scores of 2.6 and 3.2 respectively, for lidocaine gel, and 5.3 and 6.2, respectively, for amethocaine drops (P = 0.01). The mean number of additional drops required by eyes randomized to lidocaine gel was 0.3, compared with 1.6 for amethocaine drops (P = 0.02).

CONCLUSIONS

In terms of pain control, lidocaine 2% gel alone is a superior topical anesthetic for one-stage adjustable suture strabismus surgery when compared with amethocaine 1% eyedrops.

Tolerance of patients and postoperative results: topical anesthesia for strabismus surgery

PURPOSE

To assess patient tolerance and the postoperative results of intraoperative adjustment of strabismus surgery under topical anesthesia.

METHODS

Twenty-four patients with strabismus underwent rectus muscle recession under topical anesthesia without the use of additional systemic analgesics and sedatives. Patient tolerance was estimated according to the sites of procedure. In addition, the angle of strabismus was measured 1 day, 6 weeks, and 1 year postoperatively.

RESULTS

Of the 24 patients identified (11 men and 13 women; mean age: 24 years), 16 had exotropia, 7 were esotropic, and 1 was hypertropic. During the operation, 17 patients never expressed any pain, and 7 patients complained of discomfort on muscle manipulation. Postoperatively, the success rate was 95.8% (23 patients) the first day after surgery, 79.2% (19 patients) after 6 weeks, and 70.8% (17 patients) after 1 year.

CONCLUSION

Intraoperative adjustment performed with the patient under topical anesthesia is recommended in all cooperative cases of strabismus surgery and is comfortable for 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.