Reduction of oculocardiac reflex with Tetracaine eye drop in strabismus surgery.

INTRODUCTION: Recently, to reduce the incidence of oculocardiac reflex (OCR) in strabismus surgery, retrobulbar block and anticholinergic drugs or local anesthesia are also used. The present study evaluated the effects of Tetracaine eye drop as a topical nerve blocker on OCR during strabismus surgery. METHODS AND MATERIALS: In this randomized trial, 70 strabismus surgery candidates were randomly divided into placebo or synthetic teardrop (E) and Tetracaine eye drop (T) groups, so 3 drops of each solution were dropped in four directions of patients' eye immediately after applying anesthesia and before surgery. The incidence and severity of OCR during the stages of muscle release and incision (cutting), hemodynamic changes, the required time for OCR recovery and atropine dose were assessed. RESULTS: OCR was more seen in release phase compared to cutting phase. There were no significant differences between two group regarding the incidence and severity of OCR in the release phase (p > 0.05), but the incidence and severity of OCR in the cutting phase was more in group E than group T (p = 0.02, for both). The duration of OCR improvement (p-value = 0.74) and Atropine consumption (p-value = 0.92) did not differ between the groups. CONCLUSION: Tetracaine eye drop only reduces the incidence and severity of OCR during the incision stage of strabismus surgery.

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.

[The oculocardiac reflex in blepharoplasties]. / Der okulokardiale Reflex bei Blepharoplastiken.

The oculocardiac reflex (OCR) is a well-known phenomenon in ophthalmic surgery, but is rarely described in aesthetic blepharoplasty surgery. It was first mentioned in 1908 by Ascher and Dagnini. Since then, ophthalmologists and anaesthesiologists have regarded the onset of the oculocardiac reflex as a significant intraoperative problem, which is undermined by several case reports that describe dysrhythmias which have haved caused morbidity and death. Per definition the OCR is caused by ocular manipulation and involves intraoperative bradycardia by a change of 20 beats/minute compared to the preoperative heart rate or any dysrhythmia during the manipulation via a trigeminal-vagal-mediated reflex arc. Having operated on a 48-year-old, healthy woman in our clinic, who underwent a cardiac arrest during the blepharoplasty procedure, followed by a successful resuscitation, we investigated the onset of the OCR in our blepharoplasty patients within the last 3 years. The onset of the OCR was noted in 22 of 110 (20 %) blepharoplasty patients, mainly affecting younger, low-weighted patients operated under local anaesthesia. Awareness and treatment of this potentially life-threatening oculocardiac reflex are necessary. In most cases the onset of the reflex may be avoided by a gentle operation technique and by refraining from severe traction to the muscle or fat pad. The best treatment of a profound bradycardia caused by the OCR is to release tension to the muscle or fat pad in order to permit the heart rate to return to normal. Intraoperative monitoring is of utmost importance.

The human heart rate response profiles to five vagal maneuvers.

Healthy teens and adults performed four vagotonic maneuvers. A large series of strabismus surgery patients had deliberately quantified tension on extraocular rectus muscles during general anesthesia. The mean bradycardia was greatest for diving response (apneic facial exposure to cold) and Valsalva maneuver and least for pressure on the globe and carotid sinus massage. Bradycardia occurred for every subject for the non-surgical maneuvers, however, extraocular muscle tension frequently caused no change in heart rate or even tachycardia. The inter-subject variance in percent heart rate change was greatest for surgical oculocardiac reflex. Of the rectus muscles, the inferior caused the most bradycardia while the lateral caused the least. The percent oculocardiac reflex was not age dependent. Occasional patients demonstrated profound bradycardia with strabismus surgery. Of these maneuvers, diving response has theoretical advantage in treating paroxysmal atrial tachycardia. The human cardiac vagal efferent was stimulated by several carefully controlled maneuvers resulting in wide inter-maneuver differences in bradycardia magnitude. The greatest intra-maneuver variability occurred with surgical oculocardiac reflex.

Lack of global vagal propensity in patients with oculocardiac reflex.

BACKGROUND: Profound bradycardia during ophthalmic surgery is a rare but potentially serious event. Little is known about the predictability of the oculocardiac reflex. METHODS: Four vagotonic maneuvers were performed on six patients who had profound oculocardiac reflex (3- to 10-second asystole) during eye surgery, the results of which were compared with 30 previously studied control subjects. Electrocardiographs were monitored during the following vagotonic maneuvers: diving response (apneic facial immersion), Valsalva maneuver, ocular compression, and carotid sinus massage. RESULTS: The degree of heart rate slowing as a result of diving response, Valsalva maneuver, and, notably, ocular compression did not differ when these patients were compared with the 30 previously studied control subjects. Carotid sinus massage produced significantly (P = 0.01) more bradycardia in the six patients (mean +/- standard deviation, -24% +/- 6%) than in the 30 control subjects (-12% +/- 7%). The heart rate response to pressure on the eyes did not correlate with prior intraoperative oculocardiac reflex. CONCLUSION: The discrepancy in heart rate sensitivity between surgical extraocular muscle tension and ocular compression may be due to different sensory receptors and brain stem processing for the trigeminally mediated oculocardiac reflex. Carotid sinus massage may help predict low heart rates during eye surgery.

[The oculocardiac reflex during ocular operation under various anesthesia].

100 patients underwent extraocular muscle tugging of 154 extraocular muscles during ocular operations to study the oculocardiac reflex. The results showed that retrobulbar block was effective in minimizing occurrence of the reflex whether under general or local anesthesia.