The effect of anesthesia depth on the oculocardiac reflex in strabismus surgery

Abstract

The aim of this study was to investigate the effect of the bispectral index (BIS) guided depth of anesthesia to inhibition of the oculocardiac reflex (OCR) during pediatric strabismus surgery. Patients between the ages of 3 and 16 years who were scheduled for elective strabismus surgery were randomly assigned to two groups. In Group 1 (n: 32), the BIS values of the patients were maintained at <50; in Group 2 (n: 28), the BIS values of the patients were maintained at levels greater than or equal to 50 with 4-7 % desflurane in a 50 % O-air mixture by titrating the concentration during the surgery. The heart rates, presence of dysrhythmia, anticholinergic drug usage and the type of the operated extra ocular muscle were recorded. The incidence of OCR was 25 % in Groups 1 and 64.3 % in Group 2, (p < 0.05). Moreover, the incidence of OCR in group 2 was higher in medial rectus (MR) traction (78.9 %) than in lateral rectus (LR) traction (33.3 %) (p = 0.035), with no significant difference in Group 1 between MR (21.1 %) and LR (26.7 %) tractions (p = 0.83). We found that the lower BIS values are associated with the lower incidence of OCR in pediatric patients undergoing strabismus surgery. And our findings confirmed that the deeper anesthesia has a protective effect against the OCR.

Oculocardiac and Oculorespiratory Reflex during Strabismus Surgery under General Anesthesia with Laryngeal Mask Airway for Maintaining Spontaneous Respiration: A Retrospective Study

“…Retrobulbar block, premedication with anticholinergics, and gentle tension of muscle traction have been suggested to reduce the rate of OCR [11,15,16]. OCR is known to occur more frequently during MR surgery than during LR surgery, due to differences in the afferent pathways involved; it occurs less frequently under deeper anesthesia [5,7,11,12,17]. In our study, LR and MR did not show differences in the incidence of OCR, in either pediatric or adult patients; moreover, changes in HR during muscle traction were not associated with the depth of anesthesia.…”

“…The OCR is defined as a 10-20% reduction in heart rate (HR) from the baseline value or dysrhythmia [1,2,4]. The incidence of OCR ranged from 14% to 90% in previously published studies, depending on the definition used [1,[5][6][7].…”

“…Most cases of OCR resolve without treatment, but some patients exhibit cardiac arrest and, in very rare cases, sudden death [8,9]. The OCR is known to occur more often in pediatric patients, and in those undergoing surgery on medial rectus (MR) muscles, but it is less prevalent in pediatric patients when deeper anesthesia is induced [5,7,[10][11][12].…”

Key to Prevention of Bradycardia

“…One of the most frequent causes remains the anesthetic one. 2 , 3 Both general and spinal anesthesia can incite various cardiovascular perturbations; fortunately, most of them are moderate and do not require any specific treatment. The common mechanism of bradycardia and hypotension under SAB is postulated as sympathetic blockade (inhibition of cardioaccelator fibers T1–T4), decrease venous return and parasympathetic over-dominance leading to a decrease in right arterial pressure and pressure in the great veins as they enter the right atrium.…”

“… 1 In addition, surgical manipulation of different neural structures also causes similar changes. 2 , 3 Notably, majority of cases had been occurred just after initiation of the anesthesia or intraoperatively during surgical manipulation.…”