Association of oculocardiac reflex and postoperative nausea and vomiting in strabismus surgery in children anesthetized with halothane and nitrous oxide

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.

Effect of dexmedetomidine on prevention of postoperative nausea and vomiting in pediatric strabismus surgery: a randomized controlled study

BACKGROUND

Postoperative nausea and vomiting (PONV) are common side-effects following strabismus surgery. The present study aimed to compare the effects of different doses of dexmedetomidine (DEX) on PONV incidence in pediatric patients undergoing strabismus surgery.

METHODS

In this prospective randomized double-blinded study, 126 pediatric patients undergoing strabismus surgery were randomized into one of three groups: Placebo group, normal saline; DEX1 group, 0.3 μg/kg dexmedetomidine, and DEX2 group, 0.5 μg/kg dexmedetomidine. Oculocardiac reflex (OCR) events were recorded during surgery. PONV or postoperative vomiting (POV) was recorded for 24 h in the ward. Pediatric anesthesia emergence delirium (PAED) scale and emergence agitation (EA) scale were recorded in the recovery room.

RESULTS

Intraoperative OCR was significantly reduced in DEX2 group (42%) as compared to that of Placebo group (68%) (p = 0.0146). During the first 24 h post-op, the overall incidence of PONV was significantly lower in DEX2 group (10%) than that of Placebo group (32%) (p = 0.0142). There was no significant difference in POV among the three groups. PAED or EA scores among the three groups were similar during recovery time.

CONCLUSION

Dexmedetomidine (0.5 μg/kg) reduced OCR and PONV without lengthening extubation time or recovery time in pediatric patients undergoing strabismus surgery.

TRIAL REGISTRATION

The trial was prospectively registered before patient enrollment at Chinese Clinical Trial Registry (Clinical Trial Number: ChiCTR1800020176, Date: 12/19/2018).

The oculocardiac reflex during strabismus surgery: its relationship to preoperative clinical eye findings and subsequent postoperative emesis

PURPOSE

To compare the occurrence of significant bradycardia due to the oculocardiac reflex (OCR) during strabismus surgery and its relationship to preoperative clinical eye findings and subsequent development of postoperative emesis.

METHODS

The medical records of consecutive patients who underwent strabismus surgery August 2006 to June 2009 were retrospectively reviewed. OCR was defined as presence of dysrhythmia or a sudden heart rate decrease ≥ 20% after traction on the extraocular muscle. OCR incidence was compared between the first, second, and third (if any) extraocular muscles in patients who had multiple-muscle strabismus surgery and also between specific muscles (eg, medial rectus vs lateral rectus muscle). Associations with OCR were compared for different strabismus types. Vomiting was considered postoperative if it occurred before discharge of the patient at noon on the day following surgery. Risk factors for OCR and postoperative vomiting were evaluated by logistic regression analysis.

RESULTS

A total of 111 records were reviewed; 41 patients (37%) experienced OCR. Incidence of OCR and absence of OCR during traction of the first muscle were significantly associated with events during traction of the second (χ(2) = 36.681, P < 0.001) and third muscles (Fisher exact test, P = 0.030). The best predictors of OCR were the absence of fine stereopsis and a larger number of surgically treated muscles. Of the 111 patients, 30 (27%) who had postoperative vomiting, the best predictors were female sex and young age.

CONCLUSIONS

In our cohort, patients experiencing intraoperative OCR when the first extraocular muscle was manipulated during multiple-muscle strabismus surgery were likely to experience it again during traction of additional muscles. More severe postoperative vomiting was common in these patients. OCR was associated with the preoperative absence of fine stereopsis.

Anesthetic management for pediatric strabismus surgery: Continuing professional development

PURPOSE

Strabismus surgery is one of the most common pediatric ophthalmic procedures. The purpose of this continuing professional development module is to update physicians on the anesthetic considerations of pediatric patients undergoing strabismus surgery.

PRINCIPAL FINDINGS

The preoperative assessment is important, as patients undergoing strabismus surgery may have an associated neuromuscular disorder, congenital syndrome, or cardiac disease. Malignant hyperthermia is no longer considered as being an issue associated with strabismus. The laryngeal mask airway is used frequently and has been shown as being associated with a low incidence of complications in strabismus surgery. The anesthesia technique can be adapted to decrease the incidence of the oculocardiac reflex and the oculorespiratory reflex, and the use of anticholinergic prophylaxis remains debatable. Since patients are at high risk for postoperative nausea and vomiting (PONV), combination anti-emetic therapy is recommended using dexamethasone and ondansetron. Metoclopramide was not found to provide additional benefit when combined with other anti-emetics. Droperidol is effective, but there remains a black box warning for dysrhythmias. Effective analgesics in this patient population include acetaminophen, nonsteroidal anti-inflammatory drugs, peribulbar blocks, and subtenon blocks. Topical tetracaine drops have demonstrated mixed results, and topical nonsteroidal anti-inflammatory drops were found not to be effective. The use of opioids should be minimized due to the increased incidence of PONV.

CONCLUSIONS

To provide optimal care for the pediatric patient undergoing strabismus surgery, it is important to understand the unique anesthetic considerations for strabismus surgery and to appreciate how each decision regarding the anesthetic technique can alter these considerations.