Bradycardia during cold ocular irrigation under general anaesthesia: an example of the diving reflex

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.

Cardiac arrest during cornea transplant surgery

This paper describes a case of cardiac arrest during femtosecond laser enabled penetrating keratoplasty (FLEK) in a young, healthy patient with no known cardiac risk factors and discusses the risk of cardiac arrest during intraocular surgery. A healthy 22-year-old man who underwent repeat FLEK under general anaesthesia developed bradycardia and subsequent cardiac arrest while open sky during surgery. After resuscitation and completion of the transplant surgery, the patient recovered and the graft has survived with excellent uncorrected visual acuity over 1 year after surgery. Understanding the risks of cardiac arrest and death during intraocular surgery is imperative to discussing the systemic risks of surgery during the preoperative informed consent.

Surgical repair of a tibial fracture in a two-week-old grey seal (Halichoerus grypus)

Objective: To report the successful management of a suspected infected tibial fracture in a common grey seal.

Study design: Case report.

Animal: Female common grey seal (Halichoerus grypus), 2 weeks old, 20 kg.

Methods: A closed, complete, transverse fracture of the left tibial distal diaphysis was debrided, reduced and stabilized using a string-of-pearls (SOP) locking plate covered with polymethylmethacrylate impregnated with gentamicin. Fracture of the ipsilateral fibula was left untreated. Postoperative radiographs were obtained immediately, and at 10 days, three weeks, and six weeks post-surgery, and a computed tomographic examination was performed 2.5 months post-surgery. A species-specific progressive rehabilitation programme was conducted.

Results: Bone healing of both fractures and absence of injury of the distal tibial growth plate were evident on the 2.5 month follow-up examination, and also full range-of-motion of the flipper was preserved and no lameness or difficulty with swimming and hunting were detected. On computed tomography, signs of chronic left coxofemoral and ilial wing trauma were incidentally detected. The seal was released three months postoperatively.

Conclusion: A transverse infected distal fracture of the tibia and fibula in a young common grey seal was successfully managed with the combination of single SOP plating of the tibia, local antibiotic release and a specific rehabilitation programme.

Clinical relevance: Surgical treatment of a long-bone fracture in a wild immature grey seal was successful with a combination of techniques adapted to the species.

Orbital Floor Fracture with Atypical Extraocular Muscle Entrapment Pattern and Intraoperative Asystole in an Adult

Extraocular muscle entrapment in a nondisplaced orbital fracture, although a well-known entity in pediatric trauma, is atypical in adults. It can present with a triad of bradycardia, nausea, and in rare cases, syncope, and result in severe fibrosis of damaged and incarcerated muscle. We present a case of muscle entrapment in a partially nondisplaced two-wall orbital fracture with accompanying preoperative bradycardia and intraoperative asystole in an adult.

Classification of potential risk factors for trigeminocardiac reflex in craniomaxillofacial surgery

PURPOSE

Trigeminocardiac reflex (TCR) in craniomaxillofacial surgery can lead to severely life-threatening situations. At least mild forms are probably much more common than the existing surgical literature suggests. Therefore, the aim of this presentation of cases and literature review was to evaluate the predisposing factors leading to a classification of risk factors for potential TCR and to give information concerning preventive measures and management procedures.

PATIENTS AND METHODS

All surgery reports from the Department of Cranio-Maxillofacial and Oral Surgery in the University Hospital in Zurich between 2003 and 2008 were searched for severe intraoperative cardiovascular complications, and a literature review was performed for publications concerning asystole or bradycardia during maxillofacial surgical procedures.

RESULTS

Three incidents were revealed in which severe bradycardia--in 2 cases followed by asystole--had occurred. All incidents were successfully managed.

CONCLUSION

All craniomaxillofacial surgeons involved in orbital surgery in general and in the treatment of midface fractures, eyelid surgery, and orthognathic procedures in particular should be aware of the possibility of the TCR and should be familiar with its prevention and therapy.

The trigemino-cardiac reflex: an update of the current knowledge

The trigemino-cardiac reflex (TCR) is clinically defined as the sudden onset of parasympathetic activity, sympathetic hypotension, apnea, or gastric hypermotility during central or peripheral stimulation of any of the sensory branches of the trigeminal nerve. Clinically, the TCR has been reported to occur during craniofacial surgery, manipulation of the trigeminal nerve/ganglion and during surgery for lesion in the cerebellopontine angle, cavernous sinus, and the pituitary fossa. Apart from the few clinical reports, the physiologic function of this brainstem reflex has not yet been fully explored. The manifestation of the TCR can vary from bradycardia and hypotension to asystole. From the experimental findings, the TCR represents an expression of a central reflex leading to rapid cerebrovascular vasodilatation generated from excitation of oxygen-sensitive neurons in the rostral ventro-lateral medulla oblongata. By this physiologic response, the systemic and cerebral circulations may be adjusted in a way that augments cerebral perfusion. This review summarizes the current state of knowledge about TCR.

Sinus bradycardia following saline irrigation of the pleural cavity during a video-assisted thoracoscopic surgery: A case report

A 43-year-old man underwent lipoma excision operation with video-assisted thoracoscopic surgery (VATS). Upon completion of the surgery, 20degrees C cold saline irrigation was performed to clean the surgical field. During this procedure, a sudden sinus bradycardia (33 beats/min) occurred. After interruption of the irrigation, the normal sinus rhythm returned spontaneously. With the suspicion that the cold saline could have induced the bradycardia, 40degrees C warm saline irrigation was performed; however, the repeat sinus bradycardia occurred again. The saline irrigation was stopped and the heart rate returned to normal. We conclude that although warm saline irrigation is a common practice after surgical procedures to ensure hemostasis and to clean the surgical field, it may induce profound sinus bradycardia.

Bradycardia and Sinus Arrest Following Saline Irrigation of the Brain During Epilepsy Surgery

Adverse cardiac events during the intraoperative period are life-threatening. The authors report three episodes of severe bradycardia and sinus arrest that occurred in a patient undergoing anterior temporal lobectomy and amygdalo-hippocampectomy for the treatment of epilepsy. The first episode occurred during resection of the amygdala; the other two episodes were observed during subsequent irrigation of the exposed brain structures, most likely the brain stem structures, because of a rent that the surgeon had deliberately made into the basilar cistern for better anatomic appreciation of the structures to be excised. The patient responded well to treatment with no adverse outcomes. The probable mechanisms leading to this event are discussed; the authors excluded insular cortex stimulation, the effects of the anesthetic drugs used, and venous air embolism as a cause of bradycardia and sinus arrest. The amygdala resection was the most likely cause of the first episode of bradycardia; the second episode of bradycardia and sinus arrest occurred because of inadvertent stimulation of brain structures by the high temperature (42 degree C) of the saline used for irrigation. To counter its effects, saline irrigation at room temperature (20 degree C) was started, and this caused the third episode of bradycardia, most likely because of "temperature shock" of the exposed brain. Prompt communication with the surgical team and vigilance are crucial for the appropriate management of such an incident, which may pose a threat to life. Avoiding irrigation of the exposed brain with high-temperature saline may prevent such an incident.