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

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, Jun 1993

A case of bradycardia is reported which was precipitated by cold normal saline applied to the eye during general anaesthesia. The history and physiology of the diving reflex is discussed and we believe that these data suggest that this patients brady-cardia was induced by the diving reflex, and not by the oculocardiac reflex.

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

George A. Arndt 0 1 M. Christine Stock ~ 0 0 From the Departments of Anesthesiology,Universityof WisconsinClinical ScienceCenter 1 Madison , Wisconsinand Emory UniversitySchool of Medicine ,l"Atlanta, Georgia . Department of Anesthesiology , Universityof Wisconsin Clinical ScienceCenter , B6/387 CSC, 600 Highland Avenue, Madison , WI 53792 . Acceptedfor publication 22nd February , 1993 A case o f bradycardia is reported which was precipitated by cold normal saline applied to the eye during general anaesthesia. The history and physiology o f the diving reflex is discussed and we believe that these data suggest that this patient's bradycardia was induced by the diving reflex, and not by the oculocardiac reflex. Nous rapportons un cas bradycardie provoquOepar l'application oculaire de solut~ physiologique froid. La discussion porte sur I'histoire et la physiologie du r~flexe de plongke. Nous croyons que ces donn~es supportent notre hypoth~se d'un bradycardie provoqu~e par le r~flexe de plong~e et non par le rdflexe oculocardiaque. - The oculocardiac reflex, well-described in the anaesthesia literature, results from a variety of stimuli including traction on the extraocular muscles, ocular manipulation, pressure or traction on the globe, or pressure applied to an empty orbit. I-5 However, even in the absence of these stimuli, cold ocular irrigation may elicit bradycardia induced by the diving reflex. The oculocardiac reflex is active in awake and anaesthetized subjects and is manifested by a variety of dysrhythmias, which include bradycardia, bigeminy, ectopic beats, nodal rhythm, and asystole. 6-8 The diving reflex may have similar physiological mechanisms and clinical significance. Case report A 60-yr-old woman was scheduled for left scleral buckle. Her past medical history was unremarkable, with no history of cardiovascular, neurological, renal, haematopoetic, endocrinological, or pulmonary disease. She did not smoke or use alcohol or take medications. Previously she had undergone two gynaecological operations during uncomplicated general anaesthesia. Physical examination was normal and there was no syncopal history. The preoperative laboratory results were normal, with haemoglobin and haematocrit 13.7 gin. dl-I and 39.7%, respectively. The preoperative 12-lead electrocardiograph (ECG) showed normal sinus rhythm with no suggestion of ischaemia. The vital signs the day before surgery were blood pressure 140/80 mmHg, pulse 88 beats, min -I and respirations 18 breaths, min -x. She weighed 55.7 kg and was 155 cm tall. Sixty minutes before her operation, the patient received diazepam I0 mg po, and a peripheral /v infusion of lactated Ringer's solution with 5% dextrose. Intraoperative monitoring included a fivedead continuous ECG which displayed limb lead II. After preoxygenation, anaesthesia was induced with thiopentone 275 mg and lidocaine 100 mg /v. Tracheal intubation was facilitated with succinylcholine 80 mg/v, and was easily accomplished. Anaesthesia was maintained with 1% isoflurane and 50% nitrous oxide in oxygen. Ventilation was controlled so that end-tidal carbon dioxide concentration was 36 mmHg. Relaxation was maintained with 5 mg /v vecuronium bromide. Vital signs did not vary by more than 5% during anaesthetic induction and maintenance up to this point. Fifteen minutes after induction, a watertight drape was placed around the left eye and the surgeon began to irrigate the eye liberally with sterile, room-temperature, normal saline. The temperature of the saline was 19.7~ The heart rate promptly decreased from 78 beats, min -1 with normal sinus rhythm to a sinus bradycardia of 30 beats, min-l. The surgeon stopped the irrigation and atropine 0.4 mg was given/v. The heart rate increased to 90 beats- min -I with normal sinus rhythm. The episode of bradycardia was short-lived (lasting approximately 20 sec), and quickly returned to an acceptable rate with atropine administration and cessation of irrigation. During the episode, no ocular stimulus was present other than application of cold saline; the surgeon had placed no retractors, instruments, retracted the eye muscles or placed pressure on the eye. Pulse oximetry revealed that the patient was not hypoxic during the episode, neither did she become hypotensive, the blood pressure remaining at 110/80 as measured by auscultation before, during and after the episode. After the heart rate stabilized, the surgeon proceeded cautiously with ocular irrigation which caused no further change in vital signs. We were unable to record a rhythm strip during the episode. The drape was found to form a watertight seal, preventing the irrigation solution escaping from the field. The remainder of anaesthesia was uneventful. The vital signs remained stable. At the end of the procedure muscle relaxation was reversed with glycopyrrolate and neostigmine with no change in heart rate. Emergence was uncomplicated and the tracheal tube was removed when the patient opened her (...truncated)


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George A. Arndt, M. Christine Stock. Bradycardia during cold ocular irrigation under general anaesthesia: an example of the diving reflex, Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 1993, pp. 511-514, Volume 40, Issue 6, DOI: 10.1007/BF03009732