Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Review Case Reports
Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex.
Three case reports are presented to illustrate the existence and importance of reflex bradycardic responses that can occur during maxillofacial surgical procedures. All three patients were healthy young adults undergoing operations which did not include any manipulation of orbital structures. After the patients had been anaesthetized for some time and were haemodynamically stable, profound bradycardia or ventricular asystole occurred suddenly in response to manipulations of the bony structures of the maxilla or mandible, or dissection of, or traction on, the attached soft tissue structures. ⋯ Alternative afferent pathways must exist via the maxillary and/or mandibular divisions, in addition to the commonly reported pathway via the ophthalmic division of the trigeminal nerve in the classic oculocardiac reflex. The efferent arc involves the vagus, regardless of which branch of the trigeminal nerve transmits the afferent impulses. All patients undergoing maxillofacial procedures should be monitored carefully for reflex bradycardia and ventricular asystole.
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Continuous pulse oximetry was performed on 173 adults after general anaesthesia for elective inpatient surgery, throughout their post-anaesthesia care unit (PACU) stay. Supplemental oxygen was administered for greater than or equal to 30 min after arrival and subsequently discontinued before discharge to the ward. The mean and minimum oxyhaemoglobin saturation (SpO2) after discontinuing oxygen were lower than those values achieved during oxygen administration and preoperatively (P less than 0.001). ⋯ Factors associated with hypoxaemia were: ASA physical status class; surgical duration greater than or equal to 90 min; and preoperative mean SpO2 less than 95%. Factors not associated with hypoxaemia were: age, sex, % ideal body weight, smoking history, preoperative minimum SpO2, premedication and type of surgery. In conclusion, after discontinuing supplemental oxygen in the PACU, hypoxaemia was common, difficult to detect clinically, and associated with ASA class, surgical duration and preoperative mean SpO2.
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Review Case Reports
Horner's syndrome and trigeminal nerve palsy following epidural anaesthesia for obstetrics.
While Horner's syndrome is a rare but occasionally reported side-effect of epidural block administered for labour, trigeminal nerve palsy has been described only once. The cases described in this report confirmed the benign nature of these neurological complications of epidurally administered anaesthetics which were not detrimental to fetal viability. The complications may be attributed to extensive cephalad spread of local anaesthetic, sometimes via unexplained routes and with surprisingly selective targeting effect (unilateral trigeminal nerve palsy). The atypical and unusually high cephalad spread of local anaesthetic in pregnant women at term is believed to be due to pregnancy-related altered anatomy and physiology of the epidural space.