Common causes of HR slowdown during operation under general anesthesia include circulation suppression by anesthetic agents, inadequate volume, vagus nerve stimulation during intubation, and parasympathetic nervous system reflex induced by traction stimulation during surgery. The slow HR caused by anesthetics and volume insufficiency generally occur slowly and accompanied by a sharp drop in blood pressure . The two cases are not consistent with the above situation. Both cases occurred about 30 min after induction, and the hemodynamics was stable. The effects of tracheal intubation, anesthetic, and vasoactive agents on the heart rate could be excluded. There was no abnormality in two patients’ ECGs before the operation. Their heart rate all dropped suddenly at the very moment of nasal stimulation and recovered quickly after stimulation was stopped and the administration of drugs or cardiac support. Therefore, the trigeminal nerve reflex was considered the cause of cardiac arrest.
The trigeminal nerve reflex (TCR) is a brainstem vagal reflex that occurs during stimulation or manipulation of the trigeminal nerve center or any of its peripheral branches. The typical clinical presentation is sudden bradycardia with or without hypotension, respiratory arrest, or gastrointestinal peristalsis . TCR is usually defined as a drop in HR and MABP above 20% of the baseline . Rhino-cardiac reflex is a type of TCR that can be triggered by touching any branch of the trigeminal nerve. The distribution of mechanical stimulation receptors in nasal mucosa is uneven in the whole nasal cavity, and the most sensitive sites to mechanical pressure are mainly located in the posterior nasal mucosa . TCR most commonly occurs in maxillofacial surgery and direct traction stimulation of the trigeminal nerve branches during neurosurgery. TCR has been reported occasionally in skull base surgery and maxillofacial surgery [5, 6]. It commonly happens in endoscopic sinus surgery with nasal packing or transsphenoidal approach for resection of pituitary adenomas . But only one case has been reported because of nasal disinfection . In this case, the patient’s heart rate dropped to 23 beats per minute when the surgeon performed nasal disinfection when 15 min after induction of anesthesia, and gradually returned to normal after administration of 0.5 mg atropine.
Previous studies have shown that the risk factors of TCR include children, hypoxemia, hypercapnia, water-electrolyte disorders, calcium channel blocker, opioids (especially fentanyl), preoperative use of β-receptor blockers . In our cases, both patients were in mechanical ventilation, which could exclude the influence of hypoxemia and hypercapnia. Besides, patients undergoing transsphenoidal resection of pituitary tumors were given opioids during anesthesia induction. These two patients were not exceptional. They also had sufficient depth of anesthesia. No β-receptor blockers and calcium channel blockers were used. So there was no apparent cause of cardiac arrest in either case.
Although previous studies have shown that stopping surgery during TCR generally restores heart rate. If conventional methods fail to do so, patients with sudden cardiac arrest need cardiac life support. It’s a huge challenge for anesthesiologists and surgeons. Disha Awasthi et al. reported a case of death due to cardiac arrest of TCR during nasal packing operation . Disha Awasthi et al. reported a case of death due to cardiac arrest of TCR during nasal packing operation in which vasoactive drugs were not used . So it is very important to prevent rhino-cardiac reflex. First, we need to pay enough attention to the rhino-cardiac reflex. The vital signs of the patient should be closely monitored not only during the operation but also during the preoperative nasal disinfection preparation. Also, we should be more vigilant to patients with primary heart disease, such as sinus bradycardia, atrioventricular block, coronary heart disease, and so on. Drugs such as dexmedetomidine, calcium channel blocker, and β-receptor blockers, etc. that slow down heart rate should be avoided. Topical anesthesia for nasal mucosa before nasal surgery may be an effective preventive measure. Studies have shown that local infiltration anesthesia or nerve block is considered to prevent and treat TCR . However, lidocaine combined with epinephrine did not prevent TCR in some studies . Preoperative administration of anticholinergic may be another way to prevent TCR, but no literature has confirmed that preoperative intramuscular administration of atropine or glycopyrrolate is an effective measure to prevent TCR in adult patients . In a systematic review of the effects of anesthesia on TCR, Cyrill Meuwly et al. found that the risk of TCR under shallow anesthesia was 1.2 times higher than deep anesthesia . And Robert W. Arnold et al. showed that deep anesthesia has a protective effect on the oculocardiac reflex and intraoperative bispectral index (BIS) monitoring can reflect the depth of anesthesia . Therefore, it is necessary to apply BIS monitoring. In anesthesia management, we should maintain an appropriate depth of anesthesia, ensure ventilation oxygenation, avoid anesthesia shallow, hypoxemia, and hypercapnia, maintain water-electrolyte balance, and avoid low blood volume and electrolyte disorder. These are effective measures to prevent rhino-cardiac reflex. When TCR happens, we need to stop nasal operation immediately, give anticholinergic drugs when necessary to raise heart rate, and perform cardiopulmonary resuscitation rapidly when cardiac arrest occurs.
In conclusion, although the occurrence of rhino-cardiac reflex is rare, we should pay attention to it in clinical anesthesia. It is necessary to know the risk factors for preventing rhino-cardiac reflex. Once the rhino-cardiac reflex occurs, we should take active and effective rescue measures to avoid serious complications.