Asystole during Suspension Laryngoscopy: Case Report, Literature Review, and Prophylactic Strategies

Ultrasound-Guided Block of the Internal Branch of the Superior Laryngeal Nerve Reduces Postoperative Sore Throat Caused by Suspension Laryngoscopic Surgery: A Prospective Randomized Trial

Objective

Suspension laryngoscopy is commonly used in operative laryngology. Although it is efficient and minimally invasive in most cases, it can lead to postoperative sore throat (POST) and cough. Because of intensive stimulation by the rigid metal suspension laryngoscope, procedures must be implemented under general anesthesia. Together, these factors increase the possibility of postoperative complications. Blocking the internal branch of the superior laryngeal nerve (SLN) is useful in inhibiting the endotracheal intubation stress response. Thus, we evaluated the efficacy of ultrasound-guided block of the internal branches of the superior laryngeal nerve to improve postoperative complications.

Methods

A total of 64 patients was scheduled for elective laryngeal cancer resection, and suspension laryngoscopic surgery was performed under general anesthesia with a block of the internal branch of the superior laryngeal nerve (group iSLNB, n = 32) and without a block (group C, n = 32). Patients in group iSLNB received ultrasound-guided blocks of the internal branches of superior laryngeal nerve bilaterally (0.2% ropivacaine, 2 ml each side). The primary outcome measures were the incidence and severity of sore throat and cough assessed 0.5, 2, 6, and 24 h after tracheal extubation. The secondary outcome measures were heart rate and mean arterial pressure on arrival in the operating room (T0), at endotracheal intubation (T1), upon insertion of the suspension laryngoscope (T2), 5 min after insertion (T3), at tracheal extubation (T4), and 5 min after extubation (T5). Blood glucose levels were measured at T0, T3, and T5.

Results

The incidence and severity of POST and cough in the iSLNB (internal branch of superior laryngeal nerve block) group were significantly reduced within 6 h after extubation compared with those in the control group, regardless of whether swallowing was present (P < 0.05). Compared to the control group from T0–T5, except at T0, the iSLNB group had significantly lower heart rate and mean arterial pressure (P < 0.05). Compared to T0, at other time points, the heart rates in the control group were significantly increased (P < 0.05), and the mean arterial pressures at other time points in the iSLNB group were significantly lower than those at T0 (P < 0.05). The blood glucose levels at T3 and T5 in the iSLNB group were significantly reduced compared with those in the control group (P < 0.05).

Conclusion

Ultrasound-guided block of the internal branch of the superior laryngeal nerve might effectively ameliorate postoperative complications secondary to suspension laryngoscopic surgery with endotracheal intubation under general anesthesia and improve hemodynamic stability.

Clinical Trial Registration

https://www.chictr.org.cn, identifier: ChiCTR2100049801.

Sinus pause during nerve integrity monitoring tube insertion following anesthetic induction with a low-dose neuromuscular blocking agent: A CARE-compliant case report

RATIONALE

Nerve integrity monitoring (NIM) tubes are commonly used in thyroid surgery to prevent recurrent laryngeal nerve injury. To achieve the optimal electromyographic signal for NIM as intraoperative neural monitoring (IONM), the neuromuscular blocking agent (NMBA) dose should be low. The use of a low-dose NMBA increases the anesthetic and analgesic agent dose required to attenuate the laryngeal reflex during intubation. In addition, since the NMBA onset time is delayed, depending on the situation, anesthesia may become excessively deep or shallow before intubation.

PATIENTS CONCERN

A 51-year-old woman scheduled for thyroid lobectomy received 0.3 mg/kg of rocuronium. Three minutes later, when the NIM tube was inserted through the vocal cord, the patient's heart rate (HR) was undetectable for 2 seconds.

DIAGNOSIS

We suspected that the use of a high-dose anesthetic agent and remifentanil or the laryngocardiac reflex induced the sinus pause.

INTERVENTIONS

To maintain the anesthetic depth, we administered 6 vol% of desflurane. Because the patient's systolic blood pressure was 70 mmHg and HR was 30 beats/min, we discontinued the remifentanil infusion and administered 8 mg of ephedrine.

OUTCOMES

The patient's vital signs recovered to normal levels. Subsequently, there were no episodes of bradycardia or arrhythmia.

CONCLUSION

Sinus pause or severe bradycardia may occur due to the laryngocardiac reflex or the administration of a high-dose anesthetic and analgesic agent during tracheal intubation in patients who received a low-dose NMBA for IONM induction using an NIM tube. Anesthesiologists should be aware of these risks and take precautions to maintain adequate anesthesia, be prepared to administer vasoactive drugs to increase the blood pressure and HR if needed, and, if possible, intravenously administer lidocaine to attenuate the laryngeal reflex during intubation.