Superior laryngeal nerve block: an anatomical study comparing two techniques

Ultrasound-guided medial branch of the superior laryngeal nerve block to reduce peri-operative opioids dosage and accelerate patient recovery

BACKGROUND

To explore whether the medial branch block of superior laryngeal nerve can reduce the stress response of patients undergoing intubation and further reduce the dosage of opioids.

METHODS

80 patients undergoing gynecological laparoscopic surgery were selected, and randomly divided into 4 groups. All patients in the experimental groups received bilateral internal branch of superior laryngeal nerve block and transversus abdominis plane block. But the dosage of sufentanil used for anesthesia induction in the group A, B, and C was 0.4, 0.2, and 0μg/kg, respectively. Group D do not underwent supralaryngeal nerve block and the dosage of sufentanil was 0.4μg/kg. The heart rate (HR) and mean arterial pressure(MAP) were recorded at the time of entering the operating room(T1), before intubation after induction(T2), immediately after intubation(T3), 5min after intubation(T4), before extubation(T5), immediately after extubation(T6), 5min after extubation(T7). We also recorded the stay time in the recovery room, the number of cases of postoperative sore throat, the number of cases of nausea and vomiting, the first intestinal exhaust time, the length of hospital stay after operation.

RESULTS

The HR of group A, C and D at T3 was significantly higher than that at T2(P < 0.01), while the HR of group B had no significant change. The HR of group A, C and D at T4 was lower than that at T3(P < 0.01), while the HR of group B had no obvious change. The HR of group C and D at T3 was significantly higher than that at T1 (P < 0.01). The MAP of group A and D at T4 was significantly lower than that at T1 (P<0.001). The first postoperative intestinal exhaust time in group A, B and C was significantly shorter than that in group D. The length of hospital stay after operation in group B and C was shorter than that in group D.

CONCLUSIONS

Ultrasound-guided superior laryngeal nerve block combined with 0.2μg/kg sufentanil can reduce the intubation reaction, have better hemodynamic stability, reduce the first postoperative intestinal exhaust time and postoperative hospital stay, thereby accelerating the postoperative recovery of patients.

Modified anterior approach versus traditional posterior approach for ultrasound-guided superior laryngeal nerve block in awake endotracheal intubation: a randomized non-inferiority clinical trial

STUDY OBJECTIVE

This study was undertaken to compare the effect of the modified ultrasound-guided anterior superior laryngeal nerve block (SLNB) with the traditional ultrasound-guided posterior SLNB in providing intubation conditions during awake tracheal intubation (ATI) in patients without difficult airway.

DESIGN

Randomized, assessor-blind. Registration number: ChiCTR2200058086.

SETTING

West China Hospital of Sichuan University, Chengdu, China.

PATIENTS

104 patients aged 18-65 years, of American Society of Anesthesiologists status I-III, posted for elective general surgery with general endotracheal anesthesia.

INTERVENTIONS

The patients were randomized into two groups (modified group, n = 52; traditional group, n = 52). Modified anterior SLNB or traditional posterior SLNB was performed under ultrasound guidance.

MEASUREMENTS

The primary outcome was the proportion of acceptable intubation condition (AIC), which was analyzed in both per-protocol (PP) and intention-to-treat (ITT) populations. The prespecified non-inferiority margin was -4.8%. Secondary outcomes included intubation success rate on the first attempt, hemodynamic parameters during ATI, time taken for airway anesthesia and intubation, recall of intubation, patient perception of comfort, and incidence and severity of postoperative complications.

MAIN RESULTS

In the PP population, the proportion of AIC in the modified group was 49/49 (100%) and that in the traditional group was 49/49 (100%), absolute difference 0, lower limit of 1-sided 95% CI, -0.3%. In the ITT population, the primary outcomes in the modified and traditional group were 52/52 (100%) and 51/52 (98.1%), respectively, with an absolute difference of 1.9% and a lower limit of 1-sided 95% CI of -1.2%. The non-inferiority of modified ultrasound-guided anterior SLNB was confirmed in both populations.

CONCLUSIONS

Among adults without difficult airways during videolaryngoscope-assisted ATI, the modified ultrasound-guided anterior SLNB, compared to the traditional posterior approach, showed a statistically non-inferior effect in terms of providing AIC.

Superior Laryngeal Nerve Block in Transcutaneous Vocal Fold Injection: A Pilot Study

OBJECTIVES

Topical lidocaine remains the mainstay for anesthesia in transcutaneous vocal fold injection (VFI). While using topical lidocaine, laryngologists sometimes encounter uncontrolled reflexes or poor compliance. Superior laryngeal nerve block (SLNB) provides deep and rapid anesthesia on the larynx above the vocal folds and abolishes the glottic closure reflex. Herein, we present a pilot study to evaluate the feasibility and safety of SLNB for transcutaneous VFI and explored its usefulness.

METHODS

Fifty-nine patients were prospectively anesthetized with SLNB during transcutaneous VFI for unilateral vocal fold paralysis. In the SLNB group, 0.5 to 1 mL of 2% lidocaine was infiltrated on bilateral SLNs through the thyrohyoid membrane. As the control group, we included previous 47 patients who underwent VFI with topical lidocaine. In the control group, 10% lidocaine spray was applied to the laryngopharyngeal mucosa. Demographic data, laryngeal exposure, patient compliance, procedural interruption, and complications were investigated. Patient compliance was evaluated based on the frequency of cough and swallowing during VFI procedures.

RESULTS

SLNB enabled endoscopic contact on the epiglottis and pharyngeal wall without gag reflex and provided good exposure of the procedure field on the vocal folds. In the SLNB group, the laryngeal exposure is significantly better than in the control (P = 0.005). The frequency of cough and swallowing was significantly lower in the SLNB group than in the control (P < 0.001). The number of procedural interruptions was lower in the SLNB group than in the control (P < 0.001). There was no acute or delayed complication related to SLNB such as bleeding, hematoma, delayed sensory/swallowing problems, or unscheduled hospital visits.

CONCLUSIONS

SLNB might be safe and effective for anesthesia in transcutaneous VFI. SLNB could be a good anesthetic option for patients with poor compliance despite the sufficient application of topical lidocaine.

LEVEL OF EVIDENCE: 4

Airway nerve blocks for awake tracheal intubation: A meta-analysis of randomized control trials and trial sequential analysis

STUDY OBJECTIVE

This systematic review and meta-analysis aimed to assess the superiority of airway nerve blocks versus airway anesthesia without nerve blocks for awake tracheal intubation (ATI).

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING

All studies that assessed the superiority of airway anesthesia technique for awake tracheal intubation were searched in PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase and Chinese databases (including China National Knowledge Infrastructure, Wanfang database, and VIP databases) and trial registry databases from their inception to December 2022.

PATIENTS

Adult patients included in randomized controlled trials comparing airway anesthesia with or without airway nerve blocks for ATI.

INTERVENTIONS

Airway nerve (including superior laryngeal nerve, glossopharyngeal nerve, or recurrent laryngeal nerve) blocks for ATI.

MEASUREMENTS

The primary outcome was the intubation time. Secondary outcomes were quality of intubating conditions (including patient reaction to placement of the flexible scope and tracheal tube, coughing and gagging, and patient satisfaction) and overall complications during ATI.

MAIN RESULTS

Fourteen articles with 658 patients were identified for analysis. When compared with airway anesthesia without nerve blocks, airway nerve blocks significantly reduced intubation time (standardized mean difference [SMD] -2.57, 95% CI -3.59- -1.56, p < 0.00001), improved anesthesia quality of ATI with higher no reaction to placement of the flexible scope and tracheal tube (relative risk [RR] 9.87; 95% CI 4.10-23.75, p < 0.00001), lower cough or gag reflex during intubation (RR 0.35, 95% CI 0.27-0.46, p < 0.00001), higher excellent patient satisfaction rate (RR 1.88, 95% CI 1.05-3.34, p = 0.03), and lower overall complications (RR 0.29, 95% CI 0.19-0.45, p < 0.00001). The overall quality of evidence was moderate.

CONCLUSIONS

Based on current published evidence, airway nerve blocks provide better airway anesthesia quality for ATI with a shorter intubation time, better intubation conditions including higher no reaction to placement of the flexible scope and tracheal tube, lower cough or gag reflex during intubation, higher excellent patient satisfaction, and lower overall complications.

Comparison of modified anterior and traditional posterior accesses for ultrasound-guided superior laryngeal nerve block in awake endotracheal intubation: study protocol for a randomised non-inferiority clinical trial

INTRODUCTION

Awake tracheal intubation (ATI) involves placing a tracheal tube in an awake, spontaneously breathing patient. Superior laryngeal nerve block (SLNB) can effectively abolish the glottic closure reflex, and blunt the sensation of the structures above the cords. A method that consists of SLNB along with translaryngeal injection (TLI) can provide satisfactory anaesthesia and intubating conditions. We present a novel modified access of SLNB, ultrasound (US)-guided anterior SLNB, to aid awake videolaryngoscopes-assisted endotracheal intubation in adult elective surgery patients, and we compare the effectiveness and safety to traditional US-guided posterior SLNB.

METHODS AND ANALYSIS

A total of 100 adult elective surgery patients requiring general endotracheal anaesthesia will be randomly assigned to the modified group (modified US-guided anterior SLNB) or the traditional group (traditional US-guided posterior SLNB). After SLNB, all participants will be performed with TLI. The primary outcome is the proportion of acceptable intubation conditions based on intubation scores. Secondary outcomes include: (a) the first-attempt intubation success rate, (b) haemodynamic changes during ATI, (c) time taken for airway anaesthesia and intubation, (d) recall of intubation, (e) participant perception of comfort during intubation, (f) perioperative complication rate. This report describes the study design of this randomised controlled trial.

ETHICS AND DISSEMINATION

The study protocol has been approved by an ethical committee of the West China Hospital (Sichuan University), and registered at the Chinese Clinical Trials Register (www.chictr.org.cn). Results will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2200058086.