Anatomical study applied to anesthetic block technique of the superior laryngeal nerve

The Efficacy of Ultrasound-Guided Superior Laryngeal Nerve Block as an Adjuvant to General Anesthesia during Suspension Laryngoscopy Vocal Cord Polypectomy

Background

In the current study, we assessed the effect of the ultrasound-guided internal branch of the upper laryngeal nerve (USG-guided iSLN) block combined with general anesthesia on perioperative sore throat (POST), cough, hoarseness of voice, intraoperative hemodynamic changes, and the quality of early recovery for the patients undergoing suspension laryngoscopy vocal cord polypectomy (SLVCP).

Methods

This was a randomized controlled trail. Eighty patients, aged from 18 to 70 years old, ASA I ∼ II, scheduled for polypectomy of the vocal cord by using a laryngoscope, were randomized into 2 groups (n = 40 each) using a random number table. Patients in group C received general anesthesia (GA), whereas those in group S received USG-guided iSLN block bilaterally (37.5 mg of 0.375% ropivacaine, 5 ml each side) combined with GA. The primary outcome was the quality of patients' recovery using the Quality of Recovery Questionnaire (QoR-9). The secondary outcomes were postoperative cough, sore throat, hoarseness of voice, and hemodynamic changes in both groups at corresponding time points. The adverse reactions such as postoperative chocking, or aspiration, and dyspnea was recorded as well.

Results

The QoR-9 scores of patients in group C were lower than those of group S at time points of D1∼D2 (P < 0.05). Patients in group S had a significantly lower incidence of perioperative cough than those in group C in the early postoperative period (1 hour after extubation) (P < 0.05), the scores of sore throat were lower in group S than those in group C (P < 0.05), the incidence of postoperative hoarseness was increased in group S than that in group C at the time points of 30 min, 2 h, and 4 h after extubation (P < 0.05); however, the incidence of postoperative hoarseness was decreased in group S than that in group C at the time point of 24 h after extubation (P < 0.05). MAP and HR of group S was lower than those of group C at time points of T1∼T4 (P < 0.05). No serious adverse events were observed in both groups.

Conclusion

The study found that the application of ultrasound guided superior laryngeal nerve block combined with general anesthesia for the patients undergoing SLVCP could effectively promote the quality of early recovery. Clinical trial registration: This trial is registered with NCT05309174. The date of registration: March 12th 2021.Trial registry name: The Study of Bilateral Upper Laryngeal Nerve Block for Supporting the Removal of Vocal Cord Polyps Under Laryngoscopy.

Airway Anesthesia for Awake Tracheal Intubation: A Review of the Literature

Airway topicalization is frequently utilized by anesthesiologists to facilitate open airway procedures, aid intubation for a difficult airway, and prevent adverse respiratory events. This review article summarizes the techniques available for airway topicalization for a patient who is deemed to be difficult to intubate. We focus on the indications for use, local anesthetic maximum dosages and safety profiles, sedation techniques, and trials and pitfalls during airway topicalization for difficult intubation.

Ultrasound-guided superior laryngeal nerve block assists in anesthesia for bronchoscopic surgical procedure: A case report of anesthesia for rigid bronchoscopy

INTRODUCTION

Evolving techniques in the field of therapeutic bronchoscopy have led to the return of rigid bronchoscopy in the treatment of complex central airway disease. Rigid bronchoscopy is typically performed under general anesthesia because of the strong stimulation caused by metal instruments. Anesthesia for rigid bronchoscopy is challenging to administer because anesthesiologists and interventionists share the same working channel: the airway. Previously reviewed anesthetic methods are used primarily for short procedures. Balanced anesthesia with ultrasound-guided superior laryngeal nerve (SLN) block and total intravenous anesthesia might provide anesthesia for a prolonged procedure and facilitate patient recovery.

PATIENT CONCERNS

A patient with obstructed endobronchial stent was referred for therapeutic rigid bronchoscopy, which requires deeper anesthesia than flexible bronchoscopy. There were concerns of the stronger stimulation of the rigid bronchoscopy, lengthy duration of the procedure, higher risk of hypoxemia, and the difficulty of mechanical ventilation weaning after anesthesia due to the patients co-morbidities.

DIAGNOSIS

A 66-year-old female patient presented with a history of breast cancer with lung metastases. Right main bronchus obstruction due to external compression of lung metastases was relieved through insertion of an endobronchial stent, but obstructive granulation developed after 4 months. Presence of the malfunctioning stent caused severe cough and discomfort. Removal of the stent by using a flexible bronchoscope was attempted twice but failed.

INTERVENTIONS

Regional anesthesia of the upper airway through ultrasound-guided SLN block combined with intratracheal 2% lidocaine spray was performed to assist in total intravenous anesthesia (TIVA) during rigid bronchoscopy.

OUTCOMES

The patient maintained steady spontaneous breathing throughout the procedure without laryngospasm, bucking, or desaturation. Emergence from anesthesia was smooth and rapid after propofol infusion was discontinued. The surgery lasted 2.5 hours without discontinuity, and no perioperative pulmonary or cardiovascular complications were noted.

CONCLUSION

Ultrasound-guided SLN block is a simple technique with a high success rate and low complication rate. Application of SLN block to assist TIVA provides sufficient anesthesia for lengthened therapeutic rigid bronchoscopy without interruption and facilitates patient recovery.

Comparison of airway blocks versus general anaesthesia for diagnostic direct laryngoscopy: A randomised comparative trial

Background and Objective:

Direct rigid laryngoscopy and general anaesthesia (GA) are associated with many problems. Regional anaesthesia/airway blocks can be considered as safer and easier alternative techniques especially among old and comorbid patients and conditions with difficult airways as well. The present study was conducted to compare efficacy of regional anaesthesia/airway blocks versus general anaesthesia for diagnostic direct (rigid) laryngoscopy.

Methods:

A randomised comparative trial was conducted among patients undergoing diagnostic direct laryngoscopy (DLS) for perilaryngeal lesions. Eighty patients of either sex aged between 20and 80 years and categorised as American Society of Anesthesiologists(ASA) grade I, II, III or IV were divided under two groups of 40 patients each. Group-A underwent DLS with airway blocks and group-B underwent DLS under GA. Haemodynamic parameters and analgesia were interpreted statistically.

Results:

Difference in haemodynamic stability and quality of post- operative analgesia were primary outcomes. Patients in group-A were observed to be haemodynamically more stable as compared to group-B patients with statistically significant P value (0.003 and 0.016 for pulse rate at 6 min and mean arterial pressure at 4 min, respectively). In postoperative period, group-A patients were found to be more comfortable (lower VAS scores) than group-B patients with P value (0.040, 0.043, 0.044 at 0, 5, 15 min, respectively).

Conclusion:

Regional airway blocks provide better haemodynamic stability and postoperative analgesia than general anaesthesia.

Comparison of Intubating Conditions using Fentanyl plus Propofol Versus Fentanyl plus Midazolam during Fiberoptic Laryngoscopy

INTRODUCTION

Awake nasal or oral flexible fiberoptic intubation is the airway management technique of choice in known or anticipated difficult airway, unstable cervical fracture, limited mouth opening (as in temporomandibular joint disease), mandibular-maxillary fixation and severe facial burns. Both optimal intubating condition and patient comfort are important for fiberoptic intubation. Optimal intubating conditions provided by an ideal sedation regimen would ensure haemodynamic stability, patient comfort, attenuation of airway reflexes and amnesia.

AIM

To compare the intubating conditions using fentanyl plus propofol versus fentanyl plus midazolam during fiberoptic laryngoscopy.

MATERIALS AND METHODS

A prospective, comparative and randomized study was conducted on 60 patients of either gender aged between 18 and 60 years belonging to the American Society of Anaesthesiologists (ASA) grade-I or II scheduled for elective surgery. Patients were randomly allocated into two groups of 30 each. In group I, patients received i.v. fentanyl 1 μg/kg+ propofol 1 mg/kg to achieve an adequate level of sedation that is Ramsay Sedation Scale (RSS) score of 3. In group II, patients received i.v. fentanyl 1 μg/kg + midazolam 0.03 mg/kg to achieve RSS= score of 3. Haemodynamic parameters (heart rate, systolic and diastolic blood pressure, mean arterial pressure), SpO2, EtCO2, total comfort scale values and patient's tolerance were assessed during preoxygenation, fiberscope insertion and endotracheal intubation.

RESULTS

Fentanyl plus midazolam group showed better patient comfort and maintenance of oxygen saturation than fentanyl plus propofol group during fiberoptic intubation.

CONCLUSION

Both fentanyl plus midazolam and fentanyl plus propofol regimes are suitable for fiberoptic intubation. Fentanyl plus midazolam appeared to offer better tolerance, preservation of an airway and spontaneous ventilation, while maintaining haemodynamic stability.

Comparison of ultrasound and anatomical landmark-guided technique for superior laryngeal nerve block to aid awake fibre-optic intubation: A prospective randomised clinical study

Background and Aims:

Ultrasonography has emerged as a novel, portable, non-invasive tool encouraging airway assessment and procedural interventions. This study assesses the feasibility of ultrasound for block of internal branch of superior laryngeal nerve (ibSLN) block during upper airway anaesthesia to aid awake fibre-optic intubation.

Methods:

Forty American Society of Anesthesiologists’ physical status I–II patients, aged 18–60 years, deemed to have a difficult airway (modified Mallampati class III–IV or inter-incisor distance <2.5 cm) and planned for awake fibre-optic intubation were randomised to either landmark group (L, n = 20) or ultrasound group (U, n = 20). All patients received nebulised 4% lignocaine (3 mL) and transtracheal injection 3 mL 2% lignocaine. Group L received landmark-guided bilateral ibSLN block with 1 mL 2% lignocaine. Group U received bilateral ibSLN block with 1 mL 2% lignocaine using a high-frequency ultrasound transducer to define the SLN space. The primary objective was assessment of quality of airway anaesthesia. Secondary objectives were time for intubation, haemodynamic parameters and patient perception of discomfort during procedure.

Results:

The quality of anaesthesia was significantly better in Group U than in Group L (P < 0.001). The mean time for intubation was shorter in Group U (71.05 ± 9.57 s) compared to Group L (109.05 ± 30.09 s, P < 0.001). Heart rate, mean arterial pressure and patient perception of discomfort were significantly increased in Group L.

Conclusion:

Ultrasound for ibSLN block as a part of preparation for awake fibre-optic intubation improves quality of airway anaesthesia and patient tolerance.

Sonographically guided superior laryngeal nerve block during awake fiberoptic intubation

We report 5 patients who underwent ultrasound-guided superior laryngeal nerve block before awake intubation and general anesthesia. We used a 8- to 15-MHz hockey stick-shaped ultrasound transducer (HST15-8/20 linear probe, Ultrasonix) to visualize the superior laryngeal nerve. A 3.8-cm 25-G needle was inserted in real time and directed toward the superior laryngeal nerve followed by circumferential placement of local anesthetic. All 5 patients tolerated subsequent awake fiberoptic intubation with either minimal or no sedation. Sonographically guided superior laryngeal nerve block may be useful in patients where identification of landmarks in the neck is difficult as a result of patient anatomy.

A method for ultrasonographic visualization and injection of the superior laryngeal nerve: volunteer study and cadaver simulation

Superior laryngeal nerve block is a valuable technique for provision of upper airway anesthesia. In bilateral scans of 20 volunteers, we developed a technique for ultrasonographic visualization of the superior laryngeal nerve and key anatomical structures using a hockey stick-shaped 8 to 15 MHz transducer (HST15 to 8/20 linear probe, Ultrasonix, Richmond, BC, Canada). Subsequently, we simulated superior laryngeal nerve scanning and injection in bilateral injections in 2 cadavers. Ultrasound-guided in-plane advancement of a needle toward the superior laryngeal nerve and injection of 1 mL of green dye was achieved in all 4 attempts and confirmed by a postprocedural dissection performed by an anatomist. We conclude that ultrasound-guided superior laryngeal nerve block in humans may be feasible.

Ultrasound-Guided Bilateral Superior Laryngeal Nerve Block to Aid Awake Endotracheal Intubation in a Patient with Cervical Spine Disease for Emergency Surgery

Ultrasound has been widely used to locate nerves for various nerve blocks. The potential advantages of using ultrasound imaging for nerve blocks include reduction in the amount of local anaesthetic required, improved success rate, reduced time to perform the block and reduced complication rate. We describe the successful performance of ultrasound-guided bilateral superior laryngeal nerve block to facilitate awake fibreoptic intubation in a patient presenting for emergency surgery on the cervical spine.

Applications of ultrasonography in ENT: airway assessment and nerve blockade

This article presents a comprehensive narrative review of the published literature relating to ultrasound imaging relevant to anesthesia for ear, nose, and throat (ENT) surgery. The review comprises 2 main subject areas: the use of ultrasonography related to assessment and management of the airway, and the use of ultrasonography related to nerve blockade for ENT surgery. The relevant sonoanatomy and suitable probe placement are illustrated in relation to applicable regional anatomy (they are not discussed). The possible value of the use of ultrasonography to improve existing clinical practice in these areas is explored.

Surgical anatomy of the external branch of the superior laryngeal nerve and its clinical significance in head and neck surgery

Injury of the external branch of the superior laryngeal nerve (EBSLN) increases the morbidity following a variety of neck procedures and can have catastrophic consequences in people who use their voice professionally. Identification and preservation of the EBSLN are thus important in thyroidectomy, parathyroidectomy, carotid endarterectomy, and anterior cervical spine procedures, where the nerve is at risk. There are large variations in the anatomical course of the EBSLN, which makes the intraoperative identification of the nerve challenging. The topographic relationship of the EBSLN to the superior thyroid artery and the upper pole of the thyroid gland are considered by many authors to be the key point for identifying the nerve during surgery of the neck. The classifications by Cernea et al. ([1992a] Head Neck 14:380-383; [1992b] Am. J. Surg. 164:634-639) and by Kierner et al. ([1998] Arch. Otolaryngol. Head Neck Surg. 124:301-303), as well as clinically important connections are discussed in detail. Along with sound anatomical knowledge, neuromonitoring is helpful in identifying the EBSLN during neck procedures. The clinical signs of EBSLN injury include hoarseness, decreased voice projection, decreased pitch range, and fatigue after extensive voice use. Videostroboscopy, electromyography, voice analysis, and electroglottography can provide crucial information on the function of the EBSLN following neck surgery.

Unusual foreign body in the esophagus: a challenge for the anesthesiologist

A foreign body in the esophagus is usually removed by endoscopy. An elder man entered the emergency room dyspneic and dysphagic. A chest X-ray showed that he had a table fork stuck in the upper esophagus. An endoscopist tried to remove it without success. After bilateral block of the superior laryngeal nerve, transtracheal injection, topical anesthesia of the mouth, and sedation, an awake laryngoscopy was carried out. Pushing the laryngoscope into the opening of the esophagus the fork was seen and extracted by the anesthesiologist. This case focuses on the role of the anesthesiologist in the removal of esophageal foreign bodies.