Ultrasound-guided Thyroid Cartilage Plane Block for Awake Intubation

Ultrasound-guided Thyroid Cartilage Plane Block for Patients With Awake Tracheal Intubation: a Randomized Controlled Trial

The goal of this clinical trial is to investigate the clinical effectiveness and safety of superior laryngeal nerve block through surface injection of local anesthetic solution on the thyroid cartilage in patients undergoing general anesthesia with endotracheal intubation. The main questions it aims to answer are the effectiveness of ultrasound-guided Thyroid Cartilage Plane Block for superior laryngeal nerve blockadethe and the safety and ease of performance.

All patients are divided into the Thyroid Cartilage Plane Block Group (T Group) and the Control Group (C Group). Patients in the C Group receive airway surface anesthesia using the fiberoptic bronchoscope-guided local anesthetic spray method throughout the procedure. In the experimental T Group, ultrasound-guided bilateral Thyroid Cartilage Plane Block is performed using the thyroid cartilage as an anatomical landmark. Local anesthetic is injected on the surface of the thyroid cartilage.

Compare the following parameters between the two groups: duration of the blocking procedure, Ramsay Sedation Score, patient coughing upon contact of the fiberoptic bronchoscope with the vocal cords before intubation, comfort score immediately after intubation, and tracheal tube tolerance after successful intubation.

Study Overview

• Status: Completed
• Conditions: Superior Laryngeal Nerve Block
• Intervention / Treatment: Behavioral: Ultrasound-guided bilateral Thyroid Cartilage Plane Block

Detailed Description

Select 60 patients undergoing elective awake tracheal intubation surgery. Instruct patients to fast （no food or drink） for 8 hours before the procedure. Upon admission to the operating room, monitor patients' ECG （electrocardiogram）, BP （blood pressure）, and SpO2 （pulse oxygen saturation）. Establish intravenous access in the upper extremities and administer normal saline solution. Administer a loading dose of dexmedetomidine at 0.5 μg/kg over 5 minutes and remifentanil 0.5μg.kg-1, followed by an infusion at a rate of 0.3-0.6 μg/（kg·h） , 0.1μg.kg-1.min-1 by micropump infusion respectively. Perform radial artery puncture and catheter placement for invasive arterial pressure monitoring. Use a computer-generated random number table to allocate patients into two groups in a 1:1 ratio. To ensure objectivity, a nurse not involved in the study prepares sealed opaque envelopes containing the group assignments. All patients are divided into the Thyroid Cartilage Plane Block Group （T Group） and the Control Group （C Group）. All patients received topical oral and pharyngeal anesthesia using 2.4% lidocaine spray administered by an experienced anesthesiologist. The pharyngeal surface was sprayed twice, with each spray lasting one second, and repeated after a 5-minute interval. Each spray contained approximately 16 mg lidocaine. Patients in the C Group receive airway surface anesthesia using the fiberoptic bronchoscope-guided local anesthetic spray method throughout the vocal cord and tracheal with 5 ml 2% lidocaine respectively. In the experimental T Group, ultrasound-guided bilateral Thyroid Cartilage Plane Block is performed using the thyroid cartilage plate as an anatomical landmark.2.5 ml 2% lidocaine local anesthetic is injected on the surface of the thyroid cartilage plate. The blocking procedure is as follows: Use a Sonosite high-frequency linear array transducer (5-13 MHz, Sonosite, USA). Place the transducer parallel to the spine on one side of the neck, ensuring clear visualization of the thyroid cartilage plate under ultrasound. Employ ultrasound-guided out-of-plane techniques to display the needle insertion path and tip. Once the needle tip contacts the upper half of the thyroid cartilage plate, inject 2.5ml of 2% lidocaine on the surface of the thyroid cartilage plate （the dosage is consistent with the commonly used local anesthetic volume for classic superior laryngeal nerve block methods in clinical practice）. Subsequently, perform fiberoptic bronchoscope-guided subglottic, and tracheal surface anesthesia. After completing surface anesthesia, select an appropriate-sized tracheal tube and perform fiberoptic bronchoscope-guided tracheal intubation, securing it properly.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Nanjing
    • Nanjing, Nanjing, China, 210006
      • Nanjing First Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Patients scheduled for awake tracheal intubation surgery under general anesthesia.
2. Patients with difficult airways (e.g., limited cervical spine mobility, full stomach, partial airway obstruction, craniofacial deformities or trauma, micrognathia, mouth opening <3cm, Mallampati III or IV classification) posing challenges for mask ventilation or intubation.
3. Age between 18 and 65 years.
4. Gender is not restricted.
5. ASA classification of I or II.

Exclusion Criteria:

1. Cardiovascular dysfunction or arterial aneurysms.
2. Mental or neurological disorders or concomitant arterial aneurysms.
3. Infection at the puncture site.
4. Allergy to local anesthetics.
5. Continuous use of antiplatelet or anticoagulant medications preoperatively.
6. Hoarseness or coughing while drinking water.
7. Bronchial asthma.
8. Participation in other clinical trials within the previous 3 months before enrollment 9.r current participation in other clinical trials.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Thyroid Cartilage Plane Block Group (T Group); All patients received topical oral and pharyngeal anesthesia using 2.4% lidocaine spray. The pharyngeal surface was sprayed twice, with each spray lasting one second, and repeated after a 5-minute interval. Ultrasound-guided bilateral Thyroid Cartilage Plane Block is performed using the thyroid cartilage plate as an anatomical landmark. 2.5ml of 2% lidocaine is injected on the surface of the thyroid cartilage each side. Subsequently, perform fiberoptic bronchoscope-guided subglottis and tracheal surface topical anesthesia using 5ml of 2% lidocaine. After completing surface anesthesia, perform fiberoptic bronchoscope-guided tracheal intubation, securing it properly.	Behavioral: Ultrasound-guided bilateral Thyroid Cartilage Plane Block; Use a SonoSite high-frequency linear array transducer (5-13 MHz, SonoSite, USA). Place the transducer parallel to the spine on one side of the neck, ensuring clear visualization of the thyroid cartilage plate under ultrasound. Employ ultrasound-guided out-of-plane techniques to display the needle insertion path and tip. Once the needle tip contacts the upper half of the thyroid cartilage plate, injecting 2.5ml of 2% lidocaine on the surface of the thyroid cartilage each side.
No Intervention: the Control Group （C Group）; Patients in the C Group received topical oral and pharyngeal anesthesia using 2.4% lidocaine spray. The pharyngeal surface was sprayed twice, with each spray lasting one second, and repeated after a 5-minute interval. Patients in the C Group receive airway topical anesthesia using the fiberoptic bronchoscope-guided local anesthetic spray method throughout the vocal cord and tracheal with 5 ml 2% lidocaine respectively.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
quality of airway anesthesia	TThe primary outcome in this trial was quality of airway anesthesia assessed on a 5-point scale,Quality of airway anesthesia was graded as: 0=no coughing or gagging in response to intubation, 1=mild coughing and/or gagging that did not hinder intubation, 2=moderate coughing and/or gagging that interfered minimally with intubation, 3=severe coughing and/or gagging that made intubation difficult and 4=very severe coughing and/or gagging that required additional local anesthetic and/or change in technique.The lower grade means a better quality of airway anesthesia.	Upon intubation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Arterial Pressure （MAP）	Stable blood pressure indicates a good neural blockade effect.	T0: upon entry to the operating room,T1: before insertion of the tracheal tube,T2: immediately after tracheal tube insertion,T3: 5 minutes after successful intubation
Heart Rate （HR）	The smaller the heart rate fluctuations, the better the neural blockade effect.	T0: upon entry to the operating room,T1: before insertion of the tracheal tube,T2: immediately after tracheal tube insertion,T3: 5 minutes after successful intubation
Ramsay Sedation Score	The Ramsay Sedation Score is as follows: 6 points for unarousable, 5 points for slow response to stimulus, 4 points for asleep but easily aroused, 3 points for quiet and cooperative with orientation, 2 points for asleep, anxious, restless, and 1 point for asleep, agitated, and restless. Satisfactory sedation falls within 2-4 points, while oversedation is indicated by 5-6 points.	T0: upon entry to the operating room,T1: before insertion of the tracheal tube,T2: immediately after tracheal tube insertion,T3: 5 minutes after successful intubation
The number of patients with lowered pitch	A lowered pitch indicates a good neural blockade effect.	Before intubation
The time of the block procedure	The neural blockade procedure time reflects the ease of the operation, with a shorter time indicating a simpler neural blockade procedure.	From ultrasound probe positioning the target to completion of drug administration
Record coughing in patients when the fiberoptic bronchoscope touches the glottis	The patient's coughing upon contact of the fiberoptic bronchoscope with the vocal cords before intubation reflects the effectiveness of neural blockade. A lower degree of coughing indicates a better neural blockade effect. 1 point for no response, 2 points for mild cough, 3 points for severe cough.	Before intubation
The tolerance of the tube	The tolerance of the tube reflects the patient's tolerance to awake tracheal intubation. A higher level of tolerance indicates a better neural blockade effect. 3 points for severe resistance requiring immediate general anesthesia, 2 points for restlessness and mild resistance, 1 point for cooperation.	After successful intubation
Adverse reactions such as coughing and nausea/ vomiting..	The lower the incidence of coughing, nausea, and vomiting, the better the neural blockade effect.	During intubation
Occurrences of sore throat and lowered pitch	Pharyngeal pain and decreased vocal tone are used to assess postoperative complications of neural blockade.	Post-extubation,24 hours after surgery

Collaborators and Investigators

• Sponsor: Nanjing First Hospital, Nanjing Medical University
• Investigators: Study Chair: Tao Shan, Nanjing First Hospital, Nanjing Medical University

Publications and helpful links

General Publications

• Wiles JR, Kelly J, Mostafa SM. Hypotension and bradycardia following superior laryngeal nerve block. Br J Anaesth. 1989 Jul;63(1):125-7. doi: 10.1093/bja/63.1.125.
• Canty DJ, Poon L. Superior laryngeal nerve block: an anatomical study comparing two techniques. J Clin Anesth. 2014 Nov;26(7):517-22. doi: 10.1016/j.jclinane.2014.03.005. Epub 2014 Oct 16.
• Fowler JG, VanEenenaam DP Jr, Johnson KN, Courtemanche CD, Strathman AJ, Reynolds JE. Single midline injection for bilateral superior laryngeal nerve block. J Clin Anesth. 2020 Nov;66:109922. doi: 10.1016/j.jclinane.2020.109922. Epub 2020 Jun 6. No abstract available.

Study record dates

Study Major Dates

• Study Start (Actual): October 15, 2023
• Primary Completion (Actual): December 27, 2024
• Study Completion (Actual): December 28, 2024

Study Registration Dates

• First Submitted: September 17, 2023
• First Submitted That Met QC Criteria: September 26, 2023
• First Posted (Actual): October 4, 2023

Study Record Updates

• Last Update Posted (Actual): February 4, 2026
• Last Update Submitted That Met QC Criteria: February 2, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: ultrasound; Difficult airway; Thyroid Cartilage; Superior Laryngeal Nerve; Awake tracheal intubation
• Additional Relevant MeSH Terms: Endocrine System Diseases; Thyroid Diseases
• Other Study ID Numbers: KY20230829-10

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No