Relationship of Isthmus Thickness With Difficult Laryngoscopy and Difficult Intubation in Patients Receiving Hypothyroidism Treatment

NCT06896513 | Completed

• 1 other identifier: 2024/5150
• Study Type: observational
• Target: 220
• Locations: 1 country
• Sites: 1

Brief Summary

Under general anesthesia, the rate of failed intubation ranges from 1.5% to 13%, raising concerns among anesthesiologists whose primary goal is successful airway management. In this context, various physical and ultrasonographic measurement techniques have been developed to predict difficult intubation. Ultrasonography is effectively used for estimating tracheal tube size, device placement, diagnosing upper airway pathologies, and guiding percutaneous tracheostomy. In thyroid pathologies, intubation difficulty may increase; however, the impact of goiter remains debatable, as some conditions causing hypothyroidism are reported to lead to thyroid gland atrophy rather than hypertrophy. The study's hypothesis is that an atrophic or fibrotic thyroid isthmus may be associated with difficult laryngoscopy and intubation. Evaluation will be performed using the Cormack-Lehane score (Grade III-IV) and the Intubation Difficulty Scale (IDS \>5). The aim is to determine the relationship between thyroid isthmus thickness and difficult laryngoscopy and intubation during elective intubation in patients receiving hypothyroidism treatment. Preoperatively, patients' demographic and clinical data (age, gender, height, weight, BMI, comorbidities, ASA score, thyroid medication dose, treatment duration, and type of thyroid disease) will be recorded. In the premedication room, after administering 0.01 mg/kg IV midazolam, the distance between the thyroid isthmus and the skin will be measured using a linear ultrasound probe (3-13 Hz) in the supine position with neck hyperextension at the level of the 2nd-3rd tracheal rings; the average of three measurements will be recorded. In the operating room, under noninvasive monitoring and following mask pre-oxygenation, anesthesia induction will be performed using IV 2 mg/kg propofol, 1 µg/kg fentanyl, 1 mg/kg lidocaine, and 0.6 mg/kg rocuronium. Once the TOF reaches zero, an experienced anesthesiologist will intubate using a size 3 Macintosh blade for females and size 4 for males with an appropriate endotracheal tube. The intubation time, defined as the interval from laryngoscope insertion until the first capnography wave is detected, will be recorded along with the Cormack-Lehane and EZS scores and the requirement for video laryngoscopy. In cases of failed intubation, the 2022 ASA Difficult Airway Management Guidelines will be applied.

Conditions

Difficult Intubation; Difficult Laryngoscopy

Keywords

Intubation; Laryngoscopy; Isthmus

Outcome Measures

Primary Outcomes (1)

• Cormack-Lehane score and Intubation Difficulty Scale values of patients whose isthmus thickness is below 3 mm.

  From enrollment to the end of treatment at 6 Mounths

Study Arms (1)

Adult patients with known hypothyroidism who are receiving medical treatment and are scheduled for e

Adult patients with known hypothyroidism who are receiving medical treatment and are scheduled for elective intubation.

Other: Isthmus

Interventions

Isthmus OTHER

The neck skin thickness from the thyroid isthmus to the skin will be measured in millimeters using a linear ultrasound probe (3-13 Hz) in the supine position with neck hyperextension. Measurements will be taken in a transverse view at the level of the 2nd-3rd tracheal rings, and the average of three measurements will be recorded.

Adult patients with known hypothyroidism who are receiving medical treatment and are scheduled for e

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Adult patients undergoing surgery at Konya City Hospital for any reason Known hypothyroidism receiving medical treatment

You may qualify if:

• Known hypothyroidism receiving medical treatment
• ASA score of 2-3

You may not qualify if:

• Known history of difficult intubation
• Body mass index (BMI) \> 40
• Presence of airway pathology
• Diseases that restrict neck movement (e.g., RA, SLE, AS, etc.)
• Head and neck range of motion ≤ 80°
• History of cervical radiotherapy
• Refusal to participate in the study

Sponsors & Collaborators

• Konya City Hospital: lead

Study Sites (1)

Konya City Hospital

Konya, Selçuklu, Turkey (Türkiye)

Location

MeSH Terms

Interventions

pax2a protein, zebrafish

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator MD

Study Record Dates

• First Submitted: March 18, 2025
• First Posted: March 26, 2025
• Study Start: April 25, 2025
• Primary Completion: March 4, 2026
• Study Completion: March 4, 2026
• Last Updated: April 13, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL

Locations

TU (1)