NCT06896513

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

Completed Last updated 13 April 2026

What this trial tests

trial testing Isthmus in Difficult Intubation in 220 participants. Completed in 4 March 2026.

Timeline

25 April 2025

Primary endpoint
4 March 2026

4 March 2026

Quick facts

Lead sponsor	Konya City Hospital
Status	Completed
Study type	OBSERVATIONAL
Enrollment	220
Start date	25 April 2025
Primary completion	4 March 2026
Estimated completion	4 March 2026
Sites	1 location across Turkey (Türkiye)

Drugs / interventions tested

• Isthmus

Conditions studied

• Difficult Intubation — all drugs for Difficult Intubation →
• Difficult Laryngoscopy — all drugs for Difficult Laryngoscopy →

Sponsor

Konya City Hospital

Who can join

18 and older, any sex, with Difficult Intubation or Difficult Laryngoscopy. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

No peer-reviewed publications indexed yet for this trial. Completed trials usually publish results within 12-18 months.