High-concentration Small-volume Versus Low-concentration Large-volume Iodine Solution for Esophageal Chromoendoscopy

High-concentration Small-volume Versus Low-concentration Large-volume Iodine Solution for Esophageal Chromoendoscopy: a Multicenter, Randomized Equivalence Trial

This clinical trial aims to test the participants' tolerance for different concentration iodine solutions during esophageal chromoendoscopy. The main question it aims to answer is:

Under the same iodine dosage, do the participants have the same tolerance for 1% and 5% iodine solutions? Participants will be asked to score based on pain and discomfort and describe symptoms and corresponding location at 5 minutes (only for unanesthetized participants) and 30 minutes after chromoendoscopy.

Lugol's iodine chromoendoscopy is the commonly used method for detecting and diagnosing esophageal squamous cell carcinoma. However, iodine can induce mucosal irritation and has been commonly associated with adverse retrosternal symptoms, including retrosternal pain and/or heartburn. The existing research shows that spraying iodine solution neutralizers (Sodium thiosulfate solution, N-acetylcysteine, and vitamin C solution) after esophageal iodine chromoendoscopy can alleviate patient discomfort. However, a recent study has shown that excessive iodine concentration or excessive dosage of iodine can still increase patient discomfort even under spraying an iodine solution neutralizer. It is currently unclear whether the factors affecting patient tolerance are the iodine solution concentration or the total dosage of iodine used. Therefore, the multicenter randomized controlled trial will compare the patient's tolerance for the 1% and 5% iodine solutions under the same iodine dosage conditions. The trial will help determine the specific reasons influencing patient tolerance. Participants will be asked to score based on pain and discomfort and describe symptoms and corresponding location at 5 minutes (only for unanesthetized participants) and 30 minutes after chromoendoscopy.

Inclusion Criteria:

• Patients undergoing esophageal Lugol's iodine chromoendoscopy.
• Age ≥ 18

Exclusion Criteria:

• Patients allergic to iodine or with hyperthyroidism;
• Patients with esophageal varices, esophageal ulcer or other conditions inadvisable for Lugol chromoendoscopy;
• Patients with severe gastroesophageal reflux disease or reflux symptoms which may interfered with the outcome measures of current study;
• Patients with postoperative esophageal stenosis affecting endoscopic observation;
• Patients who could not cooperate with the observation and data collection including patients with mental disorders, severe neurosis, dysgnosia or communication disorder;
• Patients with advanced-stage tumors;
• Patients after upper gastrointestinal surgery;
• Patients who do not agree to sign informed consent forms or follow the trial requirement.