The purpose of this study is to determine whether premedication with Simethicone or Simethicone plus N-acetylcysteine are effective improving visibility during Upper endoscopy compared with use of water or no preparation.

While globally there has been a downward trend in the incidence of gastric cancer, it remains the second leading cause of cancer mortality in the world. In Chile is the leading cause of death from malignant tumors in both sexes, and is recognized as a problem and public health priority in our country. Detection of gastric cancer in early stages has a huge impact on healing and therefore the prognosis of patients. In countries like Japan, where the incidence of this neoplasm is one of the highest in the world, mass screening programs have failed to demonstrate significant impact at the population level, there is a body of evidence to support endoscopic screening especially with the advent of new minimally invasive procedures such as endoscopic mucosal resection for gastric cancers detected in early stages. In our country, it is estimated that about half of the patients already have lymph node metastases or involvement of adjacent organs at diagnosis. The best way to reduce disease burden from this disease would be through primary prevention interventions or effective early detection. For this purpose the upper gastrointestinal endoscopy is the method of choice to examine the gastric mucosa in search of early lesions, and this is the point where adequate visibility of the mucosa is overriding. Mucus, foam and bubbles accumulated in the gastrointestinal tract mucosa interfere with adequate endoscopic visualization and thus represent risk of failing to diagnose early lesions. For this reason is that various anti-foam agents, anti-bubbles are widely used in endoscopic centers mainly in Japan, where its use is almost a rule, unlike the West where its use is limited by the theoretical risk of aspiration. Simethicone has been proven as a good anti-foam agent prior to endoscopy to remove mucus and bubbles. It has also been studied in other scenarios such as colonoscopy as an additive in the preparation of the colon to eliminate bubbles in endoscopic capsule for small bowel preparation as well as Endoscopic Ultrasound which reduces artifacts and increases the accuracy of the study. Currently N-acetylcysteine, a mucolytic agent, either alone or in combination with Simethicone has proven effective in removing mucus and gastric bubbles when used 20 minutes prior to the upper endoscopy, improving the visualization of the gastric mucosa. Other agents such as pronase have also been described as useful in this task are not yet available in our area. In the context of the relevance of gastric cancer in our environment, our low rate of early cancer detection and the absence of national policies on the preparation and agents that may improve visualization of the mucosa, this study aims to compare the effect of products available in our country in preparation for an endoscopy in order to improve visualization of the mucosa and increase the chance of recognizing early lesions.

Inclusion Criteria:

• Diagnostic upper endoscopy performed for medical indications

Exclusion Criteria:

• Upper gastrointestinal surgery

• Gastric Cancer

• Deep sedation with propofol

• Indication of therapeutic endoscopy

• Emergency endoscopy

• Patients with a history of

  • Upper gastrointestinal bleeding
  • Caustic ingestion
  • Pregnancy
  • Diabetes mellitus
  • Asthma
  • Allergic reactions to medication