Remifentanil is used for painless gastroscopy. It can be used for induction of general anesthesia and maintenance of analgesia during general anesthesia prior to surgery or examinations such as gastroscopy, or as an adjunct to anesthesia. The generic name of this product is remifentanil hydrochloride for injection, which can only be administered by the intravenous route and needs to be diluted with a specific injection solution before it is given to the patient. Since remifentanil hydrochloride for injection does not contain any preservatives or antimicrobial agents, care must be taken to maintain sterility during the dilution process and to use it as soon as possible after it has been prepared. During the application of this product, patients may experience the typical adverse effects of μ-opioid receptor drugs, such as bradycardia, nausea, vomiting, hypotension, etc. Occasionally, constipation, fainting, coughing and other adverse reactions. This drug is contraindicated in people who are allergic to this product or other fentanyl analogs, patients with myasthenia gravis, and patients with bronchial asthma. Note: remifentanil can not be used alone for the induction of general anesthesia, in the process of clinical application is prohibited and monoamine oxidase inhibitors. To do painless gastroscopy is recommended to regular medical institutions, by a professional anesthesiologist to implement general anesthesia operation, to reduce discomfort.