Rifentanil is a fentanyl μ-type opioid receptor agonist, which can rapidly reach blood-brain equilibrium in the human body in about a minute, and will rapidly decay in tissues and blood, so it has a rapid onset of action and short maintenance time, and is a commonly used opioid for general anesthesia, whose main effect is analgesia. Usually this drug is used in combination with other drugs in the induction and maintenance of general anesthesia, and takes effect a few minutes after intravenous injection, producing dose-dependent sedation and analgesia, which is more common in the emergence of euphoria. Ultra-high doses of this drug can lead to amnesia and loss of consciousness, as well as dose-dependent respiratory depression. Because the drug directly excites the emesis chemoreceptors, patients may experience nausea, vomiting, and sometimes inability to ventilate due to stiffness of the chest wall, abdominal wall, and upper airway muscles. Rifentanil should only be used for intravenous administration and is especially indicated for continuous intravenous drip administration. Typical adverse reactions include nausea, vomiting, respiratory depression, bradycardia, hypotension and muscle rigidity, which resolve within minutes after the patient stops the drug or decreases the infusion rate. Rifentanil is an ultra-short-acting anesthetic, and while it relieves pain, ultra-short-acting means that it is metabolized relatively quickly and may be painful after surgery, so it is often used in combination with other drugs.