Eligible patients undergoing hysteroscopy were randomly assigned in a 1:1 ratio to receive intravenous anesthesia with either propofol (2 mg/kg) or remifentanil (0.4 mg/kg).Continuous monitoring of pulse oximetry (SpO2), blood pressure (BP), heart rate (HR), expired gas partial pressure of carbon dioxide, integrated respiratory index (IPI), tidal volume (TV), respiratory rate (RR), and minute ventilation (MV) was performed.During induction, the MOAA/S score was assessed every 30 seconds. If the MOAA/S score remained >1, a supplementary dose of 1/2 of the initial dose was injected within 10 seconds.If more than 5 supplementary doses were required within 15 minutes, it was considered that the painless hysteroscopy failed and propofol was used to enhance sedation.Continuous oxygen administration at a flow rate of 5 liters per minute was provided through nasal catheters until the patient was fully alert with a MOAA/S score of 5 and vital signs were stable.Observation indicators included: (1) the success rate of hysteroscopy;(2) induction time (MOAA/S ≤ 1 after the first dose);(3) full recovery time of consciousness;(4) operation duration;(5) number of additional anesthetics;(6) incidence of hypotension, hypoxemia, sinus bradycardia, delayed recovery, and injection pain;(7) respiratory parameters and minimum SpO2, IPI values before anesthesia, after induction, and after awakening.

Inclusion Criteria:

• Voluntary signing of informed consent form
• Stable vital signs and qualified anesthesia outpatient evaluation
• No contraindications to anesthesia

Exclusion Criteria:

• Not willing to sign informed consent form
• Anaesthesia drug allergy
• Severe central nervous system diseases
• Severe hypertension and diabetes
• Mental disorders
• History of using psychotropic drugs in the past 3 months