The goal of this clinical trial is to assess the viability of dexmedetomidine hydrochloride nasal spray under minimal or no supervision and to further investigate novel clinical applications for this medication. This study aims to investigate the following aspects: the incidence of adverse respiratory and circulatory events requiring medical intervention following the administration of dexmedetomidine nasal spray for pre-anesthetic sedation, its sedative efficacy and onset time, and its impact on the quality of post-anesthesia recovery and the occurrence of postoperative delirium. Researchers will compare dexmedetomidine hydrochloride nasal spray to a placebo (a look-alike substance that contains no drug) to see the incidence and severity of adverse events following administration. Participants will receive either dexmedetomidine nasal spray or a placebo 45 minutes before anesthesia induction. The blinded assessor will continuously monitor and record vital signs, adverse events, and the level of sedation. More importantly, observations and records should be made for respiratory and circulatory events that require medical intervention. A follow-up assessment will be conducted within three days after the operation to evaluate the incidence of postoperative delirium and patient satisfaction.

Inclusion Criteria:

• be 18 years of age or older, including the age of 18; no gender limitation;
• American Society of Anesthesiologists (ASA) grade I to III;
• Require general anesthesia, intraspinal anesthesia, or nerve block anesthesia for an elective surgical procedure;
• Provide informed consent for participation in this study prior to the commencement of the trial and execute a written document of informed consent willingly.

Exclusion Criteria:

• Individuals with a known hypersensitivity to dexmedetomidine hydrochloride or any excipient; patients with a documented allergy to any tranquilizers, opioids, or other substances employed in the trial;
• Individuals with airway hyperactivity, such as those suffering from chronic obstructive pulmonary disease (COPD), asthma, or sleep apnea, who are determined by the researchers to have experienced or are experiencing safety concerns related to these conditions;
• Patients with a history of nasal disorders, previous surgical procedures, or allergic reactions deemed clinically significant by the research team, which could significantly impact drug absorption (e.g., chronic nasal congestion, rhinorrhea, nosebleeds, and other symptoms, as well as anatomical or mucosal abnormalities in the nose that may affect drug uptake);
• A blood oxygen saturation (SpO2) level of less than or equal to 92% in a non-oxygenated state during the screening period;
• patients with current psychiatric disorders (like schizophrenia or depression) or cognitive impairment; those with a history of epilepsy; or individuals with a past record of psychotropic or narcotic substance abuse;
• A history of myocardial infarction or unstable angina pectoris within the past six months prior to the screening phase;
• A heart rate or pulse rate of less than or equal to 50 beats per minute during the screening period, the presence of clinically significant heart functional abnormalities as determined by the investigators, or the presence of grade II or higher atrioventricular block (excluding patients with implanted pacemakers) along with other severe arrhythmias;
• Patients with inadequately controlled hypertension (systolic blood pressure ≥160 mmHg and/or diastolic blood pressure ≥100 mmHg during the screening period) or hypotension (systolic blood pressure ≤90 mmHg and/or diastolic blood pressure ≤ mmHg during the screening period);
• Participants who have already engaged in other clinical trials and have taken the investigational drug within the three months preceding the screening period;
• Pregnant or lactating women expected to undergo a cesarean section during labor and delivery;
• The investigator concludes that the patient possesses other conditions rendering them ineligible for trial participation.