1. Objective:

   Primary: Compare the effect of Ciprofol vs Propofol on LVOT VTI at 2 minutes post-injection (T1) in elderly patients (≥65 years).

   Secondary: Assess hypotension incidence, injection pain, nausea/vomiting, hypoxia (SpO₂≤90%), bradycardia (HR<50 bpm), sedation success rate, induction/recovery times, procedure duration, drug doses, and patient satisfaction.

2. Design:

   Single-center, randomized, double-blind, controlled trial. Group C (Ciprofol):0.2-0.5 mg/kg IV induction (>30s injection). Group P (Propofol)::1-2 mg/kg IV induction (>30s injection). Rescue doses allowed (C: 0.1 mg/kg; P: 0.5 mg/kg; max 5 doses/15 min).

3. Participants:

   N = 120 elderly patients (65-80 years, ASA I-III, BMI 18-30 kg/m²) scheduled for elective painless colonoscopy.

   Exclusion: Significant cardiorespiratory, hepatic, renal, or neurological disorders; recent MI/unstable angina (≤6 months); NYHA ≥II; drug allergies; recent trial participation.

4. Key Assessments:

   Primary Endpoint: LVOT VTI (via transthoracic echocardiography, TTE) at T1.

   Secondary Endpoints:

   Adverse events (hypotension, pain, nausea/vomiting, hypoxia, bradycardia, body movement, awareness).

   Sedation success rate, induction/recovery times (MOAA/S scale), procedure time. Drug doses (induction, total, vasoactive agents). Patient satisfaction (5-point scale). LVEF and IVC Collapse Index (TTE at T0, T1, T2). Safety: Vital signs (HR, BP, SpO₂).

5. Statistical Analysis:

SPSS 26.0; α=0.05. Methods: t-test, RM-ANOVA, Mann-Whitney U, Chi-square/Fisher's exact, rank-sum tests.

This study aims to determine whether Ciprofol provides superior hemodynamic stability (as measured by LVOT VTI) and fewer adverse effects compared to Propofol for sedation in elderly patients undergoing painless colonoscopy.

Inclusion Criteria:

1. ASA classification I-III;
2. Age ≥65 years and ≤80 years;
3. BMI between 18-30 kg/m2 (including the threshold);
4. Patients undergoing painless colonoscopy on an elective basis;
5. Subjects voluntarily participated in this study and signed an informed consent form.

Exclusion Criteria:

1. Those with respiratory depression or high risk of respiratory depression (e.g., sleep apnea syndrome, bronchial asthma, etc.);
2. Suffering from major diseases such as severe hepatic and renal insufficiency, neurological and psychiatric systems;
3. Suffering from severe arrhythmias such as severe aortic regurgitation, atrial fibrillation, tachycardia (heart rate > 120 beats/minute), atrioventricular block of degree II and above, myocardial infarction or unstable angina within 6 months before the examination, and NYHA classification grade II and above;
4. Allergy to or abuse of any medication used in the study;
5. Participation in another clinical trial within the last 3 months.