Application of Remimazolam Combined With Esketamine in Painless Gastroscopy and Colonoscopy in Elderly Patients

The objective of this clinical trial is to assess the feasibility of the remimazolam combined with esketamine OFA (opioid-free anesthesia) protocol for painless gastroscopy and colonoscopy in elderly patients and to determine if it is non-inferior to the traditional OA (opioid-containing anesthesia) protocol. The main questions it aims to answer are: * Is the remimazolam combined with esketamine protocol feasible for painless gastroscopy and colonoscopy in elderly patients? * Is the OFA protocol superior to the OA protocol? Participants will: * During anesthesia induction, the experimental group will receive remimazolam combined with esketamine for anesthesia, while the control group will receive remimazolam combined with remifentanil. * Record respiratory and circulatory indicators and adverse reaction times.