Effects of Low-dose Esmolol on Myocardial Injury After Non-cardiac Surgery in Elderly Frail Patients

The treatment group was given Esmolol 0.5mg/kg load and 10μg /kg/min continuous pump

The control group received the same volume of 0.9% normal saline, which was continuously pumped until the end of the operation before extubation.Patient-controlled analgesia pump (sufentanil 2 μg/kg, 2 mL/h, for 48h) was used as the postoperative analgesia regimen in the two groups. If the VAS score was \>3, analgesic adjuvant drugs were given intravenously and recorded. If repeated treatment is ineffective, the study will be excluded.