The impact of anesthesia depths on early postoperative neurocognitive complications after total intravenous anesthesia (TIVA) remains controversial. In some studies investigating TIVA, anesthesiologists mainly achieve the target depth of anesthesia by adjusting the dose of propofol, whereas the doses of opioids remains comparable between different anesthetic depth groups, possibly resulting inadequate analgesia. This study is aimed to investigate the impact of different anesthesia depths maintained by target-controlled infusion of propofol and remifentanil at a fixed ratio on the incidence of early postoperative neurocognitive complications in older patients undergoing noncardiac surgery.
Aged ≥ 65 years.
Scheduled to undergo noncardiac surgery expected to last ≥ 1 hour under general anesthesia.
Require patient-controlled intravenous analgesia after surgery.
Provide written informed consent.
Inability to communicate in the preoperative period because of coma, profound dementia, language barrier, or other reasons.
Previous history of schizophrenia, epilepsy, Parkinson's disease, or myasthenia gravis.
Traumatic brain injury or neurosurgery.
Severe hepatic dysfunction (Child-Pugh class C), severe renal dysfunction (eGFR <30 ml/min/1.73 m2), or critical illness (preoperative American Society of Anesthesiologists physical status classification ≥IV).