To investigate the impact of acetaminophen analgesia on the frequency of postoperative delirium and 28 days mortality in elderly patients after noncardiac surgery.

Background: Delirium is a common complication following surgery contributes to adverse outcomes, including increased mortality and morbidity, longer length of ICU stays, prolonged mechanical ventilation, and costlier hospitalizations. Previous studies showed that, the incidence of delirium for seniors patients admitted to ICU can reach up to 58%-75.6% depending on the patient population and screening instrument. The current protocols for perioperative opioid use and postoperative pain management may influence the occurrence of delirium. We hypothesize that the use of oral acetaminophen (OVA) may lead to reduced opioid consumption and decreased incidence of postoperative delirium.

Objectives: To investigate the impact of acetaminophen analgesia on the frequency of postoperative delirium and 28 days mortality in elderly patients after noncardiac surgery.

Study design: A randomized and controlled trial. Setting: Departments of critical care medicine of tertiary hospital (Xiangya) in China.

Patients: 164 elderly patients (≥ 65 years) who are scheduled to admitted to ICU after major surgery (predicted duration ≥ 2 hours) Intervention: For patients in the acetaminophen group, oral acetaminophen supplemented dexmedetomidine sedation will be provided after surgery. For patients in the control group, sufentanil supplemented dexmedetomidine sedation will be provided after surgery. the other analgesia drugs will be provided as back up in study group.

Primary outcome: Early primary endpoint is the frequency of delirium in the first 5-days post-surgery. Secondary endpoints include biomark and NeuroMonitoring of delirium, 28days and in-hospital mortality, length of stay days in ICU and hospital, complication in hospital.

Predicted duration of the study: 2 years.

Inclusion Criteria:

1. Scheduled to ICU after non-cardiac surgery for any reasons；
2. Report having moderate to severe acute pain as determined by a pain score ≥ 5 from the 11-point Numeric Pain Rating Scale (NPRS) scale after postsurgery；
3. Able to take oral medication or by stomach tube；
4. Provide written informed consent.

Exclusion Criteria:

• Patients who meet any of the following criteria will be excluded.

  1. Preoperative history of schizophrenia, epilepsy, Parkinsonism, or myasthenia gravis;
  2. Inability to communicate in the preoperative period because of coma, profound dementia or language barrier;
  3. Brain injury or neurosurgery;
  4. Severe hepatic dysfunction (eg, aspartate aminotransferase, alanine aminotransferase, or bilirubin greater than or equal to 3.0 times the upper limit of normal), active hepatic disease, evidence of clinically significant liver disease, or other condition (eg, alcoholism, cirrhosis, or hepatitis) that suggests the potential for an increased susceptibility to hepatic toxicity with study drug exposure.
  5. Subject has a positive test result for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methamphetamine, methadone, or methylenedioxy-methamphetamine) at Screening.
  6. Subject has participated in another clinical study within 30 days prior to day-of-surgery or plans to participate in another clinical study while concurrently enrolled in this study.
  7. Subject has a history of any drug allergy, hypersensitivity, or intolerance to acetaminophen or morphine or to any of the excipients in the IV or oral formulations used.
  8. Subject has intra- or postoperative complications, which in the view of the investigator, makes the subject unsuitable for the participation of the study.
  9. Subject has a history of any drug allergy, hypersensitivity, or intolerance to acetaminophen or opioid or to any of the excipients in the IV or oral formulations used.
  10. Unable to take medications orally or by stomach tube