Elderly patients are vulnerable to postoperative complications. Preoperative malnutrition and poor oral hygiene are risk factors for postoperative complications especially pulmonary complications. This study aims to investigate the feasibility and efficacy of perioperative oral decontamination and immunonutrition supplement on reducing postoperative complications in elderly surgical patients.

This study is a prospective, single center, two-by-two factorial randomized controlled trial to evaluate the feasibility and efficacy of perioperative oral chlorhexidine decontamination and immunonutrition supplementation on postoperative complications in elderly surgical patients. Patients aged 65 years and older who are scheduled for elective non-cardiac surgeries will be recruited and randomized into four groups in 1:1:1:1 ratio (oral decontamination vs routine oral care with/without immunonutrition supplementation).

Inclusion Criteria:

1. age≥65 years;
2. undergoing non-cardiac surgery (expected duration >2 hours);
3. scheduled for general anesthesia and endotracheal intubation;
4. ASA classification I-IV;
5. with intermediate to high risk of respiratory complications assessed by ARISCAT score (Assess Respiratory Risk in Surgical Patients in Catalonia);
6. inform consent obtained

Exclusion Criteria:

1. emergency surgery;
2. preoperative pneumonia;
3. allergic to chlorhexidine;
4. severe hepatic/renal dysfunction, incapable of oral feeding, with autoimmune diseases, taking immunosuppressant or immunoregulation medications, or with other contraindication to immunonutrition supplementation;
5. expected intervention of immunonutrition<3 days.