Abstract: Objective To explore the risk factors for postoperative delirium (POD) in the elderly patients with preoperative malnutrition undergoing hip arthroplasty under tracheal intubation and general anesthesia. Methods A total of 149 elderly patients with malnutrition or risk of malnutrition before surgery undergoing hip arthroplasty were selected and divided into the POD group and the non-POD group according to whether they presented with delirium after the operation. The clinical data in two groups were observed and compared. Multivariate Logistic regression analysis was used to analyze the risk factors for POD in the elderly patients with preoperative malnutrition undergoing hip arthroplasty under tracheal intubation and general anesthesia. Results Among 149 patients, POD occurred in 60 patients, and the incidence rate of POD was 40.27%.There were significant differences in age, body mass index(BMI), hypoxemia, electrolyte disturbances, nutritional status, levels of cognitive function score, serum albumin and hemoglobin, length of operation, intraoperative bleeding, postoperative analgesia between the two groups (P<0.05). Multivariate Logistic regression analysis suggested that age ≥75 years, BMI <20, Mini-Nutritional Assessment Short-Form score <7, Mini-Mental State Examination score <27 and serum albumin <30 g/L were the risk factors for POD (P<0.05), and the postoperative analgesia was a protective factor for POD (P<0.05) in the elderly patients with preoperative malnutrition or malnutrition risk undergoing hip arthroplasty under general anesthesia. Conclusions The incidence of POD in the elderly patients with preoperative malnutrition or malnurtition risk undergoing hip arthroplasty under endotracheal intubation and general anesthesia is high. The incidence of POD is closely related to the patients' age, BMI, nutritional status,cognitive function, level of albumin and postoperative analgesia.

Key words: malnutrition, general anesthesia, aged, hip replacement, postoperative delirium, risk factors