Preoperative chlorhexidine mouthwash can reduce the risk of postoperative pulmonary complications in elderly patients undergoing general anesthesia with endotracheal intubation.

To investigate whether preoperative chlorhexidine mouthwash can reduce the risk of postoperative pulmonary complications(PPCs) in elderly patients with tracheal intubation under general anesthesia. 78 elderly patients undergoing elective surgery under general anesthesia and endotracheal intubation were randomly divided into the chlorhexidine group (CH group, n = 39) and the normal saline group (NS group, n = 39). Nurses instructed patients to gargle with 15 ml saline or compound chlorhexidine mouthwash the night before surgery, on the morning of surgery, and upon entering the operating room. The primary outcome was lung ultrasound score (LUS) on postoperative day 1 (D). The secondary outcome was LUS on the preoperative day (D) and postoperative day 3 (D), bacterial colony count at the tip of the endotracheal tube, inflammatory markers (IL-1β, IL-6, TNF-α), and the incidence of postoperative fever, pneumonia, cough severity and sputum production. The CH group had significantly lower DLUS compared to the NS group, whereas there was no significant difference in DLUS between the groups. Within three postoperative days, there were no significant differences between the groups in cough severity, sputum production, fever, inflammatory markers, or pneumonia incidence. Bacterial colony counts on the endotracheal tube at extubation were lower in the CH group than in the NS group. Post hoc sensitivity analysis revealed that in patients with oral frailty, the number of colonies cultured at DLUS, DLUS, and the catheter tip in the CH group was lower than that in the NS group. However, there was no significant difference between the two groups in terms of the incidence of pneumonia and other aspects. Exploratory subgroup analysis showed that chlorhexidine mouthwash significantly reduced postoperative LUS in patients with oral frailty, while there were no significant differences in gender, smoking and age subgroups. Preoperative chlorhexidine mouthwash improved early postoperative LUS in elderly patients by reducing oropharyngeal bacterial colonization, particularly in those with oral weakness, though clinical outcomes like pneumonia showed no significant differences. Chinese clinical trial registration number: ChiCTR2400089898.