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

Abstract

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 (D₁). The secondary outcome was LUS on the preoperative day (D₀) and postoperative day 3 (D₃), 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 D₁LUS compared to the NS group, whereas there was no significant difference in D₃LUS 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 D₁LUS, D₃LUS, 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.

Keywords: Chlorhexidine mouthwash; Elderly; Endotracheal intubation; Lung ultrasound; Oral frailty.

Fig. 1

Study flowchart.

Fig. 2

Display of lung ultrasound scores. (A) Paralel A-lines or fewer than two isolated B-lines (0 points). (B) >2 non-confluent B-lines(1 point). (C) multiple merged B-ines(2 points). (D) Lung consolidation or debris sign (3 points).

Fig. 3

Tissue culture medium from the tip of the tracheal tube in both groups. (A) Colonies were cultured from catheter tips of patients in NS group. (B) Colonies were cultured from catheter tips of patients in CH group.

Fig. 4

Changes in plasma levels of IL-1β, IL-6, and TNF-α in both groups at different time points. (A) Changes in plasma IL-1β levels in both groups on D₀, D₁, and D₃; (B) Changes in plasma IL-6 levels in both groups on D₀, D₁, and D₃; (C) Changes in plasma TNF-α levels in both groups on D₀, D₁, and D₃.

Fig. 5

Changes in LUS over time in patients with and without oral frailty. (A) Line chart showing changes in LUS on D₀, D₁, and D₃ for NS and CH groups in patients with oral frailty. (B) Line chart showing changes in LUS on D₀, D₁, and D₃ for NS and CH groups in patients without oral frailty. (C) Bar chart showing changes in LUS on D₀, D₁, and D₃ for NS and CH groups in patients with oral frailty. (D) Bar chart showing changes in LUS on D₀, D₁, and D₃ for NS and CH groups in patients without oral frailty. Compared to the NS group, *P < 0.05; ***P < 0.001.

Fig. 6

Forest plot of the subgroup analysis for the primary outcome. A post hoc subgroup analysis was performed based on gender, smoking status, oral frailty, and age. To evaluate the effect of the intervention within each specific subgroup, the results were presented separately as relative risks (RRs) with 95% confidence intervals (CIs). The interaction term is a test of whether the effect of the experimental intervention is statistically different in significance between subgroups.