Incidence of postoperative pneumonia as high as 28.0% significantly increases the risk of mortality after acute type A aortic dissection: a multi-hospital retrospective cohort study

To analyze the incidence and related risk factors of postoperative pneumonia (POP) in patients with acute type A aortic dissection(ATAAD) after surgery.

A multi-hospital retrospective cohort study was conducted, consecutively enrolling 493 ATAAD patients who underwent surgical treatment at the Second Affiliated Hospital of Army Medical University, Affiliated Hospital of Southwest Medical University, and Chongqing Emergency Medical Center between January 2018 and December 2022. Clinical data were collected, including general characteristics, preoperative comorbidities, surgical indicators, and postoperative monitoring parameters. The participants were divided into a POP group (n=138) and a control group (n=355) based on POP occurrence. Univariate analysis was used to screen the risk variables related to the occurrence of POP(P<0.15), followed by multivariate logistic regression using forward, backward, and enter methods to identify the independent risk factors. Receiver operating characteristic(ROC) curve analysis was used to assess the predictive efficacy of continuous variables and determine optimal cut-off values.

Among the 493 patients, the incidence of POP was 28.0%(138/ 493). The POP group exhibited significantly prolonged postoperative mechanical ventilation time(92.6±68.5 vs 45.3±32.8 h, P<0.001), length of intensive care unit(ICU) stay(156.8±88.3 vs 102.5±65.7 h, P<0.001), and length of total hospitalization stay(27.3±14.6 vs 19.8±10.2 d, P<0.001), along with significantly higher in-hospital mortality(18.8% vs 7.9%, P<0.001) when compared with the control group. Multivariate logistic regression analysis identified preoperative chronic obstructive pulmonary disease(COPD)(OR=2.447, 95%CI: 1.191 to 5.026, P=0.015), history of aspiration pneumonia(OR=2.282, 95%CI: 0.992 to 5.246, P=0.052), mechanical ventilation duration ≥68 h(OR=3.619, 95%CI: 1.963 to 6.672, P<0.001), red blood cell transfusion volume≥10 U(OR=1.984, 95%CI: 1.113 to 3.536, P=0.020), intraoperative peak blood glucose ≥11 mmol/L(OR=2.134, 95%CI: 1.190 to 3.826, P=0.011), and postoperative 24 h total drainage ≥ 1100 mL(OR=1.808, 95%CI: 1.032 to 3.169, P=0.039) as independent risk factors for POP in ATAAD patients. ROC curve analysis further validated the predictive efficacy of these continuous variables, with mechanical ventilation duration demonstrating an AUC value of 0.762(95%CI: 0.718 to 0.806), red blood cell transfusion a value of 0.682(95%CI: 0.632 to 0.732), intraoperative peak blood glucose a value of 0.658 (95%CI: 0.606 to 0.710), and postoperative 24 h drainage a value of 0.642(95%CI: 0.589 to 0.695).

The incidence of POP in ATAAD patients is as high as 28.0%, significantly increasing the mortality and hospital stay. Individualized preventive strategies targeting preoperative COPD, aspiration pneumonia history, prolonged mechanical ventilation, massive red blood cell transfusion, intraoperative hyperglycemia, and early postoperative high-volume drainage may reduce the incidence of POP and improve the prognosis of patients.