Study on the Predictive Value of a Pulmonary Edema Imaging Score for Delayed Extubation in Patients after Heart Valve Surgery on Cardiopulmonary Bypass

Background: Delayed extubation with mechanical ventilation after cardiac valve surgery is an important clinical challenge. Early extubation can improve the survival rate and prognosis of patients. The study aims to explore the predictive value of a chest X-ray pulmonary edema imaging score on the first day after surgery for delayed extubation in patients after cardiac valve surgery on cardiopulmonary bypass.

Method: Retrospective analysis of the clinical data of patients undergoing cardiac valve surgery under extracorporeal circulation admitted to the intensive care unit of Zhongshan Hospital Affiliated with Fudan University (Xiamen) from January 2020 to October 2023. The patients were divided into an early extubation group according to the postoperative mechanical ventilation time (time: <24 h) and a delayed extubation group (time: ≥24 h). The radiographic assessment of lung edema (RALE) score was performed on the chest X-ray of the patient on the first day after surgery to analyze the correlation between delayed extubation of mechanical ventilation and the chest radiograph RALE score on the first day after surgery and to verify its predictive performance.

Results: Significant differences in age, the incidence of hypertension, body mass index (BMI), left ventricular ejection fraction (LVEF), pump time, RALE score, ventilation time, oxygenation index, P_aCO₂, and brain natriuretic peptide (BNP) levels after the first 24 h were seen between patients who were extubated before and 24 h post operation (p = 0.013, 0.001, 0.034, <0.001, <0.001, <0.001, <0.001, <0.001, 0.014, and <0.001, respectively). No significant differences were observed in the proportion of males and the lactate level after the first 24 h between the two groups (p = 0.792 and 0.191, respectively). The time of mechanical ventilation was positively correlated with the RALE score in all patients, and the correlation coefficient was 0.419; the difference was statistically significant (p < 0.001). Multivariate binary logistic regression analysis with stepwise regression was performed on each research factor, and it was found that RALE score, pump time, oxygenation index, and postoperative BNP were independent risk factors for predicting delayed extubation in patients undergoing cardiac surgery on cardiopulmonary bypass. A 10-fold cross-validation revealed that the mean accuracy, sensitivity, specificity, and area under the curve (AUC) of the regression model were 0.737, 0.749, 0.741, and 0.825, respectively.

Conclusions: The RALE score on the chest radiograph on the first day after surgery is an independent risk factor for predicting delayed extubation in patients after cardiac valve surgery on cardiopulmonary bypass and has good predictive value.