Use of ultrasonic left ventricular pressure-strain loops to predict weaning failure in critically ill patients: a pilot study.

Background: Left ventricular (LV) pressure-strain loops (PSLs) can overcome afterload of the LV to evaluate myocardial work. This study used PSLs to evaluate LV function during the weaning of invasive mechanical ventilation (IMV) patients, and explored the clinical value of myocardial work parameters in evaluating weaning outcomes.

Methods: In total, 70 IMV patients were retrospectively included in the study and divided into weaning success and failure groups based on their results 48 hours after weaning. Ultrasound and clinical data were also measured after patients had passed the spontaneous breathing trial (SBT). The independent factors influencing weaning failure were identified by univariate and multivariate logistic regression analyses. The correlation between the independent risk factors and weaning failure was also evaluated.

Results: Among the 70 patients, 29 (41%) experienced weaning failure. The univariate analysis revealed significant differences in the IMV duration, LV ejection fraction (LVEF), LV global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global waste work (GWW), and global work efficiency (GWE) between the weaning success and failure groups (P<0.05). The multivariate logistic regression analysis revealed that increased IMV duration and decreased GWE were independent risk factors for weaning failure (P=0.039 and P=0.029, respectively). A significant correlation was observed between weaning failure and both the IMV duration and GWE (r=-0.414 and r=0.589; P<0.001 and P<0.001, respectively). The myocardial work parameters all had high intraclass correlation coefficients (ICCs) (all ICCs ≥0.8). Meanwhile, the diagnostic cut-off values for GWE and IMV duration were 0.835 and 5.5 days, respectively, and the area under the receiver operating characteristic (ROC) curve values for GWE, IMV duration, and GWE and IMV duration combined were 0.845, 0.742, and 0.859, respectively.

Conclusions: PSLs can be used to effectively evaluate myocardial work during weaning. GWE is an important myocardial work parameter, and could serve as an independent risk factor for accurately evaluating weaning outcomes.