Evaluation of weaning parameters for weaning readiness from mechanical ventilation among elderly patients

Abstract

Background: Numbers of elderly patients with acute respiratory failure continue to rise with increasing age of the general population worldwide. Ventilatory reserve decreases substantially with age as a result of multiple interrelated physiologic changes. Objective: This study aimed to evaluate the predictive value of conventional and composite weaning parameters among elderly patients. Methods: We conducted an observational prospective study among intubated patients ≥70 years old and readied for undergoing spontaneous breathing trial (SBT). Weaning parameters were recorded [heart rate, respiratory rate, tidal volume, minute ventilation (MV)] at 1 min, 30 min, and 2 hr after beginning of SBT. Cough peak expiratory flow (CPEF) and diaphragmatic thickness (DT) were also measured at 1 min after SBT. Weaning parameters were compared between the 2 patient groups (weaning success vs. weaning failure). Primary outcome was difference in weaning parameters between the 2 groups of patients. Results: All 48 subjects were enrolled. The mean (±SD) age was 80.2 (±6) years. Altogether, 38 patients (79.2%) were in the weaning success group and 10 patients (20.8%) in the weaning failure group. All baseline characteristics did not significantly differ between the 2 groups. While no difference was observed in other isolated weaning parameters between the 2 patient groups, we found that patients in the weaning success group had significantly lower MV than patients in the weaning failure group (8.3±1.8 vs. 9.9±2.5 L/min, p=0.025). Composite weaning parameters included MV/CPEF and MV/(CPEF x DT) increased predictive values for weaning failure than isolated MV with area under the receiver operating characteristics curves of 0.78, 0.80, and 0.72 respectively. The best cutoff point to predict weaning failure were MV ≥8.4 L/min, MV/CPEF ≥0.12, and MV/(CPEF x DT) ≥0.45 cm-1 Conclusion: MV was the only parameter associated with weaning failure among the elderly. Composite parameters demonstrated better predictive value for assessing weaning readiness among elderly patients.