The MIME framework for non-invasive longitudinal assessment of inspiratory effort during pressure support ventilation: a physiological validation study

Continuous monitoring of inspiratory effort during assisted mechanical ventilation remains challenging, yet it is vital as the transition from controlled to assisted mechanical ventilation requires careful titration of inspiratory effort to ensure patient safety. The Mixed Integer Multi-Effort (MIME) method is a physiological modeling approach that uses standard ventilator signals to non-invasively estimate inspiratory muscle pressure (Pmus). We evaluated the accuracy of MIME during pressure support ventilation (PSV) in patients with acute hypoxemic respiratory failure (AHRF). We conducted a prospective physiological validation study in adult patients with AHRF within 48 h of their first transition from controlled mechanical ventilation to PSV. Airway and esophageal pressure, flow, and volume, were recorded and analyzed offline with the MIME algorithm, which estimates Pmus by reconstructing airway pressure and separating ventilator-delivered from patient-generated pressure using a respiratory mechanics-based model. MIME-derived Pmus estimates were compared with esophageal pressure-derived Pmus using Bland–Altman analysis with mixed-effects modeling to account for repeated measurements within patients. Receiver operating characteristic analysis was used to evaluate MIME’s ability to detect high and low inspiratory effort and to compare its performance with end-expiratory occlusion pressure (ΔPocc). Sixty-two independent model-fitting windows (1240 breaths) from 18 patients were analyzed. Median inspiratory Pmus was 7.5 (IQR 6.0–9.1) cmH₂O for MIME-derived estimates and 6.9 (5.9–8.9) cmH₂O for esophageal pressure-derived measurements. Breath-by-breath analysis demonstrated a mean difference of 0.4 cmH₂O with limits of agreement ranging from − 3.4 to 4.2 cmH₂O. Agreement between methods improved when inspiratory effort was averaged over multiple breaths. Averaged values within each analyzed recording set showed a mean difference of 0.4 cmH₂O with limits of agreement ranging from − 2.2 to 3.0 cmH₂O. MIME demonstrated good discriminative performance in detecting both high and low inspiratory effort (AUROC 0.83 and 0.88, respectively). Compared with ΔPocc, MIME showed similar performance for detecting low inspiratory effort, whereas ΔPocc performed better for detecting high inspiratory effort. The MIME method provided non-invasive estimates of inspiratory effort during pressure support ventilation and may complement established physiological tools such as ΔPocc by supporting longitudinal assessment. Validation in broader populations and physiological settings, together with dedicated assessment of convergence and computational performance, is required before real-time bedside implementation.