LAUSR

Background High respiratory drive in mechanically ventilated patients with spontaneous breathing effort may cause excessive lung stress and strain and muscle loading. Therefore, it is important to have a reliable estimate of respiratory effort to guarantee lung and diaphragm protective mechanical ventilation. Recently, a novel non-invasive method was found to detect excessive dynamic transpulmonary driving pressure (∆ P L ) and respiratory muscle pressure ( P mus ) with reasonable accuracy. During the Coronavirus disease 2019 (COVID-19) pandemic, it was impossible to obtain the gold standard for respiratory effort, esophageal manometry, in every patient. Therefore, we investigated whether this novel non-invasive method could also be applied in COVID-19 patients. Methods ∆ P L and P mus were derived from esophageal manometry in COVID-19 patients. In addition, ∆ P L and P mus were computed from the occlusion pressure (∆ P occ ) obtained during an expiratory occlusion maneuver. Measured and computed ∆ P L and P mus were compared and discriminative performance for excessive ∆ P L and P mus was assessed. The relation between occlusion pressure and respiratory effort was also assessed. Results Thirteen patients were included. Patients had a low dynamic lung compliance [24 (20–31) mL/cmH 2 O], high ∆ P L (25 ± 6 cmH 2 O) and high P mus (16 ± 7 cmH 2 O). Low agreement was found between measured and computed ∆ P L and P mus . Excessive ∆ P L  > 20 cmH 2 O and P mus  > 15 cmH 2 O were accurately detected (area under the receiver operating curve (AUROC) 1.00 [95% confidence interval (CI), 1.00–1.00], sensitivity 100% (95% CI, 72–100%) and specificity 100% (95% CI, 16–100%) and AUROC 0.98 (95% CI, 0.90–1.00), sensitivity 100% (95% CI, 54–100%) and specificity 86% (95% CI, 42–100%), respectively). Respiratory effort calculated per minute was highly correlated with ∆ P occ (for esophageal pressure time product per minute (PTP es/min ) r 2  = 0.73; P  = 0.0002 and work of breathing (WOB) r 2  = 0.85; P  < 0.0001). Conclusions ∆ P L and P mus can be computed from an expiratory occlusion maneuver and can predict excessive ∆ P L and P mus in patients with COVID-19 with high accuracy.