Non-invasive method to detect high respiratory effort and transpulmonary driving pressures in COVID-19 patients during mechanical ventilation

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.