Driving pressure-guided ventilation decreases the mechanical power compared to predicted body weight-guided ventilation in the Acute Respiratory Distress Syndrome

Abstract

Background: Whether targeting the driving pressure (∆P) when adjusting the tidal volume in mechanically ventilated patients with the acute respiratory distress syndrome (ARDS) may decrease the risk of ventilator-induced lung injury remains a matter of research. In this study, we assessed the effect of a ∆P-guided ventilation on the mechanical power.

Methods: We prospectively included adult patients with moderate-to-severe ARDS. Positive end expiratory pressure was set by the attending physician and kept constant during the study. Tidal volume was first adjusted to target 6 ml/kg of predicted body weight (PBW-guided ventilation) and subsequently modified within a range from 4 to 10 ml/kg PBW to target a ∆P between 12 and 14 cm H₂O. The respiratory rate was then re-adjusted within a range from 12 to 40 breaths/min until EtCO₂ returned to its baseline value (∆P-guided ventilation). Mechanical power was computed at each step.

Results: Fifty-one patients were included between December 2019 and May 2021. ∆P-guided ventilation was feasible in all but one patient. The ∆P during PBW-guided ventilation was already within the target range of ∆P-guided ventilation in five (10%) patients, above in nine (18%) and below in 36 (72%). The change from PBW- to ∆P-guided ventilation was thus accompanied by an overall increase in tidal volume from 6.1 mL/kg PBW [5.9-6.2] to 7.7 ml/kg PBW [6.2-8.7], while respiratory rate was decreased from 29 breaths/min [26-32] to 21 breaths/min [16-28] (p < 0.001 for all comparisons). ∆P-guided ventilation was accompanied by a significant decrease in mechanical power from 31.5 J/min [28-35.7] to 28.8 J/min [24.6-32.6] (p < 0.001), representing a relative decrease of 7% [0-16]. With ∆P-guided ventilation, the PaO₂/FiO₂ ratio increased and the ventilatory ratio decreased.

Conclusion: As compared to a conventional PBW-guided ventilation, a ∆P-guided ventilation strategy targeting a ∆P between 12 and 14 cm H₂O required to change the tidal volume in 90% of the patients. Such ∆P-guided ventilation significantly reduced the mechanical power. Whether this physiological observation could be associated with clinical benefit should be assessed in clinical trials.

Keywords: Acute respiratory distress syndrome; Driving pressure; Mechanical power; Mechanical ventilation; Protective ventilation; Tidal volume; Ventilator-induced lung injury.

Fig. 1

Change in mechanical power between predicted body weight-guided ventilation (PBW-Vent) and driving pressure-guided ventilation (ΔP-Vent). A The violin plots represent the mechanical power (thick horizontal line: median; thin horizontal dashed lines: 25th and 75th percentiles). *Denotes statistical significance. B Individual data

Fig. 2

Change in ventilatory parameters according to the change in mechanical power with ΔP-Vent. MP ↘ with ΔP-Vent: patients in whom the mechanical power strictly decreased with ΔP-Vent compared with PBW-Vent (n = 36). MP → or ↗ with ΔP-Vent: patients in whom the mechanical power remained unchanged or increased with ΔP-Vent compared with PBW-Vent (n = 14). ΔP: driving pressure; Vt: tidal volume. *Denotes statistical significance