Airway driving pressure and lung stress in ARDS patients. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Chiumello, Davide; Carlesso, Eleonora; Brioni, Matteo; Cressoni, Massimo
• Is Part Of: Critical care. Volume 20:Issue 1(2016)
• Page Start: 1
• Page End: 10
• Publication Date: 2016-12
• Subjects: ARDS -- Lung stress -- Driving pressure -- VILI -- Esophageal pressure -- Mortality; Critical care medicine -- Periodicals; 616.02805
• DOI: 10.1186/s13054-016-1446-7
• Languages: English
• ISSNs: 1364-8535

Abstract

Abstract Background Lung-protective ventilation strategy suggests the use of low tidal volume, depending on ideal body weight, and adequate levels of PEEP. However, reducing tidal volume according to ideal body weight does not always prevent overstress and overstrain. On the contrary, titrating mechanical ventilation on airway driving pressure, computed as airway pressure changes from PEEP to end-inspiratory plateau pressure, equivalent to the ratio between the tidal volume and compliance of respiratory system, should better reflect lung injury. However, possible changes in chest wall elastance could affect the reliability of airway driving pressure. The aim of this study was to evaluate if airway driving pressure could accurately predict lung stress (the pressure generated into the lung due to PEEP and tidal volume). Methods One hundred and fifty ARDS patients were enrolled. At 5 and 15 cmH2 O of PEEP, lung stress, driving pressure, lung and chest wall elastance were measured. Results The applied tidal volume (mL/kg of ideal body weight) was not related to lung gas volume (r 2 = 0.0005p = 0.772). Patients were divided according to an airway driving pressure lower and equal/higher than 15 cmH2 O (the lower and higher airway driving pressure groups). At both PEEP levels, the higher airway driving pressure group had a significantly higher lung stress, respiratory system and lung elastance compared to the lower airway driving pressure group. Airway driving pressure was significantly related to lung stress (r 2 = 0.581p < 0.0001 andr 2 = 0.353p < 0.0001 at 5 and 15 cmH2 O of PEEP). For a lung stress of 24 and 26 cmH2 O, the optimal cutoff value for the airway driving pressure were 15.0 cmH2 O (ROC AUC 0.85, 95 % CI = 0.782–0.922); and 16.7 (ROC AUC 0.84, 95 % CI = 0.742–0.936). Conclusions Airway driving pressure can detect lung overstress with an acceptable accuracy. However, further studies are needed to establish if these limits could be used for ventilator settings.