The Clinical Value Of Driving Pressure And Mechanical Power In Lung Protective Ventilation In Acute Respiratory Distress Syndrome

Objective:To evaluate the clinical value of driving pressure and mechanical power in lung protective ventilation for the patients with acute respiratory distress syndrome?ARDS?.Methods:This was a single-center,prospective observational study.Patients diagnosed with ARDS according to Berlin definition and whose arterial PaO₂/FiO₂ lower than 150mmHg were enrolled.Esophageal pressure was assessed by esophageal catheter and airway pressure-time wave was recorded by Ventrak 1550 software.The different tidal volume?4,6,8,10,12ml/kg?was set for 10minutes respectively.The following data were recorded including:1.the respiratory mechanics variables and mechanical ventilation parameters,2.the end-of-inspiratory esophageal pressure and calculated the end-of-inspiratory transpulmonary pressure(P_L-ins),3.driving pressure and calculated mechanical power according to the equation proposed by Gattinoni.The P_L-ins<27cmH₂O as the standard for achieving lung protection ventilation was used to accessed the clinical value of driving pressure and mechanical power.Results:1.Clinical characteristics20 patients with ARDS were enrolled.The APACHE II score was 17±7,Murray score was 3.25?3.00-3.56?and PaO₂/FiO₂ was 82?69-119?mmHg.The main cause of ARDS was pneumonia.2.The impacts of respiratory mechanics under different tidal volumeMechanical power,driving pressure and P_L-ins were gradually increased with the increase of tidal volume.At a tidal volume of 6ml/kg,10%patients'P_L-ins were over 27cmH₂O,15%patients'driving pressure were over 15cmH₂O and 25%patients'mechanical power were over 17J/min;3.The cut-off value of driving pressure and mechanical power for lung protection ventilation.The area under curve?AUC?of the driving pressure as a predictor of P_L-ins-ins above 27cmH₂O was 0.902?CI 0.816-0.988,p<0.001?and the AUC of the mechanical power as a predictor of P_L-ins-ins above 27cmH₂O was 0.786?CI 0.652-0.920,p=0.006?.The cut-off values of driving pressure and mechanical power were 18.5 cmH₂O and 15 J/min respectively.4.The clinical value of driving pressure and mechanical power in lung protective ventilationWhen the driving pressure exceeded 18.5cmH₂O,the sensitivity of driving pressure to predict P_L-ins above 27cmH₂O was 77%and the specificity was 91%;the positive predictive value of driving pressure was 0.54 and the negative predictive value was 0.97.When the mechanical power exceeded15J/min,the sensitivity was 100%and the specificity was 63%;the positive predictive value of mechanical power was 0.27 and the negative predictive value was 1.5.The trending ability of driving pressure and mechanical against P_L-insThe total concordance rate of driving pressure against P_L-ins-ins was 1.54,and the total concordance rate of mechanical power against P_L-ins-ins was 1.45.Conclusion:Both driving pressure and mechanical power could be used in guidance in lung protective ventilation for ARDS patients.However,driving pressure was probably better than mechanical power.