Effects of different levels of pressure support variability on acute respiratory distress syndrome

Objective To compare the effects of different levels of variability duringnoisy pressure support ventilation (noisy PSV) in mechanically ventilated patients with acute respiratory distress syndrome(ARDS). Methods Seventeen patients with ARDS were enrolled in this monocentric, randomized crossover study. All patients were mechanically ventilated with different levels of noisy PSV for 10 minutes respectively, in random sequence.The subjects, such as gas exchange, lung functional parametersand distribution of ventilation by electrical impedancetomography(EIT), were obtained and analyzed. Results Oxygenation index(PaO2/FiO2)had no significant difference between groups of different levels(P>0.05). But intragroup analysis indicated that PaO2/FiO2 was improved by noisy PSV 30% in comparison with 15% (P 0.05). Spatial distribution of ventilation in regions of interet 1-4 showed no difference with different levels of noisy PSV(P>0.05). But intragroup analysis still showed that ventilation in ROI3 was significantly improved by noisy PSV30% as compared with 15%(P<0.05). Conclusion Compared to the level of 15%, noisy PSV 30% is associated with better gas exchange and improved distribution of ventilation. Key words: noisy PSV; ARDS; Variability; Distribution; Inhomogeneity