Effects of frequency and inspiratory plateau pressure during recruitment manoeuvres on lung and distal organs in acute lung injury.

PURPOSE: To evaluate the effects of frequency and inspiratory plateau pressure (Pplat) during recruitment manoeuvres (RMs) on lung and distal organs in acute lung injury (ALI). METHODS: We studied paraquat-induced ALI rats. At 24 h, rats were anesthetized and RMs were applied using continuous positive airway pressure (CPAP, 40 cmH(2)O/40 s) or three-different sigh strategies: (a) 180 sighs/h and Pplat = 40 cmH(2)O (S180/40), (b) 10 sighs/h and Pplat = 40 cmH(2)O (S10/40), and (c) 10 sighs/h and Pplat = 20 cmH(2)O (S10/20). RESULTS: S180/40 yielded alveolar hyperinflation and increased lung and kidney epithelial cell apoptosis as well as type III procollagen (PCIII) mRNA expression. S10/40 resulted in a reduction in epithelial cell apoptosis and PCIII expression. Static elastance and alveolar collapse were higher in S10/20 than S10/40. CONCLUSIONS: The reduction in sigh frequency led to a protective effect on lung and distal organs, while the combination with reduced Pplat worsened lung mechanics and histology.