These findings indicate that ventilation without RM leads to impaired lung functions, which stabilize within two hours, though at a low level. We therefore examined the effect of repetitive RM (30 cmH 2 O) every 5 min. In both the lowV T RM5 and the highV T RM5 group, lung mechanics stayed in a physiological range and remained unchanged during the whole experiment. Depending on the different tidal volumes, C and H differed reciprocally between low-and highV T groups (p,0.05). The stability of the lung mechanics demonstrates that application of deep inflations of 1 s duration and 30 cmH 2 O are sufficient to prevent the deterioration of lung functions in healthy mouse lungs ventilated with 2 cmH 2 O PEEP and moderate tidal volumes.