Effect of PEEP on breath sound power spectra in experimental XXXX .

@entity1707 @entity3952 @entity3126 @entity651 @entity358 @entity647
BACKGROUND: @entity647 ( @entity647 ) is known to be associated with the emergence of inspiratory crackles and enhanced transmission of artificial sounds from the airway opening to the chest wall. Recently, we described the effect of @entity647 on the basic flow-induced breath sounds, separated from the crackles. In this study, we investigated the effects of positive end-expiratory pressure (PEEP) on these noncrackling basic lung sounds augmented during @entity647 . METHODS: Lung sounds were recorded in six anesthetized, intubated, and mechanically ventilated @entity1707 at three locations bilaterally on the chest wall. Recordings were obtained before and after induction of @entity651 with @entity3952 and during application of incremental positive end-expiratory pressure. RESULTS: @entity3952 injections caused severe @entity3126 predominately in the dependent-lung regions. Inspiratory spectral power of breath sounds increased in all lung regions over a frequency band from 150 to 1,200 Hz, with further power augmentation in @entity358 at higher frequencies. Incremental positive end-expiratory pressure reversed the spectral power augmentation seen with @entity647 , reducing it to pre-injury levels with PEEP of 10 and 15 cmH2O in all lung regions at all frequencies. The application of positive end-expiratory pressure to normal lungs attenuated spectral power slightly and only over a band from 150 to 1,200 Hz. CONCLUSIONS: We confirm a gravity-related spectral amplitude increase of basic flow-induced breath sounds recorded over lung regions affected by permeability-type @entity3126 and show that such changes are reversible by alveolar recruitment with PEEP.
