Figure 4.

Separation of inspiratory and expiratory signals in a vibration response imaging (VRI) waveform. Separation of inspiratory and expiratory signals produced by application of an inspiratory hold during the second breath in a mechanically ventilated patient is shown. Flow was sampled directly from the ventilator and synchronized with VRI. The three waveforms depict pressure, flow, and vibration as a function of time. Exp., expiratory; Insp., inspiratory.