Recording during an inspiration with continuous fresh gas flow. Top panel: pressure signal sampled at airway opening (proximal airway pressure (Pprox)). Middle panel: computed high frequency component of the pressure signal, test lung influence eliminated. Bottom panel: computed test lung induced pressure changes. The vertical line denotes the start of simulated induced inspiration. The horizontal line in the bottom panel represents set mean Pprox. The curve represents fluctuation of set mean Pprox on account of breathing.
van Heerde et al. Critical Care 2006 10:R103 doi:10.1186/cc4968