Figure 1
Representative regional electrical impedance tomography (EIT) waveforms of relative impedance change ( rel. ΔZ ) obtained in a 57-year old male patient with normal lungs and a 52-year old male patient with acute respiratory distress syndrome ( ARDS ) during a step increase in airway pressure from 0 to 35 cm H 2 O. Original data and data fitted to a bi-exponential equation in the ventral (v) and dorsal (d) chestregions are shown. The calculated regional fast (τ 1 ) and slow respiratory time constants (τ 2 ) and the relative size of the fast compartment (A 1 ) are displayed to the right of each waveform. (The very small periodic fluctuations discernible in the original waveforms are synchronous with the heart beat and reflect the small changes in rel. ΔZ occurring at a rate of 59/min in the patient with normal lungs and of 92/min in the patient with ARDS).