Question 22.4

The following ventiator waveform shown below (Figure 4) is from a patient who is sedated and ventilated in the pressure regulated volume control mode (a pressure control mode with a target tidal volume).The patient has an arterial oxygen saturation of 94%.

Give the likely underlying lung pathology. (10% marks)

Give one feature shown in the flow waveform that supports your answer. (10% marks)

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College answer

a) Any lung pathology associated with poor compliance such as severe restrictive pathologies 
b) Inspiratory flow drops sharply very early in inspiration 


The original college image also had 100% FiO2, but the other settings were:

  • PRVC mode (not SIMV PRVC)
  • PEEP 6
  • RR 30
  • VT 260
  • Mve 7.6
  • Ppeak 33
  • Pmean 19

In every other respect, "any lung pathology associated with poor compliance" applies equally well to both images.