Real case: You are passing by the room of an awake mechanically ventilated patient with advanced IPF. Peeking in from outside the room, the following CVP waveform catches your attention.

In a recent post, we discussed the mechanistic basis of how vigorous inspiratory efforts may worsen lung injury. In the discussion that followed, the need for closer assessment of respiratory muscle intensity was highlighted. A dedicated review on this issue will be presented in a future article. For now, we will focus on a lesser appreciated tool – the CVP waveform.

The pressure measured with a CVC is the intramural CVP.

Inspiratory drop in CVP can be used as a surrogate for inspiratory drop in PPl/Pes

Inspiratory decline in CVP will systematically underestimate inspiratory drop in Ppl. This should be kept in mind while using it for assessing the intensity of inspiratory effort.

PCWP swings will more closely mirror Ppl swings. Note: a cut-off of 15 cmH20 has been used to define “significant inspiratory effort”.

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