The tracings are typical of flow starvation. Looking at the expiratory flow one can recognize that patient’s effort starts before the end of expiration (minor gas trapping possible), then triggers the breath (therefore it can not be reverse triggering) and the effort is so strong that the airway pressure cannot increase and the flow tends to slightly increase above the set value. Note that a set VT of 400 ml for a Ti of 0.8s gives a peak flow rate (volume-control, constant flow) of 500 ml/sec or 30 L/min, a really insufficient value to meet patient’s demand and classically associated with high work of breathing. At the end of patient’s effort, airway pressure goes up very quickly whereas flow tends to slightly go down transiently. The patient may need a higher peak flow rate.

A special thanks to Roy Brower from Johns Hopkins University School of Medicine, Baltimore, MD USA

To view more information about flow starvation visit our post here.

8 thoughts on “How would you interpret this waveform?”

  1. I have been in an OR as an Anesthesia Assistant since 2001…my apology for my answer…educate me.

    1. Hopefully the description helps, and there is a link to another post on this subject in the description as well. Enjoy.

  2. Increase the inspiratory flow rate, decreasing Ti and avoid the deceleration of the pattern (in this mechanical ventilation equipment).

  3. Assess depth of sedation and analgesia need, perform P0.1 an Pocc. If P-SILI is the problem, deepen sedation/analgesia, if necessary add NMBA. Other strategy would be transferring patient to pressure mode (PCV, BiPAP, PRVC, APRV) and reassess.

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