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
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