The patient is turning purple in the bed, alarms are going off, he  is desaturating: he is “fighting the ventilator.” Although a widely used description I believe that it is misused to redefine the problem away from an issue of ventilator operator competency and reframe it as a patient problem. It is not. Most of the time that patient have negative interactions with the ventilator it is a problem of triggering, flow or expiratory cycling. The treatment is not deep sedation and controlled ventilation. The treatment requires skill and nuance, and does not always work. This tutorial looks at inspiration and reasons why it may go wrong.

The most frequently seen patient ventilator dysynchrony is scooping of the pressure waveform, usually associated with flow limited volume controlled ventilation. This can be resolved by increasing the peak flow or changing to pressure control.

In general the ambition to establish a patient on spontaneous assisted ventilation is laudable, but oftentimes we have no idea about what is going on underneath the pressure, flow and volume waveforms. In this tutorial I try and correct the narrative about patient-ventilator interaction when using pressure support. I suggest that volume support in some situations may be a superior approach. I point out that the tidal volume in pressure support has little to do with patient effort and more to do with lung compliance.

I finish the tutorial with a discussion about the inspiratory rise time and explain why you must be careful when using older ventilators.

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