Virtually all “modern” modes of mechanical ventilation are built on a pressure controlled platform – the original of the species is Pressure Assist Control (PAC). This tutorial introduces PAC as it would be used on a patient admitted, for example, to ICU, with relatively normal lungs.
The tutorial commences with a clinical scenario followed by a guide to the settings on both Puritan Bennett and Drager ventilators. At this point in the course I am going to start spending more time on Drager devices as these ventilators were built from the ground up to be used as pressure controlled machines. There are nuances to the Drager ventilator that may be slightly counter-intuitive to clinicians who are familiar to other brands: in particular the use of a pressure limit (Pinsp) rather than a driving pressure above PEEP. I explain this with examples. I then explain how pressure control works and remind you of flow and time triggering.
All pressure controlled modes are time cycled with decelerating flow patterns. Care must be taken to ensure that inspiratory time is sufficiently long so as to ensure that the airway is adequately pressurized but not to long as will cause Auto-PEEP.
If you want to understand mechanical ventilation you absolutely must be able to interpret and craft ventilator waveforms – and this tutorial focuses on identifying abnormal waveforms in pressure control and correcting them. Hence there is a section on “Crafting the Pressure Waveform” and a section on “Crafting the Flow Waveform.”
Finally I discuss inspiratory time and tidal volumes