Pressure Control Ventilation - Fundamentals Part 2: Mean Airway Pressure

Описание: In the previous tutorial I introduced some of the fundamental elements of pressure control ventilation - time cycling, decelerating flow, pressure ramps etc. This time I discuss, in detail, the concept of mean airway pressure (Pmaw) and describe why increasing Pmaw is an effective way of treating patients with extensive lung disease. In volume controlled ventilation this can be achieved by titrating PEEP upwards and increasing respiratory rate. Care must be taken to keep the plateau pressure below 30cmH2O in the majority of patients. In pressure control Pmaw is generally increased by increasing inspiratory time - extreme care must be taken, though, to avoid escalating Auto-PEEP as this corrodes tidal volume and actually reduces Pmaw.

If auto-PEEP is unavoidable, as it is with inverse ratio ventilation, then extrinsic PEEP should be reduced to ensure that tidal ventilation is maintained. Pmaw can be achieved in volume control by adding an inspiratory pause, and in pressure control by increasing respiratory rate - but these are less effective approaches - in volume control because of necessary flow limitation and in pressure control because of fixed inspiratory times, and Auto-PEEP.
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Content
00:05 Introduction
00:47 Review of Previous Tutorial
01:40 Contents of This Tutorial
02:00 Clinical Scenarion (Frank ARDS)
03:00 Frank Volume Control and Inspiratory Hold (pause)
03:50 Peak versus Plateau Pressures
07:30 Understanding Mean Airway Pressure
09:10 Mean Airway Pressure Calculation
10:40 Mean Airway Pressure (Pmaw) in Inverse Ratio Ventilation (IRV)
12:00 Pmaw in IRV with Auto-PEEP
14:30 Impact of Increasing PEEP on Pmaw
15:15 Impact of Increasing Driving Pressure (inspiratory pressure) on Pmaw
15:40 Impact of Increasing Respiratory Rate on Pmaw
16:35 Impact of Increasing Inspiratory Time (Ti) on Pmaw
17:35 Peak/Plateau Pressure Versus Pmaw - and what happens next.
20:15 Understanding Phasic Ventilation/Perfusion Mismatch in Inspiration
22:30 How PEEP Partially Improves Phasic V/Q Mismatch in Inspiration and Lung Compliance
24:00 Why Flow Limited Volume Cycled Ventilation is a Problem (poor distribution of gas)
26:36 Why Pressure Controlled Ventilation with Long Inspiratory Times Improves Overall Gas Distribution in the Lungs.
28:00 Why Auto-PEEP is Inevitable with Long Inspiratory (and Short Expiratory) Times
29:45 Mean Airway Pressure in Volume Control
31:00 Frank Resolution
33:35 Summary
34:25 Review of This Tutorial
35:00 Preview of Next Tutorial