What is the proportional assist ventilation mode of mechanical ventilation?

Updated: Apr 11, 2019
  • Author: Christopher D Jackson, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Answer

Answer

This mode was designed to decrease the work of breathing and improve patient-ventilator synchrony. The mode adjusts airway pressure in proportion to the patient's effort. Unlike other modes in which the physician presets a specific tidal volume or pressure, proportional assist ventilation (PAV) lets the patient determine the inspired volume and the flow rate. This mode requires continuous measurements of resistance and compliance to determine the amount of pressure to give. The support given is a proportion of the patient's effort and is normally set at 80%. This support is always changing according to patient's effort and lung dynamics. If the patient's effort and/or demand are increased, the ventilator support is increased, and vice versa, to always give a set proportion of the breath. The patient's work of breathing remains constant regardless of his or her changing effort or demand (see image below).

The pressure, volume, and flow to time waveforms f The pressure, volume, and flow to time waveforms for proportional-assist ventilation.

This mode can be used only in patients with spontaneous respiratory efforts. PAV has promise, but the US Food and Drug Administration (FDA) has not approved it for commercial use.


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