What is the dual control within a breath 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 has been called volume-assured pressure support or pressure augmentation according to various manufacturers. This mode can switch from pressure control to volume control within a single specific breath cycle. After a breath is triggered, rapid and variable flow creates pressure to reach the set level of pressure support. The tidal volume that is delivered from the machine is monitored. If the tidal volume equals the minimum set tidal volume, the patient receives a typical pressure-supported breath, which makes this mode essentially like volume support. However, if the tidal volume is less than the set tidal volume, the ventilator switches to a volume-controlled breath with constant flow rate until the set tidal volume is reached.

One study compared volume-assured pressure support with simple assist-control volume support and showed a 50% reduction in the work of breathing, lowered airway resistance, and lowered intrinsic PEEP. However, because of its complexity, this mode is rarely used.


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