What are the benefits of average volume assured pressure support (AVAPS) in noninvasive ventilation (NIV)?

Updated: Jun 18, 2020
  • Author: Guy W Soo Hoo, MD, MPH; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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As with any pressure-cycled mode, the dependent variable is volume and it may vary widely if there is patient dyssynchrony, changes in lung compliance, or changes in resistance that can occur with changes in body position that occurs in the very morbidly obese. [8] A fixed pressure support setting will not compensate for these changes, and, as a result, delivered tidal volume will fall. AVAPS allows a target tidal volume to be identified with a range of pressure support settings that fluctuate to meet the target tidal volume. AVAPS uses an internal algorithm to make changes in the pressure support supplied to achieve the target volume, but these changes are small and occur over minutes (typically 1-2.5 cm water per minute). That is why rapidly changing, acute respiratory conditions are not suited for AVAPS as the ventilator adjustments may not be timely enough to meet the patient's requirements. Typically, the pressure support required to produce the target volume during bedside titration is used to identify the minimal pressure with the set minimal pressure (min P), typically 2-3 cm water lower to allow flexibility for adjustment in the AVAPS mode. The maximal pressure (max P) is typically set in the 20-25 cm water range as higher pressures are not well tolerated. The min P is at least 8 cm water and usually higher. Additional parameters that are part of AVAPS setting are the target tidal volume, respiratory rate, EPAP, and inspiratory time.

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