What is the pressure-cycled mode of mechanical ventilation?

Updated: Apr 07, 2020
  • Author: Allon Amitai, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Answer

Answer

A set peak inspiratory pressure (PIP) is applied, and the pressure difference between the ventilator and the lungs results in inflation until the peak pressure is attained and passive exhalation follows. The delivered volume with each respiration is dependent on the pulmonary and thoracic compliance.

A theoretical advantage of pressure-cycled modes is a decelerating inspiratory flow pattern, in which inspiratory flow tapers off as the lung inflates. This usually results in a more homogeneous gas distribution throughout the lungs. However, no definite evidence exists that this results in a reduction of the rate of ventilator-induced lung injury or overall mortality. Nevertheless, pressure-cycled ventilation has achieved considerable popularity in the intensive care setting for management of patients with ARDS, whose lungs are most likely to be characterized by a broad range of alveolar dysfunction and are also most vulnerable to the effects of barotrauma and volutrauma.

A major disadvantage is that dynamic changes in pulmonary mechanics may result in varying tidal volumes. This necessitates close monitoring of minute ventilation and limits the usefulness of this mode in many emergency department patients. However, newer ventilators can provide volume-assured pressure-cycled ventilation, which increase peak pressures as needed to deliver a preset minimum tidal volume.


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