Changes

The ST is designed for chronic obstructive pulmonary disease (COPD) and uses pressure support to overcome the restricted airway or lung on every breath. It is typically set at PS more than 8.0 cm to do this. The backup rate will then provide a breath in the event of a central event, but the machine is doing most of the work of respiration on every breath in its intended application. It cannot supplement or provide a breath at constant PS 5.0. So what we are looking at is the inadequate flow induced by the ST, not an obstructive flow limitation. With central apnea, you only want to rely on the ventilator when it is needed, and rely on spontaneous effort with low, or no pressure support. This provides a normal respiration for the idiopathic CA patient, whom is adversely affected by constant high PS. If PS is raised to where the machine can compensate for the CA, the patient will be nearly 100% reliant on the machine, because pressure support suppresses respiratory drive in people with CA.

=== Positional Apnea ===