Rise time sets the time for the VPAP bilevel device to increase from EPAP pressure to IPAP pressure. Adjusting the rise time and fall time allows for fine-tuning the transitions between inspiratory and expiratory pressures. The greater the rise time value, the longer it takes for pressure to increase from EPAP to IPAP.
Rise time should not be set longer than the patient’s normal inspiratory time as a prolonged rise time inhibits fast pressurization. The actual rise time achieved is influenced by several factors, such as compliance, resistance, leak, pressure differential and patient breathing patterns.
Fall time sets the time taken for the device to transition from the inspiratory pressure to the expiratory pressure. The greater the fall time value, the longer it takes for pressure to decrease.
Patients with a high ventilatory demand may require a fast fall time especially those needing a short inspiratory time and long expiratory time (such as COPD patients). In these patients a fast rise and fall time allows the machine to support the breath quickly. In patients with a slower respiratory rate or lungs that empty rapidly, increasing fall time can improve comfort.
Adjustable Rise Time and Fall Time, together with TiControl™ and Trigger/Cycle sensitivity adjustments all help to personalize therapy according to patient conditions.