What are the three phase variables that define the ventilator cycle?

The three phase variables that define the ventilator cycle are trigger, limit, and cycle.

The trigger variable determines when a breath is initiated, which can be patient-initiated (sensitive to the patient’s efforts) or time-based (delivered based on a preset time interval). The limit variable safeguards the maximum value of pressure, volume, or flow during the breath delivery, ensuring that parameters remain within safe and set boundaries. Lastly, the cycle variable indicates when the breath should transition from inspiration to expiration, which is based on reaching a specific threshold of pressure, volume, or flow.

Understanding these phase variables is crucial for effectively managing mechanical ventilation, as they collectively dictate how breaths are delivered and monitored, ensuring patient safety and optimal respiratory support.