What does the flow waveform of pressure support ventilation typically resemble?

In pressure support ventilation, the flow waveform characteristically features a decelerating pattern. This occurs because the ventilator provides assistance during the inspiratory phase, where the pressure support initiates flow rapidly at the beginning of inspiration and then gradually decreases as the breath is delivered. The decelerating flow pattern reflects the shift in airflow as resistance in the airways and compliance of the lungs interact; this typically results in a peak flow that diminishes over the course of the inspiratory phase.

The decelerating pattern is indicative of the way the patient’s lungs are receiving the air, allowing their inspiratory effort to result in a natural transition of airflow. This is particularly beneficial for ensuring comfort and facilitating spontaneous breathing efforts. In contrast, other waveform patterns, such as rectangular or square waves, suggest constant flow rates that do not align with the physiological needs during pressure support. Understanding the typical flow waveform can help clinicians optimize settings for individual patient needs in mechanical ventilation.