What occurs to the compliance curve on adjusting the PEEP level?

When adjusting the PEEP (Positive End-Expiratory Pressure) level, the compliance curve typically flattens out at the lower end. This phenomenon occurs because higher levels of PEEP increase the baseline lung volume, promoting lung recruitment and improving functional residual capacity (FRC). As FRC increases, the lungs become more compliant in the expanded state, which means that further increases in lung volume yield less change in pressure, resulting in a flattened compliance curve at the lower part.

This flattening represents a situation where the lungs are less stiff and therefore can accommodate more volume without significant increases in pressure. Higher PEEP prevents alveolar collapse during exhalation, enhancing gas exchange and overall lung mechanics. Understanding this response is crucial for optimizing ventilation strategies in mechanically ventilated patients, particularly those with conditions like Acute Respiratory Distress Syndrome (ARDS), where lung recruitment is important.