What condition might cause increased compliance in a patient with ARDS receiving mechanical ventilatory support?

Increased compliance in a patient with Acute Respiratory Distress Syndrome (ARDS) receiving mechanical ventilation can occur when there is a reduction in lung tissue edema. In ARDS, the lungs often become stiff due to fluid accumulation in the alveoli and interstitial spaces, which severely decreases lung compliance. When treatment is effective and lung edema reduces, the compliance of the lungs improves, allowing them to expand more easily during mechanical ventilation.

This improvement is crucial because higher compliance means that less pressure is required to achieve adequate tidal volume during ventilation, which can enhance gas exchange and reduce the work of breathing. Therefore, the reduction of edema leads to more favorable mechanical properties of the lungs, improving the patient's overall respiratory status.

The other factors, such as increased pulmonary perfusion or reduced dead space ventilation, do not directly correlate with improving compliance in the context of ARDS. Increased airway resistance would typically decrease compliance rather than increase it, as it makes it harder for the lungs to expand in response to ventilatory pressure. Thus, the reduction of lung tissue edema is indeed the key factor leading to increased compliance in this scenario.