How does ARDS impact compliance during mechanical ventilation?

In the context of ARDS (Acute Respiratory Distress Syndrome), compliance refers to the ability of the lungs to expand in response to pressure changes during mechanical ventilation. ARDS typically leads to a decrease in lung compliance due to several pathophysiological changes, including inflammatory processes that result in pulmonary edema, atelectasis (collapse of alveoli), and impaired surfactant function.

As lung tissue becomes stiff and less elastic, the volume of air that can be effectively delivered at a given pressure is reduced. This results in decreased dynamic compliance, which is measured during the actively ventilated phase when air is flowing in and out of the lungs. Lower compliance requires higher pressures to achieve adequate ventilation, leading to challenges in managing ventilation strategies in patients with ARDS.

In summary, during mechanical ventilation in patients with ARDS, the significant decrease in dynamic compliance is primarily attributed to the lung's compromised ability to expand due to fluid accumulation and tissue stiffening, necessitating a careful and often adjusted approach to mechanical ventilation strategies.