What would pulmonary function tests (PFT) reveal in a patient with Acute Respiratory Distress Syndrome?

In a patient with Acute Respiratory Distress Syndrome (ARDS), pulmonary function tests (PFT) typically reveal decreased lung volumes and capacities. ARDS is characterized by inflammation and edema in the alveoli, which leads to impaired gas exchange and reduced lung compliance.

This decrease in compliance results in a restrictive lung defect, where the ability of the lungs to expand is compromised. Consequently, both the total lung capacity (TLC) and vital capacity (VC) are often reduced, reflecting the restrictive nature of the disease. Decreased functional residual capacity (FRC) can also occur due to impaired ventilation and poor lung volumes.

The other options do not accurately reflect the physiological changes seen in ARDS. Increased lung volumes and capacities would suggest hyperinflation or an obstructive pattern, which is not typical in ARDS. Normal function with slight reductions might indicate a mild process but does not align with the significant impact ARDS has on lung mechanics. A restrictive pattern with normal peak flow would suggest that while flow rates are maintained, the overall lung volumes remain compromised, which is inconsistent with the significant reductions observed in ARDS. Therefore, the correct understanding of the PFT results in ARDS is indeed the observation of decreased lung volumes and capacities.