Acute Respiratory Failure (ARF) and Acute Respiratory Distress Syndrome (ARDS) are critical pulmonary conditions where gas exchange is insufficient to support systemic organs1.

The 80/20 Core: Pathophysiology & Clinical Care

1. Classification of ARF ARF is a symptom of inadequate lung function, categorized into two types12:

• Hypoxemic (Oxygenation Failure): $PaO_2 < 60$ mm Hg on room air2. The core defect is inadequate $O_2$exchange, caused by $V/Q$ mismatch, shunt, diffusion impairment, or alveolar hypoventilation23. Shunt is an extreme mismatch where alveoli fill with fluid, making $O_2$ therapy alone ineffective45.
• Hypercapnic (Ventilatory Failure): $PaCO_2 > 50$ mm Hg with $pH < 7.35$6. It represents insufficient $CO_2$ removal6. Pri ...