By the end of this Gold Standard lesson, the learner should be able to: - Differentiate Type 1 (hypoxemic) from Type 2 (hypercapnic) respiratory failure. - Apply the Berlin criteria to diagnose ARDS and classify severity using the P/F ratio. - Calculate the PaO2/FiO2 (P/F) ratio and interpret mild, moderate, and severe ARDS thresholds. - Explain intrapulmonary shunting and why ARDS hypoxemia is refractory to oxygen alone. - Describe the lung-protective ventilation strategy (tidal volume 4–6 mL/kg IBW, plateau ≤ 30 cmH2O, PEEP). - Apply evidence-based indications and nursing management for prone positioning in severe ARDS. - Interpret the P/F ratio, Berlin ARDS criteria, and ABG patterns to distinguish ARDS from cardiogenic pulmonary oedema. - Differentiate lung-protective ventilation, prone positioning, and the ABCDEF bundle by mechanism and evidence for outcome improvement. - Apply assessment-to-action reasoning to recognise rising PaCO2 and worsening P/F ratio as decompensation requiring escalation. - Distinguish refractory hypoxaemia from oxygen-responsive hypoxaemia and identify when supplemental O2 alone is insufficient. On the exam, writers often pair stable-sounding options with unstable data—notice the mismatch before you commit. If the...