Introduction
REx-PN Collaboration for acute distress; objective reporting of accessory muscle use and SpO₂. Traps: teaching technique while SpO₂ is falling, or SABA overuse without escalation. For REx-PN (Canada), questions rarely announce the topic in the first sentence. They hide it inside vitals, labs, and a short story. Your job is to name the clinical problem, justify why it matters now, and select the safest next step for the role you are given—before you let distractors pull you toward busywork or out-of-scope heroics. When two answers feel partly right, pick the one that closes risk first and matches your license in the stem. On the exam, writers often pair stable-sounding options with unstable data—notice the mismatch before you commit. If the stem names a license or role, reread that line; scope errors are classic trap answers even when the clinical topic is familiar. Run a 60-second scan: breathing work and oxygenation, perfusion and end organs, neuro baseline, likely infection sources, and devices that can fail quietly. When two answers feel partly right, pick the one that reduces imminent harm and **matches...