Key Concepts
Introduction
Arterial blood gas (ABG) analysis is a bedside diagnostic tool that measures the adequacy of oxygenation, ventilation, and acid-base balance. For NCLEX-RN Canada, ABG interpretation is high-yield โ it appears in questions about respiratory distress, COPD, mechanical ventilation, metabolic disorders, and sepsis. Normal ABG values (remember these exactly): - pH: 7.35โ7.45 (acidosis < 7.35; alkalosis > 7.45) - PaCOโ: 35โ45 mmHg (respiratory component โ 'acid tank') - HCOโโป: 22โ26 mEq/L (metabolic component โ 'base buffer') - PaOโ: 80โ100 mmHg (oxygenation) - SaOโ: 95โ100% - Base excess: โ2 to +2 Quick memory tool โ ROME: - Respiratory Opposite: pH and PaCOโ move in opposite directions (โCOโ โ โpH; โCOโ โ โpH) - Metabolic Equal: pH and HCOโโป move in the same direction (โHCOโ โ โpH; โHCOโ โ โpH) On the exam, writers often pair stable-sounding options with unstable dataโnotice 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...