ABG Interpretation: A Step-by-Step Approach

Arterial blood gas (ABG) interpretation is one of the most commonly tested skills on the NCLEX. Follow the ROME method: Respiratory Opposite (pH and PaCO2 move in opposite directions), Metabolic Equal (pH and HCO3 move in the same direction). Step 1: Look at pH — <7.35 = acidosis, >7.45 = alkalosis. Step 2: Check PaCO2 (normal 35-45) — if abnormal and opposite of pH, it's respiratory. Step 3: Check HCO3 (normal 22-26) — if abnormal and matches pH direction, it's metabolic. Step 4: Determine compensation — if the other value is also abnormal, the body is compensating. If pH is normal but other values are abnormal, it's fully compensated.

Oxygen Delivery Systems and Airway Management

Know your oxygen delivery systems: nasal cannula (1-6 L/min, 24-44% FiO2), simple mask (5-8 L/min, 40-60%), non-rebreather (10-15 L/min, 80-95%), Venturi mask (precise FiO2 delivery for COPD), and high-flow nasal cannula (up to 60 L/min). For COPD patients, maintain SpO2 88-92% with low-flow oxygen to avoid suppressing hypoxic drive. Airway management priorities: head-tilt chin-lift (no trauma), jaw thrust (suspected cervical injury), oral airway (unconscious patients only), nasopharyngeal airway (can use in conscious patients), endotracheal intubation (definitive airway). Tracheostomy care: suction PRN using sterile technique, limit suction to 10-15 seconds, keep obturator and spare tracheostomy at bedside.

Chest Tubes, Pneumothorax, and Pleural Disorders

Chest tube nursing care is heavily tested. Normal findings: tidaling (water level rises with inspiration in spontaneous breathing), intermittent bubbling with coughing. Abnormal findings: continuous bubbling in water seal (air leak — check connections), absence of tidaling (lung re-expanded or tube occlusion). Keep drainage system below chest level, never clamp a chest tube (risk of tension pneumothorax), and keep petroleum gauze at bedside for accidental dislodgement. Pneumothorax types: simple (partial lung collapse), tension (life-threatening — tracheal deviation away, absent breath sounds — immediate needle decompression at 2nd ICS, midclavicular line), open (sucking chest wound — 3-sided occlusive dressing).

Chronic and Acute Respiratory Conditions

COPD: two types — chronic bronchitis (blue bloater: productive cough, cyanosis) and emphysema (pink puffer: barrel chest, pursed-lip breathing, dyspnea). Teach pursed-lip breathing, energy conservation, proper inhaler technique (spacer with MDI, rinse mouth after inhaled corticosteroids). Asthma: know the difference between rescue (SABA — albuterol) and controller medications (inhaled corticosteroids, long-acting beta-agonists). Pneumonia: community-acquired vs. hospital-acquired, assess for consolidation (bronchial breath sounds where vesicular should be), incentive spirometry, turn/cough/deep breathe every 2 hours. TB: airborne precautions, negative pressure room, N95 respirator, RIPE therapy, sputum cultures until 3 consecutive negatives.