Reference — Respiratory
Respiratory Failure Reference
Respiratory failure occurs when the respiratory system can no longer maintain adequate gas exchange. It is classified as Type I (hypoxemic — oxygenation failure) or Type II (hypercapnic — ventilation failure), each with distinct causes, ABG patterns, and treatment priorities.
Educational use only. Diagnosis of respiratory failure requires provider evaluation, ABG analysis, and clinical context. This reference supports NCLEX preparation and learning — it does not replace clinical assessment or medical decision-making. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Type I — Hypoxemic Respiratory Failure
Type I respiratory failure is a failure of oxygenation. The lungs are unable to transfer adequate oxygen from the alveoli into the bloodstream. CO₂ removal is typically normal or may be low (hyperventilating to compensate).
- ARDS — most severe form; bilateral diffuse alveolar damage
- Pneumonia — consolidation blocks O₂ exchange in affected segments
- Pulmonary edema (cardiogenic or non-cardiogenic)
- Pulmonary embolism — dead space lesion with V/Q mismatch
- Pneumothorax — lung collapse eliminates ventilation-perfusion
- Pulmonary fibrosis / interstitial lung disease
Type II — Hypercapnic (Ventilatory) Respiratory Failure
Type II respiratory failure is a failure of ventilation. The patient cannot move adequate volumes of air to eliminate CO₂. CO₂ accumulates, causing respiratory acidosis. Hypoxemia is also present (from inadequate ventilation) but the primary problem is CO₂ retention.
- COPD exacerbation — most common cause of acute-on-chronic Type II failure
- Opioid/sedative overdose — suppressed central respiratory drive
- Neuromuscular disease — Guillain-Barré, myasthenia gravis, ALS, C3-C5 spinal injury
- Severe asthma with fatigue (progressing to Type II from initial Type I)
- Chest wall deformity — kyphoscoliosis, flail chest
- Obesity hypoventilation syndrome
Type I vs Type II at a Glance
| Parameter | Type I (Hypoxemic) | Type II (Hypercapnic) |
|---|---|---|
| Primary failure | Oxygenation | Ventilation (CO₂ removal) |
| PaO₂ | <60 mmHg | Low (secondary) |
| PaCO₂ | Normal or low | >45 mmHg |
| pH | Normal or high (alkalosis) | <7.35 (acidosis) — acute; may be near normal if chronic |
| Response to O₂ | Partial — high-flow O₂ improves SpO₂ (unless shunt) | Improves hypoxemia; does not fix CO₂ problem |
| Treatment priority | Optimize oxygenation — PEEP, recruitment, treat cause | Support ventilation — BiPAP, mechanical ventilation; treat cause |
Nursing Implications
- SpO₂ targets differ: Type I — target 94–98%. COPD/chronic Type II — target 88–92% to avoid blunting hypoxic drive.
- O₂ delivery choice matters: Type I (shunt physiology in ARDS) — high FiO₂ alone may not resolve hypoxemia; PEEP is essential. Type II — improve ventilation, not just FiO₂.
- BiPAP indication: Type II failure with acute respiratory acidosis (especially COPD) — BiPAP is first-line before intubation.
- Escalation triggers: Worsening SpO₂ despite supplemental O₂; rising PaCO₂ and falling pH; altered mental status; increased work of breathing with fatigue signs → notify provider.
- Monitor ABG trends: Single ABG is less informative than trending — watch for respiratory fatigue causing shift from Type I to Type II.
- Opioid reversal: Type II from opioid overdose → naloxone as ordered; position upright; BVM ready; continuous monitoring.
NCLEX Pearls
- ›Type I = oxygenation failure (PaO₂ < 60). Type II = ventilation failure (PaCO₂ > 45 + acidosis).
- ›ARDS is the most severe form of Type I respiratory failure — characterized by bilateral infiltrates and refractory hypoxemia.
- ›COPD exacerbation is the most common cause of acute-on-chronic Type II failure.
- ›Oxygen alone does not fix Type II failure — the patient needs help moving air (BiPAP, ventilator).
- ›A worsening asthma patient can shift from Type I to Type II as muscles fatigue — rising PaCO₂ is an ominous sign.
- ›Normal PaCO₂ in an acutely distressed asthma patient who was initially hyperventilating (low PaCO₂) = impending fatigue.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with American Association for Respiratory Care (AARC) · GOLD (COPD) / ATS / CHEST. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →