Makindo Medical Notes

💡 Key Point: Patients must be conscious and have sufficient respiratory drive to benefit from NIV. 😴 Those who are drowsy or unable to protect their airway may need intubation and invasive ventilation.

📖 Introduction

• 🫁 Normal breathing uses diaphragm + intercostals → negative intrathoracic pressure → air flows into alveoli.
• 💨 NIV: Tight mask/hood with ventilator provides positive pressure to push air in.
• ⚙️ Modes: CPAP (continuous) or BiPAP (two pressure levels).
• ✅ Benefits: avoids intubation, ↓ mortality, ↓ stay length, ↓ costs. Especially used in Type II RF.

🔄 Types of NIV

• 🌬️ CPAP: Constant pressure through cycle → used in Type I RF (e.g. pulmonary oedema, OSA).
• ↕️ BiPAP: Higher pressure in inspiration (IPAP) + lower in expiration (EPAP). Best for Type II RF with acidosis (e.g. COPD exacerbations).

⭐ Advantages over Invasive Ventilation

• 🛡️ ↓ Ventilator-associated pneumonia.
• 📉 Shorter admission + lower costs.
• 😌 Less sedation required.
• 💨 Particularly effective in COPD & hypercapnic RF.

🩺 Applications

• 👩‍⚕️ Used in both Type I & II RF: COPD exacerbations, pulmonary oedema, post-op support.
• 🎭 Requires tight-fitting mask + patient cooperation.
• ⚡ Reduces work of breathing, improves gas exchange, recruits alveoli.
• 🏠 Can be given at home or in hospital settings.

✅ Indications

• pH < 7.35 with hypercarbia (Type II RF).
• Cardiogenic pulmonary oedema without shock.
• Immunosuppressed patients with acute RF.
• Weaning support (esp. COPD).
• Post-op RF (e.g. after lung surgery).
• Palliative symptom relief (breathlessness).

⛔ Contraindications

• 🚨 Severe hypoxaemia (< 60 mmHg PaO₂ on 100% FiO₂).
• 😴 GCS < 9 / impaired consciousness.
• ❌ Inability to protect airway / excess secretions.
• 🤕 Facial trauma/burns preventing mask seal.
• 🫧 Untreated pneumothorax.

⚙️ NIV Settings

• BiPAP: Start IPAP 10 cmH₂O, EPAP 4–5 cmH₂O → adjust per ABG/response.
• CPAP: Start 5 cmH₂O → ↑ to 10 if needed.
• 🎯 Aim SaO₂ > 90% or PaO₂ > 60 mmHg with clinical stability.
• ⏳ If no improvement in 4h → consider intubation.

⚠️ Side Effects

• ⬇️ Venous return & CO → hypotension risk.
• 🤢 Gastric distension → discomfort + aspiration risk.
• 😣 Skin breakdown from mask pressure.

🏠 Home NIV

• Consider in chronic RF due to:
  • Severe spinal deformity
  • Neuromuscular disorders (e.g. DMD, MND)
  • Cystic fibrosis
  • Central hypoventilation syndrome
• 🌙 Often used overnight → improves sleep quality + daytime function.

🚨 Indications for Intubation

• Respiratory arrest or severe distress unresponsive to NIV.
• Severe hypoxaemia (PaO₂ < 8 kPa despite FiO₂/NIV).
• Persistent hypercapnia/acidosis despite NIV.
• GCS < 9 or unsafe airway.
• Failure to stabilise after 4h NIV trial.

📚 References

• NIV: Indications & Outcomes
• ATS Clinical Guidelines