🗝️ Key Points

💨 NIV = Support without a tube: CPAP, BiPAP, and HFNC improve oxygenation and reduce the work of breathing.
🫁 CPAP = Continuous pressure: Best for hypoxemic patients (e.g., pulmonary edema, OSA).
️ BiPAP = Two pressures (IPAP/EPAP): Great for hypercapnic failure (e.g., COPD, obesity hypoventilation).
🌬️ HFNC = Heated, humidified high flow: Reduces effort, improves comfort, and enhances oxygen delivery.
🩺 Supportive, not definitive: NIV stabilizes patients while the underlying cause is treated.

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📝 Introduction

Non-invasive ventilation (NIV) refers to respiratory support provided without endotracheal intubation. The most common modalities include continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), and high-flow nasal cannula (HFNC). These therapies aim to improve oxygenation, reduce the work of breathing, and potentially prevent invasive mechanical ventilation.

💨 CPAP and BiPAP

CPAP delivers a single, continuous pressure during inspiration and expiration. This pressure (commonly 5–10 cm H₂O) helps recruit atelectatic alveoli, reduce shunt, and improve oxygenation. It is commonly used for conditions like pulmonary edema, obstructive sleep apnea, or mild hypoxemia without significant ventilatory failure.
BiPAP alternates between two pressures:
- Inspiratory positive airway pressure (IPAP), augments tidal volume and unloads inspiratory muscles.
- Expiratory positive airway pressure (EPAP), maintains alveolar recruitment and improves oxygenation.
  The differential between IPAP and EPAP is critical for reducing hypercapnia in patients with COPD exacerbations or acute hypercapnic respiratory failure.
Indications
- CPAP: hypoxemia without major ventilatory failure (e.g., cardiogenic pulmonary edema, atelectasis, OSA).
- BiPAP: hypercapnia with increased work of breathing (e.g., COPD exacerbation, neuromuscular weakness, obesity hypoventilation).
A helpful way to conceptualize CPAP and BiPAP is through the hairdryer analogy. Imagine placing a hairdryer in your mouth:

🧭 REBEL Rundown

🗝️ Key Points

📝 Introduction

💨 CPAP and BiPAP