Continuous Positive Airway Pressure

CPAP: Mechanism & Principles - Airway's Best Friend

• CPAP: Delivers Continuous Positive Airway Pressure.
• Core Mechanism: Acts as a "pneumatic splint".
  • Maintains constant air pressure to keep the upper airway patent during sleep.
  • Prevents collapse of pharyngeal tissues, especially during inspiration.
  • Ensures unobstructed airflow from nasopharynx to larynx.
• Therapeutic Principles:
  • Positive pressure counteracts forces causing airway narrowing.
  • Reduces/eliminates apneas, hypopneas, and snoring.
  • Improves nocturnal oxygen saturation (SpO₂).
  • Aids in restoring normal sleep stages.

⭐ CPAP is considered the gold standard therapy for patients with moderate to severe Obstructive Sleep Apnea (OSA).

CPAP: Indications & Contraindications - Green Lights & Red Flags

Indications (Green Lights):

• Obstructive Sleep Apnea (OSAHS):
  • AHI > 15/hr (Moderate-Severe).
  • AHI 5-15/hr (Mild) + significant EDS, HTN, CVD, or cognitive/mood issues.
• Obesity Hypoventilation Syndrome (OHS).
• Central Sleep Apnea (CSA): e.g., Cheyne-Stokes in HF (if primary Tx fails).
• Symptomatic Upper Airway Resistance Syndrome (UARS).

Contraindications (Red Flags):

• Absolute:
  • Severe bullous lung disease (risk: pneumothorax).
  • Untreated pneumothorax/pneumomediastinum.
  • Recent facial/skull/esophageal/gastric surgery or trauma.
  • Active CSF leak / recent neurosurgery.
• Relative (Caution):
  • Severe hypotension.
  • Severe uncorrected nasal obstruction.
  • Marked claustrophobia/anxiety.

⭐ CPAP is gold standard for moderate-severe OSAHS (AHI >15), reducing AHI, EDS, and improving QoL & CV outcomes.

CPAP: Equipment & Titration - Gear, Gauges, & Goals

• CPAP Device (Generator): Delivers constant, positive airflow.
  • Types: Fixed-pressure (standard CPAP), Auto-titrating (APAP).
• Humidifier: Adds moisture to air; prevents nasopharyngeal dryness. Heated vs. Passover.
• Tubing & Mask Interface: Critical for effective seal & patient comfort.
  • Nasal Pillows: Minimal contact; good for claustrophobia, allows glasses. Cons: potential nasal irritation, mouth leaks.
  • Nasal Mask: Covers nose; good seal. Cons: forehead pressure, mouth leaks if edentulous or mouth breather.
  • Oronasal (Full Face) Mask: Covers nose & mouth; for mouth breathers or nasal obstruction. Cons: larger, aspiration risk, claustrophobia.
• Titration: Process to determine optimal pressure.
  • Goal: Eliminate apneas, hypopneas, snoring, O2 desaturations. Target AHI < 5/hr.
  • Methods: In-lab Polysomnography (PSG) - gold standard. APAP device for home titration (often uses 90th or 95th percentile pressure).
  • Pressure Range: Typically 4-20 cm H2O.

⭐ APAP devices can be used for initial titration, especially if PSG is unavailable or delayed, and for long-term management to adapt to changing patient needs (e.g., weight fluctuations).

CPAP: Benefits & Challenges - Perks, Problems, Persistence

• Perks (Benefits):
  • Improved sleep quality & daytime alertness; ↓somnolence
  • Significant ↓ in Apnea-Hypopnea Index (AHI)
  • Better blood pressure control; ↓ long-term cardiovascular morbidity
  • Enhanced cognitive function, mood, and quality of life (QoL)
• Problems (Challenges):
  • Mask interface: discomfort, air leaks, pressure sores, skin irritation
  • Nasal symptoms: dryness, congestion, rhinorrhea, epistaxis
  • Pressure-related: aerophagia, bloating, chest discomfort
  • Other: claustrophobia, machine/mask noise, partner disturbance
• Persistence (Adherence):
  • Critical for efficacy; often a major hurdle
  • Key factors: patient education, mask selection/fit, humidification, psychosocial support, regular follow-up

  ⭐ Good adherence, defined as >4 hours of use per night on >70% of nights, is essential for achieving significant clinical benefits.

High‑Yield Points - ⚡ Biggest Takeaways

• CPAP is gold standard for moderate to severe Obstructive Sleep Apnea (OSA).
• Acts as a pneumatic splint, maintaining upper airway patency during sleep.
• Indicated for AHI >15/hr, or AHI >5/hr with comorbidities/symptoms.
• Pressure titration via polysomnography (PSG) is essential for optimal therapy.
• Patient compliance is the primary challenge and key to successful outcomes.
• Common issues: mask leak, nasal dryness/congestion, skin irritation.
• Significantly improves AHI, daytime somnolence, BP, and quality of life.