Continuous Positive Airway Pressure

Continuous Positive Airway Pressure

Continuous Positive Airway Pressure

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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. Pathophysiology of Obstructive Sleep Apnea

⭐ 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. Oronasal CPAP mask interface for sleep apnea
    • 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.

Practice Questions: Continuous Positive Airway Pressure

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Stimulation of the _____ nerve can be used as a therapy for obstructive sleep apnea by increasing the diameter of the oropharyngeal airway

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Stimulation of the _____ nerve can be used as a therapy for obstructive sleep apnea by increasing the diameter of the oropharyngeal airway

hypoglossal

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