Sleep Breathing Disorders

Definition: A sleep breathing disorder (SBD), also known as a sleep-related breathing disorder (SRBD), refers to any condition characterized by abnormal respiration during sleep.
- Leads to disrupted gas exchange, fragmented sleep, or excessive daytime symptoms.
Prevalence: Varies depending on the specific disorder and population studied, but sleep-disordered breathing is very common.
- Estimated to affect 15–30% of adults in the general population, depending on definitions and diagnostic criteria.

Apnea: A pause in respiration lasting at least 10 seconds; characterized by no to very little airflow.
Hypopnea: A reduction in ventilation by at least 30%, leading to a decrease in arterial oxygen saturation (SaO2) of at least 4%.

Central Sleep Apnea Syndromes: A condition where a person's breathing repeatedly stops and starts during sleep due to brain signaling issues.
Obstructive Sleep Apnea (OSA) Disorders: Characterized by an upper airway blockage during sleep, preventing airflow through the windpipe despite normal brain signals to breathe.
Sleep-related Hypoventilation Disorders: Occurs when breathing is abnormally slow or shallow during sleep.
Sleep-related Hypoxemia Disorder: Characterized by abnormally low oxygen levels in the blood during sleep.

Apnea-hypopnea index (AHI): Used to quantify severity.
- Cessation of airflow: Defined as air flow stopping for at least 10 seconds or more.
- Reduction of airflow: Must show a resultant oxygen desaturation of ≥ 4%.
Severity Grading based on AHI:
- Mild: AHI ≥ 5–14
- Moderate: AHI ≥ 15–29
- Severe: AHI ≥ 30
Associated Symptoms: Such as excessive daytime sleepiness, impaired cognition, mood disorders, insomnia, hypertension, heart disease, or a history of stroke.

Effort to Breathe: Diminished or absent during episodes.
Airflow Reduction: At least 30% reduction in airflow is noted.
Symptoms of Sleep Quality: Includes poor-quality sleep, restless sleep, or sleep fragmentation.
Possible Snoring: May be present but not always.

Occurs when the brainstem does not properly react to changes in blood gas levels, resulting in temporary pauses in breathing without airway obstruction.
Medulla Failure: Can either fail to respond to rising CO₂ levels (reduced chemosensitivity) or overreact, leading to oscillations in breathing effort (e.g., Cheyne–Stokes respiration).

Heart Failure: Leads to delayed circulation time and unstable CO₂ feedback, producing the Cheyne–Stokes pattern.
Stroke or Brainstem Injury: Inflicts direct damage on medullary respiratory centers.
High-Altitude Conditions: Results in instability due to hypoxia-driven hyperventilation and hypocapnia.
Opioid Use: Suppresses medullary chemoreceptor sensitivity.
Idiopathic CSR: Characterized by inherent instability in CO₂ control set points.

Clinical Indicators: Includes absence of airflow, absence of respiratory effort, and presence of Cheyne-Stokes breathing as assessed by various medical standards and studies.

Continuous Positive Airway Pressure (CPAP): Creates pressurized airflow through a sealing mask.
Bilevel Positive Airway Pressure (BPAP): Offers varying pressures for inhalation and exhalation.
Adaptive Servo-Ventilation (ASV): Automatically adjusts airway pressure to stabilize breathing patterns.

Mechanism: Despite a maintained effort to breathe, airflow is obstructed due to blockage of the upper airway.
Symptoms: Drops in oxygen levels, spikes in carbon dioxide, resulting in fragmented sleep, loud snoring, gasping, or choking during sleep.

Diagnosed based on AHI:
- Mild OSA: AHI ≥ 5–14
- Moderate OSA: AHI ≥ 15–29
- Severe OSA: AHI ≥ 30
Prevalence Data:
- Mild OSA: Approximately 26% of adults.
- Moderate-to-severe OSA: Generally ranges from 10-17% in men and 3-9% in women.
- Notably increased prevalence in older adults (≥65 years) and affects an estimated 1-5% of children.

STOP-BANG Questionnaire: Evaluates risk based on binary responses to questions:
- High Risk: 5-8 “Yes” responses.
- Intermediate Risk: 3-4 “Yes” responses.
- Low Risk: 0-2 “Yes” responses.

Structure: Enlarged uvula or tonsils, elongated soft palate, and varying oral anatomy can cause airway narrowing.
Obesity and a thick neck reduce airway space due to excess tissue.
Common anatomical causes in children: Enlarged tonsils and adenoids.

CPAP: Pressurized airflow keeps the airway open during sleep.
BPAP: Supports ventilation by administering two varying pressure levels.
Oral Appliances: Reposition the jaw to prevent airway collapse.
Oral Pressure Therapy (OPT): Applies negative pressure to stabilize the airway.
Surgical Options: Such as uvuloplasty, to remove excess tissue blocking the airway.
Upper Airway (Hypoglossal) Nerve Stimulation: Helps prevent airway obstruction by moving the tongue forward during sleep.

CPAP considered the most effective for reducing AHI.
Oral appliances, while less effective physiologically, improve daytime sleepiness and quality of life due to better patient adherence.
Specific treatments tailored to severity and compliance needed.

A comprehensive understanding of sleep breathing disorders is important for diagnosis, management, and treatment.
Recognizing symptoms and risk factors ensures timely intervention.