Sleep-Related Breathing Disorders
Objectives - Identify sleep disorder definitions, pathophysiology, symptoms and clinical features, diagnostic testing, and treatment.
Sleep Disorder Classification
| Category | Source Description |
|---|---|
| Insomnias | Difficulty falling or staying asleep |
| Parasomnias | Sleepwalking, sleep eating, sleep paralysis, sleep terrors |
| Hypersomnias | Narcolepsy |
| Circadian rhythm disorders | Shift work |
| Sleep movement disorders | Restless leg syndrome, bruxism or grinding teeth |
| Sleep-related breathing disorders | Obstructive sleep apnea, central sleep apnea, child sleep apnea, infant sleep apnea |
Core Definitions
| Term | Definition |
|---|---|
| Sleep apnea | Repeated episodes of no airflow for at least 10 seconds during sleep |
| Obstructive apnea | Caused by upper airway closure |
| Central apnea | Caused by lack of ventilatory effort |
| Obstructive sleep apnea syndrome | Recurrent apneas during sleep despite persistent respiratory effort due to upper airway obstruction |
| Hypopnea | Decreased breathing without complete airflow cessation; 30% decrease in airflow with 4% decrease in SaO2 |
| Overlap syndrome | COPD with coexisting OSA |
| Mixed apnea | Elements of obstructive and central apnea |
Obstructive Sleep Apnea
The primary causes of OSA are small or unstable pharyngeal airways.
Contributing factors include:
- Obesity
- Tonsillar hypertrophy
- Small chin
During sleep, upper airway dilator muscles relax. This permits narrowing or closure at potentially multiple upper-airway sites.
Adverse Consequences of OSA
| Category | Consequences |
|---|---|
| Cardiopulmonary | Nocturnal arrhythmias, diurnal hypertension, pulmonary hypertension, right or left ventricular failure, MI, stroke |
| Neurobehavioral | Excessive daytime sleepiness, diminished quality of life, motor vehicle accidents |
| Metabolic | Insulin resistance, altered lipid metabolism |
Central Sleep Apnea
Central sleep apnea is part of a heterogeneous group of disorders characterized by periodic breathing.
Source features:
- Waxing and waning respiratory drive
- Alternating increases and decreases in respiratory rate and tidal volume
- After apnea, increased central ventilatory drive may increase tidal volume
Cheyne-Stokes respiration is often seen in CHF or stroke. It is a severe type of periodic breathing with a crescendo-decrescendo pattern and hyperneas alternating with apneas.
Overlap Syndrome
Overlap syndrome is COPD with coexisting OSA.
Patients are often obese smokers with moderate to severe nocturnal oxyhemoglobin desaturations. Desaturations are more severe during REM sleep.
The source notes prognosis and ABG results are worse than in OSA alone.
Overlap Syndrome Symptoms
Symptoms include:
- Excessive daytime sleepiness
- Routine loud snoring
- Abrupt awakenings with choking or gasping
- Observed periods of apnea
- Awakening with dry mouth or sore throat
- Nocturia
- Chronic nasal obstruction
- Hypertension
- Morning headache
- Symptoms of depression
Clinical Features
Clinical features listed in the source:
- Male, twice as likely as women
- Over 40 years old
- Overweight, especially upper body obesity with neck greater than 16.5 inches
- Right heart failure secondary to pulmonary hypertension
- Increased risk for cardiac arrhythmias associated with moderate to severe desaturations
Diagnostic Testing
Polysomnogram
A polysomnogram is an overnight study required for definitive diagnosis. The patient answers a questionnaire about sleep habits.
Monitored parameters include:
| Parameter | What It Monitors |
|---|---|
| EEG | Brain waves and sleep stages |
| Eye leads | Eye movement |
| Cannula | Airflow at the nose and mouth |
| Tracheal microphone | Snoring |
| Chest and abdominal bands | Respiratory efforts |
| Pulse oximeter | Blood oxygen saturation |
| Capnography | Exhaled carbon dioxide |
| Limb leads | Leg movements |
Apnea-Hypopnea Index
Severity is based on the apnea-hypopnea index, or AHI.
AHI is the sum of apneas and hypopneas occurring each hour. Apneas and hypopneas are events and must last at least 10 seconds to count. AHI is calculated by dividing the total number of events by the number of hours of sleep.
| AHI | Severity |
|---|---|
| Less than 5 events/hr | Normal |
| 5-15 events/hr | Mild |
| 15-30 events/hr | Moderate |
| Greater than 30 events/hr | Severe |
Treatment
Behavioral Interventions and Risk Counseling
Treatment options include:
- Sleep hygiene
- Weight loss
- Avoiding alcohol
- Avoiding sedatives
- Avoiding hypnotics
- Avoiding muscle relaxants
- Avoiding sleep deprivation
Positional Therapy
If obstruction occurs when supine, positional therapy may include:
- Elevating the head of the bed
- Tennis ball technique
Medical and Surgical Interventions
| Intervention | Source Note |
|---|---|
| Positive pressure therapy (CPAP) | Indicated for moderate to severe AHI |
| Oral appliances | Good for mild AHI and patients who will not wear a CPAP mask |
| Medications | Generally ineffective |
| Tracheostomy | Bypasses the upper airway |
| Uvulopalatopharyngoplasty | Surgical intervention |
| Maxillofacial surgery | Surgical intervention |
High-Yield Review
| Topic | High-yield point |
|---|---|
| Sleep apnea | No airflow for at least 10 seconds during sleep |
| OSA | Apnea despite respiratory effort due to upper airway obstruction |
| CSA | Lack of ventilatory effort with periodic breathing patterns |
| Overlap syndrome | COPD plus OSA, often worse ABG and prognosis than OSA alone |
| PSG | Overnight study required for definitive diagnosis |
| AHI severe | Greater than 30 events per hour |
| CPAP | Indicated for moderate to severe AHI |