Sleep Apnea: Symptoms, Etiology and Overview

Sleep Apnea Overview

• Sleep apnea is defined as "repetitive episodes of upper airway obstruction that occur during sleep and are typically associated with oxyhemoglobin desaturations." (American Academy of Sleep Medicine)
• Obstructive sleep apnea (OSA) pathophysiology involves recurrent, functional collapse of the velopharyngeal and/or oropharyngeal airway, leading to reduced or complete cessation of airflow despite ongoing breathing efforts.
• This results in intermittent gas exchange disturbances (e.g., hypercapnia and hypoxemia) and fragmented sleep.

Etiology of Sleep Apnea

• Upper airway narrowing, often due to obesity and increased peripharyngeal fat.
• Retrognathia and micrognathia (especially in children), and adenotonsillar hypertrophy.
• Potential upper airway muscle weakness due to neuromuscular disorders, primary CNS disorders, or metabolic diseases.

OSA Symptoms

• Witnessed apneas
• Snoring
• Gasping/choking at night
• Excessive sleepiness (not explained by other factors)
• Nonrefreshing sleep
• Sleep fragmentation/maintenance insomnia
• Nocturia
• Morning headaches
• Decreased concentration
• Memory loss
• Decreased libido
• Irritability

OSA Diagnosis

• Gold Standard: Nocturnal polysomnography (level 1 sleep study)
• Monitors sleep stage (EEG and EOG), EMG, ECG, oxygen saturation, airflow, and respiratory effort.
• Events: Apnea (cessation of breathing lasting 10 seconds or longer); Obstructive (continued respiratory effort); Hypopnea (nasal pressure signal excursions drop ≥50% of baseline for at least 10 seconds AND a ≥3% desaturation from pre-event baseline OR the event is associated with an arousal).

OSA Grading Scale

• Mild: 5-15 episodes/hr
• Moderate: 15-30 episodes/hr
• Severe: >30 episodes/hr

Alternative Diagnosis for OSA

• Home sleep study (level 3 sleep study)
• Monitors oxygen saturation, heart rate, airflow, and respiratory effort.

OSA Complications

• Drowsy driving and MVAs.
• Neuropsychiatric dysfunction (e.g., inattention, memory, cognitive deficits, moodiness, irritability, depression, psychosis, sexual dysfunction).
• Hypertension (HTN)
• Coronary artery disease
• Cardiac arrhythmias
• Heart failure
• Stroke
• Pulmonary Hypertension / Right heart failure
• Metabolic Syndrome
• Type 2 diabetes
• Nonalcoholic fatty liver disease

OSA Screening

• Questions to ask during routine health maintenance evaluations (e.g., is the patient obese? retrognathic? complain of daytime sleepiness? snore? have hypertension?).

High-risk OSA Patients

• Obesity (BMI > 35).
• Congestive heart failure.
• Atrial fibrillation.
• Treatment-refractory hypertension.
• Type 2 diabetes.
• Nocturnal dysrhythmias.
• Stroke.
• Pulmonary hypertension.
• High-risk driving populations.
• Preoperative for bariatric surgery.

Physical Exam Findings for Obstructive Sleep Apnea

• Increased neck circumference (>17 inches in men, >16 inches in women).
• BMI ≥ 30 kg/m².
• Modified Mallampati score of 3 or 4.
• Retrognathia.
• Lateral peritonsillar narrowing.
• High arched/narrow hard palate.
• Macroglossia.
• Tonsillar hypertrophy.
• Elongated or enlarged uvula.
• Nasal abnormalities (polyps, deviation, turbinate hypertrophy).
• Overjet

OSA Definition (AASM ICSD-3)

• PSG or HSAT demonstrates ≥ 5 obstructive respiratory events per hour of sleep and the presence of one or more of these symptoms: sleepiness, non-restorative sleep, fatigue, insomnia, wakes with breath-holding, gasping or choking, the bed partner reports habitual snoring or breathing interruptions, hypertension, a mood disorder, cognitive dysfunction, coronary artery disease, stroke, congestive heart failure, atrial fibrillation, or type 2 diabetes.
• Or, PSG or HSAT demonstrates ≥ 15 obstructive respiratory events per hour of sleep.

OSA Management - Behavior Modification

• Encouraging weight loss for overweight/obese patients.
• Advising patients to change their sleep position to non-supine.
• Warning patients that alcohol and some common medications (e.g., benzodiazepines) may worsen their sleep apnea.

OSA Management - Weight loss and Exercise

• Combining weight loss with primary OSA treatment.
• Bariatric surgery can be adjunctive treatment for OSA in obese patients.
• Weight loss generally improves quality of life and metabolic parameters.
• Exercise may also improve OSA even without significant weight loss.

OSA Management - Sleep Position

• Identifying patients with OSA that worsen in a supine position.
• Implementing positional therapy to maintain a non-supine position for sleep.

OSA Management - Alcohol avoidance

• Advising patients to avoid alcohol, even during the day, due to its depressive action on the central nervous system, exacerbating OSA, worsening sleepiness, and promoting weight gain.
• Acute alcohol use worsens obstructive respiratory events, duration, frequency of events, oxyhemoglobin desaturation, and snoring.

OSA Management - Avoid medications

• Discouraging use of medications with inhibitory effects on the central nervous system (CNS) in particular benzodiazepines
• Other medications that may exacerbate OSA and worsen sleepiness (e.g benzodiazepine receptor agonists, barbiturates, some antiepileptic drugs, sedating antidepressants, antihistamines, and opiates).

OSA Management - Positive Airway Pressure (PAP) Therapy

• CPAP is a commonly used treatment.
• Mechanisms involve maintaining a positive pharyngeal, transmural pressure, increasing intraluminal pressure to exceed surrounding pressure, and stabilizing the upper airway through increased expiratory lung volume.
• Respiratory events (apneas, hypopneas) are prevented.

OSA Management - Indications for PAP Therapy

• AHI >5 and other clinical or physiological sequelae (like hypertension).
• Insufficient and inconclusive evidence to recommend or withhold PAP for non-sleepy adults with OSA as a means for reducing cardiovascular events or mortality.

OSA Management - PAP Efficacy

• CPAP reduces respiratory events during sleep and improves sleep quality.
• It improves systemic blood pressure and blood glucose control.
• Observational studies suggest a link between CPAP use and reduced mortality.

OSA Management - Alternative Therapies

• Oral appliances (e.g., mandibular advancement devices, tongue-retaining devices) to improve airway patency and are often a preferred option before CPAP
• Can be an effective treatment for mild to moderate OSA.
• Surgical approaches (for severe obstructing upper airway lesions)

OSA Outcomes Assessment

• Resolution of sleepiness
• OSA-specific quality of life measures
• Patient and spousal satisfaction
• Adherence to therapy
• Avoidance of factors worsening OSA
• Obtaining adequate sleep
• Practicing proper sleep hygiene
• Weight loss for overweight/obese patients

Other types of sleep-disordered breathing

• Obstructive Hypoventilation Syndrome
• Central Sleep Apnea

Obesity Hypoventilation Syndrome

• Presence of awake alveolar hypoventilation in an obese individual unrelated to other medical conditions.
• Suspect in patients with BMI ≥ 50 kg/m² (although can occur in those with BMI > 30), hospital presentation with severe hypoxemic hypercapnic respiratory failure, elevated serum bicarbonate, hypercapnia (PaCO2 > 45 mmHg), hypoxemia (PaO2 < 70 mmHg).

Central Sleep Apnea

• Repetitive cessation or decrease in airflow and ventilatory effort during sleep.
• Suspect in patients with symptoms of sleep disruption (excessive daytime sleepiness, poor quality), episodic oxyhemoglobin desaturation/pauses in breathing during sleep, and other associated conditions (heart failure, stroke, atrial fibrillation, chronic opioid use).

An overview of sleep apnea, its pathophysiology, and etiology. Obstructive sleep apnea (OSA) involves recurrent collapse of the airway, leading to gas exchange disturbances and fragmented sleep. It is often caused by upper airway narrowing from obesity, retrognathia, or muscle weakness.