Obstructive Sleep Apnea
A condition where the airway repeatedly collapses during sleep, stopping breathing and causing severe snoring, poor sleep, and daytime sleepiness.
Emergency Management: Patients with severe OSA are at high risk for acute airway obstruction and respiratory failure post-operatively after receiving general anesthesia and narcotic analgesics. Require careful monitoring with continuous pulse oximetry post-op.
Obstructive Sleep Apnea is a sleep-related breathing disorder characterized by recurrent episodes of complete (apnea) or partial (hypopnea) upper airway collapse during sleep. These events lead to episodic intermittent hypoxemia, hypercapnia, and frequent micro-arousals resulting in fragmented sleep.
Detailed Overview
The airway collapse occurs at the level of the pharynx, often exacerbated by a narrow airway, obesity, or reduced upper airway muscle tone during REM sleep. The repeated drops in blood oxygen and surge in sympathetic nervous system activity during arousals trigger oxidative stress and systemic inflammation. OSA is a massive independent risk factor for cardiovascular diseases, stroke, and metabolic syndrome.
Epidemiology & Demographics
Extremely common; affects roughly 15-30% of males and 10-15% of females in North America. Prevalence sharply increases with age and rising obesity rates.
Etiological Mechanism
Anatomic narrowing of the upper airway (tonsillar hypertrophy, micrognathia) combined with state-dependent loss of neuromuscular compensation during sleep.
Primary Causes
Loss of upper airway dilator muscle tone (especially genioglossus) during sleep, allowing negative inspiratory intrathoracic pressure to collapse the pharyngeal walls.
During wakefulness, pharyngeal dilator muscles maintain airway patency against the negative intraluminal pressure of inspiration. During sleep, muscle tone decreases. In predisposed individuals, this causes the airway to occlude. Ventilation ceases, causing PaO2 to drop and PaCO2 to rise. Chemoreceptors detect this and trigger a central nervous system arousal. The patient briefly wakes up, restoring airway tone, takes a series of hyperventilatory breaths, and falls back asleep. This cycle repeats dozens of times per hour. The intermittent hypoxia causes endothelial dysfunction, sympathetic hyperactivation, and hypertension.
Diagnostic Criteria & Guidelines
Diagnosed via Polysomnography (in-lab or Home Sleep Apnea Testing). Diagnostic criteria: >= 15 predominantly obstructive respiratory events (apneas, hypopneas, or RERAs) per hour of sleep OR >= 5 events per hour combined with symptoms (sleepiness, gasping/choking, or comorbid conditions like hypertension/stroke).
Continuous Positive Airway Pressure (CPAP). Acts as a pneumatic splint to keep the airway open. Typical pressures range from 5 to 15 cm H2O, ideally auto-titrating. Concomitant aggressive weight loss program.
Second-Line & Adjunctive Therapy
Mandibular Advancement Devices (MADs) custom-fitted by a dentist for mild-moderate OSA or CPAP-intolerant patients. Hypoglossal nerve stimulator (Inspire) implantation for moderate-severe OSA patients intolerant to CPAP with BMI < 32.
Surgical & Procedural Management
Uvulopalatopharyngoplasty (UPPP) removes excess tissue from the soft palate and pharynx. Maxillomandibular advancement (MMA) for severe anatomic obstruction. Tracheostomy is curative but reserved for life-threatening, refractory cases.
Patient Counseling & Advice
Emphasize that CPAP compliance requires wearing the mask for >= 4 hours per night on >= 70% of nights to achieve cardiovascular benefits. Warn about the legal and safety risks of driving while excessively sleepy.
Follow-Up & Monitoring Schedule
Review CPAP download data (modem compliance report) at 1 month, then annually to check usage hours, mask leak, and residual AHI. Titrate pressure if residual AHI > 5.
Preventive Strategies
Weight maintenance is the primary preventative strategy.
Excellent with CPAP adherence; abolishes daytime sleepiness and normalizes mortality risk. Untreated severe OSA carries a significantly high risk of sudden cardiac death and stroke.