Obstructive sleep apnea (OSA) is a syndrome characterized by periodic episodes of apnea and/or hypopnea during sleep with oxyhemoglobin desaturation; the sleeping partner often  describes snoring, gasping, choking, or pauses in breathing followed by snorting and/or body jerking. Sufferers have excessive daytime somnolence, nonrefreshing sleep, morning headaches, decreased ability to concentrate, poor memory, irritability, mood disturbance, impotence. They also have an increased risk for hypertension, cardiovascular disease, stroke, and insulin resistance. The prevalence of OSA in adults is2% in women and 4% in men.

Clinical assessment :

Medical records review: History of airway difficulty with previous anesthetics, hypertension or other cardiovascular problems, and other congenital or acquired medical conditions.

History: Questions related to snoring, apneic episodes, frequent arousals during sleep (vocalization, shifting position, extremity movements), morning headaches, and daytime somnolence.

Physical examination: evaluation of the airway, nasopharyngeal characteristics, neck circumference, tonsil size, and tongue volume.

Review of sleep studies: Measure of severity:

1. Number of apneas plus hypopneas per hour of sleep, the apnea-hypopnea index (AHI), during an overnight sleep study (polysomnogram [PSG]).

2. Severity of HbO2 desaturations: the lowest arterial oxyhemoglobin saturation (SpO2) and percentage of time below 90% saturation.

• Compromise upper-airway patency

1. Anatomic abnormalities: large tongue and/or tonsils, redundant pharyngeal tissue and/or submucosal fat deposition, retrognathia

2. Inadequate upper-airway muscle tone during inspiration with increased collapsibility

• increased body mass index

• increased neck circumference

• snoring

• congenital airway abnormalities

• daytime hypersomnolence

• inability to visualize the soft palate

• tonsillar hypertrophy.

• observed apnea during sleep

Surgical procedures:

Anatomic nasal obstruction: evaluation for surgery or radiofrequency ablation by an otorhinolaryngologist 

Morbid obesity: bariatric surgery may be indicated

As second line therapy for those who do not respond to basic measures and cannot tolerate CPAP.

a. Uvulopalatopharyngoplasty: removes uvula and redundant pharyngeal tissue; curative in up to 50%.

b. Genioglossus/hyoid advancement

c. Maxillomandibular advancement

Investigations

Preoperative preparation

1. General measures: weight loss if indicated; good sleep hygiene with constant bedtime;  avoid sedatives and alcohol;  maintain sleep in the lateral position with pillow behind the back

2.Consider preoperative initiation of CPAP, particularly if OSA is severe; also take into account the invasiveness of the diagnostic or therapeutic procedure, and the requirement for postoperative analgesics

a. AHI less than 5: No specific treatment for OSAS; general measures

b. AHI greater than 5 to 15: start nasal CPAP only if symptoms or co-morbid conditions; general measures

c. AHI greater than 15 to 30: Start always nasal CPAP after adequate titration, re-evaluate after 2 months

d. AHI greater than 30: Nasal CPAP for 6 months and re-evaluate

Inadequate response to CPAP, consider NIPPV 

Other: Preoperative use of mandibular advancement devices or oral appliances

After corrective airway surgery (e.g., uvulopalatopharyngoplasty, surgical mandibular advancement) a patient should be assumed to remain at risk for OSA complications unless a normal sleep study has been obtained and symptoms have not returned.

If suspected OSA: patient should be managed according to the “Practice Guidelines for Management of the Difficult Airway."

Drugs

1. Antihistamine therapy if allergic rhinitis is present. 

2. Ipratropium (Atrovent) nasal spray if rhinorrhea.

Procedures that may be performed safely on an outpatient basis in OSA:

1. Superficial surgery with local or regional anesthesia

2. Minor orthopedic surgery with local or regional anesthesia

3. Lithotripsy

Further reading

1. Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea; Anesthesiology 2006; 104:1081–93