Definition
The characteristic feature of obstructive sleep apnea (OSA) is episodes of partial or complete obstruction of the upper airway during sleep that interrupt or reduce airflow, resulting in a drop in oxygen saturation and sleep disruption.
Mechanism
The anatomic narrowing of the upper airways, respiratory muscle compliance, and reflexes play a role in upper airway collapse during sleep. In addition, submucosal adipose tissue or cervical adipose tissue contributes to upper airway compression through decreased pharyngeal muscle tone at sleep onset.
Prevalence
OSA prevalence in the United States is reported to be as high as 14% for men and 5% for women. About 10% of the prevalent cases are mild, and 3.8% – 6.5% are moderate to severe OSA. The condition is more frequently noted in men than women. The prevalence of the disease increases with age. There has been an upsurge in OSA in the last couple of decades, primarily due to the obesity epidemic.
OSA causes severe adverse effects on health and contributes to a higher occurrence of other diseases, such as hypertension and heart conditions, increasing society's total burden of illness.
Major Risk Factors
The risk factors of OSA include:
Obesity (BMI 30 or higher)
Craniofacial abnormalities
Family history
Genetics
Male sex
Neck circumference of 16 inches in females and 17 inches in males (risk increases 20-fold with neck circumference > 19.2 inches).
Medical Disorders Associated with OSA
Close to half of people suffering from OSA have a diagnosis of high blood pressure at the same time. In addition, severe OSA increases the risk of fatal and non-fatal cardiac events. Other adverse health conditions associated with OSA include arrhythmias, type II diabetes, stroke, slow reaction time, and depression.
Workplace Implications
Workers with OSA demonstrate variable degrees of cognitive, emotional, and performance deficits. Reduced productivity and frequent absence from work are two commonly reported problems noted among workers with OSA. In addition, difficulties with concentration and learning due to untreated OSA leads to an increased risk of work-related injuries and accidents.
Diagnosis
The gold standard for diagnosing OSA is a sleep study (polysomnography) concurrent with a symptom assessment.
Symptoms
Symptoms associated with OSA include a history of snoring or daytime sleepiness, any witnessed apneas by a bed partner, choking or gasping episodes, morning headaches, dry throat, decreased concentration at work, memory loss, and irritability.
Sleep Study (polysomnography)
The standard test for obstructive sleep apnea is an overnight sleep study or polysomnography (PSG) performed in the sleep laboratory. This test assesses various physiological parameters or data channels. These include pulse oximetry, electroencephalogram, electrooculogram, electrocardiogram, and nasal and oral airflow obstruction channels.
Generally, home sleep apnea tests are less accurate than in-laboratory studies. They provide limited sleep monitoring data that estimates the apnea-hypopnea index, and there is a risk of data loss from detached or malfunctioning equipment. However, these tests can help identify moderate to severe OSA.
Interpretation of Sleep Studies
The most common measure used to interpret OSA is the Apnea-Hypopnea Index (AHI), the total apneas and hypopneas per hour of sleep. Apnea is the complete cessation of airflow and hypopnea is a reduction in airflow with evidence of the struggle to breathe.
The classification of OSA based on AHI (in adults) is as follows:
< 5 Normal
5–15 Mild OSA
5–30 Moderate OSA
>30 Severe OSA
Another standard measure used is the Respiratory Distress Index (RDI), the average number of apneas, hypopneas, and breathing-related arousals per hour of sleep.
Treatment
CPAP treatment
A continuous positive airway pressure (CPAP) trial is the first treatment choice for symptomatic OSA patients. The therapy is generally administered through the nose and maintains the same pressure throughout inspiration and expiration. The goal of a CPAP is to increase the upper airway pressure enough to open the airway, which may collapse during inspiration. Typically, the adjusted pressure prevents hypopnea, apnea, snoring, flow limitation, and arousals in a patient.
Research studies have shown that, compared with placebo, CPAP decreases AHI and the number of nocturnal arousals to normal or nearly normal values. In addition, it improves all daytime symptoms, particularly sleepiness, after a short period of regular treatment.
Oral Appliances
Oral appliances are a helpful alternative to CPAP for treating patients with mild to moderate OSA and for those patients with severe diseases intolerant to CPAP. They work by enlarging and stabilizing the pharyngeal airway to prevent breathing obstructions during sleep.
Two common types of oral appliances are the devices that help protrude the tongue (tongue retaining devices, TRD) and those that advance the lower jaw (mandibular advancement splints or devices).
Medical Treatments
Treatment with decongestants, intranasal steroids, antihistamines, and anti-leukotrienes may help to improve the symptoms. In addition, medical treatment can be helpful as an adjunct to CPAP treatment and with an oral appliance in OSA management.
Other Measures
Obesity is a strong risk factor for OSA. Therefore, maintaining a healthy weight should be the primary goal when treating OSA.
OSA patients should also avoid alcohol, benzodiazepines, opiates, and some antidepressants as they can exacerbate OSA symptoms. Lastly, 7 to 8 hours of sleep every night is essential as no treatment for OSA corrects the adverse effects of sleep deprivation.
-Slowik, Jennifer M, and Jacob F Collen. 2022. "Obstructive Sleep Apnea." Nih.gov. StatPearls Publishing. February 10, 2022. https://www.ncbi.nlm.nih.gov/books/NBK459252/.
-Peppard, P. E., T. Young, J. H. Barnet, M. Palta, E. W. Hagen, and K. M. Hla. 2013. "Increased Prevalence of Sleep-Disordered Breathing in Adults." American Journal of Epidemiology 177 (9): 1006–14. https://doi.org/10.1093/aje/kws342
-Morsy, Nesreen E., Nesrine S. Farrag, Nevin F.W. Zaki, et al. 2019. "Obstructive Sleep Apnea: Personal, Societal, Public Health, and Legal Implications." Reviews on Environmental Health 34 (2): 153–69. https://doi.org/10.1515/reveh-2018-0068.
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