Obstructive sleep apnea (OSA) is a very common and underdiagnosed condition across the world. It affects both pediatric and adult populations in unique but important ways. Long-term health risks associated with OSA include cardiovascular conditions, metabolic disorders, depression as well as poor work performance, and increased risk of motor vehicle accidents. Accurate and precise testing is vital to ensure accurate treatment, and specific testing methods are reviewed. Treatment options are discussed in detail for both adult and pediatric populations.
Key points
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Obstructive sleep apnea (OSA) is a commonly underdiagnosed heterogenous condition that causes a significant burden of disease across the world.
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OSA causes significant long-term sequelae beyond just significant daytime sleepiness.
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Recognition of OSA and implementation of appropriate testing and treatment at the primary care level is crucial.
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Diagnostic methods for OSA, particularly at home testing options, are rapidly changing and becoming more convenient for patients.
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While positive airway pressure (PAP) therapy remains the mainstay of treatment for OSA, other exciting viable treatment options have emerged for those who cannot tolerate PAP therapy.
History
It is a common belief that sleep apnea syndrome was first described by Charles Dickens in his novel “The Pickwick Papers” (1836), which featured a character who exhibited obesity, loud snoring, and somnolence. However, there were references to sleep disturbances dated back as far as 400 BC when Hippocrates noted the consequences of disrupted sleep on long-term health. Until the late nineteenth century, research on sleep apnea symptoms focused solely on patients’ obesity rather than the disordered breathing they experienced during sleep.
In 1965, the first polysomnography (PSG) was used by French researchers Gastaut, Tassinari, and Duron to observe apneic events during sleep, marking a crucial advancement in sleep apnea research. In 1970, the first sleep clinic was established by William Dement at Stanford University in California. Two years later, Christian Guilleminault joined the clinic and his research focused on respiratory disorders during sleep. Ever since, there has been an intense growth of sleep apnea research, especially during 1975 to 1980, with more than 300 articles on sleep apnea published in the literature.
In 1980, Dr Colin Sullivan from Sydney, Australia, who devoted his career to studying respiratory control in dogs, invented the first continuous positive airway pressure (CPAP) machine, revolutionizing the treatment of sleep apnea. The treatment was not widely accepted by the public in the beginning. It was not until almost 20 years later, in 2000, when 4 separate papers were published in the same year that found significant sleep apnea-related health effects, a turning point in sleep apnea studies occurred. Later studies also showed a strong association between sleep apnea and an increased prevalence of a range of comorbidities such as hypertension, coronary heart disease, heart failure, and stroke.
Epidemiology
Obstructive sleep apnea (OSA) is highly underdiagnosed in the United States, with 82% of men and 93% of women with OSA unaware of their conditions. Estimates of prevalence vary depending on diagnostic methods, definitions of the disease, age, gender, body mass index (BMI), and racial backgrounds.
The prevalence of OSA increases with age and appears to plateau in the elderly group. Men are twice as likely to develop OSA, although this difference declines in the middle to older age group, as menopause is a risk factor for OSA. Compared with Whites, the prevalence of OSA is higher in Blacks and similar in Asians. Despite generally having a lower BMI, differences in craniofacial bony structures predispose Asians to developing OSA. Although there is limited data on OSA prevalence rates among Hispanic and Native Americans, there is evidence that OSA prevalence has increased in these groups, likely due to rising obesity rates.
In the pediatric population, the prevalence is estimated between 1% and 4%, although this is likely underestimated given the obesity epidemic. There is no gender difference in prevalence for prepubertal children, but it is more prevalent in adolescent males compared with females. OSA is more prevalent in Black children compared with White children, but the prevalence among other ethnicities has not been well established to this point.
Pathophysiology
The 2 most common types of sleep apneas are obstructive and central sleep apnea. Central sleep apnea (CSA) results from dysfunction in the respiratory control centers of the brainstem, which fail to provide signals to inhale, causing the individual to miss one or more breathing cycles during sleep. In contrast, OSA occurs when there is a physical blockage of the upper airway despite the brain sending signals to breathe.
The pathophysiology of OSA is complex but the underlying etiology involves the upper airway dilating muscles becoming insufficient to prevent narrowing and/or closure of the upper airway during sleep. During inspiration, the negative pressure generated in the lumen of the upper airway promotes closure, and pharyngeal dilating muscles must counteract this force to maintain airway patency. Conditions that elevate negative pressure within the upper airway or impair the ability of dilating muscles to maintain airway patency disrupt this equilibrium, increasing the likelihood of upper airway obstruction.
Upper Airway Narrowing
The most prominent factors contributing to upper airway narrowing are either excessive bulk of soft tissue (tongue, soft palate, and lateral pharyngeal walls) from obesity or craniofacial anatomy, or both. Adenotonsillar hypertrophy, often linked to obesity, is a major risk factor for pediatric OSA.
Volume overload from congestive heart failure (CHF) or end-stage renal disease (ESRD) results in fluid redistribution to the parapharyngeal soft tissues in the recumbent position, which can increase upper airway resistance and collapsibility.
Additional factors, such as nasal obstruction (as seen in rhinitis), the use of intranasal corticosteroids, and the supine posture, have also been identified as adverse influences on upper airway patency.
In pediatric populations, the primary cause of airway narrowing is due to adenotonsillar hypertrophy, although abnormal neuromuscular control also contributes to the development of OSA, like adults.
Upper Airway Dilator Muscle Function
In rapid eye movement (REM) sleep, especially during phasic REM, there is an additional decrease in tone and phasic activity of the pharyngeal dilating muscle, which likely exacerbates the length and severity of apneas and hypopneas.
Apnea Threshold
The apnea threshold is the partial pressure of carbon dioxide (Pa co 2 ) at which respiratory effort ceases and apnea occurs and reflects the system’s sensitivity to changes in carbon dioxide levels. Patients with OSA and a low apneic threshold have an increased likelihood of apneic events during sleep, as minor fluctuations in Pa co 2 can trigger airway collapse or respiratory instability.
Loop-Gain
Loop-gain refers to the ratio of the ventilatory response to the disturbance causing it and is a reflection of the sensitivity and responsiveness to changes in ventilation. In patients with OSA, a high loop-gain results in an exaggerated response to respiratory disturbances, which in turn causes unstable ventilation and oscillations in breathing resulting in recurrent hypoxia. ,
Apnea Resolution
Apneas/hypopneas resolve due to 2 mechanisms: The first is increased upper airway muscle tone secondary to chemical (low Pa o 2 , high Pa co 2 ) or mechanical stimuli (stretching of mechanoreceptors). The second mechanism is an arousal from sleep which causes a shift out of the sleep state, thus restoring muscle activity seen during the wake state.
Disease Course
Long-term population studies have shown that OSA severity gradually progresses over time. Weight gain over time similarly results in worsened OSA severity. Conversely, weight loss results in decreased OSA severity. However, weight gain has a greater impact on OSA severity than weight loss, and weight impacts are greater in men compared with women.
Long-term Complications of Obstructive Sleep Apnea
OSA has been identified as a significant risk factor in cardiovascular disease including essential hypertension, coronary artery disease, CHF, pulmonary hypertension, stroke, cardiac arrhythmias, and premature mortality. , The causes of these complications are multifactorial, including an increase in the sympathetic nervous system in response to oxygen desaturations and arousals from sleep, free radical production from re-oxygenation, and large negative intrathoracic pressures that in turn increases the intramural pressure of vessels within the intrathoracic cavity. Additionally, OSA has clearly been shown to be related to the onset and recurrence of atrial fibrillation.
OSA has also been linked with metabolic disorders. New evidence suggests that untreated OSA is an independent risk factor for the development of Type 2 diabetes mellitus.
Other risks of untreated OSA include depression, poor job performance, impaired family relationships, reduction in quality of life, and increased risk of motor vehicle accidents.
Clinical evaluation
Patients with OSA often present in clinic with an assortment of complaints related to nocturnal respiratory disturbances, fragmented sleep, and daytime sequelae. In other situations, patients may present not due to their own concern, but rather due to the concerns of a bed partner or family member.
Symptoms
In the evaluation of suspected sleep apnea, it is crucial to ascertain both nocturnal symptoms as well as those that occur during the day. In our experience, nocturnal symptoms are more reliably provided by a bed partner, and it is important to include the bed partner in the evaluation when possible.
Classic nighttime symptoms of OSA include:
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Loud Snoring: Frequently reported by bed partners, loud and disruptive snoring is a hallmark symptom of OSA due to upper airway obstruction during sleep.
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Witnessed Apneas: Partners or family members may observe episodes of breathing cessation or gasping during sleep, indicating significant airflow limitation.
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Excessive Daytime Sleepiness: Patients with OSA often experience excessive daytime sleepiness despite seemingly adequate nocturnal sleep, leading to impaired cognitive function, reduced productivity, and an increased risk of accidents or errors.
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Morning Headaches: Headaches upon awakening are commonly reported by individuals with OSA, attributed to nocturnal hypoxemia and hypercapnia leading to cerebral vasodilation and increased intracranial pressure.
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Nonrestorative Sleep: Patients may describe feeling unrefreshed or unrested despite spending an adequate duration in bed, reflecting disrupted sleep architecture and poor sleep quality.
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Nocturia: Frequent awakenings to urinate during the night, known as nocturia, are often reported by individuals with OSA.
Daytime symptoms of OSA include:
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Excessive daytime sleepiness: While it is the most common daytime symptom caused by OSA, it is important to recognize that many patients with diagnosed OSA do not report significant daytime sleepiness. Some studies have shown that less than 50% of patients with moderate to severe OSA have excessive daytime sleepiness.
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Difficulty concentrating
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Memory difficulties
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Brain fog
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Irritability
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Hyperactivity
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Fatigue
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Drowsy driving.
Pediatric Considerations
In the pediatric population, daytime symptoms differ significantly from the adult population. At night, they similarly exhibit loud snoring or difficult breathing while asleep as well as significant sweating or restlessness at night.
During the daytime, particularly among younger pediatric patients, developmental, behavioral, and learning issues are most common. Many of the symptoms displayed may mimic those of attention deficit hyperactivity disorder.
Older children or teenagers may present with the symptoms of excessive daytime sleepiness, like adults.
Special attention should be paid to patients with Down syndrome or other neuromuscular disorders as there is a higher prevalence of OSA in these populations compared with the general pediatric population.
Objective Tools to Use in Clinic
The Epworth Sleepiness Scale ( Box 1 ) is an objective scale that is frequently used to assess the degree of sleepiness. A score higher than 10 indicates the patient is experiencing pathologic excessive daytime sleepiness.
How likely are you to doze off or fall asleep in the following situations, in contrast to feeling just tired? Use the following scale and indicate the most appropriate number for each situation. Answer choices for each situation range from 0 to 3. 0 = would never doze 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Situation
Sitting and Reading
Watching TV
Sitting, inactive in a public place (eg, a theater or meeting)
As a passenger in a car for an hour without a break
Lying down to rest in the afternoon when circumstances permit
Sitting and talking with someone
Sitting quietly after lunch without alcohol
In a car, while stopped for a few minutes in traffic
TOTAL (Range of 0–24)
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