Obstructive Sleep Apnea (OSA), also known as Sleep Apnea Hypopnea Syndrome (SAHS), has been written about for centuries. For example, in his Posthumous Papers of the Pickwick Club (1837), Charles Dickens wrote about the obese somnolent Joe, who “goes on errands fast asleep and snores as he waits at a table.”
In more recent years, physicians have made great advances in clearing up misconceptions about this “Pickwickian” disorder. This, in turn, has led to more accurate diagnosis and better treatment of sleep apnea.
Incidence and Risk Factors
More than 40 million people are affected by sleepdisordered breathing (SDB) in the United States alone, and many remain undiagnosed and untreated. The incidence of SAHS has been reported as high as 2% in women and 4% in men. This figure rises to 10% among elderly men and to 33% among morbidly obese individuals.
The International Classification of Sleep Disorders manual describes OPA or SAHS as “characterized by repetitive episodes of upper airway obstruction that occur during sleep, usually associated with a reduction in blood oxygen saturation,” with associated features of daytime sleepiness and snoring.
The typical OSA patient will have complaints of loud snoring, daytime sleepiness, difficulty concentrating during the day, waking up from snoring in the middle of the night, and restless sleep. There may also be a history of headaches, memory loss, sexual dysfunction, and depression. While fatigue and easy sleepiness in front of the TV at night are sure signs of OSA and indicate potential for benefit with recognition and treatment, OSA has been strongly associated with significant cardiovascular problems. These include stroke, heart attack, heart failure and arrhythmias like atrial fibrillation. It also contributes to weight gain, obesity , diabetes and metabolic syndrome (more on this in related article) and even decreased libido. The medical guideline for hypertension control includes OSA evaluation as untreated OSA usually requires more medications for BP control than if OSA is treated.
A treating physician should inquire about recent weight gain, chronic use of alcohol, sleeping pills, and other sedating drugs that can cause or exacerbate OSA.
Methods of Diagnosis
The first step in diagnosing OSA is recognizing who may be at risk. As the problem occurs while one is asleep, the individual with OSA is often reluctant to recognize they have it. Often a spouse will comment on loud sleeping, choking at night or gasping. Sometimes the individual will awaken at night with a startle. Acid reflux at night and even having to awaken to use the bathroom are indications as the increased pressure that is generated in the abdomen to push the closed airway to open can push acid from the stomach to the throat, or put pressure on the bladder to give a sensation of needing to urinate.
The upper airway extends from the nostrils to the subglottis, and anything that leads to blockage of this pathway may cause a patient to have OSA. Therefore, the primary goals of physical examination are to define the overall anatomical predisposition for airway obstruction and to recognize focal lesions that may be amenable to correction. This tends to be a less common cause of OSA as it is more common in those with larger neck sizes , often associated with some level of weight gain as we age.
If the diagnosis of OSA is suspected based on history and physical, then a polysomnography (sleep study) is indicated. A polysomnography is the simulation and continuous recording of physiologic measures during sleep. These include an electroencephalogram (EEG), electromyogram (EMG), electrocardiogram (EKG), electrooculogram (EOG), a measure of arterial oxygen saturation by pulse oximetry as well as respiratory airflow and effort. It is often done in a sleep lab overnight which are private rooms with TVs and internet to allow for privacy and comfort.
Although there is some controversy regarding the scoring of these tests, one of the most important values is the Respiratory Distress Index (RDI). The RDI reflects the total number of apneas and hypopneas per hour of sleep and is used to characterize the results to the sleep study. An apnea by definition is a cessation of breathing for more than 10 seconds. A hypopnea is defined as a respiratory event characterized by a reduction in airflow by one half. The significance of the RDI number could vary from one sleep study institution to another, but an RDI greater than 10 is considered abnormal. A severe case of OSA has an RDI greater than 50. Oxyhemoglobin levels below 85% during sleep are highly significant, and regular desaturations below 60% represent severe obstructive sleep apnea.
Think of this, often it is seen a person who temporarily stops breathing every minute, every night over years! This clearly takes its toll on one’s heart , body and mind!
In general, the natural course of OSA is to worsen with age, and untreated and severe OSA has a higher incidence of cardiac and pulmonary disease than age-matched controls. In addition, a disturbing number of nocturnal deaths have been recorded in patients with severe, untreated OSA.
Treating Sleep Apnea
Conservative treatment for OSA includes weight loss if needed, and restriction of sedating substances like alcohol and sleeping pills. Pharmacologic agents (such as protriptyline and progesterone) have had only limited success.
One of the most effective treatments for OSA is continuous positive airway pressure (CPAP). This device worn on the face every night maintains a “pneumatic splint” in the airway preventing collapse and obstruction.
Rarely, surgery be recommended due to the great success and safety of CPAP treatment. Surgical treatments (which address the nose, oropharynx, nasopharynx, and hypopharynx) need to be tailored specifically to each patient, since the level of obstruction and anatomy are different from one individual to the next.
OSA results in significant morbidity and mortality from cardiovascular disease, quality of life deficits, and performance deficits due to loss of alertness. Physicians need to be vigilant in screening for this condition, because successful treatment can reverse the risks of OSA and improve quality of life and patients often are unaware of its presence.