pulmonary disorders
Obstructive Sleep Apnea (OSA)
Diagnosis of Obstructive Sleep Apnea (OSA)
Suspected by clinical evaluation Confirmation by sleep studies The diagnosis of obstructive sleep apnea is suspected in patients with identifiable Etiology , symptoms, or both. In addition to the patient, bed partners, roommates, and/or housemates are all sources for risk assessment information. Snoring loudly enough to be heard in the next room confers a 10-fold increase in the likelihood of having an apnea-hypopnea index > 5 per hour. At-risk patients who might need more detailed evaluation include those who Are about age 65 or older Report daytime fatigue, sleepiness, or difficulty staying asleep Are overweight Have poorly controlled Hypertension (which may be caused or exacerbated by OSA), Questionnaires, such as STOP-Bang, Berlin Questionnaire (BQ), and Epworth Sleepiness Scale (ESS), can be used by nonspecialists to assess risk. However, when compared to the more accurate results of sleep studies, these questionnaires have low specificity and high false-positive rates and should not be used to make a diagnosis or to direct therapy. The multimodal STOP-Bang and the BQ are more specific than the ESS for risk of OSA and have good negative predictive value ( Diagnosis references ). Accountable care organizations and medical insurance companies have a symptomless risk score to estimate likelihood of disease, but the score lacks specificity at the individual patient level ( Diagnosis references ). (See also Research is beginning on using artificial intelligence to analyze clinical history together with physiologic inputs from wearable devices to suggest disease probability ( Diagnosis references ). This technology could be educationally valuable and beneficial, given the prevalence of poor sleep, snoring, and sleep apnea, and the consequences of untreated disease. However, diagnosis and treatment should be based on symptoms. Patients whose symptoms, screening questionnaires, and/or risk factors suggest a higher likelihood of OSA should typically have Sleep studies to determine the apnea-hypopnea index (AHI) or some surrogate like Respiratory Disturbance Index (RDI), which is needed to confirm the syndrome and grade severity. Patients who report only snoring, without other symptoms or cardiovascular risks, do not need an extensive evaluation for OSA, and can respond by increasing fitness, losing weight, improving sleep hygiene, and treating nasal allergies. Theapnea-hypopnea index(AHI) represents the total number of episodes of apnea and hypopnea occurring during sleep divided by the hours of sleep time; it is expressed as the number of apneic episodes occurring per hour. The more events that occur, the more severe the OSA and the greater the likelihood of adverse effects. AHI values can be computed for different sleep stages and body positions (side or back). Criteria for diagnosisof OSA include daytime symptoms, nighttime symptoms, and sleep monitoring results that show an AHI ≥ 5 per hour in patients with symptoms, or ≥ 15 per hour in the absence of symptoms. Symptoms should include ≥ 1 of the following: Unrefreshing sleep Daytime sleepiness*, fatigue Unintentional sleep episodes Difficulty staying asleep Awakening with breath holding, gasping, or choking Reports by a bed partner of loud snoring, breathing interruptions, or both *Sleepiness that is active (ie, intrusive into daily activities or producing crashes or errors) is particularly significant. Thedifferential diagnosisincludes many other conditions and factors that reduce the quantity or quality of sleep or cause daytime sedation or sleepiness. These include Other Approach to the Patient With a Sleep or Wakefulness Disorder : Poor sleep hygiene, narcolepsy and other hypersomnolence disorders, restless legs syndrome, periodic limb movement disorder Drug and substance use: Alcohol, sedatives, numerous therapeutic and recreational drugs (see table) Medical disorders: Cardiovascular, respiratory, and metabolic disorders (eg, Hypothyroidism ) Depressive Disorders (which often accompanies as well as contributes to disordered sleep) History and physical examination (including sleep history) should seek evidence of these conditions, including identification of clinical features of Hypothyroidism and Measurement of thyroid-stimulating hormone can be useful in those in whom hypothyroidism is clinically suspected but should not be done routinely. No other adjunctive testing (eg, upper airway imaging, facial photographs, biomarkers like cancer-related fatigue) has sufficient specificity to be recommended routinely. Sleep studies include Traditional polysomnography conducted in a sleep laboratory Portable diagnostic tools that can be used by patients at home in their own bed Testing None Continuous measurement of sleep architecture by EEG (electroencephalography) Chin electromyography to detect hypotonia Electro-oculography to assess the occurrence of rapid eye movements. Airflow sensors at the nose and mouth to detect apneas and hypopneas Chest and/or abdominal sensors to detect respiratory effort Oxygen saturation by pulse oximetry ECG monitoring to detect arrhythmias associated with apneic episodes The patient is also observed by video. Other variables evaluated include limb muscle activity (to assess nonrespiratory causes of sleep arousal, such as restless legs syndrome and periodic limb movements disorder) and body position, because apnea may occur predominantly in the supine position. Theapnea-hypopnea index (AHI)is the total number of episodes of apnea and hypopnea occurring during sleep divided by the hours of sleep time. It is a common measure of respiratory disturbance during sleep and is used to classify the severity of OSA. Note the AHI alone does not determine need for treatment. OSA is graded as: Mild: AHI ≥ 5 and < 15 per hour Moderate: AHI ≥ 15 and ≤ 30 per hour Severe: AHI > 30 per hour Some patients may have a very high AHI (> 60). Therespiratory disturbance index (RDI)is a related measure that includes the number of arousals related to respiratory effort (called respiratory effort-related arousals or RERAs) plus the number of apnea and hypopnea episodes per hour of sleep. Thearousal index,which is the number of arousals per hour of sleep, can be computed if EEG monitoring is used. The arousal index is loosely correlated with the apnea-hypopnea index and respiratory disturbance index; about 20% of apneas and desaturation episodes are not accompanied by arousals, or other causes of arousals are present. However, the apnea-hypopnea index, arousal index, and respiratory disturbance index are only moderately associated with a patient’s symptoms. Some patients with a high or extremely high AHI (eg, > 60) have few or no symptoms. Additional metrics and combinations of metrics may prove useful in diagnosis ( Diagnosis references ). Furthermore, studies now show that it is a composite of clinical and polysomnographic data (not just AHI) that are linked to outcome and to cardiovascular risk and mortality, for instance, sleepiness regardless of AHI is linked to excess cardiovascular disease. using portable diagnostic tools uses a limited subset of polysomnographic measures, typically just heart rate, pulse oximetry, respiratory effort, position, and nasal airflow to detect apnea and estimate its severity. Their role is expanding ( Diagnosis references ) because of their convenience and decreased cost and their ability to provide a reasonably accurate estimate of respiratory disturbances during sleep. However, portable tools have some limitations. They do not actually detect the presence of sleep and instead depend on patients to self-report sleeping, which can be inaccurate; if patients were not sleeping during part of the study and they did not report this, sleep-disordered breathing will be underestimated. Also, coexisting sleep disorders (eg, Periodic Limb Movement Disorder (PLMD) and Restless Legs Syndrome (RLS) , seizures, REM behavior disorder, confusional arousals) are not detected. Follow-up polysomnography may still be needed to characterize these disorders as well as to accurately provide AHI and RDI values in the different stages of sleep and with changes in position, especially when surgery or therapy other than positive airway pressure is being considered. Portable tools are often used in combination with questionnaires (eg, STOP-Bang, Berlin Questionnaire). 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