Humans spend almost 30% of their lives sleeping. Over the past 30 years, physicians have begun to recognize many of the detrimental consequences of sleep disturbances produced by abnormal breathing patterns termed sleep-disordered breathing (SDB).SDB is not a newly discovered disease entity however in the past, it was not considered a serious health problem, and just during the recent decades researchers have declared its serious consequences and the condition has come into physician's attention. Researchers continue to develop an understanding of the risks created by and associated with sleep apnea syndrome (SAS). Associated risks include the following: Hypertension Stroke Ischemic heart disease Pulmonary hypertension Congestive heart failure Sexual malfunction Traffic accidents SDB and SAS are much more prevalent than older believes, in more conservative studies the prevalence had been reported at about 4 percent; in the more recent studies the rate has raised to 25-40% among adults 40 years of age or older. SDB refers to a wide spectrum of sleep-related breathing abnormalities; those related to increase upper airway resistance include snoring, upper airway resistance syndrome (UARS), and obstructive sleep apnea-hypopnea syndrome (OSAHS). Many authors regard SDB as a continuum of a spectrum of diseases ranging from simple snoring to Obstructive Sleep Apnea Syndrome (OSAS); this concept suggests that an individual who snores may be exhibiting the first manifestation of SDB and that snoring should not be viewed as normal. A patient can move gradually or rapidly through the continuum, from a less annoying to serious disabling condition. Early detection and appropriate management is essential and potentially life saving for individual patients. Nocturnal, laboratory-based polysomnography (PSG) is the most commonly used test in the diagnosis of obstructive sleep apnea syndrome (OSAS). It is often considered the criterion gold standard for diagnosing OSAS, determining the severity of the disease, and evaluating various other sleep disorders that can exist with or without OSAS. PSG consists of a simultaneous recording of multiple physiologic parameters related to sleep and wakefulness. PSG can directly monitor and quantify the number of respiratory events (i.e., obstructive, central, or complex) and the resultant hypoxemia and arousals related to the respiratory events or even independent of the respiratory events. A single-night PSG is usually adequate to determine if OSAS is present and the degree of the disorder. However, night-to-night variability may exist in patients have a high probability but a low apnea index. In addition, variability in laboratory equipment, scoring technique, and interscorer reliability may also play roles. Scoring by computer software is not reliable and a scorer has to recheck all of the events by him/herself to make a realistic report. PARAMETERS MONITORED Assessment of sleep stages requires 3 studies: to be monitored during a whole night sleep: Electroencephalography (EEG) Electrooculography (EOG), Surface electromyography (EMG). Other monitored parameters include: Airflow (nasal and/or oral) Electrocardiography Pulse oximetry Respiratory effort (thoracic and abdominal) Sound recordings to measure snoring Continuous video monitoring of body positions An experienced Sleep study physician can determine the presence of SDB and/or its severity, and suggest the most suitable management plan.
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