Obstructive sleep apnea, polysomnography, and split-night studies: consensus statement of the Connecticut Thoracic Society and the Connecticut Neurological Society.

Obstructive sleep apnea is a state-dependent syndrome. It is characterized by repeated collapse of the upper airway as the result of the loss of waking neuromuscular drive as the brain changes from wakefulness to sleep. This produces a state-dependent decrease in muscle tone, which, together with other predisposing factors such as obesity and anatomical narrowing of the upper airway, results in the spectrum of sleep disordered breathing. Sleep-disordered breathing describes the continuum from simple snoring (pharyngeal vibration), to flow limitation (hypopnea), to complete cessation of breathing (apnea). Obstructive sleep apnea (OSA) is the common description of what is now appreciated as the sleep apnea/hypopnea syndrome. The cardinal symptoms are snoring, observed apneas, and excessive daytime sleepiness. The immediate physical consequences are hypoxia, repeated sympathetic discharges, increased cardiac load, and repeated brain arousals. The repetitive arousals are required to restore airway patency, resulting in severely fragmented sleep and consequent sleep deprivation. The syndrome, untreated, produces significant cognitive and cardiorespiratory morbidity, and potential mortality. Compared to matched controls, patients with undiagnosed sleep apnea use twice the health resources and spend double the health-care dollars in the 10 years prior to diagnosis. Both trends are reversed by successful treatment. It is by definition a sleep-related illness and can be observed and evaluated only when the patient is asleep. Polysomnography is the laboratory procedure to study sleep and its protean dysfunctions. Multiple physiologic parameters are required to document the various types of sleep disorders as well as to establish the origin of pathologic sleep fragmentation. Complete polysomnography includes (but is not limited to) electroencephalogram (EEG), electrooculogram ((EOG), electromyogram (EMG), electrocardiogram (ECG), respiratory effort, air flow, and oxygen saturation. Treatment options for obstructive sleep apnea include continuous positive airway pressure (CPAP), oral appliances, uvulopalatal and/or maxillomandibular surgery, positional control, and weight loss. The efficacy of each depends on the individual anatomy and the severity of the sleep-disordered breathing. CPAP is accepted as the most reliable treatment regardless of anatomy and severity. It is currently the only treatment modality which can be titrated during sleep and requires simultaneous polysomnography.