The Snoring Spectrum: Polysomnography

In: Snoring

7 Aug 2014

Polysomnography: The polysomnographic results for each patient were retrospectively abstracted from hospital medical records. Standard polysomnographic recordings consisted of 2 EEG derivations (O2-A1 and C3-A2), electro-oculogram receiver operating characteristics (ROC-A1 and LOC-A2), an electromyogram of submental and tibialis anterior muscles, and a modified V2-lead ECG. Respiration was monitored using an oronasal thermistor, and thoracic and abdominal movements were monitored with inductive plethysmography. Arterial oxygen saturation (Sao2) was recorded using finger pulse oximetry. Sleep was scored in 30 s epochs according to the criteria of Rechtschaffen and Kales. Sleep efficiency was defined as the total sleep time divided by the total time in bed. Sleep latency was defined as the time between lights out and the onset of sleep.
Apnea was defined as a complete cessation of oronasal air flow for at least 10 s. Apneas were classified as obstructive in the presence of thoracic or abdominal movements. Hypopnea was defined as a reduction of > 50% in the amplitude of the airflow waveform from a preceding stable baseline. The respiratory disturbance index (RDI) was calculated as the sum of the apneas and hypopneas divided by the total sleep time.
Clinical Information: Clinical information was retrospectively abstracted from medical records according to a standard protocol: demographics, medical history, chief complaint leading to sleep laboratory referral, polysomnogram and other related procedure information, test results, and concluding diagnosis. Positive or negative clinical history information was recorded only if specific documentation was found in the medical record this purchase zyrte. Data elements that were not specifically documented were treated as missing.
Study Database: A final computer database was developed by combining the sound intensity level data (Leq, L1, L5, and L10) with all available polysomnographic and clinical data abstracted from the medical record. The accuracy and completeness of the study database were verified by conducting range, missing value, and consistency checks for each data element. Sound level measurements were prospectively recorded at the time of testing and, therefore, are complete for all patients. There are missing clinical data and, to a lesser extent, missing polysomnographic results because this information was abstracted from medical records.

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