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Polysomnography

Medical Uses of Polysomnography: – Used to diagnose sleep disorders like narcolepsy, idiopathic hypersomnia, PLMD, REM behavior disorder, and parasomnias. – Not directly used for […]

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Medical Uses of Polysomnography:
– Used to diagnose sleep disorders like narcolepsy, idiopathic hypersomnia, PLMD, REM behavior disorder, and parasomnias.
– Not directly used for circadian rhythm sleep disorders but can help rule out other sleep disorders.
– Controversy exists regarding using polysomnography as a screening test for excessive daytime sleepiness.
– Crucial in diagnosing conditions affecting sleep quality and patterns.
– Significant role in identifying and managing sleep-related breathing disorders like sleep apnea.

Mechanism and Equipment of Polysomnography:
– Records a minimum of 12 channels with at least 22 wire attachments.
– Measures brain activity (EEG), airflow, muscle tone, eye movements (EOG), heart rate, oxygen saturation, and movements during sleep.
– EEG electrodes follow the International 10-20 system, EOG electrodes near the eyes, and EMG electrodes for muscle tension.
– Wires converge into a central box connected to a computer system for data recording and analysis.
– Various sensors monitor nasal and oral airflow, respiratory effort, and movements during sleep.

Types and Additional Diagnostic Information:
– Type I polysomnography involves overnight monitoring by a credentialed technologist.
– Limited channel polysomnography (Type II – IV) can be performed at home for specific cases.
– Video-EEG polysomnography combines video recording with polysomnography.
– Provides insights into sleep onset latency, REM-sleep onset latency, total sleep duration, sleep stage percentages, movements, respiration, and cardiovascular parameters.
– Data can be customized to include additional parameters like body temperature or esophageal pH.

Procedure, Interpretation, and Diagnosis:
– Patients come to a sleep lab for testing, with multiple channels of data recorded.
– Data is analyzed in 30-second epochs after the test.
– Sleep stages, breathing irregularities, and other factors are determined for interpretation.
– Polysomnography helps diagnose sleep disorders like sleep apnea and guides treatment recommendations.
– CPAP therapy is commonly prescribed for obstructive sleep apnea based on test results.

Importance and Additional Reading:
– Provides detailed data on sleep patterns and disorders for effective treatment.
– Interpretation by sleep medicine physicians is crucial for treatment planning.
– Split-night studies offer advantages in cost and convenience for patients.
– Resources, research articles, guidelines, and textbooks provide valuable information on polysomnography and sleep disorders.

Polysomnography (Wikipedia)

Polysomnography (PSG), a type of sleep study, is a multi-parameter study of sleep and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς (polus for "many, much", indicating many channels), the Latin somnus ("sleep"), and the Greek γράφειν (graphein, "to write").

Polysomnography
Polysomnographic record of REM sleep. Eye movements highlighted by red rectangle.
ICD-9-CM89.17
MeSHD017286
OPS-301 code1-790
MedlinePlus003932
LOINC28633-6

Type I polysomnography is a sleep study performed overnight while being continuously monitored by a credentialed technologist. It records the physiological changes that occur during sleep, usually at night, though some labs can accommodate shift workers and people with circadian rhythm sleep disorders who sleep at other times. The PSG monitors many body functions, including brain activity (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG), and heart rhythm (ECG)1. After the identification of the sleep disorder sleep apnea in the 1970s, the breathing functions, respiratory airflow, and respiratory effort indicators were added along with peripheral pulse oximetry. Polysomnography no longer includes NPT monitoring for erectile dysfunction, as it is reported that all male patients will experience erections during phasic REM sleep, regardless of dream content.

Limited channel polysomnography, or unattended home sleep tests, is called Type II – IV channel polysomnography. Polysomnography should only be performed by technicians and technologists who are specifically accredited in sleep medicine. However, at times nurses and respiratory therapists perform polysomnography without specific knowledge and training in the field.

Polysomnography data can be directly related to sleep onset latency (SOL), REM-sleep onset latency, the number of awakenings during the sleep period, the total sleep duration, percentages and durations of every sleep stage, and the number of arousals. But there can also be other information crucial for diagnostics, that are not directly linked with sleep, such as movements, respiration, and cardiovascular parameters. In any case, through polysomnographic evaluation, other information can be obtained (such as body temperature or esophageal pH) according to the patient's or the study's needs.

Video-EEG polysomnography which combines polysomnography with video recording has been described as more effective than only polysomnography for the evaluation of sleep troubles such as parasomnias, because it allows easier correlation of EEG and polysomnography with bodily motion.

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