NOCTURNAL POLYSOMNOGRAM (N-PSG)
The nocturnal polysomnogram is a diagnostic test used in the sleep laboratory most commonly for patients suspected of having respiratory disturbances, nocturnal myoclonus, REM behavior disorders, or narcolepsy.
Patients referered by their physician spend a full night at the sleep laboratory where the testing is conducted by trained sleep technologists. Patients are attached to medical equipment which transmits electrophysiological signals from various regions of the body to computerized collecting stations which continuously record the signals throughout the night.
The test permits the interpreting physician to determine total sleep time, sleep efficiency, the relative percentages of NREM and REM sleep, sleep stage latencies, respiratory function versus body position (including the presence of snoring), oxygen saturation, the presence of periodic limb movements, and arousal indices. These quantitative measures assist the interpreting physician in the diagnosis of respiratory disturbances, nocturnal myoclonus, REM behavior disorders, and narcolepsy.
Nasal CPAP/BIPAP Titration
Nasal CPAP/BIPAP titration is a specific diagnostic test used with patients that have documented respiratory disorders such as obstructive sleep apnea or upper airway resistance syndrome (UARS). The goal of CPAP/BIPAP is to increase a patient’s overall quality of sleep by reducing or eliminating the presence of sleep-disordered breathing, decreasing the number of arousals, stabilizing oxygen saturation, and eliminating snoring.
As with the initial sleep study, patients spend a full night at the sleep laboratory. Patients are attached to the same medical equipment as used in the initial sleep study. The sensor used to measure airflow in the first study is replaced by a nasal CPAP (continuous positive airway pressure) mask which delivers air at variable pressure settings.
The test permits the interpreting physician to determine total sleep time, sleep efficiency, the relative percentages of NREM and REM sleep, sleep stage latencies, respiratory function versus body position (including the presence of snoring), oxygen saturation, the presence of periodic limb movements, and arousal indices which are then compared to the results of the initial sleep study. The physician also interprets the CPAP pressure setting which provides the optimal sleep quality.
Multiple Sleep Latency Test (MSLT)
The MSLT is a diagnostic test used in the sleep laboratory most commonly for patients suspected of having narcolepsy or excessive daytime sleepiness (EDS).
The test consists of a minimum of four naps and is typically performed the morning after completion of a Level 1 Sleep Study.
This combination of tests permits the interpreting physician to establish the duration and quality of sleep associated with the patient in the night immediately preceding the MSLT.
In patients referred for narcolepsy, the purpose of the MSLT is to determine whether REM staging is present or not, elapsed time to REM staging, as well as to determine elapsed time to sleep onset. These quantitative measures assist the interpreting physician in diagnosis of narcolepsy and excessive daytime sleepiness.
Schedule of Naps
After the patient is awoken from overnight study, he/she is asked to get dressed into his/her street clothes and must stay awake at all times before initiation of the first nap or between subsequent naps. This will require the sleep technologist on duty to keep a watchful eye to ensure that the patient does not fall asleep between nap sessions.
The first nap commences between a minimum of 1 ½ hours up to a maximum of 3 hours after completion of the overnight polysomnography study and typically this begins between 9:30 am – 10:00 am (reference) . The MSLT is to be conducted in a dark, quiet setting with minimal extraneous stimuli which might other influence the results of the MSLT
There are a minimum of four naps, each a ranging in length from a minimum of 20 minutes to a maximum elapsed time of 35 minutes depending upon the specific events which occur during each specific nap.
Naps are equally spaced and begin successively at two hours past the initiation of the prior nap (i.e. Nap 1 – 9:30am, Nap 2 – 11:30am, Nap 3 – 1:30pm, Nap 4 -3:30pm, if needed Nap 5 – 5:30pm)