INTRODUCTION TO POLYSOMNOGRAPHY

INTRODUCTION TO POLYSOMNOGRAPHY
Polysomnography or sleep study is done to assess a patient with suspected sleep related disorders. Common components assessed by sleep study are:
1. EEG –to assess various stages of sleep and their association with disorders (e.g. REM sleep behaviour disorder or RBD is likely to be seen in REM sleep).
2. Respiratory functions – including effort, air flow, pulse oximetry (e.g. in obstructive sleep apnea, we expect cessation of airflow through the nose or mouth with persistence of effort)
3. Limb movements –by placing electrodes over tibialis anterior muscles (e.g. in periodic limb movements of sleep, findings will be seen in these channels)
4. ECG-to simultaneously assess cardiac functions (e.g. to see the effect of desaturation in a patient of OSA on cardiac rhythm)


References :
1. Mc Gregor PA. Updates in polysomongraphic recording techniques used for the diagnosis of sleep disorders. Am J EEG Technol 1989;29:107
2. Antonio Culebras, Clinical Handbook of Sleep Disorders: Butterworth-Heinmann