Diagnosis of Sleep-disordered Breathing
The American Academy of Sleep Medicine (AASM) strongly recommends using objective testing to diagnose the entire spectrum sleep-disordered breathing and not relying solely on screening questionnaires, tools and prediction algorithms.29
Using oximetry alone is not valid for diagnosing sleep-disordered breathing as it will not diagnose hypercapnia and can underestimate the severity of sleep-disordered breathing.33 Actigraphy, which measures sleep parameters and the average motor activity over a period of days to weeks using a noninvasive accelerometer, shows evidence of poor and fragmented sleep in CF but does not allow for the diagnosis of nocturnal hypoxia, OSA, or nocturnal hypoventilation34. Home sleep apnea tests are not recommended in the CF population because they are limited to assessing the sleep-wake pattern but do not reveal other sleep disturbances.
The gold standard diagnostic test for sleep-disordered breathing in the CF population is an overnight, attended, in-laboratory polysomnography (PSG).33 A PSG is a noninvasive diagnostic test that monitors EEG to determine sleep staging, oronasal airflow and abdominal/chest wall movement to determine the presence of sleep disordered breathing, end-tidal or transcutaneous carbon dioxide (CO2) monitoring to determine the presence of hypoventilation, in addition to several limb leads to evaluate for periodic limb movements (PLMs).30 In addition, there is video monitoring to evaluate for sleep movement disorders.30
The AASM recommends that PSG be used in patients with underlying cardiopulmonary disease, respiratory muscle weakness, hypoventilation, and/or chronic opioid use to diagnose sleep-disordered breathing.29 PSG will allow for the diagnosis of nocturnal hypoxia, obstructive sleep apnea, and nocturnal hypoventilation. Therefore, CF patients will benefit the most from PSG when sleep-disordered breathing is suspected.