What is the role of polysomnography in the workup of childhood obstructive sleep apnea (OSA)?

Updated: Feb 13, 2019
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Polysomnography remains the criterion standard for establishing the diagnosis of obstructive sleep apnea (OSA) in infants, children, and adults. Ideally, polysomnography should be performed overnight and during the patient's usual bedtime.

Polysomnography provides the following measures:

  • Sleep state (≥2 EEG leads)

  • Electrooculogram (right and left)

  • Submental electromyelogram (EMG)

  • Airflow at nose and mouth (thermistor, capnography, or mask and pneumotachygraph)

  • Chest and abdominal wall motion (impedance or inductance plethysmography)

  • Electrocardiogram (preferably with R-R interval derivation technology)

  • Pulse oximetry (including a pulse waveform channel)

  • End-tidal carbon dioxide (sidestream or mainstream infrared sensor)

  • Video camera monitor with sound montage (analog or digital)

  • Transcutaneous oxygen and carbon dioxide tensions (in infants and children < 8 y)

Multiple physiologic parameters are monitored during polysomnography, although the specific montage may vary slightly between sleep laboratories. Generally, electrooculography, chin and leg surface electromyography (EMG), and at least 2 EEG channels are included to confirm sleep and assess sleep architecture. Breathing is assessed using nasal/oral airflow sensors, pulse oximetry, and end-tidal (ET) CO2 measurements monitoring and by placing piezo crystal belts across the chest and abdomen to detect respiratory efforts. At least one ECG channel is necessary to determine heart rate and rhythm. Occasionally, other channels are incorporated into the study as needed. These might include additional EEG leads to better detect seizure activity, esophageal pH measurements, or transcutaneous carbon dioxide monitoring.

Polysomnographic normal standards differ between children and adults. In the pediatric age range, abnormalities include oxygen desaturation under 92%, more than one obstructive apnea per hour, and elevations of ET CO2 measurements of more than 50 mm Hg for more than 9% of sleep time or a peak level of greater than 53 mm Hg.

See the related polysomnographic image below.

Example of an obstructive apnea and an obstructive Example of an obstructive apnea and an obstructive hypopnea recorded during polysomnography.

Polysomnography is necessary to document obstructive sleep apnea and gauge its severity. A history of snoring alone is not adequate for making a diagnosis of obstructive sleep apnea or for determining its seriousness.

Some children with obstructive sleep apnea have primarily obstructive hypoventilation in which repetitive partial obstructions occur with some degree of relative oxygen desaturation and hypercapnia. Because of this, pediatric polysomnographic testing should include some means of determining CO2 levels, such as end-tidal (ET) CO2 monitoring or transcutaneous CO2 monitoring.

PSG, continuously monitored by appropriately trained technical personnel, may be difficult to arrange due to relative unavailability, with long waiting periods between referral and testing times. For these reasons, attempts have recently been made to evaluate the role of outpatient overnight studies to provide more accessible and practical approaches to the diagnosis of pediatric obstructive sleep apnea. However, these outpatient studies are not well validated yet or covered by third party payers and, thus, remain largely available only as research tools.

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