Investigations

After referral, the ENT surgeon will take a sleep history with reference to presenting symptoms and carry out a full ear, nose, and throat examination with a hearing assessment if indicated.

Although majority of cases are diagnosed on clinical grounds alone some patients may need additional investigations (1,2).

Investigations carried out in the secondary care include:

• overnight pulse oximetry
  • can be carried out at home using a portable pulse oximetry equipment
  • heart rate and oxygen saturations are monitored overnight
  • it has a high positive predictive value (97%) for diagnosis of obstructive sleep apnoea but the negative predictive value is low (53%) (since not all apnoeas result in a drop in saturations)
    
    
• polysomnography (a sleep study)
  • currently the optimal mode of investigation for paediatric OSA
  • measures apnoeas and hypopnoeas which is often combined and used as the apnoea-hpopnoea index (AHI) (the total number of apnoeas and hypopnoeas per hour of sleep) to determine the severity of the condition
  • additionally electroencephalography, electro-oculography, or electromyography measurements are also included

The UK Royal College of Paediatrics and Child Health's working group states that oximetry is useful as a screening tool while polysomnography is required reliably differentiate primary snoring from obstructive sleep apnoea

Reference:

• (1) Powell S et al. Paediatric obstructive sleep apnoea. BMJ. 2010;340:c1918
• (2) Powell S. Clinical review: Paediatric obstructive sleep apnoea. GPonline 2011