Continuous positive airway pressure in sleep apnoea syndrome

• many patients with documented sleep apnea require more than conservative therapy
• continuous positive airway pressure (CPAP) is the most consistently successful and extensively studied treatment for obstructive sleep apnea
• continuous positive airway pressure (CPAP) may also be used as a treatment measure in patients with sleep apnoea syndrome.
• CPAP is achieved with the use of a special nasal mask that increases the pressure in the pharynx by about 1kPa and so keeps the walls of the pharynx apart
• there is evidence that CPAP improves subjective and objective measures of sleepiness more than placebo (1) - this study shows that CPAP is effective in for improving sleepiness in a wide range of patients with obstructive sleep apnoea. CPAP provides more benefit is patients with more severe problems and is more likely to be used with these patients
• CPAP treatment prevents the throat from closing and so reduces apnoeas and hypopnoeas
  • CPAP also reduces daytime sleepiness and improves daytime vigilance and cognitive functioning - it is likely to be needed life-long (2)
• patients using CPAP therapy commonly experience minor unwanted effects, including rhinitis, sores on the nasal bridge, discomfort and claustrophobia (2) - rarer, and more troublesome, adverse effects include nosebleeds and sinusitis

NICE state that (3):

• continuous positive airway pressure (CPAP) is recommended as a treatment option for adults with moderate or severe symptomatic obstructive sleep apnoea/hypopnoea syndrome (OSAHS)
  • moderate to severe OSAHS can be diagnosed from patient history and a sleep study using oximetry or other monitoring devices carried out in the person's home. In some cases, further studies that monitor additional physiological variables in a sleep laboratory or at home may be required, especially when alternative diagnoses are being considered
    • severity of OSAHS is usually assessed on the basis of both severity of symptoms (particularly the degree of sleepiness) and the sleep study, by using either the apnoea/hypopnoea index (AHI) or the oxygen desaturation index
      • OSAHS is considered mild when the AHI is 5-14 in a sleep study, moderate when the AHI is 15-30, and severe when the AHI is over 30
• CPAP is only recommended as a treatment option for adults with mild OSAHS if:
  • they have symptoms that affect their quality of life and ability to go about their daily activities, and
  • lifestyle advice and any other relevant treatment options have been unsuccessful or are considered inappropriate
• the diagnosis and treatment of OSAHS, and the monitoring of the response, should be carried out by a specialist service with appropriately trained medical and support staff.

Notes:

• CPAP machines contain a fan that blows air under pressure into the nostrils
• the airflow acts as a pneumatic splint that keeps the pharyngeal airway open
• CPAP is recommended for patients with symptomatic obstructive sleep apnea even if the apnea–hypopnea index is in the mild range (5 to 15) (4)
• CPAP is not curative, and patients must use the mask whenever they sleep (5)

Reference:

• (1) Arch Intern Med. 2003 Mar 10;163(5):565-71.
• (2) Drug and Therapeutics Bulletin 2004; 42(7): 52-6.
• (3) NICE (2008).Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome
• (4) Basner RC. Continuous Positive Airway Pressure for Obstructive Sleep Apnea.N Engl J Med 2007; 356:1751
• (5) Lyle D. Victor. Treatment of Obstructive Sleep Apnea in Primary Care.Am Fam Physician 2004;69:561-8,572-4