Flashcards in Obstructive Sleep Apnoea Deck (13)
What is meant by obstructive sleep apnoea?
Upper airway narrowing provoked by sleep, causing sufficient sleep fragmentation to result in significant day time symptoms, usually excessive sleepiness
There is either a pre-existing small pharnygeal size or relaxation/external narrowing
What is the clinical effect of recurrent arousals?
Arousal is required to re-activate the pharyngeal dilators following upper airway collapse. There may be associated hypoxia and hypercapnia which are corrected during the inter-apnoeic hyperventilatory period. Recurrent arousals lead to highly fragmented and unrefreshing sleep. With every arousal, there is a rise in BP
How is obstructive sleep apnoea diagnosed?
- overnight oximetry alone
- limited sleep study
- full polysomnography
What are the causes of a small pharyngeal size?
Fatty infiltration of pharyngeal tissues
Extra submucosal tissues eg. Myxoedema
What are the causes of excessive narrowing of the airways during sleep?
Neuromuscular disease (stroke, MND)
What are the simple approaches in the management of OSA?
Weight loss, sleep on your side, avoid/reduce evening alcohol intake
What is the management for mild OSA and snorers?
Mandibular advancement devices, consider pharyngeal surgery as last resort
What is the management of significant OSA?
Nasal CPAP, consider gastroplasty/bypass, and rarely tracheostomy
What is the management of severe OSA and CO2 retention?
May require a period of NIV prior to CPAP if acidotic, but compensated CO2 may reverse with CPAP alone
How does CPAP work?
Usually given via a nasal mask, but nose/mouth masks can be used
Upper airways are splinted open with approx 10cm H2O pressure, this prevents airway collapse, sleep fragmentation, and daytime sleepiness
Opens collapsed alveoli and improves VP matching
Constant positive pressure - not ventilatory support
How does BiPAP work?
Form of NIV using two different levels of positive pressure
It cycles between the two selected levels of positive airway pressure to complement the patients normal ventilatory cycle
How is daytime sleepiness in OSA assessed?
Epworth Sleepiness Score >9
Points for following 0, would never fall asleep, 1, slight chance, 2, moderate chance, 3, high chance
Sitting and reading
Sitting in a public place
Passenger in a car for an hour
Lying down to rest in the afternoon
Sitting and talking
Sitting quietly after lunch without alcohol
In a car, while stopped in traffic