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Flashcards in Obstructive Sleep Apnoea Deck (13)
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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?

Sleep studies:
- overnight oximetry alone
- limited sleep study
- full polysomnography


What are the causes of a small pharyngeal size?

Fatty infiltration of pharyngeal tissues
Large tonsils
Craniofacial abnormalities
Extra submucosal tissues eg. Myxoedema


What are the causes of excessive narrowing of the airways during sleep?

Neuromuscular disease (stroke, MND)
Muscle relaxants
Increasing age


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
Watching TV
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


What driving advice needs to be given to patients with OSA?

Do not drive while sleepy, stop and have a nap
On diagnosis, the patient must inform the DVLA
The doctor can advise patients to stop altogether e.g. HGV drivers