GP - Obstructive Sleep Apnoea (OSA) Flashcards
What is Obstructive Sleep Apnoea (OSA)?
Excessive daytime sleepiness + irregular breathing at night
What is the pathophysiology behind OSA?
Upper airway patency depends on the activity of dilator muscles
During sleep, all muscles relax including the pharyngeal dilators, therefore some degree of airway narrowing is normal. However, in some people, excessive narrowing can be caused by either an already small pharyngeal size during awake state which undergoes a normal degree of muscle relaxation during sleep, or an excessive narrowing occurring with relaxation during sleep
Sleep –> pharyngeal dilators relax –> upper airway collapse –> hypoxia –> less O2 reaches the brain –> this causes the person to wake up from deep sleep to allow restoration of normal airway muscular tone –> the person then falls into deep sleep again –> the cycle repeats itself –> fragmentation of normal sleep pattern –>
reduced sleep quality + excessive daytime sleepiness + poor concentration
What are the risk factors for OSA in adults?
Men
Obesity
Neck circumference > 43 cm
FHx of OSA
Alcohol before bed (alcohol is a muscle-relaxant)
Sleeping supine
Neuromuscle disease that affects the pharyngx e.g. stroke, motor neuron disease
Hypothyroidism
What are the risk factors of OSA in children?
Enlarged adenoids and tonsils
Obesity
Craniofacial abnormalities
Down syndrome
Give 3 complications of OSA
Adults:
Hypertension
(With every arousal, there is a rise in BP, often > 50 mmHg. There is also a rise in daytime BP)
Stroke
Road traffic accidents (RTA)
Children:
Poor performance at school
Stunted growth
What are the clinical features of OSA?
Symptoms:
- Excessive daytime sleepiness
- Snoring and apnoea witnessed by partner
- Poor concentration
- Mood swings (irritability), personality changes, or depression
- Nocturia
Signs:
- Hypertension
Recurrent arousals lead to highly fragmented and unrefreshing sleep – snoring and apnoea attacks often witnessed by partner Excessive daytime sleepiness results (Epworth Sleepiness Scale score >9) With every arousal there is a rise in BP, often over 50 mmHg. It is not clear if this damages the CVS. There is also a rise in daytime BP. Nocturia Less common - Nocturnal sweating, reduced libido, oesophageal reflux
What examinations would you do as a GP?
Examine for:
- Enlarged tonsils and adenoids in children
- Small jaw
- Nasal obstruction e.g. polyps, or deviated nasal septum
- Signs of COPD, respiratory failure, or cor pulmonale
Check BP, BMI, neck circumference
What condition you MUST rule out in OSA?
Head or neck cancer
- Unilateral nasal bleeding + breathing difficulties
- Changes in voice or hoarseness
- Dysphagia
How would you further assess the severity of symptoms?
Epworth Sleepiness Scale
- It measures the perception of sleepiness i.e. the tendency to fall asleep in a variety of situations
- A total score > 10 indicates abnormal daytime sleepiness
- Mild (11-14)
- Moderate (15-18)
- Severe (> 18)
Give 3 differential diagnoses for OSA
Sleep disturbance secondary to pain or anxiety
Narcolepsy
Depression
Hypothyroidism
What investigations would you carry out in secondary care?
Overnight pulse oximetry
Limited sleep study (the usual study of choice) - oximetry, snoring, body movement, heart rate, oronasal flow, chest/ abdo movments, leg movements
Full polysomnography - limited sleep study + EEG + EMG + EOG
(note that investigations can only be done in secondary care. Therefore, as a GP, you need to refer the patient to a sleep centre for confirmation of the diagnosis using sleep studies and for secondary care treatments)
As a GP, how can you confirm the diagnosis of OSA?
Usually based on clinical features and examinations. However, to confirm the diagnosis, you have to refer the patient to a sleep centre for sleep studies!
What advice can you give to a patient with confirmed OSA in primary care?
Advice:
- Advice on lifestyle changes
- Weight loss, more exercise
- Reduce alcohol intake, esp before bed
- Smoking cessation
- Reduce sedative use
- Advice patients to sleep on their side
- Advise not to drive if feeling sleepy and advise the patient to inform the DVLA if daytime sleepiness is affecting their ability to drive
- Give information on support groups that provide self-management advice e.g. The Sleep Apnoea Trust Association
What is the management for OSA?
- Lifestyle changes
- Weight loss, more exercise
- Reduced alcohol intake, especially before bed
- Smoking cessation
- Sleep on their side rather than sleep supine
- For snorers & mild OSA where there is no daytime sleepiness
- Intra-oral devices (e.g. mandibular advancement device)
- For moderate or severe OSA
- CPAP
- Patients will require lifelong treatment and have to wear either a nasal or face mask for airflow delivery at night. Therefore, poor aderence to CPAP is common (due to poorly fitting mask, nasal dryness, nasal bleeding, or throat irritation)
- If unable to tolerate CPAP, offer intra-oral devices
- CPAP
- For severe OSA with CO2 retention
- NIV (BIPAP) first before giving CPAP if acidotic / CO2 retention
- Compensated CO2 (compensated respiratory acidosis) may reverse with CPAP alone
- Inform DVLA if OSA is causing excessive daytime sleepiness which affects ability to drive
- For children
- If caused by enlarged adenoid and tonsils –> adenotonsillectomy
When should you refer patient with suspected OSA?
- Refer urgently within 2 weeks to ENT if suspected of head and neck cancer
- Refer to a sleep centre for confirmation of the diagnosis and for secondary care treatments
- Urgent referral for those:
- Who are sleepy while driving or working with dangerous machinery
- With signs of respiratory failure or heart failure
- With symptoms suggestive severe OSA and COPD
- Urgent referral for those:
- Routine referral for those with symptoms suggestive of OSA and/or Epworth sleeping scale score > 10
- Refer children to paediatric ENT specialist if adenotonsillar hypertrophy and features of OSA
