Obstructive Sleep Apnea

Question 1

What are the complications of OSA?

Answer 1

Periop cx

• Difficult intubation
• Higher risk of aspiration
• Exaggerated respi depression in response to GA
• Increased post op respi problems
• Increased risk of AMI stroke and death in periop period
• Longer hospital stays

From repeated desat -> hypoxic pulmonary vasoconstriction -> pulmonary HTN, RV failure, cor pulmonale

Cardio (usually when OSA mod-severe): HTN arrhythmia IHD

CNS: traffic accidents (esp for bus drivers, pilots etc), poor memory, excessive daytime sleepiness, stroke

ED, poor school and work performance (esp in children) (excessive daytime somnolence)

Endocrine: IGT, DM

Note: death during sleep usually 2’ to stroke or AMI, which often happen early in the morning

Question 2

What are the symptoms of OSA?

Answer 2

Wake symptoms

• Wake up feeling unrefreshed/ w headache
• Daytime somnolence – dozing off during reading, work, driving
• Poor concentration and memory
• Sexual dysfx (poor libido)
• Deppression
• palpitations
• restlessness

Sleep symptoms

• Snoring – can be heard behind closed doors?
• Waking up at night w choking sensation/gasping
• nocturia)

Impact on QOL

• Adults: work performance, most dangerously it is the risk of falling asleep while driving
• Children: school performance

Question 3

What are the risk factors for OSA?

Answer 3

Weight (overweight, obese) [most impt risk factor]

• Increased soft tissue in the neck and oropharynx
• Increased size of tongue, predisposing to collapse of tongue base

Age: Increased collapsibility with age

Gender

Alcohol

Congenital problems

• Maxillary or mandibular hypoplasia
• Down syndrome

FHx

Question 4

What PE would you do for OSA?

Answer 4

General appearance: BMI, neck circumference, retrognathia (maxillary/mandibular retrusion)

Oropharynx assessment: Tonsil size, tongue, palpate position

Nasoendoscopic examination

• Nose: Deviate nasal septum, turbinate and adenoid hypertrophy
• Velopharynx/hypopharynx
• Large base of tongue

Dynamic manoeuvre (Muller’s manoeuvre): Reverse of Valsalva with scope in the nose; assess degree/grade of collapse at velopharynx (soft palate) and at base of tongue

BOT

• Brodsky’s tonsil grading
• Friedman tongue position – which has the tongue in neutral position, assessing soft palate position in relation to the tongue (grading is similar to modified Mallampati score, which has the tongue protruded)
• Friedman tongue 1 and 2 (small tongue), OR tonsil 3 and 4 (large tonsils) 🡪 higher degree of success with soft palate surgery

Epworth sleepiness scale (ESS)
- 8-point questionnaire
ESS ≥ 10 indicates possible excessive daytime somnolence or sleep disorder
- Useful for finding out improvement after treatment (comparing pre- and post-treatment scores to determine efficacy of treatment)

Question 5

How would you screen for OSA?

Answer 5

STOP BANG – screen for OSA

• Snoring
• Tiredness
• Observed apnoea
• Pressure (HTN)
• BMI >35
• Age >50
• Neck circumference >40cm
• Gender – male

Question 6

What investigations would you do for OSA?

Answer 6

Full attended sleep study (Level 1) (polysomnogram PSG)

• In hospitalisation, conducted by sleep technician
• Gold standard, measures the most parameters
• Especially for patients with cardiopulmonary comorbidities (e.g. congestive heart failure, COPD, epilepsy)
• Or if you suspect other sleep disorders

Home unattended sleep study

• Uncomplicated patients / “straightforward” OSA cases
• Unable to do an in-lab sleep study (e.g. cannot sleep in foreign environment)
• If study turns out to be negative but still highly suspecting OSA, recommended to repeat with a full attended PSG

Question 7

How would you manage an OSA patient (lifestyle)?

Answer 7

Weight loss

Oral appliances

• Stabilises the jaw in an advanced position, to improve retroglossal space
• Recommended only for snoring or mild-moderate OSA; not recommended for severe OSA
• Advantages: More portable than CPAP machine

Positional therapy

• E.g. sleeping against the wall, propping up a pillow on their back, positional trainers (using special pillows that tilt the patient into a lateral position)
• Useful for positional OSA (where sleeping in a non-supine position can relieve OSA significantly)
• 20-30% of OSA (not the most common subtype of OSA)

Question 8

How would you manage an OSA patient (medical [CPAP])?

Answer 8

1st line, effective treatment

Positive airway pressure acts as a pneumatic splint to keep the airway open

Pumps normal air; not oxygenated air

Effort of breathing is maintained by patient

Nasal mask is better tolerated then full-face mask

Question 9

What are the side effects of CPAP?

Answer 9

Disadvantages: noisy generating pump, uncomfortable mask -> issues w compliance and drop out, esp for young non-obese pts

Side effects

• Dry nose, sore throat
• Nasal congestion and irritation
• Irritation of the eyes and skin on the face
• Abdo bloating
• Leaks around the mask
• Nosebleeds (rare)

Question 10

How would you manage an OSA patient surgically?

Answer 10

Children: Tonsillectomy and adenoidectomy

Adults:

• Maxillomandibular Advancement surgery (MMA)
• Multi-level or stepwise surgery (MLS) to target narrowing of multiple sites in the upper airway
• Laser-assisted uvuloplasty or uvulopalatopharyngoplasty (UPPP) (unreliable)
• Bariatric surgery may also be a good surgical treatment option for severely obese OSA patients
• Hypoglossal nerve stimulation (novel treatment)

Question 11

How is OSA classified?

Answer 11

Mild: Apnoea-hypopnoea index (AHI): 5-15

Moderate: Apnoea-hypopnoea index (AHI): 15-30

Severe: Apnoea-hypopnoea index (AHI): > 30

Question 12

What is the definition of apnoea?

Answer 12

Reduction of air flow by 90% or more, for 10 seconds