Obstructive Sleep Apnoea Syndrome (OSAS)

Question 1

What is the definition of sleep disordered breathing ?

Answer 1

It is a spectrum from
intermittent, partial obstruction of the airway without sleep
disturbance (snoring) up to frequent apnoeas associated with
repetitive hypoxaemia and arousals leading to sleep disruption
and daytime sleepiness (OSAS).

Question 2

What is apnoea-hypopnoea index (AHI) ?

Answer 2

It measures the number of apnoeas or hypopnoeas that happen
within a 1-hour period.

Question 3

What is OSAS?

Answer 3

It is the most common sleep disordered breathing disease characterised by both an increased AHI >5 and 2 abnormal sleep
symptoms (gasping/choking in bed, waking from sleep, unrefreshing sleep, daytime fatigue and poor concentration).

Question 4

What is the definition of Apnoea ?

Answer 4

It is defined as > 10 sec with >80/90% reduction in flow.

Question 5

What is the definition of Hypopnoea (Shallow breathing) ?

Answer 5

It is defined as defined as > 10 secs with >50% reduction in flow and 3% drop in saturations or >30% reduction and 4% drop in oxygen saturations.

Question 6

What is the pathophysiology of OSAS?

Answer 6

Relative difference in the pressure b/w nose and lungs reduces the pharyngial dilator muscles ability to overcome the negative pressure generated within the airway causing upper airway collapse. Increased neck fat deposition, retrognathia may also worsen it.
The airway collapse will increase respiratory drive due to hypoxea and hypercapnia which arouses the patient from sleep to re-establish airway patency.

Question 7

What is the epidemiology of OSAS ?

Answer 7

It is common among obese people 7% of obese men and 5% of obese woman have it.

Question 8

What are the risk factors for OSAIS ?

Answer 8

• Obesity (especially central) - 10% increase in weight leads to 30%
  increase in AHI.
• Male sex (2-3 times risk).
• Increasing age.
• Family history of OSAS.
• Recent alcohol intake prior
  to sleep.
• Sedating medicaitons.

Question 9

What are the screening tools for OSAS ?

Answer 9

• Epworth sleepiness scale questionnaire (ESS).
• STOP-Bang questionnaire (SBQ).
• Overnight oximetry.

Question 10

What is the Dx test for OSAS ?

Answer 10

Polysomnogram.

Question 11

What is the indication for OSAS in overnight oxiometry ?

Answer 11

It is used to calculate oxygen
desaturation index (ODI) which shows how many times a person’s
oxygen levels drop >4% per hour overnight. An ODI > 10% /hour is significant.

Question 12

What is the interpretation of AHI in OSAS?

Answer 12

An AHI score of 5 or higher is considered abnormal.
*An AHI score of 5 to 15 indicates mild sleep apnea.
*An AHI score of 15 to 30 indicates moderate sleep apnea.
*An AHI score greater than 30 indicates severe sleep apnea.

Question 13

What should be the Tx approach in Sleep apnea ?

Answer 13

• AHI < 5 = no treatment, but consider looking into the patient’s
  sleep hygiene.
• • AHI >5, <15 (mild) = Treat if cardiovascular risk factors present
    or if ESS >10 as a trial to improve sleep quality.
• AHI >15 = Always consider treating.

Question 14

What are the consequences of not treating OSAS ?

Answer 14

Increased risk of:
* Developing high blood pressure.
* Inability to control high blood pressure.
* Transient ischaemic attacks and strokes.
* Heart attacks.
* Heart failure.
* Cardiac arrhythmias (atrial fibrillation).
* Insulin resistance leading to type 2 diabetes mellitus.
* Car accidents.
* Possible link with cancer

Question 15

What are the Tx in OSAS?

Answer 15

• Reverse the reversible risk factors
• Educate on good sleep hygiene
• continuous positive airway pressure (CPAP).
• Mandibular advancement device (MAD).
• Surgery for severe OSA with intolerance of all other methods and includes Uvulo-palato pharyngoplasty, Mandibular advancement osteotomy, Bariatric surgery for BMI >40.