Obstructive sleep apnea

Question 1

Sleep apnea : Definition

Answer 1

1. Irregular breathing and snoring patters which can cause ‘Apnea’
2. ‘Apnea’ is momentary ceasing of breathing

Question 2

Sleep apnea :

Answer 2

1. Obstructive sleep apnea } most common form
2. Central sleep Apnea

Question 3

Obstructive sleep apnea : Pathophysiology

Answer 3

1. Disturbed sleep and apnea 2nd to a transient obstruction of the respiratory tract during sleep
2. Sleeping causes hormonal changes at night which reduces air way tone
3. If airway tone is not able to counteract the negative pressure during inspiration or gravity
4. Airway collapses leading to apnea

Question 4

Obstructive sleep apnea : Causes

Answer 4

1. Allergies : swollen tonsils, Adenoid glands
2. Severe overbite
3. Obesity : increased weight of soft tissue surrounding the neck

Question 5

Central sleep apnea : Definition

Answer 5

Brain intermittent stops making an effort to breather for around 10-30 seconds as respiratory centre in the brain is dysfunctional

Question 6

Central sleep apnea : Pathophysiology

Answer 6

1.** Hyperpnea** : Increase in respiratory rate and hyperventilation leading to hypocapnia } drop in CO2

• Compensatory mechanism to restore respiratory alkalosis

2. ** Apnea :** no effort to breathe, causes CO2 levels to increase eventually causing Hypercapnia
3. **Trigger Hyperpnea and increased RR again **

Respiratory system goes back and forth between two states of apnea and hyperventilation

Question 7

Central sleep apnea : Causes

Answer 7

1. CNS injury of the respiratory centre / Opiod overdose

2. Congestive heart failure :

• Increases sensitivity to partial pressures of CO2 and O2 ‘Chemosenitivity’
• Increased chemosentivity means** increased CO2 triggers** a much more exaggerated response in the form of hyperventilation
• This in turn decreases the CO2 levels too much } triggers further extreme response of apnea

Question 8

Sleep apnea : Clinical features

Answer 8

1. Day time somnolence - severe sleep deprivation due to interrupted sleep
   * Assoc with nocturia
2. Loud snoring prior to apneic episodes
3. Cheyne- Stokes respiration /Cyclic respiration : Abnormal breathing pattern of Central sleep apnea associated with congestive HF.

Question 9

Sleep apnea : Complications

Answer 9

Complications are causes by chronic hypoxia secondary to Apnea

**1. **Increases RBC production : Kidneys release more erythropoietin

2. Increased physiological stress - higher levels of epinephrine release
- High levels of epinephrine cause vasoconstriction both pulmonary and systemic vasoconstriction and hypertension

3. Angina, increase CVS risk and risk of arryhmias

Question 10

Sleep apnea : Investigations

Answer 10

1. Assessment of sleepiness
   * Epworth Sleepiness Scale - questionnaire completed by patient +/- partner
2. Diagnosis :
   * Polysomnography/Sleep studies

Question 11

Sleep apnea : Management

Answer 11

1. Weight loss

2.
* Mild OSA : intra-oral device – helps to keep airway patent during sleep
* Moderate/Severe : CPAP
Helps to keep airway patent