Sleep apnoea

Question 1

What is the difference between OSA and CSA?

Answer 1

OSA - upper airway narrowing with ongoing respiratory effort
CSA - reduction/cessation of airflow due to absent/reduced respiratory effort

Question 2

What is the most common symptom of OSA?

Answer 2

excessive sleepiness
> can use ESS or STOP BANG to help differentiate between fatigue and sleepiness
> note a high ESS does not correlate with a likely Dx of OSA

Question 3

What are the likely causes of OSA?

Answer 3

o narrow collapsible upper airway (most likely factor)
o infective upper airway dilator muscles
o low arousal threshold (due to airflow limitations)
o oversensitive ventilatory control system

Question 4

Briefly outline OHS

Answer 4

Awake alveolar hypoventilation (CO2 >45) , sleep disordered breathing, and an obese individual (BMI>30) that cannot be attributed to other causes. Commonly presents as Type 2 respiratory failure and/or R heart failure

Question 5

What is the main difference between OSA and OHS?

Answer 5

• OSA patients are able to normalise paCO2 between obstructive apneic or hypopneic events
• In contrast OHS patients with OSA have reduced ventilation for longer periods between events so CO2 is not adequately eliminated&raquo_space; compensation to retain HCO3