Sleep Disordered Breathing Flashcards
Discuss the basic epidemiology of obstructive sleep apnoea
OSA is a common with significant adverse effects. It is estimated that almost 1 billion people globally are affected by the condition, with 425 million adults aged 30-69 having moderate to severe OSA.
Prevalence is higher in Hispanic, Black and Asian communities. Prevalence also increases with age, and when individuals reach 50 years of age or more. There is a higher prevalence in men.
Discuss the basic presentation & investigation of obstructive sleep apnoea
PC
- - Chronic snoring
- Daytime somnolence (tiredness)
- Morning Headaches
- Difficulty Concentrating
- Mood Swings
- Dry Throat
- Loss of Libido
In addition, the patient may appear obese, have a wide neck or small jaw, or a nasal obstruction.
Ix
Severity of their suspected OSA assessed using the Epworth Sleepiness Scale
Referred to specialist care where tests such as overnight sleep studies and polysomnography are performed. The following parameters are measured:
- Brain Activity
- Eye movements
- Oxygen and Carbon Dioxide Levels
- BP and Pulse
- Inspiratory and Expiratory Flow
15 apnoeas/hypoanpoeas (of 10 seconds or longer) per hour of sleep is diagnostic of OSA.
Discuss the basic management of obstructive sleep apnoea
Weight loss is key for those overweight.
Other conservative measures such as avoiding alcohol and sedatives that relax the upper airway, can be effective.
Most patients nightly Continuous Positive Airway Pressure (CPAP) is recommended.
With CPAP, respiratory support is given via the patient’s upper airway. The patient breathes spontaneously, and the lungs are expanded by a volume of gas delivered at a positive pressure. This decreases the work of the respiratory muscles, particularly the diaphragm. The results can be remarkable, and it is recommended in those patients with moderate or severe symptoms.
Describe a ‘sleepiness’ scale
Epworth Sleepiness Scale, which is used to measure daytime somnolence.
They score situations between 0-3 which is the chance of ‘dozing’. The situations include watching TV to In a car whilst stopped in traffic
A score of 9 or less is normal. Between 10 and 15 indicates likely mild to moderate disease, and specialist medical advice should be sought. A score of 16 or over is indicative of severe disease.
Discuss the basic pathophysiology of obstructive sleep apnoea
Upper airway obstruction during sleep is often due to negative collapsing pressure during inspiration. The magnitude of upper airway narrowing is often related to BMI, indicating that anatomical and neuromuscular factors contribute to airway obstruction.
On inspiration upper-airway pressure becomes negative, but airway patency is usually maintained by upper-airway muscle tone. During deep sleep, these muscles relax, causing narrowing of the upper airways, even in normal people. However, if the airway is already narrowed due the weight of adipose tissues in obese patients or because of a small jaw (micrognathia), the airway collapses and OSA can occur.
A cycle during sleep in which:
1. The upper-airway dilating muscles lose tone (usually accompanied by loud snoring)
2. The airway is occluded
3. The patient wakes up (often not completely, patients are not consciously aware)
4. The airway reopens
As a consequence of this cycle, sleep is unrefreshing and daytime sleepiness is common, particularly during monotonous tasks such as motorway driving.
What is Obstructive Sleep Apnoea?
Obstructive Sleep Apnoea (OSA) is a condition in which there is either a partial (hypopnea) or total (apnoea) collapse of the pharyngeal airway during sleep, causing arousal and partial wakening. This can occur many times throughout the night and result in interrupted, non-refreshing sleep.
