6.1 Sleep Disordered Breathing Flashcards
What are the 2 states of sleep?
- Rapid eye movement (REM)
- non-REM (NREM)
What are the three sources of data that enable us to determine whether someone is in REM or NREM?
- Electroencephalographic (EEG)
- Electro-occulographic (EOG)
- Electromyographic (EMG)
What are the three divisions of NREM sleep? Which is the deepest, and which is the lightest?
Divided into N1, N2, and N3
N1 is the lightest, N3 is the deepest
What is the first state that someone usually goes into when they fall asleep: REM or NREM?
NREM
Which state of sleep predominates the first third of the night? Why?
N3; this is thought to be critical to bodily recovery and growth.
Which state of sleep predominates the last third of the night? What happens to the heart during this time?
REM sleep; the heart is active, although there is general muscle atonia
Do we need more or less sleep as we age?
Less
How much does alveolar ventilation decrease during sleep (in litres/min)? Why?
- 1-2L/min
- Occurs due to decreased tidal volume, and shallower and more irregular breathing
What happens to the body’s response to hypercapnia and hypoxaemia during sleep? When is this trend more pronounced?
- It is attenuated; lower alveolar ventilation increases CO2 conc and decreases O2
- This is especially pronounced during N3, and even more so during REM
How does the body’s response to hypercapnia and hypoxaemia decrease during sleep?
- No wakefulness drive to breathe
- Reduced lung volume (when lying flat, the organs push the diaphragm upwards)
- Reduced chemosensitivity to CO2 and O2 (20-50%)
- Reduced tone of intercostal muscles
What happens to metabolic rate during sleep? By how much?
Down by 10-15%
What questions should you ask during a sleep history?
- Do you sleep well?
- Are you restless during sleep (waking up a lot)?
- Difficulty falling/staying asleep?
- Do you wake early?
- Are you uncomfortable during sleep?
- Sleep routine (alarm/no alarm)
- Are you refreshed upon waking?
- Tired?
- Inappropriate falling asleep? (Safety?)
- Snoring (other apnoea symptoms)
- Rest of history (after PC)
- Collateral history
What characterises OSA?
Repetitive episodes of upper airway obstruction during sleep; frequent arousals. Effort to breathe despite obstruction.
OSA risk factors?
- Alcohol
- Obesity
- Upper airway abnormality
(Homer Simpson)
List some consequences of sleep fragmentation that could show up in an OSA history
- Decreased memory, concentration, irritability
- Headaches
- Unrefreshing sleep