6.1 Sleep Disordered Breathing Flashcards

1
Q

What are the 2 states of sleep?

A
  • Rapid eye movement (REM)
  • non-REM (NREM)
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2
Q

What are the three sources of data that enable us to determine whether someone is in REM or NREM?

A
  • Electroencephalographic (EEG)
  • Electro-occulographic (EOG)
  • Electromyographic (EMG)
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3
Q

What are the three divisions of NREM sleep? Which is the deepest, and which is the lightest?

A

Divided into N1, N2, and N3
N1 is the lightest, N3 is the deepest

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4
Q

What is the first state that someone usually goes into when they fall asleep: REM or NREM?

A

NREM

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5
Q

Which state of sleep predominates the first third of the night? Why?

A

N3; this is thought to be critical to bodily recovery and growth.

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6
Q

Which state of sleep predominates the last third of the night? What happens to the heart during this time?

A

REM sleep; the heart is active, although there is general muscle atonia

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7
Q

Do we need more or less sleep as we age?

A

Less

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8
Q

How much does alveolar ventilation decrease during sleep (in litres/min)? Why?

A
  • 1-2L/min
  • Occurs due to decreased tidal volume, and shallower and more irregular breathing
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9
Q

What happens to the body’s response to hypercapnia and hypoxaemia during sleep? When is this trend more pronounced?

A
  • It is attenuated; lower alveolar ventilation increases CO2 conc and decreases O2
  • This is especially pronounced during N3, and even more so during REM
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10
Q

How does the body’s response to hypercapnia and hypoxaemia decrease during sleep?

A
  • 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
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11
Q

What happens to metabolic rate during sleep? By how much?

A

Down by 10-15%

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12
Q

What questions should you ask during a sleep history?

A
  • 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
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13
Q

What characterises OSA?

A

Repetitive episodes of upper airway obstruction during sleep; frequent arousals. Effort to breathe despite obstruction.

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14
Q

OSA risk factors?

A
  • Alcohol
  • Obesity
  • Upper airway abnormality

(Homer Simpson)

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15
Q

List some consequences of sleep fragmentation that could show up in an OSA history

A
  • Decreased memory, concentration, irritability
  • Headaches
  • Unrefreshing sleep
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16
Q

Obstructive vs central apneas?

A

Obstructive: Upper airways resistance and obstruction, characterised by effort to breathe against resistance

Central: Due to lack of control from brainstem resp. centres; charcterised by lack of effort

17
Q

What are mixed apnoeas?

A

Combination of central and obstructive apnoea

18
Q

Define hypopnea

A

Reduction of airflow with associated arousal during sleep, or oxygen desaturation

19
Q

How many apnoeas, hypopnoeas and “unsure” events must happen per hour to be considered abnodrmal or severe?

A

Abnormal: >10
Severe: >30

20
Q

Describe some acute consequences of OSA

A
  • Excessive somnolence (desire to fall asleep); could pose a safet risk
  • Sleep deprivation may have psychosocial consequences (including snoring, which could piss of your girlfriend…)
21
Q

Why does sleep apnoea increase risk of CVD, Cerebrovascular event, and hypertension?

A
  • Arousal releases excitatory hormones, interrupting periods of restorative sleep and leading to vascular remodelling
22
Q

How does OSA cause pulmonary hypertension?

A

Remodelling due to excessive hypoxia

23
Q

You suspect someone may have OSA, but they are not drowsy. They operate heavy machinery for a living. Do you refer them to a sleep study?

A

Yes. Of course.

24
Q

Why might patients not be very compliant with CPAP treatment?

A
  • Mask discomfort
  • Dry mouth from airflow
  • It doesn’t look very appealing
  • Claustrophobia
  • Cost
25
Q

How does a mandibular splint work? Is it effective for obese patients?

A
  • Splint pulls jaw forward to keep airways open
  • Not effective for obese patients
26
Q

True or false: weight loss has minimal impact on improving OSA

A
  • False
  • It almost always leads to an improvement, and the improvement can be significant
27
Q

What is respiratory disturbance index?

A

Total number of apnoeas/hypopneas per hour

28
Q

Is surgery available for OSA?

A

Yes

29
Q

How much less common is central sleep apnoea than obstructive sleep apnoea?

A

About 10 times less common

30
Q

Why is central sleep apnoea important?

A

It can lead to the diagnosis of other, comorbid conditions

31
Q

Can neuromuscular diseases cause central sleep apnoea? If so, how?

A
  • Yes, they can
  • Muscles are either too weak to breathe, or lack of brainstem control of muscles
32
Q

What are some parameters recorded by a sleep study?

A
  • EMG
  • EEG
  • EOG
  • ECG
  • Leg movement
  • Microphone (snoring)
33
Q

What is the minimum amount of time without breathing before an event is considered an apnoea?

A

10 seconds