Obstructive Sleep Apnoea Syndrome Flashcards

1
Q

What is Obstructive Sleep Apnoea Syndrome (OSAS)?

A

A clinical condition in which there is intermittent and repeated upper airway collapse during sleep

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2
Q

How is complete apnoea defined?

A

10-second pause in breathing activity

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3
Q

How is partial apnoea defined?

A

10-second period where ventilation is reduced by at least 50%

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4
Q

What is partial apnoea also known as?

A

Hypoapnoea

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5
Q

What is the normal sleep/wake cycle in adults divided into?

A
  • REM
  • Non-REM
  • Consciousness
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6
Q

In what state are the muscles of the throat and neck in REM sleep?

A

Completely attenuated

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7
Q

What does attenuation of the throat and neck muscles in REM sleep allow?

A

Relaxation of the tongue, soft palate and oropharynx

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8
Q

What does relaxation of the throat structures cause in sleep apnoea?

A

Impedance of the flow of air to a degree ranging from light snoring to complete collapse

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9
Q

What happens if sleep apnoea causes blood oxygen levels to fall or exertion of breathing to become too great?

A

Neurological mechanisms trigger a sudden interruption of sleep

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10
Q

What is the sudden interruption of sleep that can occur in sleep apnoea called?

A

Neurological arousal

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11
Q

What does neurological arousal normally result in?

A

Negative effect on the restorative quality of sleep (rarely complete awakening)

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12
Q

What are most cases of OSAS believed to best caused by?

A
  • Old age
  • Brain injury
  • Decreased muscle tone
  • Increased soft tissue around airway
  • Structural features that give rise to a narrowed airway
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13
Q

What can cause decreased muscle tone leading to OSAS?

A
  • Drugs or alcohol

- Neurological problems

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14
Q

What can cause increased soft tissue around airway?

A

Obesity

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15
Q

What are the risk factors for OSAS?

A
  • Obesity
  • Male gender
  • Aged 55-59 in men
  • Aged 60-64 in women
  • Smoking
  • Sedative drugs
  • Excessive alcohol consumption
  • Family history
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16
Q

What other conditions are associated with OSAS?

A
  • Hypertension
  • Cardiovascular disease
  • Obesity
  • Metabolic syndrome
  • Diabetes
  • Asthma
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17
Q

How can sleep apnoea present?

A
  • Snoring
  • Witnessed apnoea
  • Symptoms of sleep fragmentation
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18
Q

What are some symptoms of sleep fragmentation that can occur in OSAS?

A
  • Excessive daytime sleepiness
  • Impaired concentration
  • Unrefreshing sleep
  • Irritability/personality change
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19
Q

How is OSAS clinically defined?

A

As 5 or more respiratory events per hour in association with sleep disordered breathing

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20
Q

What is meant by respiratory events in the clinical definition of OSAS?

A
  • Apnoea
  • Hypoapnoea
  • Arousals
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21
Q

What are some potentially noteworthy findings on examination for OSAS?

A
  • Obesity
  • Fat deposition anterolateral to the airway
  • Large neck circumference
  • Certain craniofacial or pharyngeal abnormalities associated with OSAS
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22
Q

What craniofacial and pharyngeal abnormalities are associated with OSAS?

A
  • Micrognathia
  • Enlarged tonsils
  • Macroglossia
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23
Q

How is OSAS diagnosed?

A

Through varying levels of nocturnal monitoring of respiratory, sleep and cardiac parameters

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24
Q

What is the aim of the varying monitoring methods in diagnosing OSAS?

A

To detect obstructive events and the following changes in blood oxygen saturation

25
Q

What is the traditional gold standard in diagnosing OSAS?

A

Polysomnography (PSG)

26
Q

What physiological readings may be taken during PSG testing?

A
  • EEG
  • EOG
  • Electromyogram
27
Q

What is an EOG?

A

Electro-oculogram

28
Q

What does an electromyogram monitor?

A

Muscle movements

29
Q

How is a PSG interpreted?

A

Apnoea and hypoapnoea events are quoted as an apnoea//hypoapnoea index (AHI)

30
Q

What is an AHI used for in assessing OSAS?

A

Measuring the severity of apnoea

31
Q

How is AHI calculated?

A

Sum of apnoeas and hypoapnoeas divided by hours of sleep

32
Q

What is considered mild OSAS based on AHI?

A

AHI = 5-14/hour

33
Q

What is considered moderate OSAS based on AHI?

A

AHI = 15-30/hour

34
Q

What is considered severe OSAS based on AHI?

A

AHI >30/hour

35
Q

What are some other investigations that can be useful in diagnosing OSAS?

A
  • Domiciliary diagnostic systems
  • Thoracic and abdominal binders
  • Nasolaryngoscopy
  • Blood pressure
36
Q

What is an example of a domiciliary diagnostic system used in OSAS?

A

Respiratory multi-channel recording

37
Q

What can respiratory multi-channel recording measure?

A
  • Snoring
  • Nasal airflow
  • Oximetry
  • Pulse rate
38
Q

What do thoracic abdominal binders measure?

A

Reductions in chest movements

39
Q

What can nasolaryngoscopy help identify in OSAS?

A

Level of any obstruction

40
Q

What are the differentials of OSAS?

A
  • Fragmented sleep
  • Sleep deprivation
  • Depression
  • Narcolepsy
  • Hypothyroidism
  • Drugs
  • Neurological conditions
41
Q

What drugs could causes OSAS like presentation?

A
  • Sedatives
  • Stimulants
  • Beta blockers
  • SSRI’s
42
Q

What neurological conditions may present like OSAS?

A
  • Previous encephalitis
  • Previous head injury
  • Parkinsonism
43
Q

What is the goal of OSAS treatment?

A

To restore optimal breathing during the night and to relieve associated symptoms

44
Q

What are the 4 main management options in OSAS?

A
  • Behavioural interventions
  • CPAP
  • Pharmacological treatments
  • Surgery
45
Q

What behavioural/lifestyle interventions should be discussed with a patient with OSAS?

A
  • Weight loss
  • Smoking cessation
  • Avoidance of alcohol, sedative and hypnotic medication in the evening
46
Q

What is the gold standard of treatment for OSAS?

A

CPAP

47
Q

What are the advantages of CPAP for OSAS?

A
  • Highly effective symptom control
  • Improve QoL
  • Reduce sequelae
48
Q

What are the disadvantages of CPAP?

A
  • Can lead to claustrophobia
  • Can cause rhinitis and nasal irritation
  • Can disturb partner’s sleep
49
Q

How does CPAP work to treat OSAS?

A

It acts as a pneumatic splint to maintain airway patency

50
Q

How long each night should CPAP be worn?

A

Minimum of 4 hours

51
Q

What does the efficacy of CPAP to treat OSAS depend on?

A

Continuous use

52
Q

How good are pharmacological agents at treating OSAS?

A

Limited

53
Q

What drug may have benefit in treating daytime sleepiness in patients with OSAS?

A

Modafinil

54
Q

When is surgery considered for OSAS?

A

People in whom CPAP or oral appliances have failed or are contraindicated

55
Q

What are 3 surgical options for treating OSAS?

A
  • Suspension of hyoid bone
  • Uvulopalatopharyngoplasty
  • Radio-frequency ablation of tongue base
56
Q

What are the potential complications of OSAS?

A
  • Accidents due to daytime sleepiness
  • Irritability
  • Depression
  • Cardiovascular complications
  • Stroke
57
Q

What should patients with excessive daytime sleepiness do to avoid serious accidents?

A

Stop driving until OSAS is controlled

58
Q

What cardiovascular complications can occur as a result of OSAS?

A
  • Hypertension
  • Coronary artery disease
  • Congestive heart failure