Sleep Apnoea and Respiratory Failure Flashcards

1
Q

What happens on inspiration?

A
  • rib cage moves up and out
  • intercostal muscles contract
  • diaphragm contracts and moves down
  • pressure in lungs decreases so less than outside and air rushes in
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2
Q

What happens on expiration?

A
  • intercostal muscles relax
  • diaphragm relaxes and moves up
  • elastic recoil of lungs forces them to contract
  • pressure inside lungs greater than outside so air gets pushed out
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3
Q

What are the peripheral chemoreceptors?

A
  • carotid and aortic bodies
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4
Q

Hypoxic pulmonary vasoconstriction

A
  • if alveolus has no oxygen supply = hypoxic

- vasoconstriction occurs = no perfusion = no more oxygen = won’t be inflated

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5
Q

Type 1 respiratory failure

A
  • PaO2 <8 kPa
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6
Q

Type 2 respiratory failure

A

PaO2<8kPa AND PaCO2 >6.5kPa

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7
Q

Mechanisms of hypoxia

A
  • hypoventilation
  • diffusion abnormality
  • ventilation/perfusion mismatch
  • right to left cardiac shunt bypassing lungs
  • low inspired oxygen = high altitude/air flight
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8
Q

Example of ventilation perfusion mismatch

A
Lobar pneumonia
Asthma = mucus plugs so obstructs airflow
Lobar collapse
PE
Pneumothorax
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9
Q

Example of diffusion abnormality

A

Sarcoidosis
Pulmonary fibrosis
COPD

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10
Q

Example of hypoventilation

A
Kyphoscoliosis
Thoracoplasty for TB
COPD
Motor Neurone Disease
Muscular Dystrophy
Morbid obesity
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11
Q

Example of right to left shunt

A

Eisenmenger syndrome

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12
Q

Types of Resp Failure

A

Acute and chronic for type 1 and 2

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13
Q

LTOT

A
  • improves survival for COPD with hypoxia
  • reduces hypoxia complications = polycythaemia, cor pulmonale
  • at least 15 hours per day
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14
Q

Define COPD with hypoxia

A

PaO2<7.3kPa

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15
Q

Chronic Type 1 Resp Failure Consequences

A
  • Pulmonary hypertension
  • Cor pulmonale = peripheral oedema
  • 2ndry polycythaemia = stroke
  • symptoms from ischaemic heart/peripheral vascular diseases
  • poor sleep/fatigue
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16
Q

CPAP

A

= continuous positive airway pressure

  • pushes pressure into airways mainly during exp
  • expands collapsed portions of lungs which are under ventilated
  • improves hypoxia and V/Q mismatch
  • keeps airways open in sleep apnoea
  • doesn’t overcome hypoventilation
17
Q

Cause of type 2 resp failure

A

ventilation failure

18
Q

Treatment of acute type 2 resp failure

A
  • oxygen therapy
  • 0.5 to 2l/min via nasal cannulae
  • 24%-28% masks using venture valves
  • keep sats 88-92%
  • monitor Co2 levels via ABG regularly
  • consider nn invasive ventilation if Ph and Co2 not improving
19
Q

Causes of hypoventilation

A
  • airways obstruction = COPD< severe asthma
  • hyper expanded lungs = COPD
  • thoracic cage problems = kypho, thoacoplasty, obesity
  • weakness of resp muscles = MND, musc dystrophy
20
Q

Non invasive ventilation

A
  • improves hypoventilation
  • delivers high pressure during insp
  • improves oxygenation
  • reduces/prevents hypercapnia
  • useful in conditions causing hypoventilation and Type 2 resp failure
21
Q

When to use Non invasive ventilation

A
  • acute type 2 in hospital (COPD exacerbations)

- chronic type 2 at home

22
Q

Define obstructive sleep apnoea?

A
  • repetitive episodes of partial or complete upper airway obstruction during sleep
23
Q

Where is the problem anatomically in sleep apnoea?

A
  • between soft palate and tongue base
24
Q

How to diagnose sleep apnoea?

A
  • home sleep study
25
Q

Define apnoea?

A

complete cessation of airflow for at least 10 seconds

26
Q

Define hypopnoea?

A

Reduction in airflow to under 50% or by 30% for at least 10 seconds
- with desaturation of at least 4%

27
Q

Apnoea and Hypopnoea Index

A

number of apnoeas and hypopnoeas per hour of study

28
Q

How to measure severity of sleep apnoe

A

Apnoea and hypopnoea index

29
Q

RDI

A
Respiratory Disturbance Index
0-5 = normal
5-15 mild OS
15-30 = moderate
30+ severe
30
Q

OSA Who?

A
  • 1 in 5 adults
  • 24% mild and 9% women
  • increases with age until 65
  • most undiagnosed
31
Q

RF of OSA

A
  • obesity! = narrowed airway
  • BMI>30
  • neck circumference >16.5 inches
  • male = longer pharyngeal airway
  • Afro-Caribbean
  • micrognathia
  • tonsillar hypertrophy
32
Q

Associated conditions with OSA

A
  • micrognathia or retrognathia
  • large adenoids and tonsils
  • acromegaly
  • Downs
  • Hypothyroid
  • cushings
  • T2D
  • HTN
33
Q

Sleep History

A
  • bed partner/family
  • heavy snoring
  • witnessed apnoeas = prod to start breathing
  • arousals = wake up suddenly with snort
  • unrefreshed on waking
  • daytime tiredness
  • planned and unplanned naps
  • other CV RF
34
Q

OSA Diagnosis on history how?

A

Epworth Sleepiness Scale
out of 24
>10 abnormal

35
Q

Consequences of OSA

A
  • excessive daytime hypersomnolence
  • fall asleep at wheel
  • sustained attention required for cognitive function
  • 2-3x greater risk of car crash
  • inform DVLA of diagnosis
36
Q

Medical consequences of OSA

A

RF for

  • CV mortality
  • systemic HTN
  • T2D
  • CAD
  • Stroke
  • Congestive HF
  • Pulmonary HTN
  • cardiac arryhtmias
37
Q

Treatment for OSA

A
  • CPAP
  • weight loss
  • avoiding alcohol and sedatives
  • non supine sleep
  • tonsillectomy
  • mandibular advancement splints
  • palatal surgery
  • maxillofacial surgery
  • treat cause
38
Q

Indication for mandibular splints

A
  • for simple snorers or mild/mod OSA

- intolerance of CPAP

39
Q

Indication for CPAP for OSA

A
  • moderate or severe sleep apnoea