Respiratory Failure Flashcards

1
Q

What is respiratory failure?

A

syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system

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2
Q

What failing parts of the body can cause respiratory failure?

A
  • CNS/brainstem
  • PNS
  • NMJ
  • diaphragm and thoracic muscles
  • extra-thoracic muscles
  • airways
  • alveolar-capillary disease
  • circulation
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3
Q

What is the biggest risk factor of chronic respiratory failure for men?

A

smoking

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4
Q

What is the biggest risk factor of chronic respiratory failure for women?

A

household air pollution from solid fuels

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5
Q

What is the prevalence of acute respiratory failure?

A

6-700 people/year

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6
Q

What factors can increase the mortality of acute respiratory failure?

A
  • severity

- age

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7
Q

What possible diseases are classed as acute respiratory failure?

A
  • infection
  • aspiration
  • primary graft dysfunction
  • trauma
  • pancreatitis
  • sepsis
  • myasthenia/GBS
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8
Q

What possible diseases are classed as chronic respiratory failure?

A
  • COPD
  • Lung fibrosis
  • CF
  • lobectomy
  • muscular dystrophy
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9
Q

What are examples of acute on chronic respiratory failure?

A
  • Infective exacerbation (COPD, CF)
  • Myasthenic crises
  • Post-operative complications
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10
Q

What happens in type 1 (hypoxemic) respiratory failure?

A
PaO2 < 60
failure of oxygen exchange
- increased shunt fraction (QS/QT)
- alveolar flooding
- refractory to supplemental oxygen
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11
Q

What can cause type 1 respiratory failure?

A
  • collapse
  • aspiration
  • pulmonary oedema
  • fibrosis
  • pulmonary embolism
  • pulmonary hypertension
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12
Q

What happens in type 2 (hypercapnic) respiratory failure?

A

PaCO2 > 45
failure to exchange or remove carbon dioxide
- decreased alveolar minute ventilation
- dead space ventilation

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13
Q

What can cause type 2 respiratory failure?

A
  • CNS/PNS
  • muscle failure
  • airway obstruction
  • chest wall deformities
  • reduced minute ventilation
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14
Q

What happens in type 3 (perioperative) respiratory failure?

A
  • increased atelectasis (airway collapse) due to low functional residual capacity
  • abnormal abdominal wall mechanics (limiting chest movement)
  • hypoxaemia OR hypercapnia
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15
Q

How do you prevent type 3 respiratory failure?

A
  • anethetic or operative technique
  • posture
  • incentive spirometry
  • analgesia
  • efforts to lower intra-abdominal pressure
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16
Q

What happens in type 4 (shock) respiratory failure?

A
  • poor lung perfusion

patients that are intubated and ventilated during shock (septic, cardiogenic, nuerologic)

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17
Q

How do you prevent type 4 respiratory failure?

A

optimise ventilation to improve gas exchange and to unload the respiratory muscles, lowering oxygen consumption

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18
Q

What are the effects of ventilation on the heart?

A
reduced afterload (good for the LV)
increased preload (bad for the RV)
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19
Q

What are the risk factors for chronic respiratory failure?

A
  • COPD
  • pollution
  • recurrent pneumonia
  • CF
  • pulmonary fibrosis
  • neuromuscular diseases
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20
Q

What are the risk factors for acute respiratory failure?

A
  • infection (viral and bacterial)
  • aspiration
  • trauma
  • pancreatitis
  • transfusion
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21
Q

What are the 5 main origins of shortness of breath?

A
  • lower respiratory tract infections
  • aspiration
  • trauma
  • pulmonary vascular disease
  • extrapulmonary: pancreatitis; new medications
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22
Q

What form of lower respiratory tract infection can cause shortness of breath?

A
  • viral

- bacterial

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23
Q

What form of trauma can cause shortness of breath?

A

transfusion

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24
Q

What form of pulmonary vascular disease can cause shortness of breath?

A
  • pulmonary embolus

- haemoptysis

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25
Q

When is ventilation used?

A

Type IV respiratory shock

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26
Q

What are the pulmonary causes of ARDS?

A
  • aspiration
  • trauma
  • burns (inhalation)
  • surgery
  • drug toxicity
  • infection
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27
Q

What are the extra-pulmonary causes of ARDS?

A
  • trauma
  • pancreatitis
  • burns
  • transfusion
  • surgery
  • BM transplant
  • drug toxicity
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28
Q

what do the pulmonary causes of ARDS tend to effect?

A
  • the alveoli
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29
Q

what do the extra-pulmonary causes of ARDS tend to effect?

A
  • systemic

- cytokine release

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30
Q

What cytokines signal the inflammation pathway in the alveoli?

A

TNF-a and IL-8

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31
Q

What is a possible result of inflammation of the alveoli?

A
  • fluid build up (protein rich oedema)
  • degradation of surfactant
  • leukocyte migration
32
Q

What mechanisms cause a persistant, chronic pleural insufficiency?

A
  • infection
  • inflammatory response
  • immune response
33
Q

What is the significance of TNF signalling?

A

causes lung injury

inhibition leads to lung injury prevention

34
Q

What is involved in leukocyte activation and migration?

A
  • macrophage activation (in the alveoli)

- neutrophil lung migration

35
Q

What are the 2 DAMPs involved in lung injury?

A

HMGB-1

RAGE

36
Q

What cytokines are released during lung injury?

A
  • IL-6
  • IL-8
  • IL-1B
  • IFN-y
37
Q

What is the role of cell death is associated with ARDS?

A
  • necrosis in lung biopsies
38
Q

What mediators are associated with apoptosis?

A
  • FAS
  • FAS-I
  • BCI-2
39
Q

What forms of pharmacological interventions have been tried for ARDS?

A
  • steroids
  • salbutamol
  • surfactant (children)
  • N-Acetylcysteine
  • Nuetrophil esterase inhibitor
  • GM-CSF
  • Statins
40
Q

What forms of pharmacological interventions are being trialled for ARDS?

A
  • Mesenchymal stem cells
  • keratinocyte growth factor
  • microvesicles
  • high dose vitamin C, thiamine and steroids
  • ECCO2R
41
Q

Why is there limited evidence for treatment for ARDS?

A

because the disease is so heterogenous

42
Q

What is the key to treating ARDS?

A

that identification of the driving biological mechanism is key

43
Q

What are the three key aspects when managing ARDS?

A
  • treat the underlying disease
  • respiratory support
  • multiple organ support
44
Q

What options are available to treat the underlying cause?

A
  • inhaled therapies
  • steroids
  • antibiotics
  • anti-virals (got cold/during flu season)
  • drugs
45
Q

What inhaled therapies can be used to treat the underlying cause in respiratory failure?

A
  • bronchodilators

- pulmonary vasodilators

46
Q

What drugs can be used to treat the underlying cause in respiratory failure?

A
  • pyridostigmine (muscular failure)
  • plasma exchange
  • IVIG
  • Rituximab
47
Q

What forms of respiratory support is available for those with ARDS?

A
  • physiotherapy
  • oxygen
  • nebulisers (salbutamol, saline)
  • high flow oxygen
  • non-invasive ventilation
  • mechanical ventilation
  • extra-corporeal support (ECMO)
48
Q

What forms of cardiovascular support is available for those with ARDS?

A
  • fluids
  • vasopressers
  • inotropes
  • pulmonary vasodilators (NO)
49
Q

What forms of renal support is available for those with ARDS?

A
  • haemofiltration

- haemodialysis

50
Q

What forms of immune support is available for those with ARDS?

A
  • plasma exchange

- convalescence

51
Q

What are the consequences of ARDS?

A
  • poor gas exchange
  • inadequate oxygenation/poor perfusion
  • hypercapnoea
  • sepsis (sick with underlying infection)
  • inflammation
52
Q

What are the types of ventilation?

A
  • volume-controlled
  • pressure-controlled (most common)
  • assisted breathing modes
  • advanced ventilatory modes
53
Q

What respiratory support is necessary with ARDS?

A

mechanical intervention (ventilation)

54
Q

What is compliance?

A

the amount that the lung ‘opens’ in comparison to the amount of pressure used

55
Q

What are is the change in compliance with ARDS?

A
  • reduced in the injured lung
  • reaches peak volume slower, and peak volume is lower than that of a normal lung
  • takes longer to accept changes in the volume and pressure
56
Q

What is the significance of the the upper inflection point with ARDS?

A

above that pressure, additional alveolar recruitment requires disproportionate increases in applied airway pressure

57
Q

What is the significance of the the lower inflection point with ARDS?

A

the minimum baseline pressure (PEEP) needed for optimal alveolar recruitment

58
Q

What are the negatives of ventilation?

A
  • PaCO2 control is difficult (Type II or high chest volume)
  • Positive end expiratory pressure due to poor emptying of the lung
  • V/Q mismatch
    ventilation w/o gas exchange
  • ventilator induced lung injury (reduced by decreasing driving pressure)
59
Q

What happens in a lung recruitment CT?

A
  • high pressure ventilator
  • low driving pressure
  • aim: open up the lung
60
Q

What does it mean when consolidation reduces during a lung recruitment CT?

A

there are recruitable alveoli present

61
Q

What is the risk of over distending the lung in a lung recruitment CT?

A
  • traps more gas
  • reduces perfusion
  • limit right ventricular function
  • damage via trauma
62
Q

What are the guidelines used when trying to escalate treatment?

A

Murray score

  • PaO2
  • CXR
  • PEEP
  • Compliance
63
Q

What are the classifications of the Murray score?

A
0 = normal
1-2.5 = mild
>2.5 = severe
>3 = ECMO
64
Q

Where can ECMO occur?

A

5 national centres

65
Q

What can be done to reduce the Murray score?

A
  • proning

-

66
Q

What is the national ARDS approach?

A
  • telephone/online referral
  • consultant case review
  • imaging transfer
  • advice
  • retrieval
  • transfer
  • ongoing management
67
Q

What is the inclusion criteria for ECMO?

A
  • severe respiratory failure
  • non-cardiac score (Murray score >/=3)
  • positive pressure ventilation is not appropriate
68
Q

When may positive pressure ventilation not be appropriate?

A

eg: significant tracheal injury

69
Q

What is the exclusion criteria for ECMO?

A
  • contraindication to continuing treatment
  • significant co-morbidity (dependency to ECMO support)
  • significant life limiting co-morbidity
70
Q

What is the general requirement for ECMO?

A
  • reversible disease process

- unlikely to lead to prolonged disability

71
Q

What happens in ECMO?

A
  • cannula from groin into the IVC below the RA
  • draw blood through a pump and artificial membrane
  • gas flow above allows for CO2 removal and supplementation of oxygen
  • re-enters via jugular vein/femoral vein into the RA
72
Q

What are the issues with ECMO?

A
  • time to access
  • referral system: geographical inequity
  • awareness of ECMO
  • obtaining access: (internal jugular, subclavian, femoral)
  • circuit
  • haemodynamics
  • clotting/bleeding (required)
  • expensive
  • infection of the cannula
  • epistaxis
  • haemolysis
  • haemoptysis
73
Q

Which criteria is used to classify ARDS?

A
  • timing
  • chest imaging
  • oedema origin
  • PF ratio
74
Q

What are the common causes to acute respiratory failure?

A
  • LRT infection
  • aspiration
  • trauma
  • pancreatitis
  • pulmonary vascular disease
  • TRALI
  • PE
75
Q

What are the 3 mechanisms of acute lung injury?

A
  • inflammation
  • infection
  • immune response
76
Q

What 2 imaging options are available for diagnosis and treatment of ARDS?

A
  • recruitment lung CT

- lung USS

77
Q

What are the advantages of using ECMO?

A
  • improve oxygen delivery
  • improve carbon dioxide removal
  • rest lung
  • prevent ventilator associated lung injury
  • resolve respiratory acidosis
  • reduce multiple organ dysfunction arising from hypoxaemia and hypercapnoea