Respiratory Failure Flashcards

(77 cards)

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
When is ventilation used?
Type IV respiratory shock
26
What are the pulmonary causes of ARDS?
- aspiration - trauma - burns (inhalation) - surgery - drug toxicity - infection
27
What are the extra-pulmonary causes of ARDS?
- trauma - pancreatitis - burns - transfusion - surgery - BM transplant - drug toxicity
28
what do the pulmonary causes of ARDS tend to effect?
- the alveoli
29
what do the extra-pulmonary causes of ARDS tend to effect?
- systemic | - cytokine release
30
What cytokines signal the inflammation pathway in the alveoli?
TNF-a and IL-8
31
What is a possible result of inflammation of the alveoli?
- fluid build up (protein rich oedema) - degradation of surfactant - leukocyte migration
32
What mechanisms cause a persistant, chronic pleural insufficiency?
- infection - inflammatory response - immune response
33
What is the significance of TNF signalling?
causes lung injury | inhibition leads to lung injury prevention
34
What is involved in leukocyte activation and migration?
- macrophage activation (in the alveoli) | - neutrophil lung migration
35
What are the 2 DAMPs involved in lung injury?
HMGB-1 | RAGE
36
What cytokines are released during lung injury?
- IL-6 - IL-8 - IL-1B - IFN-y
37
What is the role of cell death is associated with ARDS?
- necrosis in lung biopsies
38
What mediators are associated with apoptosis?
- FAS - FAS-I - BCI-2
39
What forms of pharmacological interventions have been tried for ARDS?
- steroids - salbutamol - surfactant (children) - N-Acetylcysteine - Nuetrophil esterase inhibitor - GM-CSF - Statins
40
What forms of pharmacological interventions are being trialled for ARDS?
- Mesenchymal stem cells - keratinocyte growth factor - microvesicles - high dose vitamin C, thiamine and steroids - ECCO2R
41
Why is there limited evidence for treatment for ARDS?
because the disease is so heterogenous
42
What is the key to treating ARDS?
that identification of the driving biological mechanism is key
43
What are the three key aspects when managing ARDS?
- treat the underlying disease - respiratory support - multiple organ support
44
What options are available to treat the underlying cause?
- inhaled therapies - steroids - antibiotics - anti-virals (got cold/during flu season) - drugs
45
What inhaled therapies can be used to treat the underlying cause in respiratory failure?
- bronchodilators | - pulmonary vasodilators
46
What drugs can be used to treat the underlying cause in respiratory failure?
- pyridostigmine (muscular failure) - plasma exchange - IVIG - Rituximab
47
What forms of respiratory support is available for those with ARDS?
- physiotherapy - oxygen - nebulisers (salbutamol, saline) - high flow oxygen - non-invasive ventilation - mechanical ventilation - extra-corporeal support (ECMO)
48
What forms of cardiovascular support is available for those with ARDS?
- fluids - vasopressers - inotropes - pulmonary vasodilators (NO)
49
What forms of renal support is available for those with ARDS?
- haemofiltration | - haemodialysis
50
What forms of immune support is available for those with ARDS?
- plasma exchange | - convalescence
51
What are the consequences of ARDS?
- poor gas exchange - inadequate oxygenation/poor perfusion - hypercapnoea - sepsis (sick with underlying infection) - inflammation
52
What are the types of ventilation?
- volume-controlled - pressure-controlled (most common) - assisted breathing modes - advanced ventilatory modes
53
What respiratory support is necessary with ARDS?
mechanical intervention (ventilation)
54
What is compliance?
the amount that the lung 'opens' in comparison to the amount of pressure used
55
What are is the change in compliance with ARDS?
- 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
What is the significance of the the upper inflection point with ARDS?
above that pressure, additional alveolar recruitment requires disproportionate increases in applied airway pressure
57
What is the significance of the the lower inflection point with ARDS?
the minimum baseline pressure (PEEP) needed for optimal alveolar recruitment
58
What are the negatives of ventilation?
- 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
What happens in a lung recruitment CT?
- high pressure ventilator - low driving pressure - aim: open up the lung
60
What does it mean when consolidation reduces during a lung recruitment CT?
there are recruitable alveoli present
61
What is the risk of over distending the lung in a lung recruitment CT?
- traps more gas - reduces perfusion - limit right ventricular function - damage via trauma
62
What are the guidelines used when trying to escalate treatment?
Murray score - PaO2 - CXR - PEEP - Compliance
63
What are the classifications of the Murray score?
``` 0 = normal 1-2.5 = mild >2.5 = severe >3 = ECMO ```
64
Where can ECMO occur?
5 national centres
65
What can be done to reduce the Murray score?
- proning | -
66
What is the national ARDS approach?
- telephone/online referral - consultant case review - imaging transfer - advice - retrieval - transfer - ongoing management
67
What is the inclusion criteria for ECMO?
- severe respiratory failure - non-cardiac score (Murray score >/=3) - positive pressure ventilation is not appropriate
68
When may positive pressure ventilation not be appropriate?
eg: significant tracheal injury
69
What is the exclusion criteria for ECMO?
- contraindication to continuing treatment - significant co-morbidity (dependency to ECMO support) - significant life limiting co-morbidity
70
What is the general requirement for ECMO?
- reversible disease process | - unlikely to lead to prolonged disability
71
What happens in ECMO?
- 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
What are the issues with ECMO?
- 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
Which criteria is used to classify ARDS?
- timing - chest imaging - oedema origin - PF ratio
74
What are the common causes to acute respiratory failure?
- LRT infection - aspiration - trauma - pancreatitis - pulmonary vascular disease - TRALI - PE
75
What are the 3 mechanisms of acute lung injury?
- inflammation - infection - immune response
76
What 2 imaging options are available for diagnosis and treatment of ARDS?
- recruitment lung CT | - lung USS
77
What are the advantages of using ECMO?
- 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