Respiratory Failure Flashcards

1
Q

What is a respiratory infection?

A

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

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2
Q

Where does a respiratory infection affect?

A

Nervous system
CNS/Brainstem
Peripheral nervous system
Neuro-muscular junction

Respiratory muscle
Diaphragm & thoracic muscles
Extra-thoracic muscles

Pulmonary
Airway disease
Alveolar-capillary
Circulation

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3
Q

In men and women, what is the biggest risk factor for chronic respiratory disease?

A

Males: Smoking biggest risk factor
Women: Household air pollution from solid fuels

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4
Q

How does ventilation across the lung work?

A

PPL is more negative (-8 cmH2O)
Greater transmural pressure gradient (0 vs. -8)
Alveoli larger and less compliant
Less ventilation

PPL is less negative (-2 cmH2O)
Smaller transmural pressure gradient (0 vs. -2)
Alveoli smaller and more compliant
More ventilation

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5
Q

How does perfusion across the lung work?

A

Lower intravascular pressure (gravity effect)Less recruitment
Greater resistance
Lower flow rate

Higher intravascular pressure
(gravity effect)
More recruitment
Less resistance
Higher flow rate

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6
Q

Describe oxygen transport when loading in the lungs?***

Describe the pulmonary transit time?

Ventilation perfusion matchin?

A
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7
Q

Describe the structural properties of lung tissue*

A

COMPLIANCE
The tendency to distort under pressure
π‘ͺπ’π’Žπ’‘π’π’Šπ’‚π’π’„π’†= βˆ†π‘½/βˆ†π‘·

ELASTANCE
The tendency to recoil to its original volume
𝑬𝒍𝒂𝒔𝒕𝒂𝒏𝒄𝒆= βˆ†π‘·/βˆ†π‘½

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8
Q

What is an acute respiratory disorder

A

Pulmonary: Infection, aspiration, Primary graft dysfunction (Lung Tx)
Extra-pulmonary: Trauma, pancreatitis, sepsis,
Neuro-muscular: Myasthenia/GBS

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9
Q

What is a chronic respiratory disorder

A

Pulmonary/Airways: COPD, Lung fibrosis, CF, lobectomy
Musculoskeletal: Muscular dystrophy

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10
Q

What is an acute on chronic respiratory disorder

A

Infective exacerbation
COPD, CF
Myasthenic crises
Post operative

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11
Q

Lung volumes and capacities?*

A
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12
Q

How to work out minute ventilation?

A

Gas entering and leaving the lungs

Tidal volume x Breathing frequency

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13
Q

How to work out alveolar ventilation?

A

(Tidal volume - Dead space) x Breathing Frequency

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14
Q

What is the physiologic classification in terms of type I?

A

Type I or Hypoxemic (PaO2 <60 at sea level):
Failure of oxygen exchange
-Increased shunt fraction (Q S /QT )
-Due to alveolar flooding
-Hypoxemia refractory to supplemental oxygen

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15
Q

What is the physiologic classification in terms of type II?

A

Type II or Hypercapnic (PaCO2 >45): Failure to
exchange or remove carbon dioxide
-Decreased alveolar minute ventilation (V A )
-Dead space ventilation

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16
Q

What is the physiologic classification in terms of type III?

A

Type III Respiratory Failure: Perioperative respiratory
Failure
-Increased atelectasis due to low functional residual capacity
(FRC) with abnormal abdominal wall mechanics
-Hypoxaemia or hypercapnoea
-Prevention: anesthetic or operative technique, posture,
incentive spirometry, analgesia, attempts to lower intra- abdominal pressure

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17
Q

What is the physiologic classification in terms of type IV?

A

-Type IV describes patients who are intubated and ventilated
During shock (Septic/cardiogenic/neurologic)
-Optimise ventilation improve gas exchange and to unload the
respiratory muscles, lowering their oxygen consumption
Ventilatory effects on right and left heart
Reduced afterload (good for LV) Increased pre-load (bad for RV)

18
Q

What are the chronic risk factors?

A

COPD
Pollution
Recurrent pneumonia
Cystic fibrosis
Pulmonary fibrosis
Neuro-muscular diseases

19
Q

What are the acute risk factors?

A

Infection
Viral
Bacterial
Aspiration
Trauma
Pancreatitis
Transfusion

20
Q

In acute respiratory failure, what can the origin of shortness of breath be?

A

Lower respiratory tract infection
Viral
Bacterial
Aspiration
Trauma
Transfusion
Pulmonary vascular disease
Pulmonary embolus
Hemoptysis
Extrapulmonary pancreatitis, new medications

21
Q

What are the pulmonary causes of ARDS?

A

Aspiration
Trauma
Burns: Inhalation
Surgery
Drug Toxicity
Infection

22
Q

What are the extra pulmonary causes of ARDS?

A

Trauma
Pancreatitis
Burns
Transfusion
Surgery
BM transplant
Drug Toxicity
Infection

23
Q

What id driving the response in acute lung injury?

A

The lung
Leucocytes
Inflammation
Infection
Immune response

24
Q

What is the in vivo evidence for respiratory failure?

A

TNF signalling implicated in vivo and in vitro
Reduced injury in TNFR-1 animal KO

Leucocyte activation and migration
Macrophage activation: alveolar
Neutrophil lung migration

DAMP release: HMGB-1 and RAGE

Cytokine release IL-6,8,IL-1B, IFN-y

Cell death
Necrosis in lung biopsies
Apoptotic mediators: FAS, FAS-l, BCl-2

25
Q

What therapies tried pharmacological interventions?

A

Steroids
Salbutamol
Surfactant
N-Acetylcysteine
Neutrophil esterase inhibtitor
GM-CSF
Statins

26
Q

What pharmacological interventions being trialled?

A

Mesenchymal stem cells
Ex-vivo benefit
Keratinocyte growth factor
Repair factor
Microvesicles
High dose Vitamin C, thiamine, steroids…
ECCO2R

27
Q

What inflammatory endotypes are there in pro-inflammatory ARDS?

A

Hyper and Hypo

28
Q

What are 3 therapeutic interventions for respiratory disorders?

A

Treat underlying disease
Respiratory support
Multiple organ support

29
Q

Describe how an underlying disease can be treated

A

Inhaled therapies
Bronchodilators
Pulmonary vasodilators
Steroids
Antibiotics
Anti-virals

Drugs
Pyridostigmine
Plasma exchange
IViG
Rituximab

30
Q

Describe how respiratory support can be given

A

Physiotherapy
Oxygen
Nebulisers
High flow oxygen
Non invasive ventilation
Mechanical ventilation
Extra-corporeal support

31
Q

Describe how multiple organ support can be given

A

Cardiovascular support
Fluids
Vasopressors
Inotropes
Pulmonary vasodilators
Renal support
Haemofiltration
Haemodialysis
Immune therapies
Plasma exchange
Convalescent plasma

32
Q

What is the sequelae of ARDS

A

Poor gas exchange
Inadequate oxygenation
Poor perfusion
Hypercapnoea

Infection
Sepsis

Inflammation
Inflammatory response

Systemic effects

33
Q

What are specific interventions for ARDS?

A

Respiratory support
Intubation and ventilation
ARDS necessitates mechanical intervention
Types of ventilation
Volume controlled
Pressure controlled
Assisted breathing modes
Advanced ventilatory modes
Procedures to support ventilation

34
Q

Explain the parts of the pressure-volume loop?***

A
35
Q

What are the pitfalls of ventilation?

A

Minute ventilation
PaCO2 control

Alveolar recruitment
Positive end exspiratory pressure (PEEP)

V/Q mismatch
Ventilation without gas exchange vice-versa

36
Q

What is the murray score?

A

Guides the escalation for therapy

0=normal
1-2.5 = Mild
2.5 = Severe
3 = ECMO

37
Q

What is the national ARDS approach?

A

5 national centres
Telephone or online referral
Murray score > 3
pH < 7.2
Consultant case review
Transfer of imaging
Advice
Retrieval
Transfer
Ongoing management

38
Q

What is the inclusion criteria in terms of treatment?

A
  • severe respiratory failure
    non-cardiac cause (i.e. Murray Lung Injury score 3.0 or above)
  • Positive pressure ventilation is not appropriate (e.g. significant tracheal injury).
39
Q

What is the exclusion criteria in terms of treatment?

A
  • Contraindication to continuation of active treatment;
  • Significant co-morbidity οƒ  dependency to ECMO support
  • Significant life limiting co-morbidity
40
Q

What is an ECMO?

A

First major trial EOLIA
Stopped early for futility
Statistically no significant difference….

RBH survival 79%
Best study mortality 24 to 31%

? Case selection important

41
Q

What are the issues for an ECMO?

What are technicalities?

A

Time to access
Referral system- Geographical inequity
Consideration of referral

Obtaining access:
Internal jugular
Subclavian
Femoral
Circuit
Haemodynamics
Clotting/Bleeding