Respiratory Failure

Question 1

What is a respiratory infection?

Answer 1

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

Question 2

Where does a respiratory infection affect?

Answer 2

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

Respiratory muscle
Diaphragm & thoracic muscles
Extra-thoracic muscles

Pulmonary
Airway disease
Alveolar-capillary
Circulation

Question 3

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

Answer 3

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

Question 4

How does ventilation across the lung work?

Answer 4

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

Question 5

How does perfusion across the lung work?

Answer 5

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

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

Question 6

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

Describe the pulmonary transit time?

Ventilation perfusion matchin?

Question 7

Describe the structural properties of lung tissue*

Answer 7

COMPLIANCE
The tendency to distort under pressure
𝑪𝒐𝒎𝒑𝒍𝒊𝒂𝒏𝒄𝒆= ∆𝑽/∆𝑷

ELASTANCE
The tendency to recoil to its original volume
𝑬𝒍𝒂𝒔𝒕𝒂𝒏𝒄𝒆= ∆𝑷/∆𝑽

Question 8

What is an acute respiratory disorder

Answer 8

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

Question 9

What is a chronic respiratory disorder

Answer 9

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

Question 10

What is an acute on chronic respiratory disorder

Answer 10

Infective exacerbation
COPD, CF
Myasthenic crises
Post operative

Question 11

Lung volumes and capacities?*

Question 12

How to work out minute ventilation?

Answer 12

Gas entering and leaving the lungs

Tidal volume x Breathing frequency

Question 13

How to work out alveolar ventilation?

Answer 13

(Tidal volume - Dead space) x Breathing Frequency

Question 14

What is the physiologic classification in terms of type I?

Answer 14

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

Question 15

What is the physiologic classification in terms of type II?

Answer 15

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

Question 16

What is the physiologic classification in terms of type III?

Answer 16

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

Question 17

What is the physiologic classification in terms of type IV?

Answer 17

-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)

Question 18

What are the chronic risk factors?

Answer 18

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

Question 19

What are the acute risk factors?

Answer 19

Infection
Viral
Bacterial
Aspiration
Trauma
Pancreatitis
Transfusion

Question 20

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

Answer 20

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

Question 21

What are the pulmonary causes of ARDS?

Answer 21

Aspiration
Trauma
Burns: Inhalation
Surgery
Drug Toxicity
Infection

Question 22

What are the extra pulmonary causes of ARDS?

Answer 22

Trauma
Pancreatitis
Burns
Transfusion
Surgery
BM transplant
Drug Toxicity
Infection

Question 23

What id driving the response in acute lung injury?

Answer 23

The lung
Leucocytes
Inflammation
Infection
Immune response

Question 24

What is the in vivo evidence for respiratory failure?

Answer 24

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

Question 25

What therapies tried pharmacological interventions?

Answer 25

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

Question 26

What pharmacological interventions being trialled?

Answer 26

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

Question 27

What inflammatory endotypes are there in pro-inflammatory ARDS?

Answer 27

Hyper and Hypo

Question 28

What are 3 therapeutic interventions for respiratory disorders?

Answer 28

Treat underlying disease Respiratory support Multiple organ support

Question 29

Describe how an underlying disease can be treated

Answer 29

Inhaled therapies Bronchodilators Pulmonary vasodilators Steroids Antibiotics Anti-virals Drugs Pyridostigmine Plasma exchange IViG Rituximab

Question 30

Describe how respiratory support can be given

Answer 30

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

Question 31

Describe how multiple organ support can be given

Answer 31

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

Question 32

What is the sequelae of ARDS

Answer 32

Poor gas exchange Inadequate oxygenation Poor perfusion Hypercapnoea Infection Sepsis Inflammation Inflammatory response Systemic effects

Question 33

What are specific interventions for ARDS?

Answer 33

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

Question 34

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

Question 35

What are the pitfalls of ventilation?

Answer 35

Minute ventilation PaCO2 control Alveolar recruitment Positive end exspiratory pressure (PEEP) V/Q mismatch Ventilation without gas exchange vice-versa

Question 36

What is the murray score?

Answer 36

Guides the escalation for therapy 0=normal 1-2.5 = Mild 2.5 = Severe 3 = ECMO

Question 37

What is the national ARDS approach?

Answer 37

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

Question 38

What is the inclusion criteria in terms of treatment?

Answer 38

* 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).

Question 39

What is the exclusion criteria in terms of treatment?

Answer 39

* Contraindication to continuation of active treatment; * Significant co-morbidity  dependency to ECMO support * Significant life limiting co-morbidity

Question 40

What is an ECMO?

Answer 40

First major trial EOLIA Stopped early for futility Statistically no significant difference…. RBH survival 79% Best study mortality 24 to 31% ? Case selection important

Question 41

What are the issues for an ECMO? What are technicalities?

Answer 41

Time to access Referral system- Geographical inequity Consideration of referral Obtaining access: Internal jugular Subclavian Femoral Circuit Haemodynamics Clotting/Bleeding