Respiratory failure Flashcards
What is respiratory failure?
Syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system
Which aspects of the nervous system is affected by respiratory failure?
CNS/Brainstem
Peripheral nervous system
Neuromuscular junctions (Myasthenia gravis)
Which respiratory muscles are affected by respiratory failure?
Diaphragm and thoracic muscles
Extra-thoracic muscles.
Which aspects of the pulmonary system are affected by respiratory failure?
Airway disease
Alveolar-capillary disease - a vascular disease or damage to the area due to fibrosis
Circulation (pulmonary hypertension can impair vascular supply)
Which parts of the world are predominantly affected by respiratory diseases?
North America and Europe
What is the largest risk factor for chronic respiratory failure in males?
Smoking
What is the largest risk factor for chronic respiratory failure in females?
Household air pollution from solid fuels.
Which two factors increase the mortality of acute respiratory distress syndrome?
Severity and advance age
What factors are considered in the definition and classification of acute respiratory distress syndrome?
Timing- Within 1 week of a known clinical insult or new or worsening respiratory syndrome.
Chest imaging - Bilateral opacities, not fully explained by effusions, lobar/Lung collapse or nodules.
Origin of oedema: Respiratory failure not fully explained by cardiac failure or fluid overload.
Oxygenation:
How does chest imaging reveal an individual with acute respiratory distress syndrome?
Bilateral opacities
What factors are classified as causes of acute respiratory failure?
Pulmonary: Infection, aspiration, primary graft dysfunction (Lung Tx)
Extra-pulmonary: Trauma, pancreatitis, sepsis.
Neuromuscular: Myasthenia/GBS
What factors are classified as causes of chronic respiratory failure?
Pulmonary/airways: COPD, lung fibrosis, CF, lobectomy.
Musculoskeletal: Muscular dystrophy
What factors are classified as causes of acute on chronic respiratory failure?
Infective exacerbation
COPD, CF
Myasthenia crises
Post-operative
What is type 1 respiratory failure?
Hypoxemic (PaO2 <60 at sea level)
-There is a failure of oxygen exchange.
Increased shunt faction (QS/QT)
Due to alveolar flooding
Hypoxemia refractory to supplemental oxygen
What type of respiratory failure is associated with a failure of oxygen exchange?
Type I
What are the six possible causes of hypoxemic respiratory failure?
Collapse Aspiration Pulmonary oedema Fibrosis Pulmonary Embolism Pulmonary hypertension
What type of respiratory failure is associated with a decreased alveolar minute ventilation?
Type II (Hypercapnic)
What is hypercapnic respiratory failure?
Type II respiratory failure, failure to exchange or remove carbon dioxide
What are the five psosible causes of hypercapnic respiratory failure?
Nervous system Muscle failure Airway obstruction Chest wall deformity Neuromuscular
What is type III respiratory failure associated with?
Perioperative respiratory failure, there is an increased atelectasis due to low functional residual capacity with abnormal abdominal wall mechanics.
Hypoxemia or hypercapnoea
How can type III respirator failure be prevented?
Anaesthetic, operative technique, posture, incentive spirometry, analgesia, attempts to lower intra-abdominal pressure
What is type IV respiratory failure associated with?
Type IV describes patients who are intubated and ventilated during shock (septic, cardiogenic, neurologic)
What treatment is available for type IV respiratory failure?
Optimise ventilation improve gas exchange and to unload the respiratory muscles, lowering their oxygen consumption.
Ventilatory effects on right and left heart (Reduced afterload on left ventricle) due to positive pressure.
What are the chronic risk factors for respiratory failure?
COPD Pollution Recurrent pneumonia Cystic fibrosis Pulmonary fibrosis Neuro-muscular diseases
What are the acute risk factors for respiratory failure?
Infection, viral, bacterial Aspiration - conscious level drops Trauma - induces inflammatory responses Pancreatitis Transfusion
What are the main causes of acute respiratory failure?
1) Lower respiratory tract infection (viral or bacterial)
2) Aspiration
3) Trauma - transfusion
4) Pulmonary vascular disease (embolus, haemopysis)
6) Extrapulmonary - pancreatitis, new medications
What are the pulmonary causes of ARDS?
Aspiration Trauma Burns: Inhalation Surgery Drug toxicity Infection
What are the extra-pulmonary causes of ARDS?
Trauma Pancreatitis Burns Transfusion Surgery BM transplant Drug toxicity Infection
What are the five driving causes of acute lung injury?
Inflammation
Infection
Immune response
Which immune cells are resident within the alveoli?
Resident macrophages
Which cytokines are released by activated resident macrophages?
IL-6
TNF-alpha
IL-8
What is the pathophysiology of acute lung injury?
Injury can damage the alveolar interstitium, therefore this causes the activation of resident alveolar macrophages, releasing IL-6, TNF-alpha and IL-8.
Cytokine release induces alveolar fluid accumulation (a protein rich oedema forms within the lung), reducing the effectiveness in expansion.
Migration of leukocytes (neutrophils) into the interstitium before entering the site of response - secretes proteases and inflammatory mediators.
-Increases the distance between the alveoli and capillaries making gas exchange less efficient.
Which immune cells respond to acute lung injury?
Neutrophils
How does gas exchange become less efficient in individuals with acute lung injury?
Recruited neutrophils release proteases, widening the edematous interstitium between the capillary and alveoli.
Which type of signalling is implicated in acute lung injury?
TNF
Which DAMPs are released in acute lung injury?
HMGB-1 and RAGE into systemic vasculature
Which cytokines are released during acute lung injury?
IL-6, IL-8, IL-1B and IFN-y
Which apoptotic mediators are associated with acute lung injury?
FAS
FAS-I
BCL-2
Which pharmacological interventions are available for the treatment of respiratory failure?
Steroids Salbutamol Surfactant N-acetylcysteine - reduces viscosity of secretions Neutrophil esterase inhibitor GM-CSF Statins
Which therapies for respiratory failure are being trialled?
Mesenchymal stem cells Keratinocyte growth factor Microvesicles High dose Vitamin c, thiamine, steroids ECCO2R - removal of carbon dioxide
Which mediators are elevated in hyperinflammatory endotype of ARDs?
TNFR-1
IL-8
IL-6
In hyperinflamed endotype of ARDs, which DAMPs are elevated?
Epithelial predominant RAGE, ANG-2 and VEGF-D
Indicating significant induction of inflammation
Which necro-inflammatory mediator is expressed in the airway and elevated in ARDS?
IL-18
What purpose is performed by IL-18?
IL-18 initiates pro-inflammatory NF-kB signalling, and is pivotal for T-cell differentiation and IFN-Y production.
Induces airway hyperresponsiveness and macrophage activation
What role is performed by VEGF-D?
Relates to angiogenesis and cell-sprouting
How is the underlying disease treated in terms of respiratory failure?
Inhaled therapies: Bronchodilators and pulmonary vasodilators.
Steroids
Antibiotics
Anti-virals
Drugs: Pyidostigmine, plasma exchange, IViG, ritxuimab
Which drugs are used to treat the underlying disease of respiratory failure?
Pyridostigmine
Plasma exchange
IViG
Rituximab
Which inhaled therapies are available for treating the underlying disease of respiratory failure?
Bronchodilators
Pulmonary vasodilators
What respiratory support is available for respiratory failure?
Physiotherapy Oxygen Nebulisers High-flow oxygen Non-invasive ventilation Mechanical Ventilation Extra-corporeal support
What function do nebulisers have in the support of respiratory failure?
Reduced mucous load
What cardiovascular support is available during respiratory failure?
Fluids
Vasopressors
Inotropes
Pulmonary vasodilators
Which immune therapies are available for respiratory failure?
Plasma exchange
Convalescent plasma
What are the consequences of ARDS?
Poor gas exchange - inadequate oxygenation, poor perfusion, hypercapnoea
Infection - sepsis
Inflammation - inflammatory response
Systemic effects
What specific intervention is made available for ARDS?
Intubation and ventilation
What types of ventilation is available for the treatment of ARDS?
Volume controlled
Pressure controlled
Assisted breathing modes
Advanced ventilatory modes
What impact does ARDS have on lung compliance?
Is markedly reduced in the injured lung
What is the upper infection point?
Above this pressure, additional alveolar recruitment requires disproportionate increases in applied airway pressure
What is the lower infection point (LIP)?
Can be thought of as a minimum baseline pressure (PEEP) needed for optimal alveolar recruitment
What imaging is involved in ARDS?
CT Lung USS (evaluate how expanded a lung is)
What type of scoring is used to evaluate the choice of therapy?
Murray Score
What parameters are used in the Murray score?
PaO2
CXR
PEEP
Compliance
What Murray score is classed as an escalation to an ECMO?
3
Who should be treated with an ECMO?
Severe respiratory failure - non cardiac cause
Positive pressure ventilation is not appropriate
Who is excluded from an ECMO?
Contraindication to continuation of active treatment;
• Significant co-morbidity dependency to ECMO support
• Significant life limiting co-morbidity
Where is an ECMO cannula typically inserted?
inserted via the femoral vein –> leads to the inferior vena cava below the right atrium
What is the purpose performed by an ECMO?
The ECMO machine pumps blood from the patient’s body to an artificial lung (oxygenator) that adds oxygen to it and removes carbon dioxide. The ECMO machine then sends the blood back to the patient via a pump with the same force as the heart, replacing its function.
