Respiratory Failure Flashcards
Outline the epidemiology of Acute Respiratory Distress Syndrome (ARDS) (3).
- 10% to 15% of patients admitted to the intensive care unit meet the criteria for ARDS, with an increased incidence among mechanically ventilated patients
- Sex, ethnicity, and race have not been associated with the incidence of ARDS
- The mortality of ARDS is approximately 30% to 50%
What are the risk factors for Acute Respiratory Distress Syndrome (ARDS) (Chronic 6 / Acute 5)?
Chronic:
* COPD
* Pollution
* Recurrent pneumonia
* Cystic fibrosis
* Pulmonary fibrosis
* Neuro-muscular diseases
Acute:
* Infection
* Viral
* Bacterial
* Aspiration
* Trauma
* Pancreatitis
* Transfusion
Outline the pathogenesis of Acute Respiratory Distress Syndrome (ARDS).
Secondary usually to:
* Sepsis with a pulmonary origin (most common)
* Pulmonary causes:
* Aspiration
* Trauma
* Burns: Inhalation
* Surgery
* Drug Toxicity
* Infection
* Extra-pulmonary:
* Trauma
* Pancreatitis
* Burns
* Transfusion
* Surgery
* BM transplant
* Drug Toxicity
* Infection
What are the pulmonary causes of Acute Respiratory Distress Syndrome (ARDS) (6)?
- Aspiration
- Trauma
- Burns: Inhalation
- Surgery
- Drug Toxicity
- Infection
What are the extra-pulmonary causes of Acute Respiratory Distress Syndrome (ARDS) (8)?
- Trauma
- Pancreatitis
- Burns
- Transfusion
- Surgery
- BM transplant
- Drug Toxicity
- Infection
What are the 5 driving causes of acute lung injury in Acute Respiratory Distress Syndrome (ARDS)?
- The lung
- Leucocytes
- Inflammation
- Infection
- Immune response
Which immune cells are resident within the alveoli?
- Resident macrophages
Outline the pathophysiology of Acute Respiratory Distress Syndrome (ARDS) (4 steps).
- 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 cytokines are released by activated resident macrophages (3)?
- IL-6
- TNF-alpha
- IL-8
Which immune cells respond to acute lung injury in Acute Respiratory Distress Syndrome (ARDS)?
Neutrophils
How does gas exchange become less efficient in individuals with acute lung injury in Acute Respiratory Distress Syndrome (ARDS)?
- Recruited neutrophils release proteases, widening the edematous interstitium between the capillary and alveoli.
Which type of signalling is implicated in acute lung injury in Acute Respiratory Distress Syndrome (ARDS)?
TNF
Which Damage-associated molecular patterns (DAMPs) are released in acute lung injury Acute Respiratory Distress Syndrome (ARDS) (2)?
- HMGB-1
- RAGE
Which cytokines are released during acute lung injury in Acute Respiratory Distress Syndrome (ARDS) (4)?
- IL-6
- IL-8
- IL-1B
- IFN-y
Which apoptotic mediators are associated with acute lung injury in Acute Respiratory Distress Syndrome (ARDS) (3)?
- FAS
- FAS-I
- BCL-2
Which mediators are elevated in hyperinflammatory endotype of Acute Respiratory Distress Syndrome (ARDS) (3)?
- TNFR-1
- IL-8
- IL-6
In hyperinflamed endotype of Acute Respiratory Distress Syndrome (ARDS), which Damage-associated molecular patterns (DAMPs) are elevated (3)?
- 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 Acute Respiratory Distress Syndrome (ARDS)?
- IL-18
What purpose is performed by IL-18 (2 step)?
- 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 (2)?
Relates to angiogenesis and cell-sprouting
What are the consequences of Acute Respiratory Distress Syndrome (ARDS)?
- Poor gas exchange - inadequate oxygenation, poor perfusion, hypercapnoea
- Infection - sepsis
- Inflammation - inflammatory response
- Systemic effects
How would a patient with Acute Respiratory Distress Syndrome (ARDS) present (11 / know 5)?
- Hx of risk factors
- Low oxygen saturation
- Acute respiratory failure
- Critically ill patient
- Dyspnoea
- Increased respiratory rate
- Pulmonary crepitations
- Low lung compliance
- Fever
- Cough
- Pleuritic chest pain
What investigations are suggested in suspected Acute Respiratory Distress Syndrome (ARDS) (7)?
- CXR
- ABG
- Sputum culture
- Blood culture
- Urine culture
- Amylase
- Lipase
What imaging is involved in Acute Respiratory Distress Syndrome (ARDS)?
CT
Lung USS (evaluate how expanded a lung is)
What would a CXR show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- Bilateral infiltrates
What would an ABG test show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- Low partial oxygen pressure (Hypoxaemia)
What would a sputum culture show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- Positive if underlying infection
What would a blood culture show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- Positive if underlying infection
What would a urine culture show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- Positive if underlying infection
What would an amylase and/or lipase show in an Acute Respiratory Distress Syndrome (ARDS) patient?
- 3 times the upper limit of the normal range in cases of acute pancreatitis