Clinical Application Of Lung Ventilation And Mechanics Flashcards
What is Atelectasis (Lung collapse)?
Suggest 2 causes related to surfactant
Is it considered reversible?
- Collapse of alveoli
- Impaired pulmonary surfactant production
- Impaired pulmonary surfactant function
Yes
Name 3 types of Atelacasis
- Neonatal (Incomplete expansion of lungs)
- Compression (mainly in adults)
- Resorption (mainly in adults)
Describe Compression Atelactasis
Suggest 3 causes
- Alveoli collapse due to being compressed
- Tumour
- Air in pleural cavity (Pneumothorax)
- Fluid/ blood in pleural cavity (Pleural Effusion/ Haemothorax)
Describe Resorption Atelactasis
State 3 causes
- Airway obstruction (air in alveoli is resorbed by blood but not replaced hence collapse)
- Tumour (Bronchial carcinoma)
- Foreign Body
- Mucus plugs
In what 2 ways does Atelactasis impair respiratory function
- Collapsed alveoli don’t take part in gas exchange
- Collapsed alveoli more susceptible to infection (e.g pneumonia), can produce pus which prevents other alveoli from taking part in gas exchange
What is a common setting in which Atelactasis occurs?
List 6 risk factors
- Post op, typically within 24hrs
- Older age
- Underlying lung disease
- Obesity
- General anaesthesia
- Chest/ abdominal surgery
- Poor post op pain control-> Suppressed cough and shallow breathing
What is 1 key intervention used to prevent Post-op Atelactasis
- Good pain management (allows patient to cough and take deep breaths)
What does the term ‘lung collapse’ on its own usually mean?
Resorption Atelactasis (due to airway obstruction)
Interstitial Lung Disease is a term for 200 diseases (some are reversible)
What are 3 things these diseases characterised by?
What does it lead to if not treated?
- Fibroblast proliferation
- Collagen deposition
- Thickening of Pulmonary Interstitium (increased O2 diffusion distance)
- Pulmonary fibrosis if untreated
- Diffuse Pulmonary/ Lung Fibrosis (Involves tissue injury and fibrosis)
What is the Pulmonary Interstitium?
What are 4 contents?
Space between Alveoli and capillaries
- Elastin fibres
- Collagen fibres (less stretchy than elastin)
- ECM
- Fibro
What is Interstitial Lung Disease characterised by?
Stiffer lungs with reduced lung volumes (Reduced compliance, increases Elastance)
Give 3 examples of ILD (Interstitial Lung Disease)
- Asbestosis
- Untreated Hypersensitivity Pneumonitis (Immunologically mediated, caused by repetitive inhalation of antigens, notably to birds)
- Pneumoconiosis: A general term for a class of ILDs (where dust inhalation has caused interstitial fibrosis)
(Asbestosis and Pneumoconiosis are Occupational/ Environmental causes)
How are RV, FRC, TV, Total Lung Capacity, Vital Capacity and Diffusing Capacity (DCLO) affected in Interstitial Lung Disease?
All reduced
Describe the airway diameter in Interstitial Lung Disease
Not narrowed, as fibrous tissue exerts radial traction on small bronchioles
What percentage of causes of Interstitial Lung Disease are Idiopathic?
Name 1 CT disease that causes it
20%
Rheumatoid Arthritis
What is Farmer’s Lung?
Repetitive inhalation of mouldy hay-> Interstitial Lung Disease
List 4 symptoms of Interstitial Lung Disease
- Reduced exercise tolerance with dyspnoea on exertion
- Dry cough
- Malaise and fatigue
- Shortness of breath at rest
List 5 signs of Interstitial Lung Disease
- Tachypnoea
- Tachycardia
- Reduced chest movement
- Fine crackles (‘Velro’ crackles)
- Finger clubbing (increased growth of nail bed soft tissue, cant see through gap between 2 adjacent fingers)
What is Respiratory Distress Syndrome?
Who is it usually seen in?
Premature babies particularly those <30, due to lack of surfactant
When is Surfactant produced by type II pneumocytes?
In increasing quantities from 32 weeks
Describe RDS
- Insufficent surfactant-> High surface tension
- Lungs harder to expand at birth, some alveoli
remain collapsed - More effort to breathe-> Impaired ventilation
What are 3 signs of RDS in babies?
- Cyanosis
- Grunting
- Intercostal and Subcostal recession (muscles pull sharply inwards)
How do we treat RDS?
- Surfactant replacement via an Endotracheal tube
- Supportive treatment with oxygen and assisted ventilation
What is the primary cause of COPD?
- Smoking and/ or inhaled pollutants interacting with genetic variability
What is COPD characterised by?
What do all conditions share?
Chronic respiratory symptoms interacting with associated pulmonary abnormalities
Impaired airflow that is not fully reversible
What 2 medical conditions are included in the classic definition of COPD
- Chronic Bronchitis
- Emphysema
(They actually co-exist)
What is Chronic Bronchitis?
What are 6 features?
Inflammation of Bronchi and Bronchioles
- Reduced Cilia
- Hypersecretion of Mucus
- Reduced effectiveness of cilia
- Impaired clearance of mucus
- Altered surface tension in airways (due to mucus)
- Epithelial remodelling
What is the clinical diagnosis of Chronic Bronchitis
- Cough producing sputum for more than 3 months, lasting for more than a year
What happens in Emphysema?
What are 5 features?
Loss of elastin and breakdown of alveolar walls
- Increased lung compliance
- Decreased elastic recoil
- Non reversible narrowing of small airways (less radial traction)
- Loss of alveolar SA for gas exchange
- Air trapping (air can’t exit alveoli due to reduced elastic recoil)
(Harder for lungs to return to original volume after easier expansion)
In Emphysema, how do the lungs appear at rest?
Hyper inflated, with the appearance of a ‘Barrel Chest’
What are 3 symptoms of Emphysema?
- Breath shortness
- Reduced exercise tolerance
- Cough
What is a rarer cause of Emphysema? (Smoking is a common cause)
When does it present?
- Alpha-1 Antitrypsin deficiency, leads to Elastin destruction. (Alpha 1 antitrypsin is an Antiprotease)
- Presents at an early age
What happens to pleural pressure if the chest wall/ lung is breached and enters the pleural space
- Air flow into pleural space down pressure gradient
- Until intrapleural pressure= atmospheric pressure
- This breaks the pleural seal, so lungs collapse towards hilum and chest’s elastic recoil can’t counter it
What is Hypoventilation?
Failure to breathe rapidly/ deeply enough due to poor expansion of Thoracic Cavity/ Lungs
List 4 causes of Hypoventilation
What is the defining feature?
- Respiratory muscle weakness
- Severe thoracic wall deformity
- Very stiff lungs
- Severe airway obstruction
Hypercapnia
What are 5 causes of Respiratory Muscle weakness?
- Brainstem injury
- Spinal cord trauma
- Intercostal nerve damage/ abnormalities
- Neuromuscular Junction defect (Myasthenia Gravis)
- Upper airway obstruction
