Pulmonary vascular disease and Plural disease Flashcards
What are the features of pulmonary circulation?
- Dual supply - pulmonary arteries, bronchial arteries
- Low pressure system
- Pulmonary artery receives entire cardiac output (a filter)
What features arise from the fact that the pulmonary circulation is a low pressure system?
- Thin walled vessels
- Low incidence of atherosclerosis
(at normal pressures)
What is pulmonary oedema?
- Accumulation of fluid in the lung (interstitium, alveolar spaces)
- Causes a restrictive pattern of disease
What are causes of pulmonary oedema?
- Haemodynamic ( increased hydrostatic pressure)
* Due to cellular injury e.g. alveolar lining cells, alveolar endothelium
What is the most common cause of pulmonary oedema?
Haemodyanamic - cardiac failure i.e. increased hydrostatic pressure in the lungs due to left heart failure
What types of pulmonary oedema are there?
- Localised – occurs in pneumonia
* Generalised – occur sin adult respiratory distress syndrome (ARDS)
What is lung consolidation?
Inflammatory exudation with fluid
What are features of ARDS?
- Diffuse alveolar damage syndrome (DADS)
* Shock lung (causes include sepsis, diffuse infection (virus, mycoplasma), severe trauma, oxygen)
What are causes of shock lung in ARDS?
Causes include sepsis, diffuse infection (virus, mycoplasma), severe trauma, oxygen - important to monitor oxygen
What is the pathogenesis of ARDS?
- Injury caused by, for example, bacterial endotoxin
- Causes infiltration of inflammatory cells
- Inflammatory cells release cytokines and oxygen free radicals
- Causes injury to cell membranes
What is the morphology of ARDS?
- Fibrinous exudate lining alveolar walls (hyaline membranes) - leads to poor gas exchange and acute respiratory failure
- Cellular regeneration
- Inflammation
What is the outcome of ARDS?
- Death
- Resolution (ITU with respiratory support provides best chance of resolution)
- Fibrosis (chronic restrictive lung disease)
What individuals are affected with neonatal RDS?
Premature infants
What is neonatal RDS?
- Deficient in surfactant (type 2 alveolar lining cells)
* Increased effort in expanding lung causes physical damage to cells
What is an embolus?
A detached intravascular mass carried by the blood to a site in the body distant from its point of origin
What are examples of emboli?
Most emboli are thrombi – others include gas, fat, foreign bodies and tumour clumps
What is a pulmonary embolus?
An important cause of sudden death and pulmonary hypertension
What are clinical presentations of pulmonary emboli?
Often subclinical – become breathless (acute dyspnoea) so not obvious it is caused by embolus
What type of emboli are involved in PE?
95% + of emboli are thromboemboli
What is the source of most PE?
Deep venous thrombosis (DVT) of lower limbs
What are the risk factors for PE?
The same as risk factors for DVT
What are the risk factors for DVT/PE?
Virchow’s Triad
- Factors in vessel wall (e.g. endothelial hypoxia)
- Abnormal blood flow (venous stasis)
- Hypercoaguable blood (cancer patients, post-MI etc)
What are the effects of PE?
- Sudden death
- Severe chest pain/dyspnoea/haemoptysis
- Pulmonary infarction
- Pulmonary hypertension
What do the effects of PE depend on?
- Size of embolus
- Cardiac function
- Respiratory function
