Pathology of Pulmonary Vascular and Pleural Disease

Question 1

describe pulmonary circulation

Answer 1

dual supply - pulmonary arteries and bronchial arteries
low pressure system - thin walled vessels, low incidence of atherosclerosis (normal pressures)
pulmonary artery receives entire cardiac output (filter)

Question 2

describe pulmonary oedema

Answer 2

accumulation of fluid in the lung - interstitium and alveolar spaces
causes a restrictive pattern of disease

Question 3

describe causes of pulmonary oedema

Answer 3

haemodynamic (increased hydrostatic pressure)
cellular injury - alveolar lining cells and/or alveolar endothelium
localised pneumonia
generalised;
adult respiratory distress syndrome (ARDS)

Question 4

describe ARDS

Answer 4

diffuse alveolar damage syndrome (DADS)
shock lung - causes include;
sepsis
diffuse infection (virus, mycoplasma)
severe trauma
oxygen

outcome;
death
resolution
fibrosis (chronic restrictive lung disease)

Question 5

describe pathogenesis of ARDS

Answer 5

injury (bacterial endotoxin)
infiltration of inflammatory cells
cytokines
oxygen free radicals 
injury to cell membranes  
fibrinous exudate lining alveolar walls (hyaline membranes)
cellular regeneration 
inflammation

Question 6

describe neonatal respiratory distress syndrome

Answer 6

premature infants
deficient in surfactant (type 2 alveolar lining cells)
increased effort in expanding lung leading to physical damage to cells

Question 7

describe embolus

Answer 7

detached intravascular mass carried by the blood to a site in the body distant from its point of origin
most emboli are thrombi - others include gas, fat, foreign bodies and tumour clumps

Question 8

describe pulmonary embolus

Answer 8

common
often subclinical
important cause of sudden death and pulmonary hypertension 
95%+ of emboli are thromboemboli 
source - DVT of lower limbs

Question 9

describe risk factors for PE and DVT

Answer 9

virchow’s triad;
factors in vessel wall (endothelial hypoxia)
abnormal blood flow (venous stasis)
hypercoaguable blood (cancer patients, post-MI)

Question 10

describe effects of PE

Answer 10

dependent on;
size of embolus
cardiac function
respiratory function

large emboli;
sudden death
severe chest pain/dyspnoea, haemoptysis
pulmonary infarction

small emboli;
clinically silent

recurrent emboli;
pulmonary hypertension

Question 11

describe pulmonary infarct (ischaemic necrosis)

Answer 11

embolus necessary but not sufficient

bronchial artery supply compromised (cardiac failure)

Question 12

describe pulmonary hypertension

Answer 12

primary - rare, young women
secondary

hypoxia (vascular constriction)
increased flow through pulmonary circulation (congenital heart disease)
blockage (PE) or loss (emphysema) of pulmonary vascular bed
back pressure from left sided heart failure

Question 13

describe morphology of pulmonary hypertension

Answer 13

medial hypertrophy of arteries 
intimal thickening (fibrosis)
atheroma
right ventricular hypertrophy 
extreme cases (congenital heart disease, primary pulmonary hypertension) - plexogenic changes/necrosis

Question 14

describe cor pulmonale

Answer 14

pulmonary hypertension complicating lung disease
right ventricular hypertrophy
right ventricular dilation
right heart failure (swollen legs, congested liver etc.)

Question 15

describe the pleura

Answer 15

mesothelial surface lining the lungs and mediastinum
mesothelial cells designed for fluid absorption
hallmark of disease - effusion

Question 16

describe pleural effusion

Answer 16

transudate (low protein);
cardiac failure
hypoproteinaemia

exudate (high protein);
pneumonia 
TB
connective tissue disease
malignancy )primary or metastatic)

Question 17

describe purulent effusion

Answer 17

full of acute inflammatory cells;
empyema
can become chronic