Pulmonary Circulation

Question 1

what is the pulmonary wedge pressure?

Answer 1

a measure to estimate the left atrial pressure
info on risk of pulmonary oedema

Question 2

physiology of a high v/q?

Answer 2

less perfusion relative to ventilation
(less physiological dead space)
= waster ventilation = less efficient gas exchange

Question 3

what causes a high v/q ratio?

Answer 3

pulmonary embolism
emphysema

Question 4

how does a pulmonary embolism cause a high v/q ratio?

Answer 4

embolus blocks pulmonary blood flow = less perfusion = wasted ventilation = less gas exchange

Question 5

how does emphysema cause a high v/q ratio?

Answer 5

emphysema = chronic destruction of alveolar elastic spaces = air spaces permanently dilated = less air perused = wasted ventilation = less gas exchange

Question 6

what are clinical signs of high ventricular failure?

Answer 6

peripheral oedema
raised jvp

Question 7

what is the average v/q ratio?

Answer 7

0.8

Question 8

how is physiological dead space calculated?

Answer 8

anatomical dead space + air in alveoli that is not perfused
physiological dead space = total dead space

Question 9

what causes a low v/q?

Answer 9

asthma
chronic bronchitis
pulmonary oedema
acute respiratory distress syndrome
pneuonica
R to L cardiac shunts
anaphylaxis
atelectasis

Question 10

how does asthma cause a low v/q?

Answer 10

asthma = chronic inflammatory disease = smooth muscle constriction + airway narrowing = less air reach lungs

Question 11

how does chronic bronchitis cause a low v/q?

Answer 11

chronic inflammation of bronchi = mucus accumulation + narrowing of airways = less air reach lungs

Question 12

how does pulmonary oedema cause a low v/q?

Answer 12

pulmonary oedema = build up go fluid in lung interstitial and alveoli = less air reach lungs

Question 13

how does pneumonia cause a low v/q?

Answer 13

infected alveoli = consolidation = less air reaches lungs

Question 14

how does acute respiratory distress syndrome cause low v/q?

Answer 14

respiratory failure secondary to widespread infection of lung tissues = build up of fluid in alveoli = less air reach lungs

Question 15

how does R to L cardiac shunts cause a low v/q?

Answer 15

abnormal connection between the L and R ventricles = deoxygenated blood can bypass lungs and re-enter systemic circulation = deoxygenated blood is not ventilated = no gas exchange

Question 16

how does anaphylaxis cause low v/q?

Answer 16

sever allergic reaction = laryngeal oedema = upper airway obstruction = less air reach lungs

Question 17

how does atelectasis cause a low v/q?

Answer 17

atelectasis = complete or partial collapse of whole lung or lung lobe = less air reach lungs