vascular problem

Question 1

why do legs swell after DVTs

Answer 1

1. occluded deep limb veins
2. impaired venous return
3. increased hydrostatic pressure

Question 2

why can a leg get red and hot after DVT

Answer 2

• venous clot = dynamic process
• large clots can produce increase temp
• inflammation ++
• WBC activation
• cytokine release

Question 3

how do you work out when to treat atrial fibrillation with an anticoagulant

Answer 3

AF + CHADS-VAS score

CHF - 1
hypertension - 1
age >75 - 2
diabetes - 1
stroke - 2
vascular disease - 1
age >65 - 1
sex - female - 1

score >2 (or equal) = warfarin

Question 4

bleeding risk

Answer 4

H = hypertension
A = abnormal blood results (creatinine/LFTs)
S = stroke 
B = bleeding
L = labile INR
E = elderly (>65)
D = drug use (alcohol)

Question 5

difference between the treatment of AF and DVT/PE

Answer 5

DVT/PE

• urgent
• usually initially as impatient commencing with LMWH

AF

• not so time sensitive
• usually as outpatient
• no LMWH needed
• warfarin vs dabigatran

Question 6

how do you calculate oxygen consumption

Answer 6

Vo2 = Q * 1.33 * Hb * (SaO2 - SvO2)

Q = cardiac output 
Hb = haemoglobin conc 
Vo2 = O2 consumption 

therefore if you decrease Hb you have to increase Q to maintain oxygen consumption

Question 7

effects of reduced oxygen on vessels

Answer 7

increased lactic acid in response to less oxygen (metabolic hypothesis)
causes vasodilation in peripheries so you get increased blood flow to organs
- still have sympathetic activation to heart

Question 8

equation used to determine turbulence and what its determined by

Answer 8

reynolds number
- turbulence likely if Re > 2400

Re = pVD/u

determined by:
p = fluid density
V - fluid velocity
D - vessel diameter
u - fluid viscosity

Question 9

examination findings for compartment syndrome

Answer 9

• pallor
• paraesthesia
• pain
• pulselessness
• paralysis

Question 10

why does a patient with compartment syndrome still have a radial pulse when their hands are pale and cold?

Answer 10

systolic pressure is still greater than the pressure inside the cast causing compartment syndrome

Question 11

what happens to noradrenaline as temperature increases

Answer 11

as you get warmer the affinity of skin alpha receptors to NA decreases so more likely to vasodilate

Question 12

NA binding to alpha 1

Answer 12

increased IP3 which causes increased cytoplasmic Ca2+ levels

Question 13

NA binding to alpha 2 post-synaptic

Answer 13

inhibits cAMP and therefore protein kinase A which can causes vasoconstriction in SM cell

Question 14

NA binding to alpha 2 pre-synaptic

Answer 14

favours vasodilation

Question 15

describe cardiogenic pulmonary oedema

Answer 15

there’s an increased hydrostatic pressure causing increased fluid filtration into the alveolar

• protein-poor oedema fluid

Question 16

describe non-cardiogenic pulmonary oedema

Answer 16

mostly due to infection

• normal hydrostatic pressure
• immune cells come across and travel into alveolus
• protein-rich oedema fluid in alveolus (infectious cells)

Question 17

distinguishing between non-cardio and cardiogenic pulmonary oedema

Answer 17

• history
• BNP - brain natriuretic peptide, high in cardiogenic
• enlarged cardiac silhouette on CXR
• transthoracic echocardiogram
• protein count of aspirate (high in pneumonia)

Question 18

describe circulatory shock and its features

Answer 18

• sustained ischemia results in microcirculation changes that aren’t easily reversed = circulatory shock

features include loss of vascular tone due to:

• inadequate perfusion of BV walls
• depletion of NA in nerve terminals (from excess sympathetic) therefore impaired adrenergic neurotransmission
• accumulation of vasodilator metabolites

= complete loss of BP

Question 19

how do you treat circulatory shock and goal

Answer 19

-e.g. adrenaline

you want to maintain their BP for long enough that the metabolites get washed off and NA is regenerated