Transcript All of medicine in 12 hours…

iBSc: Question 9
By Alan McLeod
Getting the best marks
Read the whole question – a latter
section may give you a clue about
an earlier one.
To see how many points you need
look at the marks allocated – for
example a 3 point question is
generally looking for 3 salient
points
If giving a list answer put the best
answers first – examiners will not
usually mark answers too far
down a list
Always write something – it may
get you part of a mark and is
anonymised so no one will think
you are stupid!
If you genuinely have no clue then
re-write the question to see if this
sparks some ideas.
If not then move on and come
back at the end. And remember –
always write something.
Good luck!
Question 9
Mrs Kennedy (78)
has been in hospital
for 2 weeks after
fracturing her left
neck of femur.
Q9.1
• Describe the blood
supply of the femoral
head (3)
Question 9
The fracture is
intracapsular and
was repaired 10
days ago by a
surgical procedure
Q9.2
• Why is the
intracapsular site
important in terms of
outcome? (2)
Q9.3
• What procedure was
most likely used (1)
Question 9
On day 14, Mrs
Kennedy develops
sudden onset chest
pain and shortness
of breath.
Q9.4
• List three likely
diagnoses (3)
Question 9
A pulmonary
embolus is
diagnosed by
ventilation perfusion
scan.
Q9.5
• Describe the main
three vessels that
traverse the lung and
the function of each
(3)
Q9.6
• Which of these is
obstructed by PE (1)
Question 9
A DVT (deep vein
thrombosis) is found
in her left femoral
vein.
Q9.7
• List the common
components of a
thrombus (3)
Q9.8
• List two of her risk
factors for DVT (2)
Question 9
She is started
immediately on low
molecular weight
heparin and warfarin
Q9.9
• How do these two
drugs affect clotting
(6)
Q9.10
• Why is heparin
started as well as
warfarin? (1)
The Answers
View these on ‘note view’ rather
than on full screen – additional
notes are provided for some slides
Fractured Neck of Femur
Blood supply to head
- In order of importance
• Capsular supply
– From Med + Lat
circumflex
– From Deep femoral
• Nutrient artery
– From deep femoral
• Ligamentum teres
– From Medial
epiphyseal
Fractured Neck of Femur
Fractured Neck of Femur
Chest Pain Differentials
I
G
E
T
Infectious / inflammatory Pneumonia, pleurisy, Costochonditis
Trauma
Fractured rib, pulled muscle, pneumothorax
V
Vascular
Myocardial infarction, angina, aortic
dissection, PE
I
N
Iatrogenic / ingested
Surgical scar
Neoplastic
Bony mets
Organs / other
Oesophagus (spasm, reflux), heart
(pericarditis)
Lung, Aorta, bones, muscle, cartilege,
anxiety
O
Genetic / ideopathic
Endocrine
Vessels in the Lung
• Pulmonary Artery
–
–
–
–
Deoxygenated blood
From Right Ventricle
Oxygenated in lungs
Affected in PE
• Bronchial Artery
– Oxygenated blood
– From systemic supply
– Supplies tissues of
lung
• Pulmonary vein
– Oxygenated blood
– From lungs
– To Left atrium
Thrombosis
The three main factors
leading to thrombus
are Virchow’s Triad
• Flow changes
• Endothelial damage
• Composition changes
of blood
Usual components of
thrombus
• Platelets
• Fibrin
• Red blood cells
• Several types of
thrombus with varying
quantities of these.
Thrombus Formation
• Platelet activation
• Fibrinogen  fibrin
• Fibrin assembles into
long fibrils
• Platelets + Fibils =
Clot
• RBCs join later
DVT
Major DVT risk factors:
• Active cancer
• Paresis, paralysis or
recent plaster cast of
lower extremity
• Recently bedridden
for more than 3 days
• Major surgery within 4
weeks.
Lesser risks include:
• Oral contraceptive
• Long flights or car
journeys
• Smoking
• Obesity
• Family history
• Heart failure
• Pacemaker
Vitamin K and Warfarin
• Factors 2,7,9 & 10
must be gamma
carboxylated
• Vitamin K is a vital
cofactor
• Warfarin inhibits
enzyme
– Prevents Vitamin K
recycling
Factors
2,7,9 & 10
Gamma
carboxylated
Reduced
Vitamin K
Oxidised
Vitamin K
Vitamin K
Reductase
Vitamin K
-
Vitamin K
Reductase
Warfarin
ATIII and LMW Heparin
No substrate binding
LMW
Heparin
IIa
IIa
IIa
*
No substrate binding needed
Xa
Factor
Xa
Xa
Xa
*
* Note the change in ATII conformation
ATIII and Unfractionated Heparin
Heparin
IIa
Factor IIa
(Thrombin)
IIa
IIa
*
ATIII
Xa
Factor
Xa
Xa
Xa
*
* Note the change in ATII conformation
ATIII and Heparin - Summary
• Antithrombin III deactivates clotting factors
IIa (thrombin) & Xa
• It does NOT need heparin to do this
• BUT heparin makes it go FASTER
• LMWH only works on Xa
• Longer molecules in unfractionated
heparin work on IIa (thrombin) as well
Heparin and Warfarin
Heparin
• Effective within hours
• Subcutaneous
(LMWH) or IV infusion
(unfractionated)
• Not good for home
use
• Started early to give
immediate cover
Warfarin
• Effective within days
• Oral
• Good for home use
• Regular INR checks
needed
• Started early to build
up to therapeutic
levels before
discharge.
The End
The slides here should allow you to mark
your own work – remember 1 mark per
answer up to the maximum for the
question. Multiply by 4 to get percentage
points. I assume a 60% pass mark. Sorry
but I am unable to give further advice on
answers due to time constraints.