Transcript All of medicine in 12 hours…

iBSc: Question 6 - Asthma
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 6
Mrs Rockley, a 67
year old smoker
presents with an
acute attack of
breathlessness.
Q6.1
• List 3 differentials (3)
Q6.2
• Describe IMMEDIATE
management on
arrival at A+E (3)
Question 6
She has a
polyphonic wheeze
and a history of
asthma.
Q6.3
• As part of your
treatment you give
salbutamol – this is a
beta agonist. How on a molecular level do these drugs work?
(6)
Question 4
The airway
narrowing in asthma
is multifactorial
Q6.4
• List the three main
factors (3)
Q6.5
• If the radius is halved
with other factors
remaining equal what
happens to the flow
of air? (3)
Question 6
Most gas exchange
takes place within
the alveoli
Q6.6
• Draw and lable an
alveolus showing
cells and fluids
present and nearby
important structures
(7)
Question 6
Mrs Rockley smokes Q6.7
30 cigarettes a day – • Describe the Stages
of Change model and
you try to persuade
how it may help you
her to stop.
with getting Mrs
Rockley to stop
smokeing (8)
The Answers
View these on ‘note view’ rather
than on full screen – additional
notes are provided for some slides
Generating Differentials:
I’D GET VINO…
I
D
G
E
T
V
I
N
O
Infectious / inflammatory
Degenerative
Genetic / Idiopathic
Endocrine
Trauma
Vascular
Iatrogenic / ingested
Neoplastic
Organs
Acute Dyspnoea
I
D
G
E
T
V
I
N
O
Infectious / inflammatory
Asthma, Pneumonia, COPD exacerbation
(e.g. upper resp tract infection)
Degenerative
Genetic / ideopathic
Endocrine
Trauma
Pneumothorax
Vascular
Myocardial infarction, PE
Iatrogenic / ingested
Foreign body (mostly children)
Neoplastic
Organs / other
Lungs
Emergency Management
D Danger?
Check that the scene is safe
R Run
Check for response
H Happily
Call for HELP!
A Away and
Check and secure airway and Cspine
B Buy
Check breathing, Resp rate
C Chocolate! Pulse, Heart rate
Emergency Management
Neuro exam: minimum is pupil
D ‘Disability’
size / response + GCS or AVPU
1: Expose to seek injuries
E ‘Exposure’
2: Keep warm + take temperature
DEFG
Don’t Ever Forget Glucose!!!
An AMPLE history
A
Allergies
M
Medications
P
Past med Hx
L
Last meal (time)
E
Event – what
happened
GPCRs
Salbutamol is a beta agonist – it binds to beta
receptors – the are G-protein coupled receptors
http://uk.youtube.com/watch?v=tOcGbnBCdMM
http://uk.youtube.com/watch?v=bU4955rLv_8&feature=rela
ted
GPCR Summary
• Receptor complex + G
protein
• G Protein has 3
subunits (alpha, beta &
gamma)
• Receptor binds ligand
• Conformational change
• Loss of GDP from G
protein alpha subunit
• Binding of GTP
• Separation of alpha
subunit from betagamma dimer
• Alpha and beta-gamma
freed to interact with
effectors.
• Cascade effect.
• Cycle starts again
GPCRs in the lung
Beta receptors
• GPCRs
• Gs actvates
adenylate cyclase
– Increased cAMP
– ATP cAMP
• cAMP causes
relaxation of the
smooth muscle
• Decreases sensitivity
of the IP3 receptor,
decreasing release of
calcium from
intracellular stores in
response to IP31
• Some proponents
argue for a cAMP
independent PKA
mechanism as well2
GPCRs in the heart
Beta receptors
• GPCRs
• Gs activates adenylate
cyclase
– Increased cAMP
– ATP cAMP
• cAMP activates PKA
• PKA phosphorylates
alpha-1 subunit on
voltage-gated Ca++
channels
• Increased Ca++ influx
• Increased inotropy
• Increased rate
Ca++
In
Beta-adrenergic antagonists
‘Beta blockers’
• Combat the harmful
activation of the
sympathetic nervous
system
• Decrease HR
• Decrease contractility
Examples
• Propranalol
• Sotalol
Side effects
• Bronchoconstriction
• Bradycardia
Asthma
COS of Three Pathologies
Airway
Constriction
Oedema
Secretions
Velocity and Flow
Velocity
• Displacement of single
particle per unit time
• Inversely proportional to
cross sectional area
– Faster in thinner tubes
• Aorta is thinner than total
mass of capillaries
– V slow capillary flow
– Time for gaseous exch
Flow
• Volume of fluid passing
point A at time B
• Proportional to pressure
difference
• Inversely proportional to
tube length
• Proportional to r4
• Inversely proportional to
viscosity
The Alveolus
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
Stages of Change Model
Preparation
Contemplation
Action
Maintenance
Pre
Contemplation
• AKA ‘Transtheoretical’
• By Prochasta and
Diclemente
• Patient focus
• Explains why some
interventions don’t
work
• Allows you to predict
which ones might!
Two Useful Concepts
Body Mass Index
(BMI)
BMI=
Wt (kg)
Ht2 (M)
20-25: Ideal
26-30: Overweight
31-35: Obese
Pack Years
PY=
Cigs / day
20
x Yrs
> 20 = increased
chance complications
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 3 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.