Case 2 Flashcards
Hello Orla
What are the 4 Categorisations of asthma
Atopic
Non-atopic
Drug induced
Occupational
Atopic vs
Non-atopic
Atopic also known as extrinsic is a type 1 IgE mediated hypersensitivity reaction , DEFINITE EXTERNAL CAUSE
Non-atopic (intrinsic) - no causative agent can be identified
What is occupational asthma
This form of asthma is stimulated by fumes, organic and chemical dusts, gases, and other chemicals.
Minute quantities of chemicals are required to induce the attack, which usually occurs after repeated exposure.
The underlying mechanisms vary according to stimulus and include type I hypersensitivity reactions, direct release of bronchoconstrictor substances, and hypersensitivity responses of unknown origin.
What is Drug-induced Asthma
Several pharmacologic agents provoke asthma
What are two common Drug-induced Asthma
Aspirin (pain)
Propranolol (hypertension)
What does atopy mean
a group of disorders that appear to run in families
What are the 3 types off phases of atopic asthma
Immediate
Duel and late
Isolated
What is the Early Phase Reaction
- In the airways, the scene for the reaction is set by initial sensitisation to inhaled allergens, which stimulate induction of Th2 cells.
- Th2 cells secrete cytokines that promote allergic inflammation and stimulate B cells to produce IgE and other antibodies.
What percentage of UK adults smoke
16%
COM-B framework
Capability
Motivation
Opportunity
Behaviour
What is tidal volume
Volume of air displaced between normal inspiration and expiration
Inspiratory reserve volume
is the extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force (≈3000ml).
Expiratory reserve volume
maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration (≈1100ml)
Residual volume
volume of air remaining in the lungs after the most forceful expiration
What gives us maximum volume
Tidal
Inspiratory reserve
Expiratory reserve
Residual
Functional residual capacity
= expiratory reserve volume + residual volume
This is the amount of air that remains in the lungs at the end of normal expiration.
Vital capacity
= inspiratory reserve volume + tidal volume + expiratory reserve volume
This is the maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent and then expiring to the maximum extent.
What are the Methods of Studying Respiratory Abnormalities
4
Arterial Blood Gases
Peak Expiratory Flow Rate (PEFR)
Spirometry
Pulse Oximetry
Arterial Blood Gases
a blood test that measures
The arterial oxygen tension
The arterial carbon dioxide tension
The acidity of the arterial blood
Pulse Oximetry
• They measure the difference in absorbance of light by oxygenated and deoxygenated blood to calculate its oxygen saturation (SaO2).
Peak Expiratory Flow Rate (PEFR)
- This is the maximum rate at which a person can forcibly expel air form their lungs at any time
- Normal values are dependent on height
Spirometry
- Procedure: person inspires maximally to the total lung capacity and then exhales into the spirometer with the maximum expiratory effect as rapidly and as completely as possible.
- FEV1 is expressed as a percentage of the FVC, i.e. how much of the FVC is exhaled by the end of the first second.
Types of Respiratory Failure
- Type I: hypoxia WITHOUT hypercapnia.
* Type II: hypoxia WITH hypercapnia.
What is hypercapnia
too much co2
What is the rate of diffusion directly proportional to
partial pressure of that gas
What is Henry’s Law
Partial Pressure= (Concentration of Dissolved Gas)/(Solubility Coefficient)
What is the difference in hypoxia and hypoxaemia
Hypoxia is failure of oxygenation at the tissue level
Hypoxaemia is when PaO2 is below the normal range
How does pulse Oximetry work
Measures the difference in absorbable of light by oxygenated and deoxygenated blood to calculate the oxygen saturation (SaO2)
What is Spirometry
FEV1 expressed as a percentage of the FVC
What is the difference in Type 1 and 2 respiratory failure
Type I - hypoxia WITHOUT Hypercapnia
Type II - hypoxia WITH Hypercapnia
What are the respective pressures of Co2 and O2 in alveolar air
Alveolar Air has more Co2 and less O2
Why is a slow replacement of alveolar air important
It is important in preventing sudden changes in gas concentrations in the blood
How many alveoli are there in the lungs
300 million
What are the layers of the respiratory membranes
Layer of fluid lining the alveolus Alveolar epithelium Epithelial basement membrane Thin interstitial space Capillary basement membrane Capillary endothelial membrane
What is perfusion
The amount of blood that reaches the alveoli via the pulmonary capillaries
What is ventilation
Aeration of the lungs
If the blood flow is good what could be another factor to do with blood that makes it difficult to absorb air bitch
Blood flow going to different parts of the lungs
In quantitative terms what is Va/Q
Ventilation perfusion ratio
What does Va and Q stand for
Va is alveolar ventilation and Q is perfusion (blood flow to the lungs)
In terms of perfusion and ventilation explain the apex and the lower lobes of the lungs
Top the perfusion is decreased so Va/Q is too high so there is a moderate degree of dead space in the lung
At the lower lung there is slightly too little ventilation in relation to blood flow this Va/Q is reduced
What happens during exercise in terms of surface area and physiological shunts
Increased surface area of ventilation/ perfusion ratio in the upper lung
What nervous system at the start of exercise causes vasoconstriction
Sympathetic
What is the shunt flow
This blood is shunted past the gas exchange areas and isn’t exposed to air
What is venous admixture
Oxygenated blood from pulmonary veins to mix with shunt flow
What is the maximum the PO2 can rise in mmHG in blood
95mm Hg due to the O2 pressure in the arterial blood
What diffuses more rapidly Co2 and O2 and what does this entail when relating to pressure difference
Co2 defuses 20 times more rapidly thus a lesser conc gradient is needed
What percentage of O2 is carried in the blood / dissolved in the blood
97% is in combination with Hb and 3% is dissolved in water of the plasma and blood
What does Venus blood have
Large oxygen reserve which can be mobilised if tissue oxygen demands increase
How does oxygen diffuse from the alveoli into the pulmonary blood as a result of
Partial pressure difference
What nervous system causes vasoconstriction at the start of exercise
Sympathetic nervous system
How do you make carbonic acid
H2O and Co2
What does Haemoglobin act as
Acid-base buffer
What maintains the pH of red blood cells
Chloride shift
What is the Haldane effect
Binding of oxygen with Hb tends to displace carbon dioxide from the blood
What is the Bohr effect
Increase in carbon dioxide in the blood causes oxygen to be displaced from the haemoglobin
Combination of O2 with Hb causes a (stronger acid or base)
Stronger acid
What is Hypercapnia
Excess carbon dioxide in the body fluids
What is the transport capacity for blood of Co2 vs O2
Blood has 3 times more capacity for Co2 than O2
What is asthma
Inflammation of the air passages in the lungs and effects the sensitivity of the nerve endings in the airways so they become easily irritated.
What are the different types of asthma
Atopic
Non-atopic
Drug induced
Occupational asthma
What is the difference in atopic and non atopic asthma
Atopic is a definite external cause and is Type 1 mediated hypersensitivity reaction
Non-atopic is when no causative agent can be identified eg 007 or Jonny English
What is less humid cold or warm air
Cold bitch
What IL stimulates the production of IgE by B cells
Inter Luken 4
What happens in airway remodelling in asthma
Hypertrophy and hyperplasia of bronchial smooth muscle - thus contracts too much and too easily
Epithelial destruction and metaplasia of goblet cells thus more mucus
Increased airway vascularity
How can a mast cell be stimulated
Venoms eg bee sting
Cross linking of loaded IgE antibodies
Coding and morphine
What is a curschmann spiral
Remember the mucus plug image that Jodie showed you
What are the two classes of anti asthma drugs
Bronchodilators - revers the bronchospasm of the immediate phase
Anti-inflammatory agents - inhibit or prevent the inflammatory components of both phases
What are bronchodilators and name some and the methods of action
Beta 2 adrenergic receptor agonists and they dilate the bronchi by direct action on the B2 adrenergic receptors of smooth muscle. They also inhibit the mediator release from mast cells and Tumour necrosis factor alpha release from monocytes .
They also increase mucus clearance by action on cilia.
Drugs are - salbutamol/Salmetrol
What is the difference in salbutamol and salmetrol
Salbutamol is short acting and used for a as needed basis to control symptoms
Salmetrol is longer acting and given regularly twice daily and given to those who’s asthma is inadequately controlled by glucocorticoids
Name an Xanthine drug
Theophylline
What is the action of Xanthine drugs
Inhibitor of phosphodiesterase which results in an increase in cAMP causing muscle relaxation
Mechanism of action of Xanthine drugs
Xanthine drugs are phosphodiesterase inhibitors.
Phosphodiesterase breaks down cAMP. cAMP inhibits myosin kinase which phosphorylates myosin and causes muscles to contract.
Therefore inhibiting phosphodiesterase increases the amount of cAMP and decreases the amount of myosin kinase causing muscle relaxation. This results in bronchodilation and is used to treat asthma
What does a muscarinic receptor antagonists do
Blocks actions of Ach at receptors in parasympathetic nervous system
What are glucocorticoids used for in asthma
Prevent progression of chronic asthma
Used as a prophylactic treatment for asthma
What does glucocorticoids do bitch
Reduce production of cytokines and spas opens thus reducing bronchospasm
What is the mechanism of glucocorticoid action
Enters cells
Binds to intracellular receptors in cytoplasms
Receptor complex moves to nucleus and binds to DNA in nucleus
Alters gene transcription
Reduced synthesis of IL-3
What does IL-3 do mr poo hey Jordan x
Cytokine that regulates mast cell production
What is the systemic biases in Risk perception
- Compression: overestimate low risks, underestimate high ones.
- Miscalibration: overestimate accuracy of own knowledge.
- Availability: overestimate notorious risks.
- Optimism: underestimate personal susceptibility.
