Asthma & COPD Flashcards by Tim Resch

Define Asthma

Reversible increases in airway resistance involving bronchoconstriction and inflammation

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What is the effect of Asthma on measures of lung function?

Reversible decreases in FEV1:FVC (<70-80%)

Variations in PEF, improving w/ B2 agonist (morning dipping)

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Describe the parasympathetic control of bronchial calibre

ACh - muscarinic M3 receptors

Bronchoconstriction AND increased mucus

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Describe the sympathetic control of bronchial calibre

Circulating adrenaline - B2 adrenoceptors
Relaxation of bronchial SM
Sympathetic fibres release NA - B2 adrenoceptors
Inhibit mucus secretion
Decrease PNS activity

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What factors lead to an asthmatic attack?

Genetic predisposition, provoked by:

Allergens
Cold air
Viral infections
Smoking
Exercise

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What are the two phases of an asthmatic attack?

Early (immediate)
Late
Sometimes just one or the other

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What are the clinical features of Asthma?

Wheezing
Breathlessness
Tight chest
Cough
Decreases in FEV1, reversed by B2 agonist

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What are Spasmogens?

Factors released from mast cells
Stimulate bronchospasm (early)

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What are Chemotaxins?

Factors released from mast cells
Stimulate inflammation (late)

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What type of cell releases Spasmogens/Chemotaxins?

Mast cells (mononuclear)

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Describe the time course of an asthmatic attack?

Early phase - 1 hour after stimulus, large drop in PEF followed by quick improvement
Late phase - 3-8 hours, gradual drop in PEF

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What are the five Spasmogens involved in an asthmatic attack?

Histamine
Prostaglandin D2
Leukotrienes C4 & D4
Platelet Activating Factor (PAF)

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How are Spasmogens produced?

Arachidonic acid separated from membrane by PLA2
Leukotrienes produced by LOX
Prostaglandins by COX

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What are the two Chemotaxins involved in an asthmatic attack?

Leukotriene B4

Platelet Activating Factor (PAF)

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How do Chemotaxins lead to the late phase of an asthmatic attack?

Attract leukocytes (esoinophils + mononuclear cells)
Leads to inflammation + airway hyper-reactivity

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What are the two types of therapy for Asthma?

Bronchodilators

Preventative

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What is the purpose of Bronchodilators?

Reverse bronchospasm (early phase)
RAPID RELIEF

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What is the 1st choice Bronchodilator?

Salbutamol

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What is Salbutamol?

B2 adrenoceptor agonist

Increases FEV1

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How does Salbutamol work?

Acts on B2 adrenoceptors to increase cAMP`

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How are B2 agonists given?

Inhalation

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What is the problem with long term use of B2 agonists?

Prolonged use leads to receptor down-regulation

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What are LABAs?

Long acting beta agonists (SALMETEROL)

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What are LABAs used for?

Long term prevention/control (ie. overnight)

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What are the 2nd choice Bronchodilators?

Xanthines (THEOPHYLLINE)

How do Xanthines work?

Phosphodiesterase inhibitors - elevate cAMP

How are Xanthines given?

Oral/i.v.

What are the problems with Xanthines?

Narrow therapeutic index Large range of interactions Removed by hepatic metabolism Hypokalaemia (esp. w/ B2 agonists)

What are the 3rd line Bronchodilators?

Muscarinic receptor antagonists

What are the two common Muscarinic receptor antagonists?

Ipratropium (short acting, t.d.s.) | Tiotropium (long acting, o.d.)

How do Muscarinic receptor antagonists work?

Block parasympathetic bronchoconstriction

How are Muscarinic receptor antagonists given?

Inhalation - prevents antimuscarinic side effects

How are Muscarinic receptor antagonists mainly used?

Little value in asthma | Widely used in COPD

What are the four types of preventative medication?

Corticosteroids Steroids Cromones Leukotriene Receptor Antagonists (LTRAs)

How do Corticosteroids work?

Anti-inflammatory | Activation of intracellular receptors - altered gene transcription (decreased cytokines) - production of lipocortin

What are the two main Corticosteroids?

Beclometasone (inhalation) | Prednisolone (oral)

How does Lipocortin have it's positive effect?

Inhibits PLA2 | Decreased production of Leukotrienes/Prostaglandins

How do steroids work?

Given w/ B2 agonists | Reduce receptor down regulation

What are the side effects of steroids?

Inhalation - Throat infections, hoarseness | Oral administration - Adrenal suppression, diabetes, osteoporosis, immunosuppression

How should patients be counselled to take inhaled steroids?

Rinse out mouth after inhalation | Use spacer

How do Cromones work?

Poorly Uncertain MoA -reduce reflexes of sensory nerves? -reduce PAF/cytokine release?

What is the main Cromone used clinically?

Sodium Cromoglicate

How do LTRAs work?

Antagonise actions of LTs

What is the main LTRA used clinically?

Montelukast

What is the first stage of treating asthma?

Occasional bronchodilator (SABA)

What is the second stage of treating asthma?

SABA + regular inhaled steroid

What is the third stage of treating asthma?

Step 2 + LABA (or LTRA/Xanthine)

What is the fourth stage of treating asthma?

Step 3 + Increase dose of inhaled steroid

What is the fifth stage of treating asthma?

Step 4 + Add oral steroid

What is the management of acute asthma?

Oxygen (40-60%) Nebulised SABA (salbutamol/terbutaline) Oral prednisolone/i.v. hydrocortisone

What steps should be added to normal management when treating an acute, life-threatening attack?

Nebulised ipratropium s. c. SABA i. v. aminophylline (if patient not on Xanthine) i. v. magnesium sulphate

Define COPD

Chronic Obstructive Pulmonary Disease | Combination of Chronic Bronchitis + Emphysema

Describe Chronic Bronchitis

Increased mucus Airway obstruction Intercurrent infections

Describe Emphysema

Destruction of alveoli

What is the effect of COPD on measures of lung function?

FEV1 reduced | Little variation in PEF

Describe Mild COPD

FEV1 60-80% of predicted, smoker's cough, little/no breathlessness

Describe Moderate COPD

FEV1 59-40% of predicted, breathless on mild exertion, possibly wheezing + cough

Describe Severe COPD

FEV1 <40% of predicted, breathless on mild exertion/rest, wheeze +cough

What is the main structure of treatment in COPD?

Smoking cessation | Regular bronchodilators

What is the baseline treatment for COPD?

SABA or Short acting antimuscarinic

If the FEV1 is >50% in a COPD patient how should treatment be modified?

Add LABA or Long acting antimuscarinic (in place of SA)

If the FEV1 is <50% in a COPD patient how should treatment be modified?

Add LABA + inhaled steroid | Replace SA antiM with LA antiM

What is the final stage of treatment for severe COPD?

LA antiM + LABA + inhaled steroid

What role do antibiotics play in treating COPD?

Antibiotics for intercurrent infections | Patients given antibiotics to have for start of exacerbation

What are the clinical signs of an exacerbated chest infection?

2 of: | Purulent sputum, increased sputum, breathlessness

What role does oxygen therapy play in treating COPD?

Severe disease | 24-28% Ox for 15hrs/day

How should NSAIDs be used in asthma?

AVOIDED | Provoke asthma, increase LT production

How should B-blockers be used in asthma/COPD?

AVOIDED | ccause bronchospasm

Asthma & COPD Flashcards

(68 cards)