3. DEFINITION
ASTHMA is a chronic inflammatory disorder of the airways that causes:
– recurrent episodes of wheezing, breathlessness, chest tightness
– cough, particularly at night and/or in the early morning.
Inflammation causes an increase in airway responsiveness to a variety of
stimuli
Patients with asthma experience disabling attacks of severe dyspnea,
coughing, and wheezing triggered by sudden episodes of bronchospasm.
Rarely, a state of unremitting attacks, called status asthmaticus.
Attacks triggered by
– Exercise
– Cold
– Exposure to an allergen
4. intermittent,
mild persistent,
Moderate persistent, and
severe persistent asthma.
Based on frequency and severity of
symptoms, categorized into:
5. Typically asthma is categorized
into
• 1. Extrinsic
• 2. Intrinsic
• Other categorisation according to agents or
events that trigger bronchoconstriction are:-
• a) seasonal
• b) exercise induced
• c) drug induced
• d) occupationl induced e) asthmatic bronchitis to
smokers
9. ATOPIC ASTHMA
• most common
• begins in childhood
• triggered by environmental antigens such as
dusts, pollens, animal dander, and foods
• positive family history of atopy
• asthmatic attacks are often preceded by
allergic rhinithypersensitivity
10.
11. MEDIATORS RESPONSIBLE
1ST GROUP: role in bronchospasm is clearly supported by
pharmacological interventions
• e.g. leukotrienes C4,D4,E4, acetylcholine
2nd GROUP:- have potent asthma like effects but their actual
clinical
role appears to be minor on the basis of lack of efficacy of
potent antagonists or synthesis inhibitors
• e.g. histamine, prostaglandin D2, PAF
3RD GROUP:- whose specific antagonists are not available and
even their role in asthma is not clear
• e.g. IL-1, TNF, IL-6, chemokines, nitric oxide,
bradykinin , endothelins ,neuropeptides..
12. NON ATOPIC ASTHMA
• Triggered by respiratory tract infections
• viruses:-rhinovirus, para influenza
• positive family history of atopy is uncommon
• no associated allergies
• serum ige level normal
• skin test negative
13. PATHOGENESIS
Virus, SO2, O3, NO2
Infect respiratory mucosa
Inflammation
lowers the threshold of subepithelial vagal receptors to irritants
Hyperreactivity of epithelial layer
14. DRUG INDUCED ASTHMA
Aspirin sensitive asthma :
recurrent rhinitis and nasal polyps.
• aspirin triggers asthma by:
• inhibiting the cycloxygenase pathway of arachidonic
acid
metabolism without affecting the lipoxygenase
route,this tipping the balance towards elaboration of
the bronchoconstrictor leukotrienes
15. OCCUPATIONAL ASTHMA
• stimulated by fumes(plastics), organic and
chemical
dusts(wood,cotton, platinum), gases(toluene)
and
other chemicals(formaldehyde, penicillin
products).
underlying mechanism is type I hypersensitivity
reactions
16. MORPHOLOGY OF BRONCHITIAL ASTHMA
GROSS:-
• lungs are overdistended due to
overinflation
• small areas of atelectasis can be
seen
• occlusion of bronchi and
bronchioles by thick tenacious
mucous plug:- most striking
finding.
