Asthma prevention Community medicine

Asthma prevention Community medicine

1. Dept of Community Medicine
Asthma and its Prevention

2. Quick Overview (1)
•Asthma – What is it?
•Symptoms of asthma
•What is work-related asthma?
•How common is asthma (work and non work related)?
•What is the pathophysiology of asthma?
•How asthma is treated?
•Clues that suggest asthma may be work-related
•What YOU can do if you have asthma
•What is the take-home Public Health message
regarding asthma?

3. •What is the Epidemiology of asthma?
•What is the Prevalence of asthma
•What is the Etiology of asthma?
•What is the Etiological classification asthma)?
•What is the Etiological classification asthma (by
allergens)
•How is asthma treated?
•What is the take-home Public Health message
regarding asthma?
•What substances trigger asthma?
•What are the problems of poorly controlled asthma?
Quick Overview (2)

4. •Clues that suggest asthma may be work-related
•What YOU can do if you have asthma
•What are the diagnostic and lung function tests?
•Case presentation in young (non occupational
asthma)
•Acute severe asthma and status ashmaticus
•Case in older (example of Occupational asthma)
Quick Overview (3)

5. Asthma – What is It? (1)
•Asthma is a chronic lung
disease with recurrent, obstruct-
ion of airflow particularly at particularly at
night and early morningnight and early morning
•The obstruction is reversible
either spontaneously or either spontaneously or
with therapywith therapy
•It involves difficulty in breathing
due to
–A-Inflammation (swelling)
–B- Mucus in the airways
(hypersecretion)
–C-Tightening of muscles
around airways
(hyperconstriction)
Airway fill
with mucus
Muscles
contract
Airways swell
“B” and “C” is called
Bronchial
hyperresponsiveness

6. Asthma – What is It? (2)
1. Acute bronchoconstriction1. Acute bronchoconstriction
2. Swelling of the airway wall2. Swelling of the airway wall
3. Chronic mucus plug formation
4. Airway wall remodeling

7. Relaxation Constriction
Normal
Asthma
Airway
narrowing
Exaggerated
airway
narrowing



muscle constriction

muscle constriction
Asthma – What is It? (3)

8. –1 type hypersensitivity reaction.
–The genesis of any allergic reaction may
be divided into
–immune, pathochemical and
pathophysio-logic phases.
What is the pathophysiology of
asthma?

9. Immune phase (1)
•Allergens activate immunocompetent cells.
•As a result B-lymphocytes produce antibodies
of Ig E class.
•T-lymphocytes are inhibited, so the
•activation of B-lympocytes and Ig E production
are excessive, exceeding normal needs.
B-cell
Allergens
T-cell
Allergen-specific
IgE

10. •Antibodies bind to the surface of mast cells,
basophils and eosinophils.
•And cause release of cell contents (this leads
to reaction)
This is a first,
immune
phase of
allergic
reaction.
Immune phase (2)
Mast cells and eosinophils and basophils

11. Pathochemical phase
As a result of antigen-antibody reaction the peculiar
“explosion” occurs. The membranes of mast cells,
basophils and eosinophils break open with output of
biologically active substances ( histamine,
serotonin,etc),
which induce
•inflammation,
•mucous edema,
•spasm of smooth muscle,
•glands hypersecretion
Airway fill
with mucus
Muscles
contract
Airways swell

12. What are microscopic changes of
chronic asthma (1)?
•Bronchial wall infiltration with mast cells,
eosinophils, basophils and T-lymphocytes
•Edema of mucous and submucous tunics
•Destruction of bronchial epithelium
•Hypertrophy of bronchial smooth muscles,
•Hyperplasty of submucous glands
•Microvessels dilation

13. What are Microscopic changes in
chronic asthma ? (2)
Normal
airway
Airway wall
remodeling Epithelium
Basement
membrane
Smoot
h
muscle
Mucus
plug
Mucus
glands

14. Charcot-
Leyden
Crystals
Needle shaped crystals -
Represents breakdown products of eosinophils
Important microscopic finding (both acue or
chronic)
What are Microscopic changes in
chronic asthma ? (3)

15. Symptoms of asthma
•Coughing
•Wheezing, a whistling sound
•Shortness of breath
•Chest tightness
•Sneezing & runny nose (why?)
•Itchy and inflamed eyes (why?)

16. What is work-related asthma?
•Pre-existing asthma that is triggered or made worse
by exposure to one or more substances in the work-
environment
OR
•Asthma that is caused by exposure to substances in
the work-environment

•Signs and symptoms are the same for asthma and
work-related asthma

17. What is the Epidemiology of asthma?
According to epidemiological studies asthma affects 1-
18% of population of different countries.
Only in 2006 more than 300 million patients
suffered from asthma all over the world, 250
thousands of patients die of asthma. The incidence of
asthma is higher in countries with increased air
pollution.
•Up to 20% of all adult asthma cases maybe work-
related asthma
•Of those diagnosed with work-related asthma:
–20-27% are individuals with pre-existing asthma who react to substances
in the workplace
–Up to 80% develop asthma due to work-place exposures

18. What is the Prevalence of
asthma?
•Estimated prevalence worldwide
–10 – 15%
•Most asthmatics have mild to moderate disease, with
severe asthma thought to affect less than 10% of
asthmatics.
•More common in males ( but equal after age of 20)

19. What is the Etiology of asthma?
•Extrinsic asthma
–Allergic or atopic asthma (Skin test reactivity,
elevated IgE levels, blood eosinophilia.(some
genetic predisposition); indoor allergens
•Intrinsic asthma
–Nonallergic or nonatopic asthma ; Environmental
pollution, occupational exposure

20. A. Intrinsic asthma
•no environmental causes can be identified
•negative skin test to common airborn allergens
•rather negative family history
•(no lab findings of mast cells, eosinophils etc)
B. Extrinsic asthma
•atopy, genetic predisposition
"­ IgE, mast cells and eosinophils response to allergens
•(lab findings of mast cells, eosinophils etc)
C. Occupational asthma
•sensibilisation of airways to inhalant chemicals
What is the Etiology classification of
of asthma?

21. Early
Intervention
2
o
Prevention
1
o
Prevention
ASTHMA
Airways
Injury
• Viral infections
• Aeroallergens
• Pollutants/toxicants
Aberrant
Repair
• Persistent inflammation
• Tissue remodeling
• Lung growth/differentiation
Age
Biological &
Genetic Risk
• Immune
• Lung
• Repair
Environment
• Allergens
• Microbes
• Pollutants
• Stress
Aberrant immune development & response
Atopy
Asthma Prevention

22. The allergens are divided into:
•communal
•industrial
•occupational
•natural
•pharmacological
What is the Etiology classification of
of asthma? (Another type by
allergens)

23. Asthma Classification Based
on Severity
Disease Symptoms
Step 4: Continual symptoms
Step 3: Daily symptoms
Step 2: Symptoms > than twice weekly
Step 1: Symptoms < than twice weekly

24. What substances trigger asthma?
Type of Substance Examples
Air pollutants, including dusts,
smoke, mists & fumes
Diesel exhaust; tobacco smoke;
mineral, rock, coal, & wood dusts;
gases; fumes & vapors from aerosol
agents, chemicals, cleaning materials,
solvents, paints, welding & from heating
& cooling metals quickly
Pollens, mites & molds Trees, flowers, weeds, hay, plants
Animal dander Birds, cats, dogs
Medications Aspirin, anti-inflammatory drugs
Foods Egg, wheat, nuts

25. How is asthma treated (1)?
•Asthma can be controlled (but not cured) by:
–Avoiding triggers or reducing exposure to triggers
–Using medication to control symptoms
•Medications - generally two types are used
–Controller or long-term drugs
• Taken to prevent excess production of mucus & to reduce
the inflammation and constriction of airway muscles
–Rescue or quick-relief drugs
•Taken to relax muscles around the airways to improve
breathing

26. How is asthma treated (2)
•Repeated doses of short acting B
2
agonist
– driven by oxygen
– repeated doses every 15 – 30 min
•Systemic corticosteroids
–The earlier they are administered the better
the outcome
•Oxygen

27. Medications to Treat Asthma:
How to Use a Spray Inhaler
The health-care
provider should
evaluate inhaler
technique at each
visit.
Source: “What You and Your Family Can Do About Asthma” by the Global Initiative for
Asthma Created and funded by NIH/NHLBI

28. Drug therapy
Antiinflammatory drugs
(basic)
Bronchodilators
2 drug categories are used:
Are divided into:
hormone-containing
(corticosteroids)
nonhormone-containing
(less common)
(cromones, leukotriene
receptor antagonists)
3 groups:
anticholinergic drugs
b2-agonists
Methylxanthines
(less common)

29. Bronchodilators
b2-agonists
Anticholinergic
drugs
Smooth
muscle
relaxation
Stimulates
b2-adrenergic
receptors of bronchi
reduce tonus
of vagus

30. What are the problems of poorly
controlled asthma?:
•Increased visits to
–Doctor, Urgent Care
Clinic or Hospital ER
•Hospitalizations
•Limitations in daily
activities
•Lost work days
•Lower quality of life
•Death

31. > 50% OF THE COMPLICATIONS IN
ASTHMATIC PATIENTS BEING
VENTILATED OCCUR DURING OR
IMMEDIATELY AFTER INTUBATION

32. What clues suggest that asthma is
work-related?
•Do symptoms:
–Occur only at work or
regularly after a work-
shift?
–Improve on weekends
or vacations?
–Increase over the
course of the work
week?
–Improve after changes
in the work
environment?

33. Information to share with doctor
•Discuss your symptoms.
–When do they occur?
–How often do they occur?
–Time of day or week that symptoms
are worse
–Times you feel better
–Identify
•Substances in the work-place to
which you are exposed
•Current and previous jobs, hobbies,
and smoking habits that may affect
your lungs

34. What YOU can do if you have
asthma?
•Identify and minimize contact with your asthma
trigger(s)
•Understand and take asthma medications as
prescribed
•Recognize early signs that your asthma is
getting worse
•Know what to do when your asthma is getting
worse

35. What is the take-home public health message
regarding asthma?
Key Messages
•Asthma is an inflammatory disease in which
Environmental factors are (a) important and (b)
many types
•Health education is crucial (Awareness)
•Emphasis on recognition and avoidance of
triggers (Prevention)

36. Diagnostic Tests
•No single test can secure a diagnosis of
asthma
•Spirometry is the most helpful, preferred
method for establishing diagnosis.
–Many asthma patients are negative and
repeat testing is advised.

37. Lung function assessment
The diagnosis and severity assessment of
asthma is based mainly on parameters of lung
function. The most important of them are:
forced expiratory volume in 1
second (FEV1) and peak expiratory
flow (PEF), which
are measured
during spirometry
at forced
breathing-out.

38. Case presentation (non
occupational)
•2 year old boy
•Presents with tight chest and wheezing
•No previous episodes
•No TB contact
•No allergies
•No important previous medical history
•Cyanotic (blueness in face)
•No clubbing (this is change in shape of finger
tips; it happens because of heart or lung
problems)
•Severely distress

39. Respiratory system (young)
•Tachypnea (fast breathing; more than 20
breaths in adults but this maybe normal for
children; in 2 year boy more than 26 breaths
or so)
•Retraction of ribs
•Both are considered key signs asthma
•Also, hyperresonant on percussion

40. Chest X-ray reveals:
•hyperlucency of lung
fields
•low standing and
limited mobility of
diaphragm
•expanded intercostal
spaces
• horizontal rib position.

41. What define a severe acute attack?
•Disturbance in level of consciousness
•Inability to speak and/or feed
•Severely diminished or absent breath sounds
•Central cyanosis (cyanosis around lips).
•Use of accessory muscles while breathing.
•Increased respiratory and cardiac rate
What define a Status asthmatics
“Defined as wheezing which does not respond
to initial treatment with inhaled bronchodilators “

42. Additional points
•Sudden onsets
•Failure of the long-term management
plan.
•Acute severe asthma is one of the most
common medical emergency situations in
childhood

43. The examination of working
capacity (part of occupational
health)
– The patients with unfavorable
condition for the disease, need the
job replacement.
Case presentation 2 ( occupational)

44. Exposure to nickel dust
and occupational asthma

45. Risk classification of developing an
occupational asthma
Risk History Risk Comments
Normal
No evidence of
allergic disease
~10%
Minimal risk even upon
repeated exposure
Atopic
Pre-existing
allergic disease
Up to 73%
Risk increases with
repeated exposure
Asymptomatic
IgE antibodies
to allergenic
proteins
Up to
100%
Risk of developing
symptoms increases
with repeated exposure
Symptomatic
Clinical
symptoms on
exposure to
allergenic
proteins
100%
33% with chest
symptoms; 10% may
develop occupational
asthma; minimal
exposure may lead to
permanent impairment

46. Bonus Questions
Q) What are biopsy and non-biopsy findings of
asthma?
Q) What is the most common cause of
transient asthma in children in
Pakistan? (with microscopic findings
like asthma)

47. Charcot-Leyden crystals are non-biopsy
findings
Parasitic infestations in the GIT
cause symptoms like asthma (with
Charcot Leyden crystal formation).
Hook worm infection IS most
common cause
Answers

48. Thankyou