Asthma Sagal Yusuf #1447. General Outliune Introduction Definition Types of Asthma Epidemology ...

AsthmaSagal Yusuf #1447

General Outliune

Introduction

Definition

Types of Asthma

Epidemology

Pathogenesis

What is Asthma?

Chronic disease of the airways that may cause

Wheezing Breathlessness Chest tightness Nighttime or early morning coughing

Episodes are usualy associated with widespread, but variable, airflow obstruction within the lung that is often reversible either spontaneously or with treatment.

Pathogenetic Types of Asthma:

Extrinsic (Allergic/Immune) Typically develops in childhood (atopic)

70-80% child with asthma have other allergies Eczema Nasal allergies

Intrinsic (Non-Immune) Develops after age of 30yrs Not associated with allergies Often chronic and year-round conditions

Pathogenesis Allergens induce TH2 phenotype in CD4 T cells

of genetically susceptible individuals

TH2 cells secrete IL-4 (mediates class switch to IgE), IL-5 (attracts eosinophils), IL-10 (stimulates TH2 cells and inhibits TH1cells) and IL-13 (activates mast cells)

Re-exposure allergens leads to IgE-mediated activation of mast cells.

Early Phase Starts in 30-60 mins of exposure and lasts up

to 4-6 hours. Antigen + IgE on the mast cell in mucosa

Release of preformed histamine granules and generation of leukotrienes C4, D4 and E4 lead to broncho-constriction, inflammation and edema (early-phase reaction)

Stimulation of sub-mucosal vagal fibers leads to reflex smooth muscle contraction

Late Phase

Starts after 4-6 hours

Eosinophils play important role of the inflammation by attracting cytotoxic molecules IL-5, PAF, epithelial cells. Thus activate mast cells broncho-constriction

TRIGGERING FACTORS RESPIRATORY

INFECTIONS

Changed Temperatures (Cold Air)

Fog

Wood smoke; tobacco smoke

OCCUPATION

Emotions

Allergens (dust, pollen, etc)

Stress

Laughter

Anxiety

Exercise (dry, cold weather especially )

Early Warning Signs

Cough

Mood Changes

Change in facial appearance

Breathing changes

Verbal complaints

Itchy chin or neck

Itchy, watery, or glassy eyes

Runny nose Head stopped up Sneezing Dark Circles under

eyes Getting out of

breath Chest hurts

Asthma Flare Up Cough

Wheeze

Shortness of breath

Chest tightness

Retractions

Clinical Asthma Short, acute attacks:

Expiratory dyspnea Wheezing Dry cough

Curschman’s Spirals Thick stringy mucus, casts

Charcot Leyden crystals

Creola bodies (clusters of surface airway epithelial cells)

Cells Involved

Mast cells,

Eosinophils,

T-lymphocytes,

Macrophages,

Neutrophils,

Epithelial cells

Curschmann’s Spirals

Spiral shaped mucus plugs from the subepithelial mucus gland duct or bronchioles

Charcot-Leyden Crystals

Microscopic crystals Made up of

eosinophilic membrane proteins (lysophospholipase)

Epidemology

~300 million people with asthma around the world

Its projected that in 2025, another 100 million people will be affected

In the United States,

affects 25.7 million people, including 7.0 million children under 18

Asthma is a significant health and economic burden to patients

In 2010, 1.8 million people visited an ED for asthma-related care and 439,000 people were hospitalized because of asthma

Treatment Steroids and other Anti Inflammatory Drugs

Lifesaving Reducing swelling and mucus production in the airways Creates less sensitivity and reaction to triggers

Bronchodilators Relieve the symptoms of asthma by relaxing the muscles that

tighten within the airways, thus opening the airways. Rescue Inhalers: relieve the cough, wheezing and short breath To control all asthma need to combine with other medications

such as inhaled steroid for daily long term treatment

Continued…

Inhalers

Nebulizers Mouth piece or mask - mist

IV

Oral

Tips for USMLE on Asthma 1. If question mentions Curschmann’s spirals, think

asthma

2. If question mentions Charcot-Leyden crystals, think asthma

3. If question mentions creola bodies, think asthma

4. Status asthmaticus is an asthma attack that does not respond to pharmacologic agents and can be life threatening

5. If a 7-year-old boy suddenly complains to his mother that he can’t breath after playing with the new kitchen for the second time, think asthma

Famous Athletes with Asthma Paula Radcliffe--world record marathon runner

David Beckham

Jerome Bettis “The Bus” -- diagnosed 14yrs

References:

http://www.ginasthma.org/FAQs?faqid=2

http://www.score95.com/blog/blog/usmle-asthma/

http://www.asthma.org.uk/knowledge-bank-treatment-and-medicines-spacers

Kumar, Vinay, and Stanley L. 1915- Robbins. Robbins Basic Pathology. 8th ed. Philadelphia, PA: Saunders/Elsevier, 2007.