Asthma, All about Asthma

ASTHMA
Worldwide, 4% of children and 8.6% of young adults have Asthma

Pathophysiology of Asthma:
Asthma is not a single disease entity, it is the name ascribed to a constellation of breathing disorders, resulting from airway inflammation, that leads to narrowing and swelling of airways, and excess mucus production, in the inflamed airways.

Airway inflammation may be triggered by: Allergens, Chemicals and Microorganisms.

Persons who develop asthma have bronchial airway that, hyper-responds to the presence of Allergens, chemical and microorganisms, each of which may lead to airway inflammation.

Inflammation leads to the release of mediators in the airways. The mediators released during inflammation, include: Nitric Oxide, Prostaglandins, Leukotrienes, Enzymes and histamine, and their release leads to edema of the bronchial airways, excessive mucus secretion and constriction of the airways.

Actually, the concentration of Nitric oxide in the expired air, is now being used to determine the degree of inflammation, and hence, the asthma severity.

Uninhibited inflammation, may damage and thicken the wall of the airways, leading to permanent narrowing the caliber of these airways.

Factors that trigger inflammation in Asthma

Among the many factors that trigger asthma are:
1.) Allergens: especially in persons with genetic tendency to develop allergies.

a. Indoor Allergens: Cockroaches, dust Mites, Carpet and stuffed Furniture, Mouse, Molds, Pet dander (dried saliva, secretions, feathers, fur, hair).

b. Outdoor Allergens: grass, Pollen (tree. Grass, weed), molds,

2.) Viral upper respiratory tract viral infections.

3.) Respiratory Irritants: Smoke (tobacco, wood, coal), Dust, Molds, Perfume, hair spray, incense sticks

4.) Cold dry air.
5.) Exercise
6.) Chemical irritants in workplace: paint fumes, farm exposure, formaldehyde

7.) Comorbid conditions: rhinitis, sinusitis, heartburns, nasal polyps

8.) Emotions: crying, laughter, hyperventilation
RISK FACTORS FOR ASTHMA
Asthma runs in families
Being overweight. Asthma is usually worse in the obese

Being a smoker (active or passive)
Exposure to fumes, chemicals and perfumes
SYMPTOMS OF ASTHMA.
The inflammation in the airways leads to more inflammation and swelling, mucus build-up, as well as constriction of the airways. Asthma symptoms range from mild and moderate that may interfere with daily activities to severe and life-threatening.

Asthma symptoms include:
. Cough
. Wheezing/whistling
. Chest tightness or chest pain (chest tightness, almost always connotes Asthma)

. Shortness of breath, making it difficult to lie down and sleep.

DIAGNOSIS OF ASTHMA.
LUNG FUNCTION TESTS: Asthma is diagnosed by doing Breathing tests (using Spirometry and Bronchoprovocation).

Spirometry is available for Children 5 years and older and adults. This means, asthma cannot be confirmed in children younger than 5 years.

Spirometry measures how fast and how much one can blow air out of the lungs.

The ratio of the volume of Air blown(forced) out in 1 second (FEV1) to the forced vital capacity of the lung(FVC) should normally be greater than 80% {FEV1/FVC> 80%}.

A reduced ratio specifies airway disease like Asthma, and chronic Bronchitis

During asthma exacerbation, FEV1/FVC is reduced to less than 75%.

After administration of a bronchodilator, if FEV1 improves by 12% or more then Reversibility is confirmed. Reversibility is specific for asthma.

Persons with history suggestive of asthma may have a normal FEV1/FVC ratio., in between asthma attacks. For such persons, a second test, bronchial provocative test is done to confirm the diagnosis.

This Provocative test, is done to demonstrate bronchial hyperresponsiveness.

Metacholine is an inhalable spray which irritates the airway of people with asthma.

When metacholine is administered, the FEV1 shall drop by 20% in patients with Asthma.

PEAK FLOW METERS
Once a diagnosis of asthma has been established, Home Peak flow meters are used at home to monitor airway narrowing, even before the person becomes symptomatic

All persons with Asthma, must have a peak flow meter to monitor their lung function at home.

A peak flow meter, is a hand held and portable device, and it is used to monitor asthma symptoms only, (not to diagnose asthma)

Exhaled Nitric Oxide Test.
Nitric Oxide is one of the inflammatory mediators of asthma. A high level of Exhaled nitric oxide indicates inflamed airways and a sign of asthma.

Nitric oxide testing is also used to monitor the effect on asthma treatment, with steroid medication.

ASTHMA MEDICATIONS.
Asthma medications have been grouped under a.) acute or rescue b.) preventive or controller treatment.

A: MEDICATIONS USED TO RESCUE ASTHMA:
Three classes of Asthma rescue medications are available to treat acute asthma.

1.) Short Acting Beta Adrenergic(SABA) inhalers. (Rescue inhalers) Example is Albuterol (ventolin).

Rescue inhalers have rapid onset of action, usually within minutes. They reverse bronchospasm and are used to rescue patients from acute asthma attack. Rescue inhalers may be administered in the form of nebulizers or inhaled in the form of a canisters 90mcg/inhalation.

2.) Ipratropium(Atrovent)
Ipratropium, an anticholinergic, reduces vagal tone and blocks reflex bronchoconstriction to irritants, leading to bronchodilatation.

Ipratropium augment the action of Albuterol, when the 2 are given together as emergency asthma medications. Singly, they are less potent than Albuterol.

3.) Short course corticosteroids(CS) Prednisone, Prednisolone, Methylprednisolone

Corticosteroids relieve the airway inflammation causing the asthma. Corticosteroids are available in oral and injectable forms.

Oral corticosteroids are taken for 3-5 days, to gain initial control of asthma, and to speed resolution of moderate asthma

B.) LONG TERM ASTHMA CONTROLLER MEDICATIONS.

Who needs long term asthma control?
All Persons who experience asthma exacerbation, that requires the administration of short course of oral corticosteroids, two or more times, in a single year.

There are several classes of these medications.
1.) Inhaled corticosteroids (ICS) Fluticasone, Budesonide, Mometasone

Daily use of inhaled steroids prevents airway inflammation and reduce airway hyperresponsiveness.

Remember to rinse the mouth after each inhalation, to prevent molds from growing in your throat.

2.) Leukotriene inhibitors: Montelukast, Zafirlukast, Zileuton

As the name indicates, leukotriene inhibitors, block leukotrienes, a mediator of asthma inflammation. Leukotriene inhibitors are anti-inflammatory, and bronchodilators. They are taken daily and orally for poorly controlled asthma

They also mitigate Exercise Induced Asthma, and Aspirin induced bronchospasm

As single agents, they are considered alternative to the Inhaled corticosteroids.

3.) Long Acting Beta Adrenergic(LABA) Salmeterol, Formoterol

These inhaled bronchodilators, are considered long acting because, their duration of action is longer than 12 hours. Example is Salmeterol.

LABA are not used during acute asthma or exacerbation.

LABA are never used alone. They are used as add on therapy to asthma uncontrolled with Inhaled Corticosteroids. When used alone, these agents may worsen the asthma.

A combination of Long Acting Bronchodilators + Inhaled Steroids is synergistic and superior to Inhaled Corticosteroids alone. Combination forms include Fluticasone-Salmeterol(Advair), Budesonide-Formeterol (symbicort)

Long Acting Beta Adrenergic, agents must be discontinued once asthma control has been achieved.

4.) Theophylline tablets are, nowadays, reserved for difficult to control asthma, due to their side effects

.WHAT, ARE THE VARIOUS TYPES OF ASTHMA?.
1.) Allergy Induced Asthma:
This is the commonest type of asthma.
Individuals develop symptoms on exposure to indoor and outdoor allergens like pollen, waste products of cockroaches and Mice and dried saliva of cats and dogs.

Allergy induced asthma, usually begins in childhood (especially in those with atopy), however, it may start in adulthood.

There is often, a family history of allergies, and/or maternal asthma.

The asthma symptoms may be seasonal.
2.) Cough variant Asthma:
Asthma presents as a cough, only. There is no wheezing.

Usually, Cold air, and other irritants may either bring about the cough, or make the cough, worse.

Diagnosis: Asthma is confirmed with Pulmonary function tests, (Spirometry and Bronchial challenge).

3.) Exercise induced Asthma. (EIA)
Asthma symptoms occur with exercise, especially when there has been no warm-up, and the weather is cold. As ventilation increases, cool, dry air may cause drying of the airway surfaces. This may trigger inflammation and bronchoconstriction.

Prevention of Exercise Induced Asthma.
. Breathing through the nose, (instead of mouth breathing), warms and humidifies, the inhaled air.

. Cover the nose and mouth when exercising in cold weather.

. A 10minute Pre-exercise Warm up, prevents exercise induced asthma, for up to 4 hours.

MEDICATION FOR E.I.A.
For EIA symptoms occurring only a few times per week, Albuterol inhalation, given 5-20 minutes before the exercise, can protect against EIA, for 2-4 hours.

Inhaled corticosteroids, and daily Anti-leukotrienes (montelukast) are used for those with more frequent EIA symptoms.

4.) Occupational Asthma
Approximately, 10% of workers exposed to sensitizing agents at work places, develop asthma.

The agents may be, paint fumes, hair spray, perfumes, incense sticks, formaldehyde, etc.

Those at risk for occupational asthma include Hair dressers, factory and farm workers.

Diagnosis of occupational asthma: A Serial Peak flow monitoring during work hours, or Spirometry before and after workplace exposure, will confirm this diagnosis.

Management of occupational Asthma:
a.) First, Control and eliminate exposure to workplace allergens

b.) Occupational asthma is treated as regular asthma.

5.) Aspirin Sensitive Asthma
Aspirin and NSAIDs like ibuprofen, may block the enzyme cyclooxygenase, and lead to an increase in the production of Leukotriene. Leukotrienes are among the inflammatory mediators that cause asthma.

Management of Aspirin sensitive asthma:
Avoid aspirin or NSAIDs.
Treat as regular asthma.
6.) Virus Induced airway bronchospasm.
The commonest is respiratory syncytial viral infection (RSV bronchiolitis)

Viral infection may lead to airway hyperresponsiveness and obstruction, in both non-asthmatics, and asthmatics. In non-asthmatic, the obstruction resolves 1-2 months after the respiratory tract infection

Viruses, including cold virus, may also exacerbate the disease in patients with allergic asthma.

7.) Fungus Induced Allergic Bronchopulmonary Aspergillosis

Molds(aspergillus) inhaled into the lower airways, may induce chronic inflammation and mucus build up in the airways. This may eat into and destroy the lung parenchyma.

Affected person presents with difficult to control asthma, and weight loss.

Diagnosis: skin test for aspergillus, serum Ig E titers for aspergillus.

TREATMENT OF BRONCHO-PULMONARY ASPERGILLOSIS
Antifungal: Fluconazole
Anti Ig E: Omalizumab, (Ig)E receptor blocker, marketed as Xolair, and administered as subcutaneous injections.

ASTHMA PREVENTION
Clean your home regularly to decrease dust and pollen levels. Wear a nose-mask when cleaning.

Carpets collect dust, avoid them; Floor tiles and wood floors, are preferred.

For those with household pets, bath and groom them regularly to decrease dander levels.

Clean damp areas in the bath and around the house to prevent molds developing.

Humidifiers can help optimize home-air humidity
Air conditioners, when affordable and available, reduce dust mite density, and improve air humidity

Asthma is worse in those who are overweight and obese. Adopting an active life-styles, and weight loss help.

ASTHMA COMPLICATIONS
Asthma may interfere with adequate sleep, and other activities

Absenteeism when asthma flares up.
Recurrent flare up narrows the airways, permanently.

Severe asthma is life-threatening. A hand-held peak flow meter, can help monitor breathing at home.

When to See A Doctor
When there is no improvement after using rescue inhaler

When there is Worsening of chest tightness and wheezing

When there is Shortness of breath on minimal exertion.

When a peak flow meter shows lower than normal peak flow readings.

POORLY CONTROLLED ASTHMA: Frequency of exacerbations of Asthma.

Asthma is said to be well controlled, if the person has no more than 1 exacerbation per year.

If the person has 2 or more exacerbations, requiring oral steroids, per year, the asthma is poorly controlled.

All poorly controlled asthmatics, should started on asthma controller medications.

No matter how well controlled the asthma is, frequent asthma exacerbations lead to permanent narrowing of the airways, and that must be avoided.

WHAT ARE THE RISK FACTORS FOR DEATH FROM ASTHMA.?
Deaths from asthma occur, especially in those who are non-compliant with their medications.

For individuals with asthma, the frequency of use of rescue treatment, can be a gauge of asthma severity. Frequent use of rescue inhalers has been associated with increased risk of death and near deaths.

Any asthmatic, with history of any of the following events, are at risk for asthma related deaths.

1.) Previous severe asthma exacerbation (requiring ventilators, intensive asthma care)

2.) 2 or more hospital admissions for asthma in the past year.

3.) 3 or more emergency room visit for asthma, in the past year

4.) A hospital admission or emergency room visit in the past 1 month.

5.) Using more than 2 rescue inhaler canisters per month.

6.) Concomitant use of Illicit drugs.
7.) Persons with major psychosocial problems, including Depression

All persons at risk for death from asthma, should be followed closely by Asthma specialists.