Asthma

5th December, 2008 - Posted by Andy - No Comments

Introduction

Originating from the ancient Greek, asthma, meaning panting, the disease indicates an inability to breathe properly. When any person inhales, the air travels down the wind pipe (trachea) into the upper lungs. At this juncture the trachea bifurcates into the left and right bronchus and air flows through progressively smaller airways called bronchioles. The lungs contain millions of these airways. All bronchioles lead to alveoli, which are microscopic sacs where oxygen and carbon dioxide are exchanged.

Asthma is a chronic condition in which these airways undergo changes when stimulated by allergens or other environmental triggers. Such changes appear to be two specific responses:

The hyper-reactive response (also called hyper-responsiveness).
The inflammatory response.

These actions in the airway cause patients to cough, wheeze, and experience shortness of breath (dyspnoea), the classic symptoms of asthma.

Hyper-reactive Response
In the hyper-reactive response, smooth muscles in the airways of the lungs constrict and narrow excessively in response to inhaled allergens or other irritants. Everyone’s airways respond by constricting when exposed to allergens or irritants, but a special hyper-reactive response occurs in people with asthma:

When people without asthma breathe in and out deeply, the airways relax and open to rid the lungs of the irritant. When people with asthma try to take those same deep breaths, their airways do not relax and narrow, causing patients to pant for breath. Smooth muscles in the airways of people with asthma may have a defect, perhaps a deficiency in a critical chemical that prevents the muscles from relaxing.

Inflammatory Response
The hyper-reactive stage is followed by the inflammatory response, which generally contributes to asthma in the following way - in response to allergens or other environmental triggers, the immune system delivers white blood cells and other immune factors to the airways. These so-called inflammatory factors cause the airways to swell, to fill with fluid, and to produce a thick sticky mucus.

This combination of events results in wheezing, breathlessness, inability to exhale properly, and a phlegm-producing cough. Inflammation appears to be present in the lungs of all patients with asthma, even those with mild cases, and plays a key role in all forms of the disease

SYMPTOMS

Asthma symptoms vary in severity from occasional mild bouts of breathlessness to daily wheezing that persists despite taking large doses of medication. After exposure to asthma triggers, symptoms rarely develop abruptly but progress over a period of hours or days. Occasionally, the airways have become seriously obstructed by the time the patient calls the doctor. The classic symptoms of an asthma attack include:

Wheezing when breathing out is nearly always present during an attack. Usually the attack begins with wheezing and rapid breathing, and, as it becomes more severe, all breathing muscles become visibly active.

Shortness of breath(dyspnoea). Shortness of breath is a major source of distress in patients with asthma. However, the severity of this symptom does not always reflect the degree to which lung function is impaired. Some patients are not even aware that they are experiencing shortness of breath. Such patients are at particular risk for very serious and even life-threatening asthma attacks, since they are less conscious of symptoms. Those at highest risk for this effect tend to be older, female, and to have had the disease for a longer period of time.

Coughing. In some people, the first symptom of asthma is a non-productive cough. Some patients find this cough even more distressing than wheezing or sleep disturbances.

Chest tightness or pain. Initial chest tightness without any other symptoms may be an early indicator of a serious attack. Neck muscles may tighten, and talking may become difficult or impossible. Rapid heart rate. Sweating. Chest pain occurs in about three-quarters of patients. It can be very severe, although the pain’s intensity is not necessarily related to the severity of the asthma attack itself.

The end of an attack is often marked by a cough that produces a thick, stringy mucus. After an initial acute attack, inflammation persists for days to weeks, often without symptoms. (The inflammation itself must still be treated, however, because it usually causes relapse.)

CAUSES

Asthma has dramatically risen worldwide over the past decades, particularly in developed countries, and experts are puzzled over the cause of this increase. The mechanisms that cause asthma are complex and vary among population groups and even from individual to individual. Many asthma sufferers have allergies, and some researchers are targeting common factors in both these conditions. Not all people with allergies have asthma, however, and not all cases of asthma can be explained by allergic response.

Asthma is most likely to be caused by a convergence of factors that can include genes (probably several) and various environmental and biologic triggers (e.g., infections, dietary patterns, hormonal changes in women, and allergens).

The Allergic Response
Nearly half of adults with asthma have an allergy-related condition, which, in most cases developed first in childhood. (In patients who first develop asthma during adulthood, the allergic response usually does not play a strong causal role.) Important irritants or allergens include:

- Dust mites, specifically mite faeces, which are coated with enzymes that contain a powerful allergen. These are the primary allergens in the home.
- Animal dander.
- Pollen. An asthma attack from an allergic response to pollen is more likely to occur during extreme air changes, such as thunderstorms. Major weather changes, such as El Nino, can affect the timing of allergy seasons. For example, in 1998, when the effects of El Nino were very strong, allergy and asthma attacks were markedly increased and maximum tree pollen counts occurred 2 to 4 weeks earlier and mold counts 2 to 3 months earlier than in the previous year.
- Molds. A 2002 study suggested that molds might produce a worse asthma attack in adults than other allergens.
- Fungi.
- Cockroaches. Cockroaches are major asthma triggers and may reduce lung function even in people without a history of asthma.
- Fossil Fuels. Certain chemicals may trigger allergic rhinitis. Some experts believe that refined fossil fuels, such as diesel fuel and particularly kerosene, may be important triggers for allergic rhinitis. And, in people who already have allergies or asthma, exposure to such fossil fuels may worsen symptoms.

TRAVELLING WITH ASTHMA

Medications
Take with you a detailed list of medications showing prescription refill number, prescribing physician and dosage. (Each medication’s original label should have all the needed information.)
Pack the needed quantities of medications and, if possible, also pack a backup quantity to avoid being caught short. Be sure to pack your medication in your carry-on luggage in case checked luggage is lost.
Be sure to bring an emergency, insect-sting epinephrine injection kit if you or someone in your family has this form of hypersensitivity.
Include with your medications a topical hydrocortisone cream and antihistamine (prescription medication if available, or an over-the-counter brand previously used with good results).

Equipment
If someone with asthma is using a peak flow meter, be sure to bring it along on your vacation, with the chart that is used to record results. If you are using a nebulizer to deliver anti-asthma medication, it should not be left at home when going on vacation. Be sure that, if traveling abroad, you have an electrical current converter for the nebulizer. For campers and others who will be spending vacation periods in “the rough,” portable nebulizers powered off an auto cigarette lighter receptacle are available.
To protect against dust mites, it may be wise to pack your own allergy-proof pillow or mattress casings.
People with acute asthma and allergy conditions should consider wearing a medical alert-type necklace or bracelet at all times.

Insuring Health Care Availability on Vacation
Check the extent and limitations of your medical insurance policies before leaving the country or your state. Know in advance if your plan or group will cover physician and hospital visits away from its operating territories.

[sources: medline, NhsDirect]

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