Tuesday, 26 July 2011

Asthma & Allergies

Published in City Times

Asthma and Allergy

Dr.Osman Yusuf, Specialist Allergist, Belhoul European Hospital, Dubai, talks to us on Allergy and Asthma. Dr.Yusuf is one of the collaborators for the ISAAC Study, is a member of the International Advisory Committe of WHO's programme: Allergic Rhinitis Impact Asthma (ARIA), a Regional Faculty Member for the World Allergy Organisation and Regional Chairman for the International Primary Care Respiratory Group which is responsible for teaching GPs and Primary Care physicians to recognise respiratory allergies and asthma and treat them. He is also a member of the Advisory Committee of The American Academy of Allergy, Asthma Immunology.

• About 300 million people worldwide are suffering from asthma. The people suffering from allergies would be approximately twice this, or more.
• As per the ISAAC (International Study on Asthma and Allergy in Children), the largest study ever done in the world on the subject (It has entered the Guinness Book of World Records on account of this), the prevalence of Asthma and Allergy increased more than 50% between 1997 – 2002 in Pakistan where the study was done.
• Asthma is a chronic lung condition that can develop at any age.
• It is most common in childhood and occurs in approximately 7-10% of the pediatric population.
• Though asthma and allergy can occur at any age, the first attack predominantly occurs in children either in the first year of life or when they are 3 years old or when they are 5 years of age.
• If at these ages, they are treated appropriately, they normally do not become symptomatic at all.
• By puberty, children tend to grow out of their allergy. However, the allergy might restart when the child becomes mature (between the ages of 15-17) and again after their body stops growing (between the ages of 20-21).
• It affects twice as many boys as girls in childhood; more girls than boys develop asthma as teenagers and in adulthood, the incidence is slightly more in females than in males.
• In women, asthma might tend to flare up or surface during their second and subsequent pregnancies and during menopause.
• Parents who suffer from any form of allergy like hayfever, eczema, hives, etc, could give birth to offsprings who could suffer from asthma or similar allergies.
• If both parents suffer from allergy, there is 60% chance of their offspring suffering from an allergy.
• The probability of an offspring suffering from an allergy is slightly reduced if one of the parents and either ‘A’ or ‘B’ grandparent has an allergy.
• Asthma is seen to skip a generation and affects children whose grandparents suffered from an allergy while their parents themselves are free of asthma or allergy.
• Also, these children suffer from asthma at an earlier age and in a more intense form, than did their grandparents.
• Asthma affects children in varying degrees, from very mild to very severe.
• There is a general trend of increased deaths and hospitalizations from asthma recorded in all the industrialized countries of the world.
• In Canada, approximately 20 children and 500 adults die each year from asthma. However, with adequate treatment most deaths from asthma can be prevented.

What is asthma and what happens when a person is suffering from the condition?
Asthma is a disease of the respiratory system. Muscles around the airways are loose and relaxed when we breathe. This allows the airways to open up wide enough to allow an easy passage of air in and out of the small air sacs that make up the lungs. However, when a person has an attack of asthma, the muscles around the airways tighten and the normally thin lining inside the airways swell or thicken, getting clogged with thick mucous. This makes it difficult for the air to move in an out.

What are the factors that contribute to asthma?
Lots of different things can cause an asthma attack. Among the many causes which include hereditary and environmental factors, allergy is one of the major contributory factors in asthma. Some common triggers of asthma attacks other than allergies include infections like colds or bronchitis, exercise, changes in the weather, cold air, smoking, stress, artificial flavourings and food additives, keeping late nights and not having sufficient and sound sleep, tired body and hormonal factors. For instance, in children, respiratory viral infections may cause deterioration in his or her asthma. While these factors may not in themselves cause asthma, they may trigger off an attack in a prone person who has perhaps not rested well, is under stress, et al.

What are the most common allergens that trigger asthma episodes?
The housedust mite from carpets, AC vents, etc., is the commonest allergen that has been identified. This is the biggest cause of allergy all over the world and also a factor in asthma. The most common inhaled allergens include: molds, pollen from grasses, trees, and weeds and animal secretions especially of cats, dogs and horses.

What are the symptoms of asthma and are there any warning signals of an oncoming attack?
Everybody doesn't feel the same things when they have an asthma attack. Typical signs of asthma include tightness and heaviness in the chest, laboured breathing, wheezing and cough. Cough is something that needs attention, since a lot of people do not associate a cough to be asthmatic. They think it’s due to a sore throat and take antibiotics which don’t help. If you have a persistent cough, you must have your physician listen to your chest to make sure it is not wheezy! This may be the first sign of asthma! Asthma has a typical late night appearance in that the person has to get up in the latter half of the night with coughing and difficulty in breathing.

The asthma might be associated with a nasal allergy which could involve sneezing, especially early in the morning, runny nose, blocked nose and mucous dripping into the throat.

How is diagnosis of asthma confirmed?
Yes, symptoms of asthma mimic that of other conditions as well. Thorough history taking and clinical examination is the first step in the diagnostic process. The simplest diagnostic measure is to measure the lung function with the speakphometer. This allows us to know whether it’s the airways and passages that are constricted or whether the lung substance that is damaged, thereby not allowing the patient to breathe. The latter could happen in the case of chronic smokers, lung or upper respiratory tract cancer patients or in other conditions.
The quickest and simplest diagnostic test is to give the patient a proper dose of broncho-dilators. Within a minute of two following this dose, the lungs open up if it is due to airway passage blockage and asthma. If it is due to lung damage itself, the broncho-dilator will obviously not help.

In what form are these broncho-dilators given?
Usually they are inhalers and if the person is suffering from asthma, within 30 seconds, the wheezing and cough clear up and patients’ breathing becomes normal. This confirms asthma and no more tests need be done for diagnostic purposes.

What is the role of chest X Rays in asthma?
Asthma will never show up in an X Ray. An asthmatic patient may even be on the verge of dying but an X Ray will not reveal the condition. However, chest X Ray may be done once to exclude the possibility of conditions other than asthma, which mimic symptoms of asthma.

How important is it to do a Skin Prick Test for asthma and when is it indicated?
This test is done if the doctor suspects an underlying allergy. But the skin prick test has to be done by a specialist because interpretation of the test is very important. You can have 10% of the population, who are normal and healthy, and could show up a positive skin prick without manifesting any signs of allergy. Alternatively, you could have 10% of severe asthmatics and allergy patients, who give you a negative skin prick test. The second thing is that this test has to be correlated with the clinical symptoms.

How fatal can asthmatic attacks be?
The severity of an attack depends on the extent to which a person is sensitized to anything. There are some people whose first attack is their last. These people may not have any noticeable symptoms except, may be, a runny nose or flu. Then, for some reason, in a very high pollen or dust environment, they have such a severe asthmatic attack, which if not diagnosed and treated on time, could be fatal. With some allergies, the reaction can be systemic, involving the entire body. When this happens, the release of allergy mediators, mainly histamine, causes capillaries all over the body to dilate. This can assume a dangerous proportion, leading the victim to pass into an anaphylactic shock. However, prompt action with appropriate medication can very well prevent fatalities.

How does asthma become chronic?
Asthma is a disease of the airways in which the airways get constricted. Because of the system constriction, they start becoming thick and swollen. So sometimes, even when the airways do open up, they still don’t open up that well because the walls are now thick. This thickening or change in the airways is known as remodeling. When the muscular breathing passages become thick and non-muscular fibres fuse, it becomes difficult to open up. This is what leads to chronic asthma?

How is asthma treated?
Medication with bronchodilators and steroids are the mainstay of treatment in asthma. However, in the event of an acute attack of asthma, broncho-dilators like ventolin and salbutamol inhalers are the first line of treatment to open up the air passages. Steroids or inhaled cortico-steroids are a long term therapy meant to prevent further attacks and mucous from being formed.

Where the asthmatic attacks are primarily triggered by allergy, how is the allergy component of the condition treated?
Avoidance, medication and allergy vaccination, form the basis of allergy treatment. Vaccination is not a first line of treatment, however. It is a backup, a preventive which has very good results in the hands of a specialist. Allergy vaccinations are individual-specific, tailor made to suit individual needs as per their particular condition. No two individuals suffering from the same allergy may be given identical doses of the vaccination.

Does this mean that the vaccination is not a one time shot that can rid the patient of his/her allergy?
Yes. According to WHO recommendations, allergy vaccinations have to be continued for a minimum period of three years since the patients could be late responders in that the effects of the vaccine take time to show up results in them. Vaccination therapy can be continued for up to five to eight years, depending on patient profile and response.

How often in this 3 to 8 year period is the vaccine given?
To begin with, the patients may be vaccinated once every four days or once a week. Once they have reached a certain level of protection, the interval between vaccines could be lengthened to a month.

What are the adverse effects of the vaccines?
There would be a lot of adverse effects if the vaccines are not tailor-made for the patient. As per the international recommendations, a patient should be observed in the clinic or hospital for at least 20 minutes to 45 minutes, soon after being vaccinated. The side effects could include local reactions at the site of the injection, itching, swelling and redness. A second effect could be the aggravation of the condition for which the patient has been vcaccinated! In the worst possible scenario, there could be a reaction as from any other drug like penicillin and the patient could go into anaphylactic shock. However, in the hands of an experienced specialist, the probability of such risk is extremely low.


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