Bronchial asthma, commonly called asthma, consists of repeated attacks of breathlessness and wheezing.When the patient is not in an attack, he feels normal.When an asthma patient comes in contact with an allergic substance it behaves as an antigen and reacts with the corresponding antibodies already present in his body.The histamine and other substances liberated during the allergic reactions cause the following changes in the bronchi:
1. Bronchial muscles are constricted to the extent of lessening the diameter of the bronchi.
2. Mucous membrane of the bronchi gets swollen, which further restricts the lumen of the bronchi.
3. Secretions are poured out from the swollen mucous lining into the constricted lumen of the bronchi.
When the bronchi are constricted and they are full of secretions the patient has difficulty in breathing and his breath has a wheezing sound in it, which is more on breathing out because then the bronchi get narrower.
Asthma is a disease of the larger and medium sized airways of the lungs and there is obstruction to outflow of air from the lungs.Since enough air does not reach the lungs for the exchange of gases, there is hurried breathing to compensate it.
Cough is a frequent symptom in asthmatics.This occurs in order to throw out the excessive secretions produced in the lungs.This is particularly so in those who have respiratory infection as well.Cough gets relieved by the same measures as breathlessness.
The airways of the asthmatics are over reactive to pollens, air pollution, changes in temperature, physical exercise, etc. and they react strongly to these factors.Persons who are asthmatics find it extremely difficult to tolerate smoking or air pollution.Smoke or strong fumes, smell of fresh paint, white washing, house dust, or dust from old files, or the opening of dusty almirahs or trunks cause symptoms in some patients.
Asthma patients are liable to some complications such as thoracic deformity in children, diminished growth, recurrent infection or pneumonia, chronic bronchitis and hyper inflation of the lung tissues.
Types of Asthma
Bronchial asthma can be categorized, depending upon the predominant factors that cause the disease.This categorization is helpful in the treatment of the individual case.
Extrinsic Asthma: The patients have an inherited liability to develop asthma when exposed to allergic agents like pollens, house dust, certain fungi, etc.These patients have many a time.other manifestations of allergy as well, such as recurrent bouts of sneezing and eczema.These patients benefit from anti allergy treatments of different types.This type of asthma occurs in the early period of life.
Intrinsic Asthma: These patients do not seem to have an allergic background, but develop the disease because
of some pre existing disease of the lung such as past infections or existing diseases like chronic bronchitis.These patients do not respond well to anti allergic measures.This type of asthma occurs in the later period of life.
There is another type of asthma which occurs in some people after taking exercise.This is called exercise induced asthma.This occurs more commonly when physical exercise is done in cold weather.
What is not Asthma?
Chronic Bronchitis: In an elderly patient, the main difficulty arises in distinguishing asthma from chronic bronchitis and emphysema sometimes asthma and chronic bronchitis may coexist in a patient. A patient may begin with asthma because of an allergy to pollens, etc. and if improperly or inadequately treated he may develop chronic bronchitis and later on emphysema, as well.On the other hand, a patient may begin with chronic bronchitis, and after many years, develop so called intrinsic asthma, without any apparent allergic background or known cause and end up as a case of emphysema.Many a time it is difficult to establish which is the primary disease, and which the complicated one.
Cardiac Asthma: An important disease which simulates bronchial asthma is cardiac asthma.In this condition the breathlessness is primarily due to heart disease.This condition also occurs in paroxysms of breathlessness usually in sleep but at times also due to exertion.An attack usually rises to a peak is accompanied by difficulty in breathing both during inspiration and expiration, and frequently by a terrifying sense of suffocation which causes the patient to sit up or stand erect and even to go to the window for air.The attacks last from a few minutes to a few hours averaging about an hour, and leave the patient in an exhausted condition for hours or even days.
Cardiac asthma is precipitated by acute failure of the pumping action of the left ventricle of the heart.It is a common feature with hypertensive heart disease and coronary artery disease.
During an attack the presence of cardiac asthma should be suspected if the patient is more than forty years old if he has a previous history of hypertension or heart disease if he is sweating profusely if he seeks for fresh air and if he has a sudden fear of death.
Hysterical Asthma: Some patients in particular young girls claim the complaint of asthma but history and examination reveal that all they have is sighing respiration there is no wheeze and no difficulty in either breathing in or breathing out.Such cases present no serious problem in differential diagnosis.
Other Conditions: Diseases which at Some Stage may simulate bronchial asthma are malignant tumors of the chest, such as lymphosarcoma and Hodgkin’s disease.Pressure of enlarged glands in lung cancer may also give rise to wheezing and breathlessness.The same may happen with the dilatation and swelling of the wall of the aorta in the chest.Aorta is the most important blood vessel which carries the pure blood from the heart for the rest of the body.
Some of the diseases caused by inhalation of different types of dusts, vegetative and non vegetative can also give to symptoms akin to bronchial asthma.With inorganic dust, the history of the patient or his occupation usually reveals a true diagnosis.In the case of organic dust, it becomes difficult to make a diagnosis unless all laboratory investigations are undertaken.
Diagnosis of asthma does sometimes pose a problem in children and in elderly people in young adults the diagnosis rarely presents difficulty.