Asthma

Clinical features, Diagnosis, Management, Prognosis,

Bronchial asthma is characterised by paroxysms (episodes) of breathlessness, chest tightness and wheezing, resulting from narrowing of the airways by a combination of muscle spasm, mucosal swelling and viscid bronchial secretions. These changes are thought to be manifestations of a complex inflammatory reaction within the bronchial wall involving mast cells, eosinophils and other inflammatory cells. 

The airflow obstruction, which characteristically fluctuates markedly, causes mismatch of alveolar ventilation and perfusion and increase the work of breathing. A narrowed bronchus can no longer be effectively cleared of mucus by the act of coughing and many of the smaller bronchi become obstructed by mucus plugs. 

Bronchial asthma occurs at all ages and it has been estimated that 5% of adults and 7% to 10% of children suffer from it. Because asthma is a heterogeneous disease triggered by a variety of inciting agents, there is no universally accepted simple classification. Nevertheless, it is customary to classify asthma into two major categories based on the presence or absence of an underlying immune allergic disorder: early onset (also called extrinsic or atopic asthma) and late onset (also called intrinsic or non-atopic asthma).

Early Onset (Atopic) Asthma - Extrinsic Asthma

This is the most common type of asthma. Atopy is a hereditary tendency to be hypersensitive to certain allergens and to readily produce large quantities of IgE antibodies. It is common for asthma to have its onset in childhood and generally it occurs in atopic individuals who readily form IgE antibodies to commonly encountered allergens. Fortunately, complete remissions are common among children. 

Other allergic disorders such as hay fever and atopic eczema are often present, and a family history of these disorders and of “early onset?asthma is common. It is unusual for a single allergen to be the sole cause of asthma. The allergens responsible for asthma in atopic individuals generally enter the bronchi with the inspired air and are derived from organic material such as pollen, mite-containing house dust, cockroaches, feathers, animal dander and fungal spores. 

Previous exposures to these agents will have stimulated the formation of IgE and an anaphylactic antigen-antibody reaction (Type I hypersensitivity) in the bronchi may follow further exposure to specific allergen. This causes the release, from the cells in the bronchial wall, of pharmacologically active substances (e.g., histamine, leukotriens, prostaglandins) which provoke mucus secretion, bronchial constriction and an inflammatory reaction of allergic type in the bronchial wall characterised by increased vascular permeability, oedema formation and accumulation of inflammatory cells (mainly eosinophils). Persistent inflammation of bronchi leads to damage to the bronchial epithelium, which is thought to be responsible for bronchial hyper-responsiveness and bronchospasm. Much less frequently similar effects may be produced by ingested allergens derived from certain foods such as fish, eggs, milk, yeasts and wheat, nuts, peas, which presumably reach the bronchi via the blood stream.

Late Onset (Non-Atopic) Asthma - Intrinsic Asthma

Asthma can occur at any age in non-atopic individuals and because the majority of these patients are adults this type of asthma if often called late onset asthma. It would appear that external allergens play no part in the production of this form of the disease to which the term ?i style="mso-bidi-font-style:normal">intrinsic asthma?is sometimes applied. Triggering mechanisms are non-immune and include: exposure to cold air, strong scents, dust and tobacco smoke; respiratory viral infections, strenuous exertion, emotional stress. These factors can also precipitate episodes of extrinsic asthma. Possible underlying mechanism in non-atopic asthma is an imbalance between the sympathetic and parasympathetic system but the actual details of this are unknown.

Clinical features:  < BACK TO TOP >

1. Episodic asthma:

       This pattern is usually consistent with atopic asthma, when there are episodes of wheezing and dyspnoea with sudden onset.

       Usually there are no respiratory symptoms between episodes.

       The patient may have initially unproductive cough, but toward the end of the episode some thick, tenacious and clear mucus may be brought up.

       Episodes can be triggered by known factors (exposure to allergens and non-specific stimuli) or may be spontaneous.

       Attacks may be mild or severe and may last for hours or days, stopping spontaneously or, usually, on therapy.

       In severe cases there is very marked dyspnoea, cyanosis, sweating (signs of respiratory failure), and this condition must be treated as an emergency (so called status asthmaticus). 

2. Chronic asthma:

       It is often found in non-atopic individuals.

       The main complaints are chest tightness, wheeze, breathlessness especially marked on exertion.

       Spontaneous cough and wheeze during the night can also occur.

       Symptoms are chronic unless controlled by appropriate therapy.

       Episodes of more severe asthma can occur with cough and productive mucoid sputum.

Diagnosis:  < BACK TO TOP >

       Patient’s history often provides very important clues.

       Physical signs in the chest. During an attack the chest is held near the position of full inspiration and the percussion note may be hyper-resonant, reflecting the hyperinflation of the lungs. Expiration phase is prolonged and high pitched expiratory wheezing may be heard. There are usually no abnormal physical signs between attacks except in patients with chronic asthma who are seldom without some expiratory wheezing.

       Radiological examination. In an acute attack of asthma the lungs may appear hyperinflated. Between episodes the chest X-ray is usually normal.

       Pulmonary function tests. Due to hyperinflation TLC and RV are both increased. Measurement of the FEV₁, VC and PEF (all of them are diminished) provide a fairly reliable indication of the degree of airflow obstruction and can also be used to determine whether and to what extent it can be relieved by inhaled bronchodilator drugs, or to confirm that the obstruction is provoked by exercise or occupational exposure (challenge test).

       Arterial blood gas analysis. Measurements of arterial blood-gas pressures (PO₂ and PCO₂) are important in the management of patients with severe acute asthma (status asthmaticus). Expected findings are reduced partial pressure of oxygen and sometimes increased partial pressure of carbon dioxide. Blood pH can be reduced (respiratory acidosis).

       Skin hypersensitivity tests. A prick is made in the skin with a fine needle through a drop of an aqueous extract of the substance to be tested. A positive reaction is indicated by the development of oedema and redness, which begin to appear within a few minutes. It is seldom possible with these tests to identify one particular allergen as the cause of asthma in an individual patient (usually several allergens give a positive result) and their chief value is to distinguish atopic from non-atopic subjects.

       Specific IgE antibodies to inhalants may be detected by radioallergosorbent test (RAST). If this testing is not available or inconclusive, measuring total serum IgE may help establish the patient’s atopic constitution (however this is not specific for asthma).

       Eosinophilia (increased count of eosinophils) is a common finding and in many asthmatics it correlates with severity of asthma. Eosinophilia may also be found in other allergic conditions as well as in parasitic infestations (e.g., intestinal worms).

Management  < BACK TO TOP >

       Avoidance of allergens can be effective only if one allergen is the cause of the asthma. The vast majority of asthmatic patients are hypersensitive to a wide range of allergens and attempts to avoid them are all impracticable. Some measures such as having polished floors instead of carpets and regular washing of curtains and blinds, frequent cleaning/wet dusting/vacuuming and using dust mite protectors on pillows and mattresses are always helpful.

       Hyposensitisation is the only specific measure for the prevention of damaging antigen-antibody reaction. It involves the subcutaneous injection of initially very small, but gradually increasing doses of extracts of allergens, believed to be responsible for the patient’s asthma as demonstrated on the skin hypersensitivity test. Due to the possible risk of producing an acute anaphylactic reaction, this method has been largely abandoned in many countries.

       Anti-inflammatory drugs in asthma

cromoglycate [Intal] and nedocromil [Tilade] administered by inhalation can prevent mediator release from mast cells, therefore must be given regularly (they are not effective during an attack); they appear to be more effective in children than adults for unknown reasons

corticosteroids can be administered by inhalation (beclomethasone [Becotide], budesonide [Pulmicort], fluticasone [Flixotide]) or orally (prednisolone [Delta-Cortef, Panafcortelone] and methylprednisolone [Medrol]) in prevention of attacks; or even intravenously (hydrocortisone [Hysone, Nordicort]) in status asthmaticus

leukotriene antagonists (montelukast [Singulair], zafirlukast [Accolate]) are the latest drugs that block inflammatory mediators leukotrienes which have an important role in bronchospasm, mucus secretion and chronic inflammation. These drugs are administered prophylactically in form of one tablet a day for long-term control and prevention of symptoms.

       Bronchodilator drugs

b₂-adrenoreceptor agonists such as salbutamol [Ventolin], salmeterol [Serevent] or eformoterol [Foradile, Oxis] are given by inhalation, adrenaline is used in children usually by intramuscular or subcutaneous injection

methyl xanthine drugs such as theophylline [Aminophylline] which is usually used intravenously in asthmatic attack

muscarinic-receptor antagonists (ipratropium [Atrovent]) are given by inhalation, but they are less effective than b₂-agonists; however they can be given together

       Oxygen in case of severe acute asthma, which is a medical emergency

Prognosis  < BACK TO TOP >

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Nutrition  < BACK TO TOP >

Nutrition that alleviate or prevent asthma :-

Herbs  < BACK TO TOP >

Herbs that alleviate or prevent asthma :-
Bacopa monniera (Bacopa)
Camellia sinensis (Green tea)
Codonopsis pilosula (Codonopsis)
Ginkgo biloba (Ginkgo)
Glycyrrhiza glabra (Licorice)
Schisandra chinensis (Schizandra)

(source : Dr Zoran Pletikosa)