What Asthma Is

Causes Of Asthma The main component of bronchial asthma is Airflow obstruction This airflow obstruction is due to 3 factors: A-Contraction of the airway smooth muscle(Bronchoconstriction) Smooth muscle tissue is a type of muscle tissue found in blood vessels, digestive tract, some sphincters and bronchioles. This type of muscle tissue is innervated by the autonomic nervous system thus it is involuntary acting. In a normal individual, bronchial smooth muscle tissues relax causing dilatation of the airways when more oxygen supply is needed as in fight or flight, they contract causing bronchoconstriction when there is no demand for more oxygen as during rest and sleep. In an asthmatic, there is an exaggerated bronchoconstriction and airway narrowing on exposure to allergens. This is due to hyperresponsiveness of their airways ( This was discussed in the previous article). B-Increased secretion of the epithelial glands Airways are lin

It is chronic inflammation of the respiratory airways characterized by: – Air flow obstruction that is reversible either spontaneously or with treatment. – Airway hyperresponsiveness to many stimuli. – Genetic predisposition (it tends to run in families). It is the most common chronic respiratory disorder among all age groups. Chronic is a medical term which means that this disease tends to persist more than 3 months. Another example of chronic illnesses are hypertension (persistent high blood pressure above 120/80 ) and diabetes mellitus (persistent high plasma glucose level above 110 mg/dl after fasting for 8 hours). Inflammation means redness, hotness, swelling, pain and loss of function of the affected organ. It is an immune system response to any harmful stimuli such as injury, infection and irritation.  Inflammation is a beneficial response as the inflamed organ gets increased blood supply through the dilatation of its supplying blood vessels. Th

Spirometer The most common widely used laboratory investigation done in all patients suspected to have bronchial asthma is Spirometry. Spirometry specifically measures the volume and speed of air that the patient can inhale (breathe in) and exhale (breathe out). It is done using a device called the spirometer. To understand how spirometry works, we need to know some definitions first. Forced vital capacity (FVC): It is the volume of air that can be forcibly blown out After full inspiration. Forced expiratory volume in 1 second (FEV1): It is the volume of air that can be forcibly blow out in 1 second After full inspiration . Normal values of FEV1 differ according to age, sex, height, weight and smoking. FEV1 is the best measure for assessing severity of obstruction. FEV1 /FVC ratio (FEV1%): This is the ratio of FEV1 to FVC . In healthy adults, this should be 0.75 – 0.8 In asthmatics, there is an increased airways

It is very important to know that there is no diagnostic blood test, radiographic or histopathological investigation done to confirm the diagnosis of asthma. The diagnosis of bronchial asthma is based upon clinical diagnosis. It is important during the diagnosis of asthma to keep its definition in mind It is a chronic inflammatory disorder of the airways in susceptible individuals, the inflammatory symptoms are usually associated with widespread but variable airflow obstruction and an increase in airway response to a variety of stimuli. The obstruction is often reversible either with or without treatment. Remember Symptoms produced by asthma such as cough, wheeze and shortness of breath can be caused by other respiratory diseases as well, this also applies to signs produced by bronchial asthma such as rhonchi. How is a clinical diagnosis of asthma made ? A Detailed history taking is the most important step for the diagnosis of bronchial asthma What should the doctor ask