Asthma Detection
Is asthma hereditary?
In many cases, we find that asthma does run in families and in what we refer to as a hereditary disease. Asthma very often is associated in families where there are other allergic problems, people who have nasal allergies or eye allergies, break out in hives, or have severe eczema. There is not a specific genetic predisposition, in that if your mother has asthma you will definitely have it or if your father has it you'll definitely have it, but in general we find that in allergic diseases such as asthma, if you have one parent who has it you have about a fifty percent chance; if you have two parents you have about a seventy-five percent chance. So, as a result, we always get a family history when we're doing a diagnostic workup for asthma and other allergic diseases.
What tests are used to detect asthma?
Lung function tests, referred to as spirometry, are an accurate way of diagnosing airflow through the lungs, and determining whether that airflow is decreased compared to normal people. Lung function tests also determine whether that airflow reverses what we refer to as reversible obstruction, or reversible obstructive airway disease. It helps us make the diagnosis of asthma. There may be other tests that the doctor may want to perform, such as allergy tests to see if the triggers of the asthma are due to allergy problems. A doctor also may check a chest x-ray or sinus x-ray, to make sure there are no other complicating factors regarding the asthma.
What is "peak flow" and how is it measured?
Peak flow is a way to easily measure the maximal velocity of the air that goes through your lungs. A peak flow meter is a very simple device that has a little scale on the side, and when you hit your maximal velocity, or your peak flow, that number will be recorded. Peak flow usually in a scale of liters per minute. We know what normal peak flow should be at each age, and so if someone's peak flow is below that level, that sometimes will help us determine that they have airway obstruction, and then to see if they respond well to the medications. Peak flows are most often used to help patients monitor their own asthma at home. Very often doctors will give them zones at which their peak flows should be. There's a green zone, which is the normal level of peak flow, a yellow zone, which is the warning that there may be some trouble, and a red zone, where there are certain things that need to be done and a pending asthma attack may be occurring.
What is "spirometry"?
Spirometry is a very important tool for physicians to help diagnose asthma and other lung conditions. When you do spirometry, you're basically trying to blow out as hard as you can and maintain that for about six seconds. That allows the doctor to look at a diagram and very often a computer readout that tells him what your flow rate is like compared to normal individuals who don't have asthma. Very often a bronchodilator will be given to see if that abnormally low flow rate will then improve, will increase. The spirometry helps the doctor determine what your lung capacity is, how much air you get out in the first second, and what the ratio is between how much air you get out in the first second and what your total lung capacity should be. The doctor uses this in many different ways, to help diagnose the problem, help diagnose if the patient has asthma, and also to follow the patient on intervals to see how their asthma is doing after treatment has been initiated.
