Asthma Complexities (cont.)

Chronic coughing is frequently defined by doctors as a cough that lasts longer than three weeks. Chronic cough can have several causes such as postnasal drip, pneumonia, bronchitis, cigarette smoking, acid reflux, heart disease, lung cancer, and medications such as ACE inhibitors used for treating high blood pressure. Asthma also can cause chronic cough.

A chronic cough may be the only symptom of asthma. The cough may first appear after a cold or an upper respiratory tract infection. The cough may also start as a "tickle" in the throat. In some patients with asthma, laughing or exercise can bring on coughing. Other patients tend to cough at night while others cough at any time of day without provocation. It is very important that anyone with an undiagnosed chronic cough receive a chest radiograph to exclude more serious disease.

Coughing due to asthma may not respond to cough suppressants, antibiotics, or cough drops but only to medications for asthma. Therefore, accurately diagnosing asthma (by using pulmonary function tests) is important. Thus, a doctor, preferably a lung specialist or an allergist, should evaluate any cough that does not resolve on its own within three to six weeks.

More than 90% of patients with asthma experience nighttime wheezing and coughing. Symptoms of asthma are most common between midnight and 8 a.m. and are important causes of insomnia and sleep deprivation among patients with asthma. In fact, sleep disturbances in patients with asthma usually mean that there is inadequate control of the asthma and should prompt a visit to the doctor to re-evaluate the treatment being used for the asthma.

Function of the lungs in a patient with asthma can decline by up to 50% during an episode of nocturnal asthma. The reasons are not clear, but possible explanations include:

• exposure to allergens at night such as dust mites or animal dander;



• a decrease in cortisone and adrenaline levels that normally occurs at night, resulting in increased reactivity of the airways;



• reflux of stomach acid into the esophagus;



• cooling of the airways that cause spasm of the major airways;



• sinusitis and postnasal drip; and



• sleep apnea.

It is possible to test for nocturnal asthma by taking measurements of airflow out of the lungs during expiration in the evening and again upon awakening in the morning. This is done with a small portable meter that measures the flow of air. (An asthma specialist can demonstrate the correct technique for making these measurements.) A greater than 20% decrease in the peak flow measurement from the evening to the morning suggests nocturnal asthma.

Source: MedicineNet.com
http://www.medicinenet.com/asthma_complexities/article.htm