Asthma is primarily caused by inflammation of the airways. The inflammation hyper-irritates the already sensitive airways, which respond with mucus production and decreased airflow. This irritability may be associated with coughing, wheezing, shortness of breath, mucus production, and chest tightness. During a severe asthma attack, an asthmatic may have only a few minutes in which to access medication to ease their breathing before their situation becomes life threatening.

Air enters your lungs through a series of airways that begin at your mouth and nose. Air passes through your throat (pharynx) into a series of tube-like channels beginning with your voice box (larynx) and windpipe (trachea). The air then flows into the 2 main bronchial tubes, each of which supply air to a lung. The bronchial tubes (bronchi) in your lungs are like branches of a tree, but turned upside down. As your bronchi go further out from the trunk (main bronchi) they get progressively smaller, (bronchioles) eventually ending in tiny air sacs or alveoli, where the exchange of oxygen and carbon dioxide occurs.

The bronchial tubes are lined with tissue similar to that in your mouth (mucosa) and, like your mouth, they contain mucus glands. There are also muscles that run at right angles along the length of your bronchial tubes. If you breathe in something that bothers your airways, three changes occur in your lungs that constitute an asthma attack: the smooth cells in your bronchi go into spasm and the tissues lining the airways swell from inflammation and secrete mucus. This mucus is very thick and sticky and it tends to clog up your bronchial tubes. Then the muscles in your bronchial tubes tighten: this is called bronchospasm. All these changes cause your tubes to narrow, which means you have to work harder to move air in and out of your lungs. In severe asthma attacks breathing can literally become impossible.

David Ostrow, MD 
in association with the MediResource Clinical Team