by S. Todd Stolp MD
©November 2007
Often in the climax of adventure tales the protagonist discovers a weak spot in the armor of the antagonist which provides the last sliver of opportunity to slay evil – Odysseus and the Cyclops, Luke Skywalker and the Death Star, etc… For humans, one of our greatest weaknesses is our respiratory system. Because of our need to exchange approximately 500 liters (approximately 450 quarts) of air every hour in order to burn about 12 liters of oxygen, our respiratory system represents the largest interface between the world outside and the world within. Therefore, it should not surprise us that the respiratory system has some of the most elegant devices in place to protect us from damage by the elements. Asthma represents an illness caused by the malfunction of some of those devices. It is one of the most common chronic diseases in the United States. Even though there is no cure for asthma, there are many medications and monitoring strategies that can control symptoms and minimize the impact of this condition on patient’s lives.
Asthma is caused by an inflammatory reaction in the airways of the lung which leads to the spasm of the muscles around our air tubes that control where air is distributed. Why on earth would one engineer muscles around the air tubes to control the distribution of air? Because to absorb oxygen most efficiently we must expose the proper amount of blood to the proper amount of air evenly throughout the lung, whether we are standing on our head, lying down, or jogging.
In some people these muscles are stimulated into spasm by substances that are irritating or mistaken by our immune systems for being agents of irritation. Substances such as chlorine gas or air pollutants, such as ozone or small smoke particles, can irritate anybody’s air tubes, leading to asthma-like symptoms. However, in people with a diagnosis of asthma, agents such as pollen, house dust or cat skin can be mistaken for infectious particles by the immune system “soldiers” that line our airways, leading to the release of potent chemicals which stimulate muscle spasm in the air “hoses.” These immune response substances also lead to the secretion of mucous into the airways. This results in wheezing as the person tries to exhale gas from the lungs by breathing out through diminished airway openings. Note that the wheezing in asthma typically occurs with exhalation.
Nearly 3 million Californians currently are diagnosed with asthma, and another 2 million have been diagnosed at some time in the past. Because there are many new and effective treatments to control asthma, it is interesting to note that hospitalization rates for asthma are high not only where smoke and pollutants in the air are elevated, but also where access to doctors and health care providers is limited. By using a simple device at home to measure the rate at which air can be emptied from the lungs (a measure of the “openness” of the airways, called a “peak flow” measurement) patients can participate in their care and assist their health care provider with developing a plan by which to adjust medications in order to prevent asthma attacks, and therefore hospitalizations.
The good news about asthma is that there has been a decline in hospitalizations and deaths due to asthma over the past few years. However, the cost of hospitalizations due to asthma in 2005 still remained over $700,000. Asthma patients should plan regular visits with their health care providers to consider adjustments of medications. As we fire up our wood stoves this winter and welcome the warmth of our heating systems, it is a good time to seal leaks and replace messy filters that help protect us from airborne irritants. And may the force be with you.