Starving for air

Cover a burning candle with a glass jar and see how long it burns. As the oxygen in the contained space is consumed, the flame fades and disappears entirely. Our bodies too, need oxygen, and if the delivery of that vital gas is somehow interrupted or diminished, the results can be tragic. (Tissue damage due to lack of oxygen may result in heart attack or stroke and possibly death, but this is usually the result of a blockage such as a clot that prevents oxygen-bearing red blood cells from reaching the oxygen-dependent tissue.) Diminished oxygen levels can occur on a systemic basis through conditions such as chronic obstructive pulmonary disease (COPD), a term that encompasses chronic bronchitis and emphysema. The affected person is left short of breath, frustrated, frightened and physically and emotionally debilitated.

Every breath you take

The Canadian Lung Association motto neatly sums up the feelings of someone struggling with shortness of breath (dyspnea): When you can’t bathe, nothing else matters. Inhalation is the result of muscular activity, primarily of the dome-shaped diaphragm, located below the lungs, as well as the external intercostal muscles of the rib cage. When the diaphragm and rib cage muscles contract, the chest volume increases, the pressure within it decreases and the lungs inflate. When these muscles relax, air is normally exhaled without active effort, in part due to the lungs’ normal elasticity.

Air enters the lungs from the trachea or windpipe, which branches into the right and left bronchi as it reaches the right and left lungs. (These airways are fairly stiff rings of cartilaginous material.) Each bronchus divides further into numerous narrower, shorter airways called bronchioles whose walls are made of smooth muscle. At the very end of these bronchioles are balloon-like clusters of alveoli (some 300 million in total) — small air sacs whose thin walls allow the exchange of gases between the air and the blood. Lung tissue, made up as it is of these tiny sacs, looks like fine pinky-grey sponge material. Small hair-like processes called cilia, found in the mucous membranes lining the respiratory tract, trap small particles of dust or other pollutants and with a wave-like motion, gradually move mucus laden with this debris to the pharynx where it’s removed by swallowing.

Chronic obstructive pulmonary disease

The effective functioning of this system can be compromised over time, when airways are continuously narrowed by COPD. In chronic bronchitis, the bronchi and smaller airways in the lungs become plugged with an over-abundance of mucus that can’t be dislodged by frequent coughing. It’s a perfect setting for bacterial infection. Airway walls also swell and spasms may occur in their smooth muscle fibre. Chronic bronchitis differs from the acute bronchitis that may occur in the course of a bad cold but which eventually resolves, leaving the bronchi in a normal state. With chronic bronchitis, coughing and clearing of mucus will persist for months, then re-occur yearly. People suffering from chronic bronchitis are nearly always smokers and may dismiss their coughing as "smoker’s cough."

As time goes by, however, they’ll notice shortness of breath that’s out of proportion to the activity in which they’ve been engaged. Blood levels of oxygen in people with chronic bronchitis tend to be low and those people may benefit from oxygen therapy. Bronchodilator drugs may be helpful in alleviating spasm of the smooth muscle tissue, but ultimately, there is no cure for chronic bronchitis.

Emphysema is an irreversible disease in which some of the alveoli — the small end-point air sacs where the exchange of gases occurs — lose their elasticity and become ineffective. The small airways leading from the alveoli collapse as well. In the vast majority of cases, the damage is caused by irritants inhaled during smoking.

The lungs are further compromised because smoking increases mucus production, prevents the cilia from clearing pollutants and interferes with the action of macrophages, cells that consume toxins that find their way to the airways. Destruction of alveoli results in a less efficient transfer of oxygen to the blood and removal of carbon dioxide to be exhaled.

To deliver the oxygen the body craves, the heart has to work harder pumping blood through the lungs. Eventually, the lungs enlarge, creating a barrel-shaped chest; they also become less elastic, so air is not forced out of the body in a normal, fairly quick fashion. The person with emphysema has the feeling the airway is obstructed and they must work harder exhaling. In rare cases, emphysema may result when a person genetically lacks an enzyme known as alpha 1-antitrypsin that protects lungs from damage done by the enzyme trypsin. Such people are likely to get emphysema if they smoke and in this case will probably be affected more severely and at a younger age than people who have the protective enzyme.

People who suffer from asthma may have episodes of shortness of breath, but their extra-sensitive airways, swollen by exposure to environmental triggers such as moulds, house dust mites or animal dander, usually respond to drug treatment. This may be hindered if the patient also has a degree of chronic bronchitis or emphysema.

Lung disease and its toll on society
Three-quarters of a million Canadians responded in the affirmative to a Statistics Canada question that asked whether they had chronic lung disease that had been diagnosed by a health professional. "That doesn’t include people who may have it and can’t remember the diagnosis or people who haven’t been diagnosed," says Dr. Roger Goldstein, professor of medicine at the University of Toronto. "Usually it’s people with the more moderate to severe disease who recognize they have it."

Deaths from COPD are rising. From two or three per cent of all deaths in 1980, Goldstein notes by the 1990s, the rate had risen to four per cent of deaths in Canada yearly. Alarmingly, although the rate for men remains stable, the rate of death from COPD for women has more than doubled as a consequence of greater numbers of women smoking.

While the results of COPD manifest in the 50-plus years, it’s actually a process that has been under way for years. Usually, smoking or exposure to second-hand smoke is the main cause of the condition. There is occasionally an environmental or occupational component to COPD, but cigarette smokers tend to lose lung function more quickly and have higher death rates than do non-smokers.

"There’s an ever-increasing percentage of seniors each year with COPD — chronic obstructive pulmonary disease," says Dr. Josiah Lowry, a family physician practising in Orillia, Ont. "In Canada, the mortality is rising significantly, especially in women over 75."

Lowry wants doctors and their patients to recognize the need for early diagnosis of the condition. A professor of family medicine at the University of Toronto, he’s taught courses on spirometry and written books on the subject. (The device measures the volume of air as the patient breathes.) "We need more family doctors in primary care first of all suspecting it, and then making the diagnosis so they can intervene early and prevent the long-term disability. The early signs can be quite subtle," he says, "and yet there may be significant lung trouble there. It’s extremely important to recognize it." Diagnosis followed by treatment that slows or prevents further damage is infinitely preferable to the downward spiral COPD can become. Its primary symptom — shortness of breath — encourages people to become physically less active which causes further deterioration in their health.

"There are emotional implications," says Dr. Goldstein who is also a respirologist at West Park Hospital in Toronto. "If you can’t do much, after a while you get frustrated, depressed, anxious. It’s very unfortunate and it’s very grueling for people who have it. They feel as though every day is a battle to breathe properly."