Ask anyone what they know about their lungs and you’ll likely get an answer involving the need to breathe. It’s true that the lungs are essential to delivering oxygen to the bloodstream — and, thus, the cells of the body — and removing gases such as carbon dioxide.
However, most people probably don’t realize the complex and intricate nature of the constant work going on within their rib cage. Like an upside-down tree, the bronchial tubes within the lungs branch downward 23 times into consecutively smaller units. “If it were a family tree, it would have at least 23 generations of family members,” says Dan Culver, DO, a pulmonary specialist in the Cleveland Clinic Respiratory Institute.
The “branches” lead to air sacs called alveoli, where oxygen is transferred from inhaled air to the blood. Each smaller than the head of a pin, these air sacs number around 300 million in a human adult, who breathes, on average, between 20,000 and 25,000 times a day. In children, it is closer to 30,000 times a day.
For the lungs to perform their best, the airways need to be open and free from inflammation and abnormal amounts of mucus. Cancer, asthma, chronic obstructive pulmonary disease, or COPD, and sleep apnea all are a threat to proper lung function.
By far, the No. 1 cancer-related cause of death in the United States is lung cancer. And the No. 1 cause of lung cancer, by far, is smoking.
“More than 90 percent of lung cancer is related to tobacco exposure,” Dr. Culver says, noting the results of a study that followed the health of British physicians beginning in the early 20th century. “The average adult nonsmoker life expectancy in 1945 would be the same as an adult smoker today. In other words, if you think of all the medical advances since 1945, on average, you’re throwing that out the window by smoking.”
Particularly frightening is the fact that most lung cancers are advanced when diagnosed because it normally takes a long time to develop symptoms. Why? There are no pain nerves inside lung tissue.
“It usually doesn’t hurt until it gets so advanced that it’s pressing on something outside the lungs,” Dr. Culver says, adding that the symptoms can include coughing, coughing up blood, shortness of breath and weight loss.
In addition, the once male-dominated disease now kills nearly an equal number of women. While there is much discussion about lung cancer screening, Dr. Culver says it’s not ready for prime time yet because screening hasn’t been shown to reduce lung cancer deaths.
This disease is on the rise in children, in part because it is diagnosed more often today. Physicians also are recognizing that asthma can start in adulthood. “People think of it as kids’ disease, but it’s not,” Dr. Culver says.
There are two types of asthma triggers: the extrinsic/allergic type, made worse by pollen, animal dander, perfumes and particulates, and the intrinsic type, which has no obvious environmental cause.
Doctors are discovering the importance of maintenance therapy, such as using a corticosteroid inhaler, for those with moderate to severe asthma. “Over time, you can get permanent damage, so people should be on maintenance therapy every day,” Dr. Culver says. “If you have uncontrolled asthma as a child, it can impair your development, so your lung function is not as good as you get older.”
Cleveland Clinic recently took part in a pivotal trial for U.S. Food and Drug Administration approval of a new therapy called thermoplasty. The procedure involves trying to shrink the smooth muscle around the airways by applying heat to the airway walls with a scope passed through the nose or mouth. The smooth muscle can contract or squeeze the airway, so reducing its size leads to less airway-passage narrowing.
Chronic obstructive pulmonary disease, in almost all instances, is smoking-related permanent lung damage. Its two main forms are chronic bronchitis and emphysema.
Chronic bronchitis is characterized by inflammation and airway damage, and symptoms include coughing, wheezing and shortness of breath. Emphysema is typified by destruction of the lung’s air sacs and involves wheezing and shortness of breath.
“The rate of lung function decline slows down a lot as soon as you stop smoking,” Dr. Culver says. “For people with moderate to severe COPD, using controller/inhaler treatments can slow down the damage and decrease the number of flare ups per year. By far, the best thing is to stop smoking.”
This fairly common condition occurs when the upper airway collapses during the deeper stages of sleep.
The body interprets the decreasing oxygen levels as a stressful event and it starts pumping adrenaline. Sufferers partially awaken, and sleep becomes fragmented. People with sleep apnea don’t feel refreshed in the morning and may nod off during the day.
“You’re driving that adrenaline all night. It contracts blood vessels, makes the heart beat harder. Years of that happening starts to affect your body,” Dr. Culver says. “It also may cause inflammation that may lead to heart attacks, strokes and high blood pressure.”
Links between lung and heart health continue to be discovered. A recent study reports that smoking affects the heart’s ability to pump blood.
“If you have poor lung function, more of the burden shifts to the heart,” Dr. Culver says, adding that severe lung disease can lead to pulmonary hypertension, or high blood pressure in the blood vessels of the lungs. “It can be very serious and it can lead to heart failure.”