Medical Health Encyclopedia

Over time, both varieties of COLD cause low oxygen levels (hypoxia) and high levels of carbon dioxide (hypercapnia). In order to boost oxygen delivery, the body compensates in a number of ways:

• The rate of breathing is increased.
• More red blood cells are produced to increase the blood's oxygen-carrying capacity.
• The heart rate increases to pump more blood.
• Vessels in the lung constrict to force blood and oxygen through the circulatory system.

Eventually these activities can lead to very serious and even life-threatening conditions:

• Patients with prolonged and severe hypoxia and hypercapnia are at risk for acute respiratory failure, which can cause heart rhythm abnormalities or other life-threatening conditions if not treated immediately.
• Abnormally high pressure in the lungs (pulmonary hypertension) can cause a complication called cor pulmonale, in which the right ventricle of the heart enlarges, eventually leading to heart failure.
• The effects of COLD can threaten the heart. Chronic bronchitis itself is associated with a 50% higher risk of death from coronary artery disease, even after considering the effects of smoking.
• Low oxygen levels can also impair mental functioning and short-term memory.

Chronically low blood levels of oxygen may lead to pulmonary hypertension (high blood pressure in the lungs), and possibly to cor pulmonale. Cor pulmonale is also called right-sided heart failure, and is characterized by enlargement of the right ventricle. Treatment targets the underlying illness and may include supplemental oxygen, a low-salt diet or calcium channel blockers.

Effects of Respiratory Infections

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Any disease that affects the lungs is dangerous for COLD patients. Pneumonia can cause acute attacks of chronic bronchitis, which in turn may precipitate acute respiratory failure, which is life threatening for COLD patients. Viral or bacterial infections in the lungs, seasonal changes, certain medications, and exposure to irritants in the air may also trigger serious lung events.

Other Serious Medical Problems Associated with COLD