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Hypercapnia is synonymous with hypoventilation, or inadequate inhalation of fresh air. It is generally the result of alveolar hypoventilation, a failure of the air cells in the lungs to take in adequate amounts of clean oxygen. It may also be related to lung disease or to environmental conditions that result in increased levels of carbon dioxide in the breathable air.
Hypercapnia is characterized by an increase in the partial pressure of carbon dioxide in the arterial blood. Carbon dioxide is a normal part of the atmosphere, and a normal component of the chemical make-up of the mammalian body. Carbon dioxide is the end product of aerobic cellular metabolism (the function of cells that require oxygen to operate). It is considered the primary drive to breath, by stimulation of central chemoreceptors in the medulla oblongata (the lower portion of the brainstem). It is carried in the blood in three forms: 65 percent is as a bicarbonate; 30 percent is bound to hemoglobin; and 5 percent is dissolved in plasma. As a natural part of the atmosphere and the air that is inhaled, carbon dioxide is constantly being added to and removed from the air cells in the lungs. The normal amount of carbon dixide in the arterial blood is 35-45 mm Hg (a measurable unit of pressure).
However, an excess of carbon dioxide in the bloodstream can lead to an abnormal condition, causing symptoms ranging from dizziness to convulsions. Left untreated, a state of hypercapnia can lead to death.
Any breed, age, or gender of cat can be affected by this disorder.
Because the brain is primarily affected by this condition, nervous system signs abound. Other symptoms include:
Hypoventilation that results from a decrease in alveolar ventilation; may be the result of one of the following:
It may also occur spontaneously in patients during inhalation of anesthesia or due to increased inhaled carbon dioxide, such as what occurs from rebreathing gases that had been exhaled. The most common cause, however, is due to an exhausted carbon dioxide absorbent in the anesthesia machine is the most common cause.
Because there are several possible causes for this condition, your veterinarian will most likely use differential diagnosis. This process is guided by deeper inspection of the apparent outward symptoms, ruling out each of the more common causes until the correct disorder is settled upon and can be treated appropriately. If your cat is conscious, your doctor will check your cat for symptoms of hyperthermia (body temperature that is too high), hypoxemia (lack of oxygen), and head trauma. If your cat is not conscious, especially if it is due to being anesthetized, your veterinarian will check your cat for hypoxemia.
If none of these disorders are found to be the cause of the symptoms, your veterinarian will perform an upper airway endoscopy to rule out a laryngeal mass or paralysis of the larynx (muscles of the throat).
The group of processes that involve the use of nutrients by the body
The inside part or region of something
The area between the folds of the pleura; airtight
Pertaining to the lungs
Pertaining to the chest
The voice box; this is one part of the respiratory system
High body temperature
The muscle in the abdomen that aids in breathing
The protein that moves oxygen in the blood
The condition of having a part of a body part protruding through the tissue that would normally cover it
High levels of carbon dioxide in the blood
A condition of the body in which pH levels are abnormally low.