Body tissues metabolize sugar to produce energy, releasing carbon dioxide as a byproduct. Carbon dioxide enters the bloodstream and travels to the lungs. With each exhalation, the lungs rid the body of excess carbon dioxide. The lungs serve as the primary regulator of the amount of carbon dioxide in the blood. Elevated levels of blood carbon dioxide, or hypercapnia, usually indicate a problem with the lungs or brain control of the respiratory rate.
Chronic Obstructive Pulmonary Disease
Patients with severe chronic obstructive pulmonary disease, or COPD, exhibit poor gas exchange with each respiration due to obstructed airflow in the lungs. The inefficient gas exchange leads to impaired release of carbon dioxide, which accumulates in the bloodstream. Among COPD patients with a chronically elevated carbon dioxide level, the kidneys compensate to prevent the blood from becoming too acidic, note Drs. Sarah Faubel and Joel Topf in the reference text "The Fluid, Electrolyte and Acid-Base Companion."
Asthma
During an acute asthma attack, airway obstruction occurs. The reduced airflow causes poor gas exchange, leading to an increased carbon dioxide level in the blood. Since the carbon dioxide level rises rapidly with an asthma attack, the kidneys cannot compensate, and the blood commonly becomes too acidic. This condition, known as acute respiratory acidosis, causes confusion, drowsiness, fatigue and shortness of breath, notes the National Library of Medicine encyclopedia MedlinePlus.
Pickwickian Syndrome
Exceedingly obese patients may exhibit Pickwickian syndrome, also known as obesity hypoventilation syndrome. Patients with this condition cannot fully inflate the lungs due to encroachment caused by excess body fat. The resulting poor ventilation may lead to chronic hypercapnea. These patients often have heart failure and may require mechanical ventilation, notes MedlinePlus.
Depressant Intoxication
Alcohol and depressant medications can cause an abnormally-decreased respiratory rate. These substances act on the respiratory control center of the brain and have additive effects when taken simultaneously. Depressant medications include prescription and illicit narcotics, barbiturates and benzodiazepines. A decreased respiratory rate associated with depressant intoxication commonly leads to elevated blood carbon dioxide levels. Respiratory depression or arrest proves the primary toxic effect of a narcotic, or opioid, overdose, reports "The Merck Manual for Healthcare Professionals."
Sleep Apnea
Sleep apnea is a condition wherein patients stop breathing multiple times during the night for variable periods. The net effect is an overall decrease in ventilation, leading to an increased level of carbon dioxide and a decreased level of oxygen in the blood while sleeping. During the day, the levels of carbon dioxide and oxygen typically return to normal levels. Overweight and obesity increase the likelihood of developing sleep apnea, notes the National Heart Lung and Blood Institute.
References
- "The Fluid, Electrolyte and Acid-Base Companion"; Sarah Faubel, M.D., Joel Topf, M.D.; 1999
- MedlinePlus: Respiratory Acidosis
- MedlinePlus: Obesity Hypoventilation Syndrome
- The Merck Manual for Healthcare Professionals: Opioids, Toxicity or Overdose
- National Heart Lung and Blood Institute: Sleep Apnea
