respiratory alkalosis

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Respiratory Alkalosis



Respiratory alkalosis is a condition where the amount of carbon dioxide found in the blood drops to a level below normal range. This condition produces a shift in the body's pH balance and causes the body's system to become more alkaline (basic). This condition is brought on by rapid, deep breathing called hyperventilation.


Respiratory alkalosis is an alkali imbalance in the body caused by a lower-than-normal level of carbon dioxide in the blood. In the lungs, oxygen from inhaled air is exchanged for carbon dioxide from the blood. This process takes place between the alveoli (tiny air pockets in the lungs) and the blood vessels that connect to them. When a person hyperventilates, this exchange of oxygen for carbon dioxide is speeded up, and the person exhales too much carbon dioxide. This lowered level of carbon dioxide causes the pH of the blood to increase, leading to alkalosis.

Causes and symptoms

The primary cause of respiratory alkalosis is hyperventilation. This rapid, deep breathing can be caused by conditions related to the lungs like pneumonia, lung disease, or asthma. More commonly, hyperventilation is associated with anxiety, fever, drug overdose, carbon monoxide poisoning, or serious infections. Tumors or swelling in the brain or nervous system can also cause this type of respiration. Other stresses to the body, including pregnancy, liver failure, high elevations, or metabolic acidosis can also trigger hyperventilation leading to respiratory alkalosis.
Hyperventilation, the primary cause of respiratory alkalosis, is also the primary symptom. This symptom is accompanied by dizziness, light headedness, agitation, and tingling or numbing around the mouth and in the fingers and hands. Muscle twitching, spasms, and weakness may be noted. Seizures, irregular heart beats, and tetany (muscle spasms so severe that the muscle locks in a rigid position) can result from severe respiratory alkalosis.


Respiratory alkalosis may be suspected based on symptoms. A blood sample to test for pH and arterial blood gases can be used to confirm the diagnosis. In this type of alkalosis, the pH will be elevated above 7.44. The pressure of carbon dioxide in the blood will be low, usually under 35 mmHg.

Key terms

Hyperventilation — Rapid, deep breathing, possibly exceeding 40 breaths/minute. The most common cause is anxiety, although fever, aspirin overdose, serious infections, stroke, or other diseases of the brain or nervous system.
pH — A measurement of acid or alkali (base) of a solution based on the amount of hydrogen ions available. Based on a scale of 14, a pH of 7.0 is neutral. A pH below 7.0 is an acid; the lower the number, the stronger the acid. A pH above 7.0 is a base; the higher the number, the stronger the base. Blood pH is slightly alkali with a normal range of 7.36-7.44.


Treatment focuses on correcting the underlying condition that caused the alkalosis. Hyperventilation due to anxiety may be relieved by having the patient breath into a paper bag. By rebreathing the air that was exhaled, the patient will inhale a higher amount of carbon dioxide than he or she would normally. Antibiotics may be used to treat pneumonia or other infections. Other medications may be required to treat fever, seizures, or irregular heart beats. If the alkalosis is related to a drug overdose, the patient may require treatment for poisoning. Use of mechanical ventilation like a respirator may be necessary. If the respiratory alkalosis has triggered the body to compensate by developing metabolic acidosis, symptoms of that condition may need to be treated, as well.


If the underlying condition that caused the respiratory alkalosis is treated and corrected, there may be no long-term effects. In severe cases of respiratory alkalosis, the patient may experience seizures or heart beat irregularities that may be serious and life threatening.



"Fluid, Electrolyte, and Acid-Base Disorders." In Family Medicine Principles and Practices. 5th ed. New York: Springer-Verlag, 1998.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

res·pi·ra·to·ry al·ka·lo·sis

alkalosis resulting from abnormal loss of CO2 produced by hyperventilation, either active or passive, with concomitant reduction in arterial plasma bicarbonate concentration.
See also: compensated alkalosis.
Synonym(s): acapnial alkalosis
Farlex Partner Medical Dictionary © Farlex 2012

respiratory alkalosis

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

respiratory alkalosis

Metabolism A condition characterized by ↑ pH due to excess CO2 excretion Etiology Hyperventilation–eg, due to anxiety, pain, panic attacks, psychosis, CVA, fever, encephalitis, meningitis, tumor, trauma, hypoxemia–severe anemia, high altitude, right-to-left shunt, drugs–progesterone, methylxanthines, salicylates, catecholamines, nicotine, hyperthyroidism, pregnancy, ↑ ambient temperature, lung disease–pneumo/hemothorax, pneumonia, pulmonary edema, PE, aspiration, interstitial lung disease, etc–sepsis, liver failure, mechanical ventilation, heat exhaustion, recovery from metabolic acidosis DiffDx Asthma, A Fib, flutter and tachycardia, heatstroke, metabolic acidosis or alkalosis, acute MI, and other causes of RA Clinical Hyperventilation, paresthesia, twitching–positive Chvostek and Trousseau signs, N&V, focal neurologic signs, depressed consciousness, or coma Lab pH > 7.42, HCO3- < 22 mEq/L–if compensating, PaCO2 < 35 mmHg. See Metabolic acidosis, Metabolic alkalosis, Respiratory acidosis.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

res·pi·ra·to·ry al·ka·lo·sis

(res'pir-ă-tōr-ē al'kă-lō'sis)
Alkalosis resulting from an abnormal loss of CO2 produced by hyperventilation, either active or passive, with concomitant reduction in arterial bicarbonate concentration.
See also: compensated alkalosis
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

res·pi·ra·to·ry al·ka·lo·sis

(res'pir-ă-tōr-ē al'kă-lō'sis)
Alkalosis resulting from an abnormal loss of CO2 produced by hyperventilation, either active or passive, with concomitant reduction in arterial bicarbonate concentration.
Medical Dictionary for the Dental Professions © Farlex 2012