Respiratory alkalosis

From Wikipedia, the free encyclopedia - View original article

Respiratory alkalosis
Classification and external resources
Davenport Fig 11.jpg
ICD-10E87.3
ICD-9276.3
DiseasesDB406
MedlinePlus000111
eMedicinemed/2009
MeSHD000472
 
Jump to: navigation, search
Respiratory alkalosis
Classification and external resources
Davenport Fig 11.jpg
ICD-10E87.3
ICD-9276.3
DiseasesDB406
MedlinePlus000111
eMedicinemed/2009
MeSHD000472

Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH (a condition generally called alkalosis). It is one of four basic categories of disruption of acid-base homeostasis. This condition is commonly associated with a decrease in PaCO2 (hyperventilation).

Terminology[edit]

Types[edit]

There are two types of respiratory alkalosis: chronic and acute.

Mechanism[edit]

Respiratory alkalosis generally occurs when some stimulus (see "Causes" below) makes a person hyperventilate. The increased breathing produces increased alveolar respiration, expelling CO2 from the circulation. This alters the dynamic chemical equilibrium of carbon dioxide in the circulatory system, and the system reacts according to Le Chatelier's principle. Circulating hydrogen ions and bicarbonate are shifted through the carbonic acid (H2CO3) intermediate to make more CO2 via the enzyme carbonic anhydrase according to the following reaction:

\rm HCO_3^- + H^+ \rightarrow H_2CO_3 \rightarrow CO_2 + H_2O

The net result of this is decreased circulating hydrogen ion concentration, and thus increased pH (alkalosis). There is also a decrease in ionized blood calcium concentration.

Causes[edit]

Respiratory alkalosis may be produced accidentally (iatrogenically) during excessive mechanical ventilation. Other causes include:

Symptoms[edit]

Symptoms of respiratory alkalosis are related to the decreased blood carbon dioxide levels, and include peripheral paraesthesiae. In addition, the alkalosis may disrupt calcium ion balance, and cause the symptoms of hypocalcaemia (such as tetany and fainting) with no fall in total serum calcium levels. However, chronic respiratory alkalosis leads to hyperphosphatemia and hypocalcemia, by inducing renal PTH-resistance.[1]

In popular culture[edit]

In The Andromeda Strain, Michael Crichton's first novel published under his real name, only two people exposed to a pathogenic extraterrestrial microbe survive. Scientists investigating these survivors discover that each had abnormal blood pH. One, a baby, had respiratory alkalosis due to constant crying; the other, an old man, drinks Sterno. As a result, it becomes clear that the microbe cannot survive outside a narrow pH range.

See also[edit]

References[edit]

  1. ^ Krapf, Reto; Jaeger, Philippe; Hulter, Henry N (10 April 1992), Chronic respiratory alkalosis induces renal PTH-resistance, hyperphosphatemia and hypocalcemia in humans, Kidney International (42): 727–734, doi:10.1038/ki.1992.340, ISSN 0085-2538