|Classification according to ICD-10|
|ICD-10 online (WHO version 2019)|
A metabolic alkalosis (also non-respiratory alkalosis ) is understood to mean an increase in the blood pH value above 7.43 (alkalosis) caused by the metabolism (metabolically ).
In general, a distinction is made between addition and subtraction alkaloses.
Additionsalkalosen are the consequence of treatment with basic -acting drugs , z. B. Sodium hydrogen carbonate .
Subtraction alkaloses are often triggered by treatment with loop diuretics . In the event of vomiting or gastric drainage (secretion of gastric contents ), the loss of gastric acid ( hydrogen and chloride ions ) can also lead to subtraction alkalosis.
Physiological compensation mechanisms
The rule of thumb that metabolically induced derailments of the acid-base balance are balanced out respiratory and vice versa, leads to the problem of hypoxia due to hypoventilation in the case of metabolic alkalosis. For respiratory balance, hypoventilation is necessary in order to increase the carbon dioxide partial pressure in the alveolar air and in the blood and thus the balance of the carbonic acid-bicarbonate system (CO 2 + H 2 O ↔ H 2 CO 3 ↔ H + + HCO 3 - ) to the right. This leads to an "acidification" of the blood pH and thus to the compensation of the alkalosis.
Due to the organism's need for oxygen, however, hypoventilation is only possible to a limited extent, so that metabolic alkalosis is better compensated for by the renal excretion of bicarbonate (base) .
In addition to the above-mentioned hypoventilation as a compensation mechanism, ventricular arrhythmias often occur as a result of the associated hypokalaemia . The predominant extracellular volume deficit (caused by the exchange of Na + and K + - for H + ions taking place in the kidneys as a further compensation mechanism, with Na + H 2 O being involved) manifests itself in hypotension and weakness. Neurologically, these electrolyte shifts lead to paresthesia , spasms up to tetany , confusion and sopor (since a low Na + concentration in the EZV causes persistent depolarizations , which, however, due to the low K + level via the Na + -K + -ATPase, do not can be undone, but remain locked).
The therapeutic focus is on the correction of the usually strong electrolyte disturbance. With pronounced alkalosis, arginine hydrochloride is also used intravenously. Small amounts of hydrochloric acid can also be administered via a central catheter .
( Infusion therapy )