Respiratory alkalosis
Marked by a decrease in the partial pressure of arterial carbon dioxide (Paco2) to less than 35 mm Hg and a rise in blood pH above 7.45, respiratory alkalosis results from alveolar hyperventilation. Uncomplicated respiratory alkalosis leads to a decrease in hydrogen ion concentration, which raises the blood pH. Hypocapnia occurs when the lungs eliminate more carbon dioxide (CO2) than the body produces at the cellular level. In the acute stage, respiratory alkalosis is also called hyperventilation syndrome.
Causes
Predisposing conditions to respiratory alkalosis include:
compensation for metabolic acidosis
heart failure
central nervous system (CNS) injury to the respiratory control center
extreme anxiety
fever
overventilation during mechanical ventilation
pulmonary embolism
salicylate intoxication (early).
Complications
In extreme respiratory alkalosis, related cardiac arrhythmias may fail to respond to usual treatment. Seizures may also occur.
Assessment
The patient’s history may reveal a predisposing factor associated with respiratory alkalosis. The patient may complain of light-headedness or paresthesia (numbness and tingling in his arms and legs).
On inspection, he may seem anxious, with visibly rapid breathing. In severe respiratory alkalosis, tetany may be apparent, with visible twitching and flexion of the wrists and ankles. Auscultation may reveal tachycardia and deep, rapid breathing.
