Respiratory alkalosis
| Respiratory alkalosis | |
 | |
|---|---|
| Davenport diagram | |
| ICD-10 | E87.3 |
| ICD-9 | 276.3 |
| DiseasesDB | 406 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Respiratory alkalosis results from increased alveolar respiration (hyperventilation) leading to decreased plasma carbon dioxide concentration. This leads to decreased hydrogen ion and bicarbonate concentrations.
Types
There are two types of respiratory alkalosis: chronic and acute.
Acute respiratory alkalosis
- Increased levels of carbon dioxide are "blown off" by the lungs, which are hyperventilating.
- During acute respiratory alkalosis, the person may lose consciousness where the rate of ventilation will resume to normal.
Chronic respiratory alkalosis
- For every 10 mM drop in pCO2 in blood, there is a corresponding 5 mM of bicarbonate ion drop.
- The drop of 5 mM of bicarbonate ion is a compensation effect which reduces the alkalosis effect of the drop in pCO2 in blood. This is termed metabolic compensation.
Causes
Lung and airways
Central respiratory drive
- Pain
- Anxiety
- Fever
- High altitude
- CNS tumor
- Drugs like doxapram and large doses of aspirin (stimulate the respiratory center)
- CNS causes, including stroke, subarachnoid haemorrhage, meningitis
- Caffeine overdose and coffee abuse
Systemic diseases
- Sepsis
- Salicylates
- Liver failure
- Hyperthyroid
- Pregnancy
- Hypotension
- CHF
- Anxiety, hysteria, and stress
- Iatrogenically during mechanical ventilation of patients
Special considerations
- Sepsis or salicylate toxicity are the only single disorders that cause both an elevated anion gap metabolic acidosis and a respiratory alkalosis.
- Ischemia, infection or infarction of the central respiratory centers may result either respiratory acidosis (decreased respiratory drive) or respiratory alkalosis (increased respiratory drive)
Symptoms
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) with no fall in total serum calcium levels.