From the Guidelines
Hyperventilation due to anxiety and stress is the most common cause of primary respiratory alkalosis.
Causes of Primary Respiratory Alkalosis
- Hyperventilation syndrome, often associated with psychogenic disorders such as anxiety, hysteria, and panic disorders, is a common cause of primary respiratory alkalosis, as evidenced by studies on cardiopulmonary exercise testing 1.
- This condition is characterized by abnormal breathing patterns, including rapid and shallow breathing, which can lead to respiratory alkalosis due to decreased PaCO2 levels.
- In contrast, other conditions such as septic shock may also cause respiratory alkalosis, but this is often a secondary effect of centrally mediated hyperventilation in the early stages of sepsis 1.
Key Characteristics
- Hyperventilation is a key feature of primary respiratory alkalosis, leading to decreased PaCO2 levels and respiratory alkalosis.
- Psychogenic disorders such as anxiety and stress are common underlying causes of hyperventilation syndrome, which can be diagnosed through careful history taking and review of systems 1.
- Arterial blood gas analysis can help confirm the diagnosis of respiratory alkalosis by showing decreased PaCO2 levels.
From the Research
Causes of Primary Respiratory Alkalosis
- The most common cause of primary respiratory alkalosis is disorders that increase alveolar ventilation, resulting in an arterial partial pressure of CO2 <35 mm Hg and subsequent alkalization of body fluids 2.
- This can be due to various factors, including hyperventilation syndrome, which is a common etiology of respiratory alkalosis in the emergency department setting 3.
- Other causes may include pulmonary or extrapulmonary disorders, such as salicylate poisoning, which can lead to hyperventilation and respiratory alkalosis 4.
- Respiratory alkalosis can also be caused by direct stimulation of the respiratory centers in the medulla, leading to hyperventilation and a compensatory mechanism to avoid acidemia 4.
Key Characteristics
- Primary respiratory alkalosis is defined by an arterial partial pressure of CO2 <35 mm Hg, with subsequent alkalization of body fluids 2.
- It is often associated with concurrent decreases in Paco2, increases in pH, and compensatory decreases in blood HCO3- levels 5.
- Respiratory alkalosis can be acute or chronic, with metabolic compensation initially consisting of cellular uptake of HCO3- and buffering by intracellular phosphates and proteins 5.