From the Guidelines
Respiratory alkalosis is primarily caused by hyperventilation, which can be triggered by various factors including anxiety, panic attacks, and certain medical conditions. This condition occurs when the respiratory rate increases beyond what is needed for normal gas exchange, resulting in a decrease in blood carbon dioxide levels and a subsequent increase in blood pH. According to a study published in the American Journal of Respiratory and Critical Care Medicine 1, psychogenic disorders such as anxiety and hyperventilation syndrome can lead to respiratory alkalosis. The study found that subjects with hyperventilation syndrome often have abnormal breathing patterns at rest and during exercise, which can result in impressive hyperventilation and respiratory alkalosis.
Some common causes of respiratory alkalosis include:
- Anxiety or panic attacks, which trigger rapid breathing
- High fever, which increases metabolic rate and respiratory drive
- High altitude exposure, where lower oxygen levels stimulate breathing
- Severe pain, which can induce hyperventilation
- Certain medications like salicylates (aspirin), progesterone, and some stimulants
- Central nervous system disorders affecting respiratory control
- Pregnancy, due to hormonal changes
- Liver disease
- Mechanical ventilation when settings are too aggressive
- Sepsis and severe infections, which can cause respiratory alkalosis as the body attempts to compensate for metabolic acidosis
- Pulmonary disorders like pneumonia, pulmonary embolism, and asthma, which may trigger increased respiratory rates
A more recent study published in the Journal of Clinical Sleep Medicine 1 found that periodic hyperventilation, as seen in central sleep apnea with Cheyne-Stokes breathing, can assist forward cardiac output and provide a buffer against acidosis in patients with heart failure. The study suggests that respiratory alkalosis, which is characterized by low PaCO2 and high pH, can be a compensatory mechanism in certain medical conditions. Therefore, it is essential to address the underlying cause of respiratory alkalosis while monitoring blood gases to ensure proper correction of the acid-base imbalance.
From the Research
Causes of Respiratory Alkalosis
- Respiratory alkalosis can be caused by pulmonary or extrapulmonary disorders 2
- Hyperventilation syndrome is a common etiology of respiratory alkalosis in the emergency department setting and is a diagnosis by exclusion 2
- Hyperventilation is defined as breathing in excess of the metabolic needs of the body, eliminating more carbon dioxide than is produced, and, consequently, resulting in respiratory alkalosis and an elevated blood pH 3
- Panic disorder may be related to respiratory alkalosis, as some panic patients have a chronic, subtle respiratory disturbance and acute hyperventilation is neither necessary nor sufficient for panic to occur 4
- Chronic hyperventilation may engender a self-perpetuating mechanism within the pathophysiology of panic disorder, which may contribute to the chronicity of panic and anxiety symptoms 5
- Respiratory abnormalities, such as low end-tidal CO2 and high variance in minute ventilation at baseline, may predict panic attacks during CO2 inhalation 6
Specific Causes
- Pulmonary disorders, such as chronic obstructive pulmonary disease, may lead to respiratory alkalosis 2
- Extrapulmonary disorders, such as cardiac conditions, may also cause respiratory alkalosis 2
- Hyperventilation syndrome, which can be caused by physiological or psychological mechanisms, is a common cause of respiratory alkalosis 3
- Panic disorder, which may be related to hypersensitive CO2 chemoreceptors, can also lead to respiratory alkalosis 4, 5, 6