hyperventilation

Hyperventilation is a state in which ventilation exceeds the body's metabolic needs, leading to a decrease in arterial carbon dioxide (PaCO2) and often to respiratory alkalosis. It can occur in otherwise healthy individuals during anxiety or panic, but may also arise from medical or respiratory conditions.

Symptoms commonly include lightheadedness or dizziness, numbness or tingling around the mouth and in the hands and feet, shortness of breath, chest tightness, palpitations, and sometimes faintness. The reduced PaCO2 causes cerebral vasoconstriction, which contributes to these sensations and may lead to syncope in some cases. Other signs depend on the underlying cause.

Causes are diverse and range from psychogenic to medical. Acute anxiety, panic attacks, stress, or pain are frequent triggers. Other contributors include fever, infection, metabolic disturbances, drug effects, strenuous exercise, high altitude, and certain toxins. Chronic or pattern hyperventilation, known as hyperventilation syndrome, involves persistently altered breathing patterns that are not explained by an acute illness.

Diagnosis is clinical and guided by history and examination. Arterial blood gas analysis typically shows respiratory alkalosis: low PaCO2 and elevated blood pH. Capnography or end-tidal CO2 monitoring can reveal reduced CO2. It is important to exclude other causes of dyspnea or chest pain, such as asthma, pulmonary embolism, pneumothorax, or cardiac events, when symptoms are concerning.

Management focuses on treating the underlying cause and calming the breathing. Reassurance and breathing retraining techniques (slow, diaphragmatic breathing, pursed-lip breathing) help restore normal ventilation. Avoidance of unnecessary measures that may pose risks (for example, indiscriminate bag rebreathing) is advised. Severe cases or persistent symptoms may require medical evaluation or treatment of anxiety disorders, with behavioral therapies and, when appropriate, pharmacotherapy.