Etiology and Clinical Manifestations of Respiratory Alkalosis

Definition and Pathophysiology

Respiratory alkalosis is a condition characterized by a decrease in arterial carbon dioxide (PaCO2) due to excessive alveolar ventilation. This leads to an increase in blood pH, resulting in alkalemia.

Etiology

There are several causes of respiratory alkalosis, including:

• Psychogenic Hyperventilation: Anxiety or panic attacks can cause increased respiratory rate.
• Hypoxemia: Conditions such as pneumonia, pulmonary embolism, or severe anemia may stimulate ventilation.
• Central Nervous System Disorders: Stroke, traumatic brain injury, or infections affecting the brainstem respiratory centers.
• Medications: Salicylate intoxication, progesterone therapy, and excessive mechanical ventilation settings.
• Sepsis and Fever: Systemic infections lead to increased metabolic demand, enhancing ventilation.

Clinical Manifestations

Patients with respiratory alkalosis may exhibit various symptoms, including:

• Dizziness or lightheadedness due to cerebral vasoconstriction.
• Paresthesias (tingling sensation), particularly in the fingers and around the mouth.
• Carpopedal spasms and tetany caused by hypocalcemia.
• Confusion or difficulty concentrating.
• Dyspnea (shortness of breath) despite excessive breathing.

Diagnosis

Diagnosis of respiratory alkalosis is confirmed through arterial blood gas (ABG) analysis, which reveals decreased PaCO2 and elevated pH.

Treatment

Management of respiratory alkalosis depends on its underlying cause:

• For anxiety-induced hyperventilation, reassurance and breathing exercises may help.
• Oxygen therapy for hypoxemia-induced hyperventilation.
• Adjusting ventilator settings in mechanically ventilated patients.
• Addressing infections or metabolic disorders contributing to hyperventilation.

In most cases, addressing the primary condition normalizes ventilation and corrects the alkalosis.