Acidosis, respiratory

Respiratory Acidosis

Respiratory acidosis is a medical condition characterized by an excess of carbon dioxide (CO₂) in the blood, leading to a decrease in blood pH. This condition occurs when the lungs cannot remove enough CO₂ produced by the body, resulting in a disturbance of the acid-base balance.

Pathophysiology

Respiratory acidosis is primarily caused by alveolar hypoventilation, which leads to an accumulation of CO₂ in the blood. The increase in CO₂ results in the formation of carbonic acid, which dissociates into hydrogen ions and bicarbonate, thereby lowering the pH of the blood.

Causes

Several conditions can lead to respiratory acidosis, including:

• Chronic obstructive pulmonary disease (COPD): A group of lung diseases that block airflow and make it difficult to breathe.
• Asthma: A condition in which your airways narrow and swell and may produce extra mucus.
• Obstructive sleep apnea: A potentially serious sleep disorder in which breathing repeatedly stops and starts.
• Neuromuscular disorders: Conditions such as myasthenia gravis or Guillain-Barré syndrome that affect the muscles involved in breathing.
• Chest wall disorders: Conditions like kyphoscoliosis that restrict lung expansion.

Compensation

The body attempts to compensate for respiratory acidosis through renal mechanisms. The kidneys increase the excretion of hydrogen ions and reabsorb bicarbonate to help normalize blood pH. However, this compensation is slow and may take several days to be effective.

Diagnosis

The diagnosis of respiratory acidosis is typically made through arterial blood gas (ABG) analysis, which measures the levels of oxygen, carbon dioxide, and blood pH. A high partial pressure of carbon dioxide (PaCO₂) and a low pH indicate respiratory acidosis.

Treatment

Treatment of respiratory acidosis focuses on addressing the underlying cause of hypoventilation. This may include:

• Bronchodilators: To open the airways in conditions like asthma or COPD.
• Non-invasive ventilation: Such as continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) to support breathing.
• Oxygen therapy: To ensure adequate oxygenation.
• Mechanical ventilation: In severe cases where non-invasive methods are insufficient.

Prognosis

The prognosis of respiratory acidosis depends on the underlying cause and the effectiveness of treatment. Chronic respiratory acidosis, often seen in COPD, may require long-term management strategies.

Also see

• Metabolic acidosis
• Acid-base homeostasis
• Chronic obstructive pulmonary disease
• Arterial blood gas