Hypercapnia

Abnormally elevated arterial carbon dioxide (PaCO₂) above the normal range (35–45 mmHg or 4.6–6.1 kPa), usually caused by alveolar hypoventilation and commonly associated with respiratory acidosis.

Causes

• Pulmonary causes

  • Chronic obstructive pulmonary disease (COPD)

  • Asthma with severe airflow obstruction

  • Cystic fibrosis

  • Pulmonary fibrosis

  • Severe pneumonia

• Mechanical and upper airway causes

  • Obstructive sleep apnea

  • Obesity hypoventilation syndrome

  • Tracheal tumor or airway obstruction

  • Chest wall disorders limiting ventilation

• Neuromuscular and neurological causes

  • Muscular dystrophy

  • Myasthenia gravis

  • Guillain-Barré syndrome

  • Spinal cord injury

  • Stroke

  • Traumatic brain injury

  • Encephalitis

• Medications: Sedatives, opioids

• Environmental causes

  • Poor air circulation

  • Deep-sea diving

  • Rebreathing of carbon dioxide-rich air

• Sepsis

• Depressed respiratory drive

• Postoperative hypoventilation

• Inadequate mechanical ventilation settings

• Sleep-related hypoventilation disorders