CO2 narcosis

Background

Respiratory system complete en.svg
Normal gas exchange showing compositions of the ambient air, the alveolar air (light blue) with which the alveolar capillary blood equilibrates, and the blood gas tensions in the pulmonary arterial (blue blood entering the lung on the left) and venous blood (red blood leaving the lung on the right). All the gas tensions are in kPa (to convert to mm Hg, multiply by 7.5).
  • Increased CO2 in the blood leading to depressed mental status
  • Most commonly seen in acute exacerbations of obstructive pulmonary diseases (e.g. COPD, asthma)
  • Can also be seen in SCUBA divers

Clinical Features

Differential Diagnosis

Altered mental status

Diffuse brain dysfunction

Primary CNS disease or trauma

Psychiatric

Evaluation

  • VBG (ABG not required to make this diagnosis[1])

Management

  • Hyperventilation with either NIPPV or intubation/mechanical ventilation depending on severity and patient's mental status

Disposition

  • Admission to a monitored setting

See Also

External Links

References

  1. McCanny P, Bennett K, Staunton P, McMahon G. Venous vs arterial blood gases in the assessment of patients presenting with an exacerbation of chronic obstructive pulmonary disease. Am J Emerg Med. 2012; 30(6):896-900.