Relationship between venous and arterial carboxyhemoglobin levels in patients with suspected carbon monoxide poisoning

Ann Emerg Med. 1995 Apr;25(4):481-3. doi: 10.1016/s0196-0644(95)70262-8.


Study objective: To test the hypothesis that venous carboxyhemoglobin (V-COHb) levels accurately predict arterial (A-COHb) levels.

Design: Prospective comparison of A-COHb and V-COHb levels in patients with suspected carbon monoxide (CO) poisoning.

Setting: Municipal hospital emergency department with contiguous multiplace hyperbaric chamber staffed 24 hours a day.

Participants: Unselected convenience sample of 61 adults with suspected CO toxicity.

Intervention: Simultaneous sampling of arterial and venous blood.

Results: Correlation between V-COHb and A-COHb showed an r value of .99 (95%CI, .99 to .99), and an r2 value of .98. Agreement between V-COHb and A-COHb levels was examined by use of a plot of arteriovenous differences against the mean of the two measurements. The mean arteriovenous difference was .15% COHb (95%CI, .13% to .45%), with 95% of the differences ranging from 2.4% COHb to -2.1% COHb.

Conclusion: Venous COHb levels predict arterial levels with a high degree of accuracy. Patients with suspected CO poisoning can be screened with the use of venous blood, without the need for arterial puncture.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Arteries
  • Blood Specimen Collection / methods
  • Carbon Monoxide Poisoning / blood*
  • Carboxyhemoglobin / metabolism*
  • Emergency Service, Hospital
  • Female
  • Humans
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prospective Studies
  • Veins


  • Carboxyhemoglobin