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Finger tip carboxyhemoglobin saturation monitor.

CO-oximeter is a device that measures the oxygen carrying state of hemoglobin in a blood specimen. Co-oximetry is useful in defining the causes for hypoxemia, hypoxia, or oxygen deficiency at the tissue level.

The test is done with a device that measures absorption at several wavelengths to distinguish oxyhemoglobin from carboxyhemoglobin and determine the oxyhemoglobin saturation: the percentage of oxygenated Hemoglobin compared to the total amount of hemoglobin (Hb), including carboxyhemoglobin (carboxy-Hb), Methemoglobin (met-Hb), oxyhemoglobin (oxy-Hb), and reduced hemoglobin (reduced Hb). When a patient presents with carbon monoxide poisoning (CO), the CO-oximeter will detect the levels of each hemoglobin and will report the oxyhemoglobin saturation as markedly reduced.[citation needed]


Traditionally, this measurement is made from arterial blood processed in a blood gas analyzer with a CO-oximeter.[1][2] More recently, pulse CO-oximeters have made it possible to estimate carboxyhemoglobin with non-invasive technology similar to a Pulse oximeter.[3] In contrast, the use of a standard pulse oximeter is not effective in the diagnosis of CO poisoning as patients suffering from carbon monoxide poisoning may have a normal oxygen saturation reading on a pulse oximeter.[4]


  1. ^ Rodkey FL, Hill TA, Pitts LL, Robertson RF (August 1979). "Spectrophotometric measurement of carboxyhemoglobin and methemoglobin in blood". Clinical Chemistry 25 (8): 1388–93. PMID 455674. Retrieved 2009-07-17. 
  2. ^ Rees PJ, Chilvers C, Clark TJ (January 1980). "Evaluation of methods used to estimate inhaled dose of carbon monoxide". Thorax 35 (1): 47–51. doi:10.1136/thx.35.1.47. PMC 471219. PMID 7361284. Retrieved 2009-07-17. 
  3. ^ Coulange M, Barthelemy A, Hug F, Thierry AL, De Haro L (2008). "Reliability of new pulse CO-oximeter in victims of carbon monoxide poisoning". Undersea & Hyperbaric Medicine 35 (2): 107–11. PMID 18500075. Retrieved 2009-07-17. 
  4. ^ Vegfors M, Lennmarken C (May 1991). "Carboxyhaemoglobinaemia and pulse oximetry". British Journal of Anaesthesia 66 (5): 625–6. doi:10.1093/bja/66.5.625. PMID 2031826.