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Home | Critical Care Compendium | Co-oximeter

Co-oximeter

by Chris Nickson, Last updated April 27, 2016

USES

  • measurement of blood concentration of various forms of haemoglobin

DESCRIPTION

  • a device that uses spectrophotometry to measure relative blood concentrations of oxyhemoglobin, carboxyhemoglobin, methemoglobin, and reduced haemoglobin

METHOD OF INSERTION AND/OR USE

  • a laboratory test involving a blood sample heated to 37 C and subjected to light of various length and assesses absorption spectra.
  • does not require pulsatile flow
  • measures MetHb, COHb and other forms of Hb
  • uses many other wavelengths

OTHER INFORMATION

  • measures either venous, arterial or capillary oxygenation

COMPLICATIONS

Causes of HIGH Co-oximetery and LOW Pulse Oximetry Readings

  • Poor peripheral perfusion
  • Ambient light
  • Poor probe contact
  • Dyes (e.g. methylene blue)
  • Tricuspid regurgitation (and other causes of venous pulsations)

Causes of LOW Co-oximetry and HIGH Pulse Oximetry Readings

  • COHb
  • MetHb
  • Radiofrequency interference
  • Leukocyte larceny (oxygen consumption by cells in the collection tube, may also occur in situations such as severe thrombocytosis)

References and links

FOAM and Web resources

  • AVOXimeter® 4000 Whole Blood Co-Oximeter manual
  • Oximetry.org

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About Chris Nickson

An oslerphile emergency physician and intensivist suffering from a bad case of knowledge dipsosis. Key areas of interest include: the ED-ICU interface, toxicology, simulation and the free open-access meducation (FOAM) revolution. @Twitter | + Chris Nickson | RAGE | INTENSIVE| SMACC

Reader Interactions

Comments

  1. Malini says

    April 27, 2016 at 6:54 am

    what does TR stand for?

    Reply

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