Co-oximeter

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