Authors
Kate S. Farrell
Topics
Hemoglobin structure and functionHeme Oxygenase-1 and Carbon MonoxideNeonatal Health and BiochemistryPulse oximetry and co-oximetry have become ubiquitous monitoring tools for the assessment of hemoglobin saturation and oxygenation in anesthetized and critically ill human patients, and they have found widespread use in veterinary medicine as well. While a small percentage of oxygen travels in the blood as dissolved gas, the bulk of oxygen is bound to hemoglobin in red blood cells. Oxygen binding changes the light absorption pattern of hemoglobin. Oximetry monitoring takes advantage of this fact and uses light absorbance characteristics to determine the percentage of oxygenated hemoglobin compared with other hemoglobin species (described later). Hemoglobin oxygen saturation of arterial blood (SO 2 ) can be measured with pulse oximetry (peripheral capillary oxygen saturation, SpO 2 ) or co-oximetry (SaO 2 ). Pulse oximetry uses two wavelengths of light (red and infrared) to determine the percentage of oxyhemoglobin compared with deoxyhemoglobin in arterial blood of a patient's tissues. SpO 2 has been used as a surrogate marker for the partial pressure of oxygen in arterial blood (PaO 2 ), although in veterinary patients there is potential concern for its accuracy. Co-oximetry, on the other hand, uses multiple wavelengths of light to detect numerous hemoglobin forms, including carboxyhemoglobin and methemoglobin, in a blood sample.
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PublishedFeb 17, 2023
Citations2
References48