Accuracy of calculated arterial saturation in oxygen in neonatal foals and effects of monitor, sensor, site of sensor placement, and degree of hypoxemia on the accuracy of pulse oximetry.

The research investigates the accuracy of measuring oxygen saturation (SaO2) levels in newborn foals using different monitors, sensors, and sensor placements under varied oxygen supply circumstances. The study highlights that transmission sensors placed on the lip or tongue, or reflectance sensors on the tongue yield the most precise results, and manually calculated saturation does not display greater accuracy than the use of pulse oximetry.

Objective of the Research

• The research aimed at comparing the agreement between architecturally calculated oxygen saturation (SaO2) values and those obtained through co-oximetry, a method considered as the gold standard in this context.
• Another objective was to ascertain the reliability of two pulse oximetry monitors in assessing SaO2 levels in neonatal foals.
• The research also sought to establish the best combination of sensor type and placement for effective and accurate monitoring of SaO2.

Research Methodology

• This study employed a prospective experimental design performed at a university teaching hospital.
• Six neonatal foals were anesthetized using isoflurane, and their SaO2 levels were manipulated by altering the proportion of inspired oxygen.
• Researchers calculated SaO2 from oxygen tension or measured SaO2 using two different pulse oximeters armed with transmission or reflectance sensors positioned variously on the foal’s tongue, ear, lip, and rectally (only for the reflectance sensor).

Results of the Study

• In comparison with the accepted standard, SaO2 as measured by co-oximetry varies significantly based on the oxygen administered – 65.2% ± 11.8%, 85.4% ± 2.5%, and 97.2% ± 0.4% at low, intermediate, and high levels of oxygen supply respectively.
• Sensors attached to the ear were mostly ineffective in providing SaO2 readings.
• There were significantly large biases in the SaO2 readings taken at low oxygen levels with reflectance sensors placed on the lip or rectally (-17.0% and -23.6% respectively) versus the readings at higher oxygen levels.
• All other combinations of monitors, sensors, and placements didn’t display a significant difference with the level of SaO2 and were not significantly different from each other (Bias of -1.8 to -4.1%).
• The calculated saturation bias was similar to that of pulse oximetry.

Conclusion of the Research

• Transmission sensors placed on the tongue or lip of the foals and reflectance sensors on the tongue offer the most reliable assessment of SaO2 in anesthetized neonatal foals.
• Calculated saturation does not bear more accuracy than pulse oximetry when estimating SaO2 levels.