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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
- Giguère, Steeve, Sanchez, L. Chris, Shih, Andre
- Journal of veterinary emergency and critical care 2014 v.24 no.5 pp. 529-535
- ears, foals, hemoglobin, isoflurane, monitoring, oxygen, reflectance, tongue
- OBJECTIVES: To (1) assess the agreement between calculated values for arterial hemoglobin saturation of oxygen (SaO₂) and values obtained by co‐oximetry, (2) assess the accuracy of 2 pulse oximetry monitors for measurement of SaO₂ in foals, and for each monitor, and (3) determine the optimal combination of sensor type and site of sensor placement for SaO₂ monitoring. DESIGN: Prospective experimental study. SETTING: University teaching hospital. ANIMALS: Six neonatal foals. INTERVENTIONS: Foals were anesthetized with isoflurane and SaO₂ was manipulated by varying the inspired fraction of oxygen. SaO₂ was calculated from oxygen tension or measured by pulse oximetry using 2 monitors equipped with transmission or reflectance sensors attached to the foal's tongue, lip, ear, or inserted rectally (reflectance sensor only). SaO₂ values measured by co‐oximetry were used as the gold standard to calculate bias. MEASUREMENTS AND MAIN RESULTS: Mean (±SD) SaO₂ determined by co‐oximetry was 65.2% ± 11.8%, 85.4% ± 2.5%, and 97.2% ± 0.4% at the low, intermediate, and high SaO₂ level, respectively. Sensors attached to the ear failed to provide SaO₂ readings for most attempts. Reflectance sensors placed on the lip or rectally gave significantly larger biases at low SaO₂ (−17.0% and −23.6%, respectively) than at higher levels. Bias of all other combinations of monitors, sensors, and sites (−1.8 to −4.1%) was not significantly influenced by the level of SaO₂ or different from each other. The bias of calculated saturation was similar to that of pulse oximetry. CONCLUSIONS: Transmission sensors placed on the lip or tongue or reflectance sensors placed on the tongue give the most accurate assessment of SaO₂ in anesthetized neonatal foals. Calculated saturation is not more accurate than pulse oximetry to estimate SaO₂.