Agreement of SpO₂, SaO₂ and ScO₂ in anesthetized cynomolgus monkeys (Macaca fascicularis)

Objective: To assess the agreement between three measurements of arterial oxygen saturation (SpO₂, SaO₂ and ScO₂) in anesthetized cynomolgus monkeys.

Study design: Prospective study.

Animals: Eleven mature, male cynomolgus monkeys (Macaca fasicularis).

Methods: Monkeys were anesthetized with intramuscular ketamine followed by intravenous propofol. The trachea of each was intubated and the lungs ventilated. Arterial oxygen saturation was measured with a Nonin 8500 V pulse oximeter, using a lingual clip on the cheek. Arterial blood samples were taken from an indwelling catheter. Inspired oxygen concentration was varied from 12 to 20%, and 88 paired arterial blood samples and saturation measurements were taken. Arterial oxygen saturation in the blood samples was measured using a cooximeter. The saturation was also calculated from the arterial oxygen tension using the Adair equation. The results were compared using Bland and Altman's method.

Results: The pulse oximeter readings were 2.7% higher than that of the cooximeter, with a limit of agreement of -3.9 to 9.3%. The pulse oximeter readings were 1.8% higher than the calculated saturation, with a limit of agreement of -6.5% to 10.1%. The cooximeter readings were 0.9% lower than the calculated saturation, with a limit of agreement of -5.6% to 3.8%.

Conclusions: The agreement between SpO₂ and other measurements of arterial oxygen saturation in this study is typical for this technique. The bias and limits of agreement are consistent with reports in other species.

Clinical relevance: The Nonin 8500 V is a useful pulse oximeter for clinical use in primates.