Model of SpO2 signal of the neonate

Abstract

The advantages of automatic control of the fraction of inspired oxygen in neonates have been documented in recently published clinical trials. Many control algorithms are available, but their comparison is missing in the literature. A mathematical model of neonatal oxygen transport could be a useful tool to compare and enhance both automatic control algorithms and manual control of fraction of inspired oxygen. Besides other components, the model of neonatal oxygen transport must include a module linking arterial (SaO2) and peripheral (SpO2) oxygen saturation. The pulse oximeter module must reflect issues of SpO2 measurement typical for clinical practice, such as overestimation of SpO2 over SaO2 documented by several studies, or inaccurate pulse oximeter readings due to high noise. The aim of this study was to describe both the bias between SaO2 and SpO2 and the noise, characteristic for continuous SpO2 recording, for a computer model of oxygenation of a premature infant. The SpO2-SaO2 bias, derived from available clinical data, describes a typical deviation of the SpO2 measurement as a function of the true SaO2 value in three different SaO2 intervals. The SpO2 measurement noise was considered as a random process that affects biased SpO2values at each time point with statistical properties estimated from SpO2 continuous recordings of 5 stable newborns. The results of the study will help to adjust a computer model of neonatal oxygenation to the real situations observed in the clinical practice.

Statistical Description of SaO2–SpO2 Relationship for Model of Oxygenation in Premature Infants

“…The model of the output of the pulse oximeter consists of two parts: the SaO 2 -SpO 2 bias and the SpO 2 measurement noise. The SaO 2 -SpO 2 bias was determined from the Ross' clinical data [11] in the SaO 2 range of 70-100% in our previous study [30]. The bias values slightly differ between previously published clinical studies [11,14,18].…”

“…The model of the output of the pulse oximeter consists of two parts: the SaO 2 -SpO 2 bias and the SpO 2 measurement noise. The SaO 2 -SpO 2 bias function was determined in our previous study [30]. The SpO 2 measurement noise was estimated for two different groups of patients, physiological neonates and pathological neonates.…”

“…The SaO 2 -SpO 2 bias function was determined in our previous study [30] based on clinical data acquired by Ross et al [11]. We used the part of the data that included mechanically ventilated hypoxemic premature and term infants aged between the 37th week of gestation and the 60th day after delivery.…”