The Development of a Measuring System for Intraoral SpO2

Blood oxygen saturation (SpO2) is an essential indicator of a patient's general condition. However, conventional measurement methods have some issues such as time delay and interference by ambient light. Improved measurement methods must be developed, and there are no reports on intraoral measurements of SpO2 using wearable devices. Therefore, we aimed to establish an intraoral SpO2 measurement method for the first time. Twelve healthy adults participated in this study. The following steps were taken: (1) to identify the optimal measurement location, mid-perfusion index (PI) values were measured at six places on the mucosa of the maxilla, (2) to validate the optimal measurement pressure, PI values were obtained at different pressures, and (3) using the proposed mouthpiece device, SpO2 values in the oral cavity and on the finger were analyzed during breath-holding. The highest PI values were observed in the palatal gingiva of the maxillary canine teeth, with high PI values at pressures ranging from 0.3 to 0.8 N. In addition, changes in SpO2 were detected approximately 7 s faster in the oral cavity than those on the finger, which is attributed to their proximity to the heart. This study demonstrates the advantage of the oral cavity for acquiring biological information using a novel device.

Maternal and Neonatal Prognostic Factors for Cardiorespiratory Events in Healthy Term Neonates During Early Skin-to-Skin Contact

BACKGROUND

During early skin-to-skin contact (ESSC), alterations in peripheral oxygen saturation (SpO₂) and heart rate (HR) have been frequently observed.

OBJECTIVES

This study aimed to determine the incidence of cardiorespiratory events (CREs) during ESSC in healthy term newborns (HTNs) and estimate the association of maternal and neonatal prognostic factors with the risk of CREs.

METHODS

A pooled analysis of the cohort from a clinical trial involving healthy mother-child dyads during ESSC was performed. Pulse oximetry was employed to continuously monitor SpO₂ and HR within 2 h after birth. The individual and combined prognostic relevance of the demographic and clinical characteristics of dyads for the occurrence of a CRE (SpO₂ <91% or HR <111 or >180 bpm) was analyzed through logistic regression models.

RESULTS

Of the 254 children assessed, 169 [66.5%; 95% confidence interval (95% CI), 60.5-72.5%] had at least one CRE. The characteristics that increased the risk of CRE were maternal age ≥35 years (odds ratio, 2.21; 95% CI, 1.19-4.09), primiparity (1.96; 1.03-3.72), gestational body mass index (BMI) >25 kg/m² (1.92; 1.05-3.53), and birth time between 09:00 p.m. and 08:59 a.m. (2.47; 1.02-5.97).

CONCLUSION

CREs were more frequent in HTNs born during nighttime and in HTNs born to first-time mothers, mothers ≥35 years, and mothers with a gestational BMI >25 kg/m². These predictor variables can be determined during childbirth. Identification of neonates at higher risk of developing CREs would allow for closer surveillance during ESSC.

Accuracy of Pulse Oximetry in the Presence of Fetal Hemoglobin-A Systematic Review

Continuous monitoring of arterial oxygen saturation by pulse oximetry (SpO2) is the main method to guide respiratory and oxygen support in neonates during postnatal stabilization and after admission to neonatal intensive care unit. The accuracy of these devices is therefore crucial. The presence of fetal hemoglobin (HbF) in neonatal blood might affect SpO2 readings. We performed a systematic qualitative review to investigate the impact of HbF on SpO2 accuracy in neonates. PubMed/Medline, Embase, Cumulative Index to Nursing & Allied Health database (CINAHL) and Cochrane library databases were searched from inception to January 2021 for human studies in the English language, which compared arterial oxygen saturations (SaO2) from neonatal blood with SpO2 readings and included HbF measurements in their reports. Ten observational studies were included. Eight studies reported SpO2-SaO2 bias that ranged from −3.6%, standard deviation (SD) 2.3%, to +4.2% (SD 2.4). However, it remains unclear to what extent this depends on HbF. Five studies showed that an increase in HbF changes the relation of partial oxygen pressure (paO2) to SpO2, which is physiologically explained by the leftward shift in oxygen dissociation curve. It is important to be aware of this shift when treating a neonate, especially for the lower SpO2 limits in preterm neonates to avoid undetected hypoxia.