A novel fontanelle probe for sensing oxygen saturation in the neonate

Monitoring of blood oxygen saturation (SpO 2 ) of the neonate is essential to the quality of health care provided on a neonatal intensive care unit (NICU). Current sensors are usually placed at the hand or foot, which are dependent of a peripheral blood supply. When the peripheral blood circulation of neonates is compromised conventional peripheral pulse oximeters, in many cases, fail to operate accurately or at all. A new reflectance anterior fontanelle (ANTF) SpO 2 sensor and instrumentation has been developed to investigate SpO 2 s from the neonatal fontanelle. The hypothesis is that perfusion at a central site should be preserved at times of compromised peripheral circulation. Fifteen neonates on an NICU (9 male, 6 female) with a median age of 7 d (IQR = 41.5 d) were selected for monitoring. ANTF photoplethysmographic (PPG) signals were monitored for a maximum period of 2 h. The developed system and custom made sensors were successful at acquiring good quality signals at both wavelengths necessary for pulse oximetry calculations. ANTF SpO 2 s, estimated from the acquired PPGs, were in broad agreement with SpO 2 s obtained from the commercial foot pulse oximeter. A Bland and Altman analysis of the differences between SpO 2 s from the fontanelle PPG sensor and the commercial device show a relatively small mean difference (d = ±2.2%), but with a wide variation (2s = ±17.4%) this observation may be due to the varied levels of ill health patients and is backed up by comparing the commercial device SpO 2 readings at the same moment a blood gas sample was taken (d = 4.8%, 2s = ±15.8%)