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%).