Electro-Optical Detection of Vital Signs During the Resuscitation and early life of Newborns

10% of births require some form of resuscitation - ie 80,000 births/year in the UK. The best indicator for resuscitation success is heart rate (HR). The traditional method of recording HR for newborns is with a stethoscope but this has delays & errors [Voogdt 2009, ArchDisChild 94] whilst the clinician counts the beats over say 10 seconds in these early golden seconds of life. The patented technology transferred to Surepulse Medical Ltd (also from UoN EPSRC PhD CASE) detects
HR of newborn babies via an instrumented head-mounted cap. The cap incorporates an optical sensor (utilising green wavelength in "reflection mode") that senses the pulsing blood and hence generates HR quickly and without errors
on the progression of the resuscitation. Surepulse has now been awarded its Medical Devices CE mark for this product. Moving forward, by addition of red and infra-red wavelengths it is possible to measure the level of oxygen in the blood (SpO2). The monitoring of SpO2 is customary practice in operating rooms and intensive care units for assessing the condition of patients. However, current SPO2 sensors are deployed on the finger where the light passes through the digit - "transmission mode". In patients with poor peripheral perfusion (low blood flow) such as newborns then a forehead sensor is more relevant than digit sensors. However, here the optical device must operate in "reflection mode" - the exact mode operated by Surepulse. Consequently, this proposed research initially involves the detection of SpO2 in "reflection mode" in low perfusion cases directly applicable for newborns. Here the signal levels are very small and present a research challenge based around wavelength choice, source/sensor separation and low noise optoelectronics - a specialist area of our team. In this research stage a spectrophotometer will be used to capture the tissue reflectance spectrum.
The additional (above two wavelengths) data will enable more accurate estimates of SpO2 to be made in order to evaluate a future two wavelength device. Further, given the low oxygenation levels at birth and difference in the spectra of fetal-haeomoglobin it is possible that the usual red and infrared wavelengths used may be sub-optimal in this application. The deployment of a combined Heart Rate (via the PPG) and SpO2 will allow us to
undertake studies by integrating the Surepulse's new ECG device. This will allow the measurement of Pulse Transit Time as a surrogate for the measurement of blood pressure to be explored along with a wealth of other physiological variables. Note: Although this work is primarily for the field of Newborns the extent of the research work will not be limited to this. For example, applications to other low perfusion or reflection mode settings, such as the elderly, will not be excluded during the course of this project.