BGscope: a non-invasive, continuous, and accurate O2 AND CO2 sensing

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PROJECT SUMMARY/ABSTRACT: Blood gases are the primary indicators of effectiveness of ventilation, circulation and perfusion in neonates. Every year ~ 4 million babies are born in the United States. Of these, 15% (~500,000) suffer from respiratory distress mainly due to prematurity and/or low birth weight. These babies are transferred to the neonatology intensive care unit (NICU) immediately after birth, for whom approximately 10 million blood gas tests are performed annually. The gold standard of measuring blood gases are invasive procedures where blood is drawn through arterial lines connected to the umbilical cord, through needle pokes of the heel (known as heel stick) for capillary blood or through a venous line. While arterial sampling provides the highest accuracy, it is not easy to perform and poses a high risk of infection; capillary sampling is the most frequently performed procedure, with the consequences of being painful and a high chance of sample clotting; venous sampling is very easy to perform with the least accuracy among all the previous methods. Therefore, non-invasive, continuous monitoring devices are essential to avoid the adverse effects of the blood gas test. Oxygen (O2) and carbon dioxide (CO2), are the most important respiratory gases, and their partial pressures (PO2 and PCO2) and oxygen saturation (SO2) collectively reflect the overall adequacy of respiratory function. Conventional O2 sensors (popularly known as pulse oximeters) are based on optical spectrophotometry technology and are relatively large to be placed on the limb of the premature/ preterm neonate and consequently lose signal integrity. CO2 sensors (popularly known as transcutaneous CO2) detect the dissolved CO2 gas in blood through skin by depositing heat onto a localized capillary bed. In both cases, the blood gas measurement is at the capillary level and is unable to provide the accuracy of the gold standard. In addition, these sensors are capable of only measuring one of two blood gases. Moreover, continuous operation of these sensors generates heat and may damage the sensitive skin of neonates. Therefore, frequent repositioning of the sensor is required, and further blood draws are necessary for the sensor recalibration. Our product non-invasively measures arterial blood gas; partial pressures of O2 and CO2 (PO2 and PCO2) and SO2. It is a simple wristband that can be used at the wrist or ankle. It does not generate heat or damage sensitive tissue. It continuously measures arterial blood gases (O2 and CO2) with high accuracy. Our proposed device will help reducing the blood draws from NICU babies by ~75%. We have named it BGScope for Blood Gas Scope. BGScope works based on the principles of multispectral photoacoustic imaging. Our short-term goals are: (i) to develop the BGScope device and a computational kernel to non-invasively measure arterial blood gases including, partial pressures of O2 and CO2 and oxygen saturation (SO2); and (ii) to conduct a pilot study to evaluate the BGScope on rabbits.