It is a rare event when new and useful medical parameters can be added to the suite of monitoring and diagnostic tests available in a clinical setting. Of particular importance is the ability to measure crucial physiological parameters or analytes in a continuous and noninvasive manner-evidenced by the importance of noninvasive vital signs monitoring-because it reduces expense, eliminates delays in diagnosis, and removes the potential for exposure to blood-borne pathogens. The project for which this SBIR Grant proposal is being submitted will determine the feasibility of creating a new patient monitor capable of accurate, noninvasive, and continuous measurements of total hemoglobin (tHb). The measurement of total hemoglobin is a crucial and frequently performed blood test used in nearly all areas of healthcare. The accurate measurement of this parameter is particularly important for patients potentially requiring a transfusion, receiving rapid administration of fluids, undergoing a surgical procedure, or having experienced trauma that has resulted in significant blood loss. The proposed new monitor would look much like conventional pulse oximeter, the ubiquitous vital-signs monitor that has been in clinical use since the 1980s and which uses a clothespin-like sensor to "shine" red and infrared light through the finger and report a measure of the oxygen level in the arterial blood. And, in fact, the ultimate goal of the product development effort that would follow this feasibility study will be the integration of total-hemoglobin-measuring capability into a pulse oximeter. Successful completion of the proposed grant work will be a crucial first step toward the creation of this new medical monitor. This work will prove that the high measurement precision provided by the use of narrow-band lasers in pulse oximetry can make possible the accurate noninvasive measurement of tHb over the entire clinically-relevant range. The continuation of this work into the development of a full commercial version that can be calibrated and verified on animal and human subjects will then lead to submission for FDA 510(k) clearance to allow the marketing and sale of this device to the medical community. Availability of a noninvasive total hemoglobin monitor will help diagnose anemic patients sooner and contribute to the judicious use of blood transfusions, all with less pain or risk of infection while reducing the time burden on caregivers and costs to the healthcare system. PUBLIC HEALTH RELEVANCE: An important part of medical care is the use of tests that help clinicians diagnose disease or other medical conditions, but often these tests require that blood or other samples be drawn from the body and sent to a central hospital laboratory. The proposed work has an ultimate goal of creating a monitor that can measure the levels of red blood cells in a patient's blood without the need to draw a blood sample. This will ease patient distress and risk of infection, speed diagnosis, and result in improved patient outcomes and reduced healthcare costs.