Equitable and accessible wearable device for continuous calculation of blood loss for postpartum hemorrhage

Postpartum hemorrhage (PPH), defined as the loss of 1 L of blood or more within 24 hours after birth, is the leading cause of maternal mortality worldwide. In the US, there are disturbing racial disparities, with black mothers having a 3X increase in PPH-related death. Importantly, PPH is the most preventable cause of maternal mortality, and the leading factors causing preventable PPH are delays in diagnosis and treatment. Thus, there is an urgent need for an early, accurate, and equitable PPH detection system that can facilitate prompt treatment to prevent PPH-related morbidity and mortality. During hemorrhage, several physiologic compensation mechanisms occur to help stabilize the patient, delaying the time until global vascular indicators such as blood pressure and heart rate are affected. These vital signs, as well as the visual estimate or quantitative measurement of blood loss, are the current methods used to detect PPH, but provide delayed measures of PPH. Additionally, vital signs can be affected by medications or intravenous fluid administration, making the interpretation of vital signs difficult. Non-invasive and continuous monitoring of cardiovascular parameters would enable rapid determination of blood loss, even in the presence of strong compensation or medical intervention, to reduce morbidity and mortality caused by PPH. Light-based technologies are well suited to noninvasively measure blood flow and blood content, which can provide accurate estimates of cardiovascular parameters. However, light-based tools can be biased to skin pigmentation due to melanin absorption and must be carefully designed and tested to ensure they are not contributing to racial disparities. The study team has specifically designed novel light-based sensors to minimize potential skin pigmentation bias and capture important cardiovascular parameters. Preliminary experiments have demonstrated strong correlations between the wearable sensor data and hemorrhage severity. This proposal will use a novel bicolor swine hemorrhage model to test the wearable sensor performance on swine with differently pigmented forelegs to isolate skin pigmentation as a potential source of bias. The sensor will also be tested in a diverse group of human subjects undergoing blood loss to assess wearable sensor accuracy in a wide range of skin tones. If successful, the wearable sensor will provide a continuous and accurate estimation of blood loss, facilitating early warning for improved PPH management and patient outcomes. Project Number: 1R01HL179205-01 | Fiscal Year: 2025 | NIH Institute/Center: National Heart Lung and Blood Institute (NHLBI) | Principal Investigator: CHRISTINE O'BRIEN | Institution: WASHINGTON UNIVERSITY, SAINT LOUIS, MO | Award Amount: $639,165 | Activity Code: R01 | Study Section: Instrumentation and Systems Development Study Section[ISD] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01HL17920501