Monitoring Blood Clot Formation and Lysis in Vitro Using High Frequency Photoacoustics

Abstract

Clotting is a survival mechanism that prevents blood loss after injury. An imbalance in clotting factors can lead to lethal consequences such as exsanguination or inappropriate clotting. Existing methods to monitor clot formation and lysis measure viscoelasticity of whole blood or optical density of plasma over time. Though these methods provide insights into coagulation and fibrinolysis, they require 1-3 millilitres of blood which can worsen anemia especially in small pediatric patients or provide partial information as seen with acellular plasma-based measurements. To overcome these limitations, a high frequency (HF) photoacoustic (PA) imaging was developed to detect clot formation and lysis in whole blood. Frequency spectra showed continuous changes in unclotted blood which became more stable during clotting. After clot lysis, the frequency spectra changed continuously as seen with whole blood. HFPA imaging can differentiate clotting and lysis with small volumes of blood (25µL/test).