Ultrasonic evaluation of blood coagulation from stroke patients

Abstract

It is already known that the ultrasound speed and attenuation coefficient are increasing during the blood clotting process. A pulse echo system was set up to measure the sound speed and attenuation coefficient of human blood at 37 C. From ten healthy volunteers, the blood was taken to measure sound speed and attenuation coefficient during blood coagulation without and with heparin. For ten stroke patients, sound speed and attenuation were measured with aPTT or PT for comparison. The variation of sound speed and attenuation coefficient of blood after adding heparin was small. Sound speed of plasma from healthy volunteers was increased to 7 from 1535 m/s over 50 min without heparin, but to 1 m/s during the first 5 min for heparin‐added blood. Sound speed of plasma from stroke patients was changed little compared to that from healthy volunteers without heparin. Attenuation coefficient was increased linearly during plasma coagulation for both volunteers and stroke patients, but its temporal slopes were much smaller for stroke patients. The blood samples from the stroke patients that investigated how heparin affects sound speed and attenuation as a function of time before and after taking the heparin and the results will be discussed.