Observing temporal variation in hemolysis through photoacoustics with a low cost LASER diode based system

Patients under hemolytic condition need continuous monitoring of lysis as depletion of Red Blood Cells (RBC) and the presence of antioxidant free hemoglobin (Hb) in excess amount due to hemolysis lead to severe deterioration of their health. Out of many modalities, Photoacoustics (PA) offers real time information noninvasively from deep lying blood vessels since Hb is the strongest chromophore in mammalian blood and the PA response of blood varies with the amount of Hb present. During hemolysis, total Hb content in blood however remains unchanged, thus, questions the use of PA in hemolysis detection. In this report, a hypothesis that the amplitude of the PA signal would not change with the amount of lysis is framed and tested by applying osmotic shock to the RBCs in hypotonic environment and the PA response is recorded over time using a low cost NIR based PA system. The experimental outcome indicates that PA amplitude falls off as lysis progresses in course of time consequently rejecting the hypothesis. The decaying PA response also carries the signature of RBC swelling during the early phase of lysis. The PA measurement can detect hemolysis as low as 1.7%. These findings further advocate transforming this NIR-PA system into a portable, noninvasive patient care device to monitor hemolysis in-vivo.