Assessing storage-induced red blood cell lesions using photoacoustic measurements of oxygen saturation and the frequency content of photoacoustic signals

Determining the quality of stored blood remains a persistent challenge. It is well documented that morphological and physiological changes occur during routine storage of whole blood units impacting the ability of red blood cells (RBCs) to deliver oxygen to tissues. We propose the use of photoacoustic (PA) imaging and microscopy for assessing the storage-induced changes that occur to RBCs. Whole blood units were measured for a period of 40 days using a PA imaging system (VevoLAZR, Fujifilm VisualSonics) and a PA microscope (SASAM, Kibero GmbH). The oxygen carrying capacity of stored blood was assessed by a two-wavelength approach by computing the oxygen saturation as a function of time. Morphological changes were assessed by PA microscopy through measuring the PA signals and the respective frequency spectra from individual RBCs. As RBCs aged, their oxygen carrying capacity significantly diminished and distinct features in the frequency spectra from the PA signals formed. This suggests that PA techniques are sensitive to storage-induced RBC lesions and can potentially be used to assess the quality of stored blood.