Feasibility of photoacoustic imaging for the non-invasive quality management of stored blood bags.

BACKGROUND AND OBJECTIVES

During the in vitro storage of red blood cells (RBCs), unfavourable changes (storage lesions) cause a rapid consumption of intracellular diphosphoglycerate. The latter deregulates the oxygen-haemoglobin binding potential, subsequently increasing oxygen saturation (SO ) and membrane degradation, transforming RBCs from biconcave discs to rigid spherical bodies (spheroechinocytes). Current laboratory techniques invasively extract RBC samples to assess the quality of red cell concentrate (RCC) units. Optical technologies could provide a means of assessing quality non-invasively.

MATERIALS AND METHODS

A photoacoustic (PA) imaging technique was developed for acquiring the SO of blood bags non-invasively. Seven RCC units were monitored every 3-5 days until expiry (6 weeks). Measurements were validated against a conventional blood gas analyzer (BGA). Using an image flow cytometry assay, morphological profile trends were compared against the SO trends during blood bag storage.

RESULTS

A strong correlation (r ≥ 0·95) was found when comparing temporal data between PA and BGA SO measurements. Inter-sample PA variability was found to be similar to that produced by BGA (±0·8%). A strong correlation was found to exist between the temporal changes in SO and relative spheroechinocyte population (0·79 ≤ r ≤ 0·97).

CONCLUSION

This study suggests that PA imaging can non-invasively track the SO of stored RBCs non-invasively. By longitudinally monitoring the change in SO , it is possible to infer the effects of the storage lesion on RBC morphology. This non-invasive monitoring technique allows for the assessment of blood bags, without compromising sterility pre-transfusion.