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ICFO diffuse optics improves blood transfusion monitoring

05 Feb 2025

Hybrid optical system observes blood flow and oxygen levels for patient safety.

Diffuse optical techniques have proven to be valuable methods for non-invasively observing blood flow in living subjects.

A number of modalities have been developed, with diffuse correlation spectroscopy (DCS) being one of the most common. This uses the fluctuations of scattered near-infrared light shone onto the skin to measure the flow of red blood cells further beneath the surface.

Spain's ICFO research center has been at the forefront of this research for some time, having studied the application of speckle contrast imaging techniques to blood flow for over a decade.

A new project from ICFO and partners has now developed a hybrid diffuse optical system designed to be particularly valuable for monitoring the health of patients receiving blood transfusions. The work was published in Biophotonics Discovery.

Transfusions of red blood cells (RBCs) can be life-saving treatments for patients suffering from anemia, where the body lacks enough healthy RBCs to effectively deliver oxygen around the body. But the transfusion procedure itself can disrupt both blood flow and oxygen distribution, causing unwanted harm.

ICFO's hybrid diffuse optics method uses near-infrared light to continuously measure changes in both blood flow and oxygen levels noninvasively. A clinical study of patients was undertaken using the platform to monitor the effect of transfusion on both a patient's brain and peripheral muscle, as a first assessment of whether this technique could enhance decision-making and improve outcomes.

Helping critically ill patients

The platform is based around DCS and time-resolved spectroscopy (TRS), two complementary techniques already deployed separately or together in the study of blood flow, with DCS quantifying the motion of scattering objects and TRS measuring absorption and scattering coefficients.

The European LUCA project, co-ordinated by ICFO, used the two techniques alongside ultrasound to improve thyroid cancer screening, with the diffuse optics component of the platform assessing tissue hemodynamics, microvascular blood flow and blood oxygenation, alongside simultaneous examination of the chemical constitution of the tissue examined.

In ICFO's new study the techniques were used as a novel method to monitor critically ill patients undergoing RBC transfusions. Probes positioned on the forehead of the subject assessed the cerebral blood flow, with a second probe on the subject's thigh to observe blood in a peripheral area of the body.

Results confirmed that the hybrid platform could detect higher levels of oxygenated hemoglobin and total hemoglobin in both the brain and the muscles. While the brain maintained stable blood flow, the muscles experienced a significant increase in blood flow after transfusion, commented ICFO. This suggests that the brain has protective mechanisms at play to regulate oxygen supply.

The study points to the potential of hybrid diffuse optics as a tool for optimizing blood transfusions, potentially helping doctors develop personalized medical treatments.

"The research pioneers the application of this method to characterize and quantify the physiological changes induced by red blood cell transfusion therapy in both cerebral and peripheral tissues," noted the project in its paper. "This provides a better understanding of the impact of this therapy, which remains controversial in critically injured patients."

LASEROPTIK GmbHIridian Spectral TechnologiesChangchun Jiu Tian  Optoelectric Co.,Ltd.Berkeley Nucleonics CorporationSacher Lasertechnik GmbHOmicron-Laserage Laserprodukte GmbHNyfors Teknologi AB
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