Sanguine rheology: Blood that's not so thick

Skip to Navigation

Ezine

  • Published: Mar 1, 2014
  • Author: David Bradley
  • Channels: Raman
thumbnail image: Sanguine rheology: Blood that's not so thick

Phlebs

The failure of blood to clot, or coagulate, following serious bodily trauma or a surgical procedure is one of the leading causes of preventable death in patients. Now, a new optical device based on laser speckle rheology requires only a few drops of blood and a few minutes to measure the key coagulation parameters that can guide medical decisions about how to proceed in the emergency room or operating theatre.

The failure of blood to clot, or coagulate, following serious bodily trauma or a surgical procedure is one of the leading causes of preventable death in patients. Now, a new optical device based on laser speckle rheology requires only a drop or two of blood and a few minutes to measure the key coagulation parameters that can guide medical decisions about how to proceed in the emergency room or operating theatre.

The body's natural defence against severe blood loss is the clotting process, in which platelets, various proteins in the plasma and numerous other blood components come together in a complex interaction to increase blood's viscosity and to form a sticky, mesh-like structure to seal a wound. Various disorders arise when this process fails or when it occurs when there is no wound to heal.

Researchers at Massachusetts General Hospital have developed a relatively simple to use optical device that can provide healthcare workers with critical and timely information about the clotting factors in a patient's blood and so guide their treatment decisions. For instance, the information could be used to estimate the volume of blood required for transfusion or what dose of anticoagulant drug might need to be administered. Details of the device are published in journal Biomedical Optics Express.

Blood clot or not?

"Currently, the most comprehensive measures of coagulation are a battery of lab tests that are expensive and can take hours to perform," explains Seemantini Nadkarni of the Wellman Center for Photomedicine at Massachusetts and Harvard Medical School. There are other systems that have been developed for point of care clotting measurements but these are cumbersome, expensive and require a significant volume of blood rather than a single drop. Moreover, in general they measure only clotting time rather than the critical factors present in the blood sample and often are unable to detect the underlying coagulation abnormality.

"Our goal is to provide as much information as a lab test, but to provide it quickly and cheaply at a patient's bedside," Nadkarni adds. She and her colleagues have thus pioneered the use of an optical analytical technique they refer to as laser speckle rheology (LSR). In LSR, researchers shine laser light into a sample and monitor the scattered pattern that bounces back. The team had previously been investigating the use of LSR for measuring the mechanical properties of a range of different tissue types when they discovered that it was particularly sensitive to the coagulation of blood. When light hits a blood sample, blood cells and platelets scatter the light. In unclotted blood these light scattering particles move easily about, making the pattern of scattered light, called a speckle pattern, fluctuate rapidly.

In non-coagulating blood, the speckle pattern resembles the view of twinkling stars on a clear night. "But, explains Nadkarni, "as the blood starts to coagulate, blood cells and platelets come together within a fibrin network to form a clot. The motion is restricted as the sample get stiffer, and the twinkling of the speckle pattern is reduced significantly."

The researchers used a miniature high-speed camera to record the changes in the intensity or brightness of the fluctuating speckles and then correlated the intensity of these changes with two other important blood coagulations parameters: clotting time and concentration of fibrinogen, the key protein involved in the blood clotting process. The LSR approach could be implemented using a palm-sized portable device for use by doctors in an accident and emergency department at a hospital or when performing surgery so that they know how much blood might be needed in a transfusion and whether platelets or fibrinogen needs to be administered.

Timely clotting defects

"The timely detection of clotting defects followed by the appropriate blood product transfusion is critical in managing bleeding patients," Nadkarni said. "If you transfuse too much, there could be further coagulation defects that occur, but if you don't transfuse enough, bleeding continues."

On the other end of the spectrum, Nadkarni says the device could also help patients whose blood coagulates too easily, forming clots inside of blood vessels, thrombosis. Patients with chronic thrombosis take anticoagulants and must regularly visit their doctor for appropriate blood tests and consequent medication adjustments. Similarly, those exposed to risk factors for acute deep-vein thrombosis might also be assessed more readily with a portable device. Such a device based on LSR could be used in the doctor's clinic, at home or in hospital and so reduce the cost and inconvenience of routine laboratory testing, while increasing the efficacy and safety of anticoagulant treatment.

Wellman Center post-doctoral fellow Markandey Tripathi, one of Nadkarni's co-authors is looking forward to working on the next step in this work, which is to carry out clinical testing with a portable LSR device in surgical theatre or the doctor's surgery. The potential of such a device could be great for patients. Currently the optical device developed by Nadkarni and her colleagues is about the size of a shoebox and requires a connection to a personal computer. The team hopes to miniaturize the system and to incorporate the necessary hardware and software into a mobile phone-enabled, palm sized device, they hope to achieve that goal within the year. "The potential of such a device could be great for the millions of patients worldwide on anticoagulant drugs," Nadkarni told SpectroscopyNOW.

Related Links

Biomed Optics Express, 2014, 5, 817-831: "Assessing blood coagulation status with laser  speckle rheology"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

Social Links

Share This Links

Bookmark and Share

Microsites

Suppliers Selection
Societies Selection

Banner Ad

Click here to see
all job opportunities

Most Viewed

Copyright Information

Interested in separation science? Visit our sister site separationsNOW.com

Copyright © 2017 John Wiley & Sons, Inc. All Rights Reserved