Clotting at home
Thrombosis is a natural process necessary to stop bleeding and prevent blood loss after injuries or during operations. But in some cases, for example, in the presence of artificial valves in the heart or stents in the vessels, as well as with increased blood clotting, this process can lead to a stroke or heart attack. Such patients are forced to take blood thinning medications for life.
However, treatment with anticoagulants requires caution, because excessive thrombosis threatens with thrombotic complications, and insufficient – internal bleeding or large blood loss after injury. These patients should periodically come to the laboratory and donate blood to assess the coagulation system.
Doctors can evaluate blood clotting using two values:
- the time required for the formation of a blood clot, or prothrombin time;
- the ratio calculated on the basis of prothrombin time is the international normalized ratio (INR).
Researchers from the University of Washington have developed a new blood clotting test, for which a drop of blood is enough and which the patient can perform independently at home. To do this, you need a smartphone with a special application and a holder – a plastic mount that fixes a small container in front of the camera.
A person puts a drop of blood in a container that contains a small particle of copper and substances that trigger the blood clotting process. The phone's vibrating motor then shakes the container while the camera tracks the movement of the copper particle, which slows down and then stops completely as the clot forms. Researchers have shown that this method falls within the accuracy range of standard instruments.
To calculate the prothrombin time and INR, the phone records two timestamps: the first when the patient injects blood, and the second when the copper particle stops moving.
Thus, patients can independently monitor prothrombin time and INR and consult a doctor only if the test showed that the indicators are outside the recommended range.
The researchers tested this method in various experiments. As a proof of concept, they started with plasma, a blood component that is transparent and therefore easier to test. The researchers used plasma samples from 140 anonymous patients at the University of Washington Medical Center, as well as 79 patients with known coagulation problems. The results of the analysis were similar to the available tests.
The group also tested the whole blood of 80 anonymous patients. The new method again showed results that were within the accuracy range of the available tests.
The device is still in the proof-of-concept stage. The next step is to work with patients to conduct testing at home.
Article J.Chan et al. Micro-mechanical blood clot testing using smartphones is published in the journal Nature Communications.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru according to the University of Washington: Smartphone app can vibrate a single drop of blood to determine how well it clots.