Thromboelastometry ROTEM® is derived from “rotational thromboelastometry”,a powerful technique for the assessment of blood coagulation disorders.
- Blood is added into a disposable cuvette
(measuring cell) in a heated cuvette holder
- Disposable pin (sensor) is fixed on the tip of a
rotating shaft (axis).
- The rotating shaft is stabilized by a high precision
ball bearing system
- Shaft rotates back and forth 4.75 degrees
- Shaft is connected to a spring to measure elasticity
- Exact position of the shaft is detected by reflection
of light on small mirror on the shaft.
- Data obtained from the reflected light is then
computer processed into a graphical output
TEM® is performed on the ROTEM® system, an enhancement of the traditional thromboelastography (TEG®) method, developed by Hartert in 1948.
A whole blood sample is placed into a cuvette and a cylindrical pin is immersed. Between pin and cuvette remains a gap of 1 mm, bridged by the blood. The pin is rotated by a spring to the right and the left. As long as the blood is liquid, the movement is unrestricted.
When blood starts clotting, the clot increasingly restricts the rotation of the pin with rising clot firmness. This kinetic is detected mechanically and calculated by an integrated computer to the typical curves (TEMogram) and numerical parameters.
With a set of dedicated assays, TEM® detects hypo- and hyperfunctional stages of the clotting process. The rapidly available results enable a differential diagnosis. They discriminate between surgical bleeding and a haemostasis disorder, hyperfibrinolysis, the extent of dilutional coagulopathy, requirement for fibrinogen or platelet substitution and allow heparin and protamin dosage monitoring.
The traditional TEG® by Hartert works with a free-pending pin in a rotating cuvette. The clotting process is detected via a torsion wire. Due to the free suspension of the pin, the TEG®, according to Hartert, is extremely sensitive to vibrations and mechanical shocks. This flaw is overcome in the ROTEM® system by using a rotating pin, fixed on a steel axis which is stabilized by a unique ball bearing and the precise optical detection method.
This technology-enhancement, combined with automated pipette, touch screen operation and intuitive user-friendly software in ROTEM® has optimized the TEM® for use in point of care (POC), emergency laboratories and deployed settings.