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Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer
Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0002-1920-3962
Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine . Linköping University, Faculty of Health Sciences.
2006 (English)In: Platelets, ISSN 0953-7104, Vol. 17, no 8, 545-554 p.Article in journal (Refereed) Published
Abstract [en]

Free oscillation rheometry (FOR) using the ReoRox® 4 instrument makes it possible, at bedside, to study the coagulation process in blood over time and gives information on clotting time and coagulum elastic properties. In order to find out how various factors influence the FOR analysis we studied the coagulation process and change of elasticity over time in non-anticoagulated and citrated blood samples, plasma samples with various platelet concentrations (0-200 109/l) and blood samples with various haematocrit (0-40%). Blood samples supplemented with fibrinogen were analysed to elucidate the importance of fibrinogen on elasticity. The importance of the GPIIb/IIIa receptor on platelets was investigated by comparing the elasticity development in blood samples in presence and absence of a GPIIb/IIIa receptor inhibitor, abciximab. Anticoagulation with citrate did not have major influence on the viscoelastic properties of the coagulum. Increasing number of platelets and increasing fibrinogen concentration resulted in higher elasticity while increasing haematocrit gave lower elasticity. Blood samples with GPIIb/IIIa receptor inhibitor had very low elasticity indicating the importance of functional GPIIb/IIIa receptors. In conclusion we consider FOR to be a useful method to study the elastic properties of the coagulum. Various factors such as the number of red blood cells and platelets as well as the fibrinogen concentration should be taken into consideration when evaluating the results. The ReoRox® 4 instrument had excellent measuring range and unusually small artefactual effects on clot elasticity induced by the instrument in comparison with published results on other instruments.

Place, publisher, year, edition, pages
2006. Vol. 17, no 8, 545-554 p.
Keyword [en]
Coagulation; clot retraction; elasticity; platelets; rheology
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13164DOI: 10.1080/09537100600759238OAI: oai:DiVA.org:liu-13164DiVA: diva2:17954
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2015-03-13
In thesis
1. Free oscillation rheometry in the assessment of platelet quality
Open this publication in new window or tab >>Free oscillation rheometry in the assessment of platelet quality
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Platelets play an important role in the haemostatic process in order to seal damaged blood vessels. The platelets form a platelet plug at the damaged area and prevent blood loss. Once the damage to the vessel wall has been covered, the platelets retract the coagulum, to allow the blood to flow freely in the vessel. Free oscillation rheometry (FOR) can be used for analysis of coagulation as measured by clotting time and changes in clot elasticity (G'). Clot G' provides information about the fibrin network in the coagulum and the platelets’ ability to retract the coagulum. FOR analysis is performed using the ReoRox® 4 instrument. The blood sample is added to a cylindrical sample cup, which is set into free oscillation. The frequency and damping of the oscillation is recorded over time as the blood coagulates. The change in G' is calculated from the frequency and damping measured. Patients with malignant haematological diseases are often thrombocytopaenic and require platelet transfusions to prevent or stop bleeding. To ensure good haemostatic function in the recipient it is important that the quality of the platelets used for transfusion is well preserved. The aim of this thesis was to determine the quality of platelet concentrates (PCs), during storage, using various in vitro methods, including FOR, and to investigate how various preparation processes affect the quality. We also investigated whether FOR can be used to evaluate the haemostatic status in subjects at risk for thrombosis or bleeding as well as how the haemostatic status was affected by a platelet transfusion.

We show that FOR can provide information about the coagulation properties in subjects at risk of thrombosis (pregnant women) or bleeding (thrombocytopaenic patients). We also show that the coagulation as measured by FOR is influenced by red blood cells and the fibrinogen concentration. However, the presence of functional platelets accounted for 90% of the G'. Furthermore we present data that FOR can provide information on the haemostatic effect of platelet transfusions and on the function of the transfused platelets.

PCs produced by two different cell separators showed similar quality during storage for 7 days as assessed by FOR analysis. Leukocytes in the PCs can cause transfusion-associated graft-versus-host disease which can be prevented by gamma irradiation of the PCs. Gamma irradiation did not affect the quality of PCs during 7 days of storage as analysed by FOR. The clotting time was unchanged during the storage period. The capacity of platelets to retract the coagulum was reduced from days 1 to 5 of storage as seen by a prolonged time to reach maximum G' and the reduced mean change in G' per minute. However, if sufficient time is allowed for the platelets to regain their function, the clot will be fully retracted (as seen by a well maintained maximum G'). The FOR parameters were similar for 5- and 7-day old PCs, which, combined with other in vitro tests (e.g. hypotonic shock response, changes in pH, swirling, lactate and glucose), support the prolongation of the platelet storage period to 7 days. Intercept treatment of PCs can be performed to inhibit replication of contaminating bacteria in PCs. Intercept treatment of PCs did not diminish the clot-promoting capacity of the platelets as assessed by FOR clotting time.

In conclusion, FOR is a promising method for assessing hyper- and hypocoagulability. It can provide information on the haemostatic effect of platelet transfusions and the function of the transfused platelets. FOR was also shown to be useful for analysing PC quality during different preparation and storage conditions.

Place, publisher, year, edition, pages
Linköping University Electronic Press, 2008. 53 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1056
Keyword
Coagulation, elasticity, platelets, rheology, transfusion
National Category
Other Medical Sciences not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-11525 (URN)978-91-7393-935-5 (ISBN)
Public defence
2008-05-08, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2015-11-19

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Tynngård, NahreenLindahl, Tomas LRamström, SofiaBerlin, Gösta

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