In-vitro hypocoagulability on whole blood thromboelastometry associated with in-vivo expansion of red cell mass in an equine model.
Abstract: In several species, there is a strong correlation between indicators of red cell mass (RCM) and thromboelastometry results. The horse has a reliable, temporary, polycythemia in response to phenylephrine infusion. Our objective was to evaluate the effects of an in-vivo increase in circulating RCM on thromboelastometry results in an equine model of transient polycythemia. Six healthy research horses had whole blood thromboelastometry with contact activator and tissue factor initiation after recalcification of citrated samples. Additional samples were frozen for thrombin-antithrombin (TAT). Complete blood count biochemical analysis, fibrinogen, activated partial thromboplastin time (aPTT), and prothrombin time (PT) were performed. Additional samples were taken at 5 min and 2 h after phenylephrine infusion. Thromboelastometry was performed separately on four horses not receiving phenylephrine with the samples divided and spiked with phenylephrine ex vivo. Red cell count (P<0.001) and hematocrit (P<0.001) were significantly higher at 5 min after phenylephrine compared with baseline and 2 h. There was no change in platelet count, fibrinogen, PT, aPTT, or TAT at any time point. Both ex-tem and in-tem parameters were hypocoagulable at 5 min after phenylephrine compared to baseline and 2 h. There was no effect of phenylephrine in the ex-vivo spiking studies on any of the thromboelastometry parameters. Whole blood thromboelastometry results were hypocoagulable in this equine model of in-vivo transient polycythemia only during the polycythemic phase. All other coagulation parameters were unchanged. In the absence of other indicators of hypocoagulability, this may point to an artifact of thromboelastometry. Alternatively, the data may reflect true in-vivo hypocoagulability in patients with increased circulating RCM.
Publication Date: 2011-04-22 PubMed ID: 21508831DOI: 10.1097/MBC.0b013e3283464f83Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This article highlights a study investigating the impact of an increase in red blood cells (transient polycythemia) induced by phenylephrine on whole blood thromboelastometry results in horses, showing that thromboelastometry results are less coagulable during the polycythemic phase with no change in other coagulation parameters.
Objective of the Study and Methodology
- The primary objective of this study was to assess the relationship between a temporary increase in the circulating red cell mass (RCM), induced by polycythemia, and thromboelastometry results. This was studied using a horse model as horses are known to have a reliable and temporary increase in polycythemia when infused with phenylephrine.
- The experiment involved six healthy research horses. After the recalcification of citrated samples, whole blood thromboelastometry was conducted with both contact activator and tissue factor initiation.
- Apart from these, additional samples were also taken to carry out several other analyses including complete blood count biochemical analysis, activated partial thromboplastin time (aPTT), prothrombin time (PT), and fibrinogen. Additionally, some samples were frozen for thrombin-antithrombin (TAT).
Process and Results
- Additional blood samples were obtained at 5 minutes and 2 hours post phenylephrine infusion, which induced transient polycythemia.
- Results showed that red cell count and hematocrit levels were significantly higher at 5 minutes post phenylephrine infusion compared to the initial baseline and at 2 hours post infusion.
- No changes were noticed in the platelet count, fibrinogen, PT, aPTT, or TAT at any of the given time points. On the other hand, both ex-tem and in-tem parameters were observed to be hypocoagulable at 5 minutes after phenylephrine as compared to baseline and 2 hours.
- A separate thromboelastometry test conducted on four horses, not treated with phenylephrine, showed that spiking the samples with phenylephrine ex-vivo (outside the body) did not have any effect on any of the thromboelastometry parameters.
- Based on these findings, the researchers concluded that whole blood thromboelastometry results were less coagulable only during the polycythemic phase. This points to a potential artifact of thromboelastometry or could indicate the occurrence of true in-vivo hypocoagulability in patients with increased RCM circulation.
Cite This Article
APA
McMichael M, Smith SA, McConachie EL, Lascola K, Wilkins PA.
(2011).
In-vitro hypocoagulability on whole blood thromboelastometry associated with in-vivo expansion of red cell mass in an equine model.
Blood Coagul Fibrinolysis, 22(5), 424-430.
https://doi.org/10.1097/MBC.0b013e3283464f83 Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, , University of Illinois at Urbana-Champaign, 1008 West Hazelwood Dr., Urbana, IL 61802, USA. mmcm@illinois.edu
MeSH Terms
- Animals
- Artifacts
- Blood Coagulation Disorders / diagnosis
- Blood Coagulation Disorders / physiopathology
- Blood Coagulation Tests
- Diagnostic Errors
- Erythrocyte Volume
- Horses
- Models, Animal
- Phenylephrine / pharmacology
- Polycythemia
- Thrombelastography / standards
Citations
This article has been cited 7 times.- Wang WH, Lynch AM, Balko JA, Duffy DJ, Robertson JB, Posner LP. Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period. BMC Vet Res 2022 Sep 14;18(1):346.
- Zhang M, He K, Ye D, Zhang Q, Zhang Z. To Investigate Whether Hematocrit Affects Thromboelastography Parameters. Contrast Media Mol Imaging 2022;2022:8877321.
- Whitehead Z, Goddard A, Botha WJ, Pazzi P. Haemostatic changes associated with fluid resuscitation in canine parvoviral enteritis. J S Afr Vet Assoc 2020 Jul 29;91(0):e1-e9.
- Coleman JR, Moore EE, Samuels JM, Cohen MJ, Sauaia A, Sumislawski JJ, Ghasabyan A, Chandler JG, Banerjee A, Silliman CC, Peltz ED. Trauma Resuscitation Consideration: Sex Matters. J Am Coll Surg 2019 May;228(5):760-768.e1.
- Mersich I, Bishop RC, Diaz Yucupicio S, Nobrega AD, Austin SM, Barger AM, Fick ME, Wilkins PA. Decreased Circulating Red Cell Mass Induced by Intravenous Acepromazine Administration Alters Viscoelastic and Traditional Plasma Coagulation Testing Results in Healthy Horses. Animals (Basel) 2024 Oct 28;14(21).
- Vokes JR, Lovett AL, de Kantzow MC, Rogers CW, Wilkins PA, Sykes BW. Comparison of Citrated Whole Blood to Native Whole Blood for Coagulation Testing Using the Viscoelastic Coagulation Monitor (VCM Vet™) in Horses. Animals (Basel) 2024 Oct 8;14(19).
- Bishop RC, Jonk KM, Migliorisi A, Austin SM, Mullins EC, Wilkins PA. Increased packed cell volume alters point of care viscoelastic clotting parameters in horses. Equine Vet J 2025 May;57(3):766-773.
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