Hypothermia-induced Haemostatic and Biochemical Phenomena. An Experimental Model

Abstract

Hypothermia (24°C) was induced in 7 healthy male dogs. Hematological, hemostatic and biochemical parameters were evaluated before the onset and after 3 h of hypothermia. Following hypothermia, there was a significant increase in red cell count, hematocrit and haemoglobin concentration. The white cell and platelet counts were decreased significantly and the mean platelet volume increased significantly. The activated partial thromboplastin time was significantly prolonged whereas the prothrombin time was unchanged. Associated with these changes there was a significant increase in serum glucose and a small increase in aspartate transaminase activity probably due to muscle leakage. No change occurred in the more liver-specific alanine transaminase. The arterial pH decreased and the changes in gasses observed as a result of hypothermia were compatible with a mixed respiratory-metabolic acidosis. The mean aortic blood pressure also dropped markedly. The hematological and hemostatic changes suggest that widespread tissue 'injury' occurs even in short term hypothermia with platelet activation and accumulation in the liver and spleen. This model of hypothermia may be of use in the study of the thrombotic diathesis observed in this condition and serve as a test bed for drugs of potential use in conditions such as Raynaud's syndrome and hypothermic surgery (e.g. coronary artery bypass).

Angiotensin II can induce and potentiate shape change in human platelets: effect of losartan

“…This is important since these agonist are released from activated platelets. 15,[18][19][20][21][22][23][24][25] In this context, it is also relevant that the enhancement of thrombininduced platelet aggregation by Ang II has been reported by others. 6 Losartan, at levels similar to those achieved during treatment, [2][3][4][5] inhibited the stimulatory effect of Ang II on human platelets despite the use of high concentrations 29 of Ang II (in vivo ϭ 10-60 ng/L; in vitro, in our study ϭ 0.25-0.5 g/L).…”

Hypothermia: effects on platelet function and hemostasis

“…Hypothermia has been shown to result in hemoconcentration, leukopenia and thrombocytopenia, slowing down of coagulation enzymes, disordered fibrinolysis, and disruption of platelet function [ 6 , 32 - 34 ]. Some hematologic diseases are directly influenced by temperature changes; for example, cold agglutination disease exhibits an increase in cold agglutinin titers [ 35 ].…”

Platelet Function During Hypothermia in Experimental Mock Circulation

“…Hypothermia has been shown to result in hemoconcentration, leukopenia, and thrombocytopenia, slowing down of coagulation enzymes, disordered fibrinolysis, and disruption of platelet function . The decrease in platelet count observed in vivo during hypothermia is reversible as normal body temperature is restored.…”