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Effect of hypothermia on the coagulation cascade
1Division of Vascular Surgery, University of Massachusetts Medical School, Worcester.
Critical Care Medicine
|October 1, 1992
Summary
Hypothermia significantly impairs blood coagulation, prolonging prothrombin time and partial thromboplastin time. This temperature effect on coagulation is critical for hypothermic patients receiving massive transfusions.
Area of Science:
- Biochemistry
- Hematology
- Physiology
Background:
- Massive transfusion in critically ill patients often leads to coagulopathy.
- Hypothermia is a common complication accompanying massive transfusion.
- The isolated impact of temperature on coagulation integrity is not fully understood.
Purpose of the Study:
- To investigate the independent effect of temperature variations on the coagulation cascade.
- To quantify changes in coagulation test results at different temperatures.
Main Methods:
- Prothrombin times and partial thromboplastin times were measured.
- Tests were performed on pooled normal plasma samples.
- Temperatures tested ranged from hypothermic (28-34°C) to normothermic (37°C) and hyperthermic (39-41°C).
Main Results:
- Prothrombin time significantly increased as temperature decreased below 37°C.
- Partial thromboplastin time also significantly increased with decreasing temperatures.
- Coagulation tests showed only minimal shortening at hyperthermic temperatures.
Conclusions:
- Hypothermia markedly inhibits the enzymatic reactions of the coagulation cascade.
- Prolonged prothrombin time and partial thromboplastin time at lower temperatures demonstrate this inhibition.
- The contribution of hypothermia to coagulopathy in transfused patients may be underestimated if testing is not temperature-adjusted.