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J Trauma. 2003 Nov;55(5):886-91.

The effect of temperature and pH on the activity of factor VIIa: implications for the efficacy of high-dose factor VIIa in hypothermic and acidotic patients.

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1
Department of Pathology, Duke University Medical Center, Durham, NC 27705, USA.

Abstract

BACKGROUND:

Recombinant coagulation factor VIIa (FVIIa) is approved for treating hemophiliacs with inhibitors. High-dose FVIIa has also been used off-label to manage hemorrhage in trauma and surgical patients, many of whom also develop hypothermia and acidosis.

METHODS:

We examined the activity of FVIIa on phospholipid vesicles in the presence and absence of tissue factor (TF) and on platelets as a function of temperature and pH.

RESULTS:

FVIIa activity on phospholipids and platelets was not reduced at 33 degrees C compared with 37 degrees C. The activity of FVIIa/TF was reduced by 20% at 33 degrees C compared with 37 degrees C. A pH decrease from 7.4 to 7.0 reduced the activity of FVIIa by over 90% and FVIIa/TF by over 60%.

CONCLUSION:

FVIIa should be effective in enhancing hemostasis in hypothermic patients. However, because the activity of FVIIa is so dramatically affected by pH, its efficacy may be reduced in acidotic patients.

[Indexed for MEDLINE]

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