Coagulation factor levels in neurosurgical patients with mild prolongation of prothrombin time: effect on plasma transfusion therapy

Abstract

Object Neurosurgical patients often have mildly prolonged prothrombin time (PT) or international normalized ratio (INR). In the absence of liver disease this mild prolongation appears to be due to the use of very sensitive PT reagents. Therefore, the authors performed relevant coagulation factor assays to assess coagulopathy in such patients. They also compared plasma transfusion practices in their hospital before and after the study. Methods The authors tested 30 plasma specimens from 25 patients with an INR of 1.3–1.7 for coagulation factors II, VII, and VIII. They also evaluated plasma orders during the 5-month study period and compared them with similar poststudy periods following changes in plasma transfusion guidelines based on the study results. Results At the time of plasma orders the median INR was 1.35 (range 1.3–1.7, normal reference range 0.9–1.2) with a corresponding median PT of 13.6 seconds (range 12.8–17.6 seconds). All partial thromboplastin times were normal (median 29.0 seconds, range 19.3–33.7 seconds). The median factor VII level was 57% (range 25%–124%), whereas the hemostatic levels recommended for major surgery are 15%–25%. Factors II and VIII levels were also within the hemostatic range (median 72% and 118%, respectively). Based on these scientific data, plasma transfusion guidelines were modified and resulted in a 75%–85% reduction in plasma orders for mildly prolonged INR over the next 2 years. Conclusions Neurosurgical patients with a mild prolongation of INR (up to 1.7) have hemostatically normal levels of important coagulation factors, and the authors recommend that plasma not be transfused to simply correct this abnormal laboratory value.