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Emergency Case
Bruce Fleming, MD, FRCPC
Dr Fleming is Associate Head of the Department of Emergency Medicine at Vancouver Hospital in British Columbia.
A
76-year-old man came to the emergency depart- ment after slipping on the ice and hitting his head. He believed he was briefly unconscious, but he was able to stand on his own and walk. He remem- bered losing his balance and then finding himself on his side on the ice.He arrived at the hospital 30 minutes later accom- panied by his son. He stated that, other than a headache, he felt fine. His medications included hydrochlorothiazide, acetaminophen, and 4 mg of war- farin daily for chronic atrial fibrillation.
His son stated that he seemed somewhat confused about impor tant dates. Half an hour later, he was noted to be only opening his eyes to the sound of a voice and to be confused as to date and place.
QUESTIONS
W h a t a r e t h e k e y m a n a g e m e n t i s s u e s f o r patients taking war farin who have sustained h e a d i n j u r i e s ? W h a t i s t h e r e c o m m e n d e d approach for reversing the effects of warfarin in the setting of acute intracranial hemorrhage?
Warfarin is being prescribed to an increasing num- ber of people with atrial fibrillation, prosthetic heart valves, and thromboembolic disease, conditions that are seen more and more frequently in our aging popu- lation. With age also comes an increased incidence of falls and other mishaps that result in blunt head injuries. It is not surprising, then, that the number of patients taking warfarin who present with head trau- ma is increasing.1,2
There is about an 8- to 12-fold increase in the fre- quency of spontaneous intracranial hemor rhage among patients taking warfarin.2,3Patients using war- farin are thought to have a similarly increased risk of intracranial hemorrhage as a result of blunt injury to the head.4The usual bleeding pattern is intracerebral
rather than epidural or subdural.5 The prognosis of patients taking warfarin who present with intracranial hemorrhage is generally poor, with a mortality rate of approximately two out of three.5
Headache is the most common warning symptom.6 Patients appearing aler t and oriented can quickly become confused and then obtunded. Intracranial bleeding must be recognized and reversal of anticoag- ulation initiated. Steps must be taken quickly to identi- fy the nature of the injur y and prevent irreversible brain damage from continued intracranial hemor- rhage.6
Initial assessment
Patients at risk must be identified by triage staff upon arrival in the emergency department and be monitored.
A detailed histor y and examination should include determination of Glasgow coma scale score (GCSS). A detailed neurologic examination must be carried out, with attention to features that indicate a focal deficit.7 Family members or witnesses can be particularly helpful and can aid in evaluating the nature of the mishap. They can also often detect subtle alterations in thinking and behaviour, which might be early indi- cations of brain injury.
A careful evaluation of the cervical spine and exam- ination for associated injuries must be included in the assessment. Initial investigations should include a complete blood count, international normalized ratio (INR), and partial thromboplastin time. The cause of the fall must be established, and further investigations might be indicated in that regard.
Some patients taking war farin do not require computed tomography scans after head injur y.4The availability of equipment and the individual features of each presentation must be considered.6 With patients taking warfarin, however, the threshold for ordering CT scans of the head and for admitting and
Head injury in patients using warfarin
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monitoring them3,4is substantially lower than for other patients.
Therapy
Any suggestion of an adverse intracranial process war- rants initiation of focused therapy to reverse anticoagula- tion.8Progressive confusion, decline in the GCSS, or any new focal neurologic deficit indicate the need for rapid reversal of the ef fects of war farin.8 The decision to reverse anticoagulation might precede completion of imaging studies. Locating and ascertaining the nature of the hemorrhage by CT scan might need to follow rever- sal of anticoagulation, and empiric reversal of anticoagu- lation might be required before the INR is known.8
Administration of fresh-frozen plasma is the recom- mended method for rapid reversal of the effects of war- farin.5There are other approaches, but they are either ineffective or impractical in this special setting.
Warfarin depletes vitamin K–dependent clotting fac- tors II, VII, IX, and X. Frozen plasma, which can be thawed and administered in about 20 minutes, will effec- tively replace these depleted factors immediately.8 Normalizing a patient’s clotting profile requires 8 to 10 mL/kg of frozen plasma, which corresponds to two to three units of plasma because each unit contains 200 to 280 mL.8
Frozen plasma, which contains no platelets, has replaced stored plasma, which was deficient in factors V and VIII. Frozen plasma can be given without major con- cerns regarding antibody (ABO) compatibility. In cases where ABO sensitivity is of concern, ABO-typed plasma can be given. Testing for serologic compatibility is not required before administration.8Administration of frozen plasma carries no risk of transmitting infectious agents or of serious volume or osmotic overload.8
When there is less urgency, vitamin K can be admin- istered to correct factors depleted by warfarin, but the process is slow. Vitamin K can be given orally or par- enterally at a dose of 1 to 10 mg. The INR is a measure of vitamin K–dependent factor levels. Some normalization of a prolonged INR can be expected 2 hours after admin- istration of vitamin K. Hemorrhage is usually controlled in 3 to 8 hours, and normalization of the INR is expected in 12 to 18 hours.8
In conclusion, recognition that patients taking war- farin are at high risk of bleeding is impor tant for all members of the emergency team. Rapid identification of features suggestive of intracranial bleeding and prompt reversal of anticoagulation can save lives.
ANSWERS
Patients taking warfarin have a high risk of intracranial hemorrhage with catastrophic results following head injur y. Initial signs and symptoms can be subtle. Any clinical evidence of intracranial bleeding requires prompt administration of 8 to 10 mL/kg of frozen plasma and definitive imaging as part of overall management.
References
1. Mattie H, Kohler S, Huber P, Ronner M, Stemslape KF. Anticoagulation-related intracranial extracerebral hemorrhage. J Neurol Neurosurg Psychiatry 1989;52:829-37.
2. Saab M, Gray A, Hodgkinson D, Irfan M. Warfarin and the apparent minor head injury.
J Accid Emerg Med1996;13:208-9.
3. Grossman RG, Loftus CM. Principles of neurosurgery. 2nded. Philadelphia, Pa:
Lippincott-Raven; 1998.
4. Volans AP. The risks of minor head injury in the warfarinized patient. J Accid Emerg Med 1998;15:159-61.
5. Hart RG, Boop BS, Anderson DC. Oral anticoagulants and intracranial hemorrhage:
facts and hypotheses. Stroke 1995;26:1471-7.
6. Tindall GT, Cooper PR, Barrow DL. The practice of neurosurgery. Vol 1. Baltimore, Md:
Williams and Wilkins; 1996.
7. American College of Surgeons. ATLS instructors manual. Chicago, Ill: American College of Surgeons; 1993. p. 160-83.
8. Hoffman R, Benz EJ, Shattil SJ, Furie B, Cohen HJ, Silberstein LE, et al. Hematology basic principles and practice. 3rded. Philadelphia, Pa: Churchill-Livingston; 2000.
