Hemophilia

Factor 8

General Calculation

(weight in kg) x (50ml plasma/kg) x (desired F8 level - native F8 level) = total units^

Recommended Factor VIII Therapy for Specific Problems in Hemophilia

TYPE OF BLEEDING	INITIAL DOSAGE	DURATION	COMMENT
Skin
Abrasion	None	None	Treat with local pressure and topical thrombin
Laceration	Usually none; if necessary, treat as minor	None	Local pressure and anesthetic with epinephrine may benefit; watch 4 hours after suturing; reexamine in 24 hours
Superficial
Deep	Minor bleeding (12.5 mg/kg)	Single-dose coverage	May need hospitalization for observation; repeat may be necessary for suture removal
Nasal epistaxis
Spontaneous	Usually none; may need to be treated as mild bleeding	None	Uncommon; consider platelet inhibition; treat in usual manner
Traumatic	Moderate bleeding (25 mg/kg)	Up to 5–7 days	Trauma-related bleeding can be significant
Oral
Mucosa or tongue bites	Usually none; treat as minor if persists	Single dose	Commonly seen
Traumatic (laceration) or dental extraction	Moderate (25 U/kg) to severe (50 U/kg)	Single dose; may need more	Saliva rich in fibrin lytic activity; oral ε-aminocaproic acid (Amicar) may be given at 100 mg every 6 hr for 7 days to block fibrinolysis; check contraindications; hospitalize patients with severe bleeding
Soft tissue/muscle hematomas	Moderate (25 U/kg) to severe (50 U/kg)	2–5 days	May be complicated by local pressure on nerves or vessels (e.g., iliopsoas, forearm, calf)
Hemarthrosis
Early	Mild (12.5 U/kg)	Single dose	Treat as earliest symptom (pain); knee, elbow, ankle more common
Late or unresponsive cases of early hemarthrosis	Mild to moderate (25 U/kg)	3–4 days	Arthrocentesis rarely necessary and only with 50% level coverage; immobilization is critical point of therapy
Hematuria	Mild (12.5 U/kg)	2–3 days	Urokinase, the fibrinolytic enzyme, is in urine; with persistent hematuria an organic cause should be ruled out
Major bleeding	Major bleeding (50 U/kg)	7–10 days or 3–5 days after bleeding ceases	In head trauma, therapy should be given prophylactically; early CT scan of head recommended for all
Gastrointestinal severe bleeding
Neck/sublingual
Retroperitoneal
Intra-abdominal
Major trauma
Head injury (see text)
Central nervous system bleeding (see text)
Surgical procedure
CT, computed tomography

 Dosage of Factor VIII (Antihemophilic Factor)

BLEEDING RISK	DESIRED FACTOR VIII LEVEL (%)	INITIAL DOSE (U/KG)
Mild	5–10	12.5
Moderate	20–30	25
Severe	50 or greater	50

Standard Calculation Patient's plasma volume (50 mL/kg × weight in kg) × (Desired level of factor VIII [percent]) − (Present level of factor VIII [percent]) = Number of units for initial dose. In emergency therapy, the present level of factor VIII is assumed to be zero. One unit is the activity of the coagulation factor present in 1 mL of normal human plasma. Because the half-life of factor VIII is 8–12 hr, the desired level is maintained by giving half the initial dose every 8–12 hr. Cryoprecipitate is assumed to have 80–100 U of factor VIII:C per bag; factor VIII:C concentrates list the units per bottle on the label. Factor 9 (weight in kg) x (100ml plasma/kg) x (desired F9 level - native F9 level) = total units^ ^half this dose should be readministered in 24 hours ^^DDAVP is not helpful in F9 deficiency Source DONALDSON 10/08 (From "Kaji Questions"), Rosen's