Patient selection:
(1) ability to start treatment within 24 hours of frostbite injury
(2) no contraindications to thrombolytic therapy (trauma, recent surgery, neurological impairment, hemorrhagic condition, etc.)
(3) presence of severe frostbite injury (full-thickness tissue involvement, hemorrhagic blisters, absent pulse)
(4) evidence of decreased perfusion in the affected extremity (by Doppler studies, angiography or other means)
An intra-arterial catheter is placed in the proximal limb (in brachial artery for the upper extremity; in the femoral artery in the lower extremity).
Dosing of tissue thromboplastin activator (tPA) through the intra-arterial catheter:
(1) initial bolus of 2-4 mg
(2) continuous infusion of 0.5 to 1 mg per hour for up to 48 hours
Reasons for discontinuation of the tPA:
(1) development of hypofibrinogenemia (plasma fibrinogen < 150 mg/dL)
(2) hemorrhage
(3) evidence of complete reperfusion on angiography
(4) reached time limit (48 hours)
Heparin is infused at a rate of 500 units per hour) in conjunction with tPA infusion and is maintained for up to 72 to 96 hours after the tPA is discontinued.
Performance:
• This protocol reduced the rate of digital amputations 4-fold, from 40% to 10%. In addition, no proximal amputations were performed.
