QOD 1 4 10

Which of the following statements is true regarding thrombolysis in cases of frostbite?
		A.	Doppler signals should be detectable in the extremity before thrombolysis.
		B.	Infusion of vasodilators should be avoided.
		C.	Intraarterial infusion of the thrombolytic agent is preferred.
		D.	Priority should be given to the feet rather than the hands. After rewarming, if the patient's feet or hands remain without evidence of perfusion, the presence of vascular thrombosis should be suspected. In this situation, emergency lytic therapy would seem to address the primary pathophysiology, if ischemia time has been brief. Intravenous or intraarterial thrombolytic therapy has been reported in two retrospective studies to reduce the rate of major amputation. Because it is primarily the smaller arteries that are occluded in frostbite, thrombolytic agents may be more effective when selectively infused intraarterially, with the catheter tip positioned near the target areas of malperfusion. Catheter-directed administration of tissue plasminogen activator (t-PA) may be more effective, since a higher concentration of the agent locally permeates and binds to thrombus at the target. The use of an ultrasound-accelerated thrombolysis catheter to deliver the thrombolytic agent has been performed; ultrasonography has been shown to reversibly loosen fibrin strands and reduce their diameter, exposing more individual strands, increasing thrombus permeability, and exposing more plasminogen-receptor sites for binding. More rapid and complete thrombolysis has been reported with the use of this technique than with standard catheter-directed thrombolysis. The treatment end points for thrombolytic therapy include angiographic or clinical demonstration that perfusion has been reestablished, failure to show any improvement in perfusion on angiograms obtained after 24 hours and after 48 hours of therapy, and the development of bleeding complications such as hematoma, stroke, or hemorrhage involving solid organs or the gastrointestinal tract. Answer: C