THAWING THE SYSTEM: FROSTBITE TREATED WITH EPOPROSTENOL

SESSION TITLE: Medical Student/Resident Pharmacotherapeutics SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Frostbite treatment begins with rewarming, wound care, and analgesia. Historically, this was the extent of intervention until affected digits either recovered or were amputated. A better understanding of the pathophysiology of frostbite has led to the development of treatment protocols centered around early administration of intra-arterial (IA) thrombolytic therapy; these protocols have demonstrated decreased amputation rates. However, optimal therapy still remains unclear. CASE PRESENTATION: A 47-year old male was admitted with cold exposure and frostbite of the hands. Hemorrhagic bullae were observed over the intermediate and proximal phalanges of digits 3-4 on the left hand and digits 2-5 on the right (Fig 1). Because there was no protocol for frostbite treatment, there was a delay in the next steps of care. Forty-eight hours after admission, a technetium-99 bone scan revealed preserved flow in the digits of the left hand, but absent flow in the majority of the right fifth digit, as well as the middle and distal portions of the fourth digit. Based on these findings, nifedipine and sildenafil were initiated for vasodilation. On day four, intravenous (IV) epoprostenol was initiated for further vasodilation per an established protocol for treatment of digital ischemia secondary to scleroderma. A repeat bone scan on day 14 demonstrated bone necrosis in the distal phalanx of the left fourth digit, middle and distal phalanges of the right fourth and fifth digits, and distal phalanx of the right third digit. The patient was discharged on day 15 with ongoing wound care and occupational therapy. DISCUSSION: This case highlights a shift in frostbite treatment from support and observation towards early intervention with thrombolytic therapy. Protocols developed at multiple medical centers initiate either IA or IV tPA and heparin within 24 to 48 hours of exposure. Some institutions also use IV iloprost after or in place of thrombolytic therapy. Because IV iloprost is not available in the US, IV epoprostenol may be a reasonable alternative. IV epoprostenol is currently used to treat pulmonary arterial hypertension and digital ischemia secondary to scleroderma. Despite treatment with IV epoprostanol, this patient's overall outcome was poorer than those reported in the published studies. This was likely due to a delay in initiating epoprostenol rather than a failure of the medication. Further investigation is needed to determine whether epoprostenol is an effective alternative to iloprost. CONCLUSIONS: This case illustrates the importance of early intervention when treating frostbite. Prior studies have shown significant success utilizing IA thrombolytics and/or IV iloprost. Because IV iloprost is not available in the US, epoprostenol might be a reasonable substitute since it has been beneficial in severe digital ischemia from Raynaud’s phenomenon. Reference #1: Bruen KJ, Ballard JR, Morris SE, Cochran A, Edelman LS, Saffle JR. Reduction of the incidence of amputation in frostbite with thrombolytic therapy. Arch Surg. 2007;142:546-50. Reference #2: Lindford A, Valtonen J, Hult M, Kavola H, Lappalainen K, Lassila R, Aho P, Vuola J. The evolution of the Helsinki frostbite management protocol. Burns. 2017;43:1455-63. Reference #3: Twomey JA, Pelti GL, Zera RT. An open-label study to evaluate the safety and efficacy of tissues plasminogen activator in treatment of severe frostbite. J Trauma. 2005;59:1350-5. 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