Thrombolytic therapy performed by interventional radiologists could reduce amputation rates due to frostbite

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frostbite
John Lee (L) and Mikhail Higgins

An ahead-of-print article in the April issue of the American Journal of Roentgenology (AJR) reviewing various techniques and clinical management paradigms to treat severe frostbite injuries—relevant for interventional radiologists, especially—shows promising results using both intra-arterial (IA) and intravenous (IV) tissue plasminogen activator (tPA) to reduce amputation.

“Severe frostbite injuries can lead to devastating outcomes with loss of limbs and digits,” write radiologists Mikhail Higgins and John Lee (both Boston Medical Center, Boston, USA). Speaking specifically to this newspaper, they add: “In an era where the clinical paradigm for management of frostbite injuries has been primarily tissue rewarming, prolonged watchful waiting, and often delayed amputation, it is particularly exciting to have a meta-analysis that supports and validates a promising endovascular therapy performed by interventional radiologists that can significantly mitigate digit loss.”

Elaborating to Interventional News, Higgins and Lee comment: “The management of frostbite injury has been limited to conservative management and supportive care until now, mainly due to lack of studies on additional treatment options. Patients with severe frostbite injuries have often had bad outcomes—including amputations—due to the lack of reliable treatment options in the acute setting. Our meta-analysis shows promising results of intra-arterial and intravenous tPA therapy in the acute management of severe frostbite involving thrombosis of the digital arteries.”

A search of the literature by Lee and Higgins yielded 157 citations. After manually screening for inclusion criteria of case reports, case series, cohort studies, and randomised prospective studies that reported the use of tPA to treat severe frostbite injuries, 16 qualified for review.

Higgins and Lee analysed series included 209 patients with 1,109 digits at risk of amputation treated with IA or IV tPA—116 and 77 patients, respectively. A total 926 at-risk digits were treated with IA tPA and resulted in amputation of 222 digits, for a salvage rate of 76%. Twenty-four of 63 patients underwent amputation after IV tPA, resulting in a 62% salvage rate.

Both digital subtraction angiography (DSA) and triple-phase bone scan were utilised for initial imaging evaluation of patients with severe frostbite injuries.

Additional concurrent treatment included therapeutic heparin at 500U/h, warfarin with target international normalised ratio of 2:3, nonsteroidal anti-inflammatory drugs, pain management, and light dressings with topical antimicrobial agents.

Interventional radiologists are well-placed to be offering this digit-saving treatment, they add. “Not only are we interventional radiologists trained in catheter and guidewire manipulation skills to successfully navigate the arterial anatomy, but we are also clinically facile with managing patients’ unique endovascular needs with tPA therapy, given our deep experience with its use in catheter-directed thrombolytic therapy of other pathologies, such as pulmonary thromboembolism and thrombosed arteriovenous fistulas and grafts. In addition, the skill of diagnostic angiography, particularly of micro-arterial anatomy, that is needed to quickly and accurately diagnose frostbite-related thrombosis of the digital arteries as well as during post treatment evaluation is a long-held point of expertise by the clinically trained interventional radiologist.”

“For many years,” Higgins and Lee concluded, “the axiom ‘frostbite in January, amputate in July’ was an accurate description of the common outcome in frostbite injuries. Through a meta-analysis of thrombolytic therapy in the management of severe frostbite, this article provides a useful guideline for interventional radiologists, including a suggested protocol, inclusion and exclusion criteria, and potential complications.”

The author’s recommendation is based off the multidisciplinary care protocol that they co-implemented at their own institution, Boston Medical Center. Higgins and Lee say this “begins with an objective evaluation of the affected digits, including grading post-rapid rewarming in the emergency department.” This might then include collaborative clinical triaging of severe frostbite injury patients to intravenous or intra-arterial thrombolytic management with conservative management for low grade injuries, with contributions from emergency medicine, trauma surgery, podiatry, orthopaedics, internal medicine, diagnostic and interventional radiology.

“It is important to note,” they add, “that such multidisciplinary efforts reliably and reproducibly support early and accurate diagnosis and triaging of patients with frostbite injuries and are vital in providing appropriate management and oversight of these patients, particularly during thrombolytic therapy.”

When asked how this research will impact clinical practice, Higgins emphasises the importance of promoting these procedures: “Publicity on the use of thrombolytic therapy in treating acute severe frostbite is vital to ensure that frostbite patients are afforded the most efficacious management option to preserve their digits in the unfortunate event of an acute frostbite injury. With global warming as a real though daunting consideration, who knows which city or hospital might experience a rush of frostbite cases amenable to this important digit-salvaging therapy, and when? Knowing how to protect our patients from digit loss should such events occur is now a critical consideration for the forward-thinking, patient-centric interventional radiologists that we all aspire to be. In that vein, I would consider encouraging periodic efforts to inform healthcare providers about thrombolytic management of severe frostbite, especially during each winter season.”

Higgins and Lee hope to see the results of randomised trials in comparing the effectiveness and complications of intra-arterial and intravenous thrombolytic therapy. “With these results,” they determine, “we will be able to provide more effective and safe digit-saving care for patients with acute severe frostbite injuries.”


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