Bedside Fluorescence Microangiography for Frostbite Diagnosis in the Emergency Department.

INTRODUCTION: Frostbite leads to progressive ischemia eventually causing tissue necrosis if not quickly reversed. Patients with frostbite tend to present to the emergency department (ED) for assessment and treatment. Acute management includes rewarming, pain management, and (when indicated) thrombolytic therapy. Thrombolytic therapy in severe frostbite injury may decrease rates of amputation and improve patient outcomes. Fluorescence microangiography (FMA) has been used to distinguish between perfused and non-perfused tissue. The purpose of this study was to evaluate the potential role of FMA in the acute care of patients with frostbite, specifically its role as a tool to identify perfusion deficit following severe frostbite injury, and to explore its role in time to tissue plasminogen activator (tPA). METHODS: This retrospective analysis included all patients from December 2020-March 2021 who received FMA in a single ED as part of their initial frostbite evaluation. In total, 42 patients presented to the ED with concern for frostbite and were evaluated using FMA. RESULTS: Mean time from arrival in the ED to FMA was 46.3 minutes. Of the 42 patients, 14 had clinically significant perfusion deficits noted on FMA and received tPA. Mean time to tPA (measured from ED arrival to administration of tPA) for these patients was 117.4 minutes. This is significantly faster than average historical times at our institution of 240-300 minutes. CONCLUSION: Bedside FMA provides objective information regarding perfusion deficits and allows for faster decision-making and improved times to tPA. Fluorescence microangiography shows promise for quick and efficient evaluation of perfusion deficits in frostbite-injured patients. This could lead to faster tPA administration and potentially greater rates of tissue salvage after severe frostbite injury.

Research progress in the pathogenic mechanisms and imaging of severe frostbite.

PURPOSE: This article reviews the pathological mechanisms and progress of imaging of severe frostbite to assist in the search for targets for clinical diagnosis and treatment of severe frostbite. This review also aims to provide strong evidence for clinical diagnosis and treatment of deep frostbite. METHODS: The review was based on the summary and analysis of the existing literature, and explored the pathological mechanism of deep frostbite and the advantages and disadvantages of imaging diagnostic methods. RESULTS: According to the depth of tissue involvement, frostbite is divided into 4 levels. Severe frostbite includes Grade 3 and Grade 4 frostbite. Clinical performance evaluation and imaging diagnostic research have always been the mainstream of severe frostbite diagnosis. Imaging methods focus on vascular patency and tissue vitality. This article introduces angiography, SETCT/CT and MRA, and we summarize the advantages and disadvantages of these imaging methods. We recommend corresponding imaging modalities according to the state of frostbite patients. CONCLUSIONS: Imaging examination, especially angiography and bone scans, provide useful information for determining the diagnosis and prognosis of severe frostbite. In order to obtain a good clinical prognosis, clinicians should first perform SPECT/CT. MRA does not burden the patient's body, but the balance between cost and benefit must be considered. Angiography provides a good feedback on the changes in blood vessel status before and after treatment, which is helpful for discovering the response of limbs to treatment.

What Interventional Radiologists Need to Know About Managing Severe Frostbite: A Meta-Analysis of Thrombolytic Therapy.

OBJECTIVE. The purpose of this study is to review the various techniques and clinical management paradigms using tissue plasminogen activator (tPA) to treat severe frostbite injuries, which are relevant to the interventional radiologist. MATERIALS AND METHODS. A literature search yielded 157 citations, which were manually screened for inclusion criteria of case reports, case series, cohort studies, and randomized prospective studies that reported the use of tPA to treat severe frostbite injuries, of which 16 qualified for review. Data extracted from the studies included authors, journal, year of publication, initial assessment and management of severe frostbite injuries, inclusion and exclusion criteria for tPA therapy, treatment and control group size, different imaging modalities used in evaluation of severe frostbite injuries, tPA treatment protocols, outcomes, and side effects or complications. RESULTS. The analyzed series included 209 patients with 1109 digits at risk of amputation who were treated with intraarterial (IA) or IV tPA (116 and 77 patients, respectively). A total of 926 digits at risk 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 salvage rate of 62%. Both digital subtraction angiography and triple-phase bone scan were used for initial imaging evaluation. Additional concurrent treatment included therapeutic heparin, warfarin, nonsteroidal antiinflammatory drugs, pain management, and light dressings with topical antimicrobial agents. CONCLUSION. Severe frostbite injuries can lead to devastating outcomes with loss of limbs and digits, yet clinical management continues to consist primarily of tissue rewarming, prolonged watchful waiting, and often delayed amputation. Recent studies have shown promising results using both IA and IV tPA to reduce amputation after severe 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.

Utilization of bone scan and single photon emission computed tomography on amputation planning in acute microvascular injury: Two cases.

The use of single photon emission computer tomography (SPECT/CT) in acute vascular injury is not well documented. SPECT/CT combines the anatomic detail of computer tomography with the functional vascular perfusion of photon emission to determine the viability of osseous structures and surrounding soft tissue. The superimposed imaging provides the practitioner with a reliable anatomic image of viability of a specific anatomic area following insult or injury. We present two cases, bilateral lower extremity frostbite, and symmetric peripheral gangrene in which this imaging modality provided guidance for surgical intervention with adequate predictability and results.

Microangiography: An Alternative Tool for Assessing Severe Frostbite Injury.

Assessment of frostbite injury typically relies on computed tomography, angiography, or nuclear medicine studies to detect perfusion deficits prior to thrombolytic therapy. The aim of this study was to evaluate the potential of a novel imaging method, microangiography, in the assessment of severe frostbite injury. Patients with severe frostbite were included if they received a post-thrombolytic Technetium 99 (Tc99) bone scan, a Tc99 bone scan without thrombolytic therapy, and/or post-thrombolytic microangiography (MA) study. We included all patients from the years 2006 to 2018 with severe frostbite injury who had received appropriate imaging for diagnosis: Tc99 scan alone (N = 82), microangiography alone (N = 22), and both Tc99 and microangiography (N = 26). The majority of patients received thrombolytic therapy (76.2%), and the average time to thrombolytics was 6.9 hours. Tc99 scans showed strong correlation with amputation level (r = .836, P < .001), and microangiography showed a slightly stronger positive correlation with amputation level (r = .870, P < .001). In the subset who received both Tc99 scan and microangiography (N = 26), we observed significant differences in the mean scores of perfusion deficit (z = 3.20, P < .001). In this subset, a moderate correlation was found between level of perfusion deficit on Tc99 bone scan and amputation level (r = .525, P = .006). A very strong positive correlation was found between the microangiography studies and the amputation level (r = .890, P < .001). These results demonstrate that microangiography is a reliable alternative method of assessing severe frostbite injury and predicting amputation level.

Frostbite arthropathy - a rare case of osteoarthritis, review of the literature and case presentation.

Frostbite affects more commonly the northern population then it was suspected earlier, but wherever cold winter occurs, cold caused lesions are reported. Most often, it is described as soft tissue lesions, but deeper structures like tendons, ligaments, muscles, cartilage or bones can be affected. All extremities can be involved; lesions can lead to necrosis and amputations. First documented cases were described during military actions, but occupational or recreational activities can also be a risk factor for frostbite. Frozen or frostbite arthropathy is a rare cause of osteoarthritis. Usually, arthritis appears after a long time after frostbite, it can be decades apart. Frostbite arthropathy can result in different debilitating conditions. The current review describes the most important changes in frostbite and a rare but very serious late complication, which lead to arthropathy.

The utility of bone scintigraphy with SPECT/CT in the evaluation and management of frostbite injuries.

OBJECTIVE:: Frostbite is a localized cold-thermal injury resulting from prolonged exposure of flesh to freezing and near freezing temperatures. The depth and extent of frostbite injuries are not easily assessed, from a clinical standpoint, at the time of injury making it challenging to plan appropriate management and treatment. METHODS:: A review of the literature of management of cold-related injuries and retrospective case review of the imaging and clinical course of frostbite injury. RESULTS:: Bone scintigraphy with single photon emission computed tomography (SPECT)/CT was performed in the acute and subacute course of frostbite injuries, subsequently leading to earlier definitive management and shorter hospital stay. CONCLUSION:: Multiphase technetium-99m-methylenediphosphonate (99mTc-MDP) bone scintigraphy with SPECT/CT can expedite clinical management of frostbite injuries by determining the extent of injury and can accurately predict the level of amputation if needed. ADVANCES IN KNOWLEDGE::  SPECT/CT is underutilized at many facilities but can have a profound and immediate impact on clinical management of patients with frostbite when used in combination with physiological bone scan imaging.

Microangiography to Monitor Treatment Outcomes Following Severe Frostbite Injury to the Hands.

Frostbite injury causes direct damage to tissues following exposure to temperatures below their freezing point causing tissue death potentially leading to serious amputations. After rewarming, a variety of treatment options have been employed to avoid amputation. This case report details the use of indocyanine green fluorescence microangiography to monitor the clinical progression of perfusion following hyperbaric oxygen therapy (HBOT) for severe frostbite injury. We present a case report of a man with deep frostbite of the bilateral hands treated with thrombolytics and HBOT. After rewarming, the patient received thrombolytics shortly after arrival and then went on to be treated with HBOT on hospital day 5. Patient's healing progress was monitored using serial microangiography. Microangiography evaluation was performed on day 6 and then weekly to track treatment progress. A more uniform brightness appears in his left hand by completion of his therapies, consistent with normal perfusion. The dark ischemic areas in the right hand receded in digits 1 to 3 and appeared normalized in the fourth digit. The patient received a total of 20 HBO treatments. After completion of therapy, the patient went on to have a partial amputation of his first, second, and third fingers on his right hand. Our case report demonstrates serial microangiography to monitor a frostbite patient's progress during HBOT and provided additional information allowing us to plan duration of treatments. Our case report describes the role that microangiography may serve in monitoring patient progress following severe frostbite injury.

The evolution of the Helsinki frostbite management protocol.

BACKGROUND: Severe frostbite can result in devastating injuries leading to significant morbidity and loss of function from distal extremity amputation. The modern day management approach to frostbite injuries is evolving from a historically very conservative approach to the increasingly reported use of early interventional angiography and fibrinolysis with tPA. The aim of this study was to evaluate the results of our frostbite treatment protocol introduced 3 years ago. METHODS: All frostbite patients underwent first clinical and then Doppler ultrasound examination. Angiography was conducted if certain clinical criteria indicated a severe frostbite injury and if there were no contraindications to fibrinolysis. Intra-arterial tissue plasminogen activator (tPA) was then administered at 0.5-1mg/h proximal to the antecubital fossa (brachial artery) or popliteal fossa (femoral artery) if angiography confirmed thrombosis, as well as unfractionated intravenous heparin at 500 units/h. The vasodilator iloprost was administered intravenously (0.5-2.0ng/kg/min) in selected cases. RESULTS: 20 patients with frostbite were diagnosed between 2013-2016. Fourteen patients had a severe injury and angiography was performed in 10 cases. The total number of digits at risk was 111. Nine patients underwent fibrinolytic treatment with tPA (including one patient who received iloprost after initial non response to tPA), 3 patients were treated with iloprost alone and 2 patients received neither treatment modality (due to contraindications). The overall digital salvage rate was 74.8% and the Hennepin tissue salvage rate was 81.1%. One patient developed a catheter-site pseudoaneurysm that resolved after conservative treatment. CONCLUSIONS: Prompt referral to a facility where interventional radiology and 24/7 laboratory services are available, and the combined use of tPA and iloprost, may improve outcome after severe frostbite.

SPECT/CT in the Evaluation of Frostbite.

Frostbite remains a challenging clinical scenario with multiple treatment algorithms and variable results. Currently, frostbite management often follows a conservative approach with rewarming followed by wound care and delayed amputation. We review seven patients where single-photon emission computed tomography (SPECT) fused with conventional computed tomography was used to evaluate tissue viability for earlier directed debridement and limb salvage. The goal of this report is to evaluate SPECT/CT as an appropriate modality for the screening of necrotic bone for earlier amputation in patients with frostbite. We retrospectively analyzed the records of seven patients (19 extremities) with frostbite who received SPECT/CT scans to evaluate deep tissue necrosis before digit amputation. All patients who presented within the first 24 hr following their injury without contraindications were initially treated with tissue plasminogen activator. Three patients met criteria and were treated with tissue plasminogen activator. Of the seven patients analyzed, none required revision amputation beyond the level predicted on SPECT/CT scan. No patients had viable tissue distal to the most distal extent of bone perfusion. In six of the patients, the SPECT/CT scan led to more distal amputation with proximal debridement of soft tissues thus maintaining extremity length. Frostbite remains a challenging clinical scenario for which there are a wide number of clinical algorithms. SPECT/CT appears to be valuable in the evaluation of frostbite to determine the need for amputation. Fusion of the nuclear images with the CT allows for more exact delineation of the level of amputation than a bone scan alone.

Frostbite: Spectrum of Imaging Findings and Guidelines for Management.

Frostbite is a localized cold thermal injury that results from tissue freezing. Frostbite injuries can have a substantial effect on long-term limb function and mobility if not promptly evaluated and treated. Imaging plays a critical role in initial evaluation of frostbite injuries and in monitoring response to treatment. A multimodality approach involving radiography, digital subtraction angiography (DSA), and/or multiphase bone scintigraphy with hybrid single photon emission computed tomography (SPECT)/computed tomography (CT) is often necessary for optimal guidance of frostbite care. Radiographs serve as an initial survey of the affected limb and may demonstrate characteristic findings, depending on the time course and severity of injury. DSA is used to evaluate perfusion of affected soft tissues and identify potential targets for therapeutic intervention. Angiography-directed thrombolysis plays an essential role in tissue preservation and salvage in deep frostbite injuries. Multiphase bone scintigraphy with technetium 99m-labeled diphosphonate provides valuable information regarding the status of tissue viability after initial treatment. The addition of SPECT/CT to multiphase bone scintigraphy enables precise anatomic localization of the level and depth of tissue necrosis before its appearance at physical examination and can help uncover subtle findings that may remain occult at scintigraphy alone. Multiphase bone scintigraphy with SPECT/CT is the modality of choice for prognostication and planning of definitive surgical care of affected limbs. Appropriate use of imaging to direct frostbite care can help limit the effects that these injuries have on limb function and mobility. ©RSNA, 2016.

Catheter-Directed Intraarterial Thrombolysis as Part of a Multidisciplinary Management Protocol of Frostbite Injury.

PURPOSE: To evaluate intraarterial catheter-directed thrombolysis for prediction and prevention of delayed surgical amputation as part of multidisciplinary management of frostbite injury. MATERIALS AND METHODS: A retrospective review was performed of 13 patients (11 men, 2 women; median age, 33.4 y; range, 8-62 y) at risk of tissue loss secondary to frostbite injury and treated with catheter-directed tissue plasminogen activator (t-PA) thrombolysis. Amputation data were assessed on follow-up (mean, 23 mo; range, 9-83 mo). Angiographic findings were classified into complete, partial, and no angiographic response and assessed for association with follow-up amputation rates. Correlation between amputation outcome and duration of cold exposure (mean, 23 h; range, 5-96 h), time between exposure and rewarming therapy (mean, 25.5 h; range, 7-95 h), and time between exposure and t-PA thrombolysis (mean, 32 h; range, 12-96 h) was assessed. Complications were recorded. RESULTS: Of 127 digits at risk on baseline angiography that were treated with catheter-directed thrombolysis, complete recovery was seen in 106 (83.4%). Total mean t-PA dose per extremity was 27.5 mg (range, 12-48 mg) over a mean period of 34 hours (range, 12-72 h). Patients with complete angiographic response (8 patients; 79.5% of digits) did not require amputations; 4 of 5 patients (80%) with partial angiographic response (20.5% of digits) underwent amputation (P = .007). There was no significant correlation between amputation rates and duration of cold exposure (P = .9), time to rewarming therapy (P = .88), and time to thrombolysis (P = .56). Femoral access site bleeding in 2 patients was managed conservatively. One patient underwent surgical exploration for brachial artery hematoma. CONCLUSIONS: Intraarterial catheter-directed thrombolysis should be included in initial management of frostbite injury, as it may prevent delayed amputations. The degree of angiographic response to thrombolysis can potentially predict amputation outcomes.

Pathophysiologic Determination of Frostbite Under High Altitude Environment Simulation in Sprague-Dawley Rats.

OBJECTIVES: Pathophysiologic changes of frostbite have been postulated but rarely understood, especially the changes caused by chilly high altitude environment. Therefore, we investigated the pathophysiologic changes of high altitude frostbite (HAF) caused by cold and hypoxia. METHODS: Forty Sprague-Dawley rats were randomly divided into 5 equal groups, namely, control, superficial HAF (S-HAF), partial-thickness HAF (PT-HAF), full-thickness HAF (FT-HAF), and partial-thickness normal frostbite (PT-NF) groups. The S-HAF, PT-HAF, and FT-HAF groups were fed under hypobaric hypoxic conditions simulating an altitude of 5000 m. Then, the PT-NF, S-HAF, PT-HAF, and FT-HAF models were constructed by controlling the duration of the direct freezing by liquid nitrogen. Animal vital signs were measured after the operation, and histopathologic changes were observed after routine hematoxylin and eosin staining. In addition, the microcirculation of frostbite tissues was monitored and compared by contrast ultrasonography during wound healing. RESULTS: The S-HAF, PT-HAF, and FT-HAF groups showed significant differences in the microcirculatory and histopathologic changes in the various tissue layers (P < .05). In addition, combined cold and hypoxia caused more damage to frostbite tissue than pure cold. The circulation recovery of HAF models was significantly slower relative to NF models (P < .05). CONCLUSIONS: A safe and reproducible HAF model was proposed. More important, pathophysiologic determination of HAF provided the foundation and potential for developing novel and effective frostbite therapies.

The emerging role of tissue plasminogen activator in the management of severe frostbite.

This article presents a small case series demonstrating clinical success with thrombolytic agents for severe frostbite injury to the lower extremities. The authors report three patients with severe frostbite injuries to their distal lower extremities who were managed with urgent interventional radiology and intra-arterial tissue plasminogen activator infusion according to a prespecified protocol. Limbs and digits were successfully salvaged and patients returned to normal activity within 2 weeks. Although further studies are needed, results of this study support a new approach in the management of frostbite: from conservative management and observation to urgent interventional radiology and possible tissue plasminogen activator infusion. A protocol for the management of such injuries is presented.

[Amputation level after frostbite: role of bone scan. A case report]. / Nivel de amputación tras lesiones por congelación: papel de la gammagrafía ósea. Reporte de un caso.

BACKGROUND: frostbite is defined as the damage sustained by tissues while subject to temperatures below their freezing point. The severity of tissue damage is variable, but frequently can result in amputation. Early surgical debridement is contraindicated in almost all patients because it can take weeks for definitive demarcation of non-viable tissues to occur. Bone scan is indicted in the evaluation of frostbite injuries and helps to establish the prognosis early. CLINICAL CASE: a 42 year old man suffered frostbite injury in the fingers and toes after more than 24 hours at 8,000 meters of altitude. The patient was treated with anticoagulant therapy and topical cures for six weeks. During this period, we performed two consecutive bone scan studies showing no changes in the level of vascularization. However, clinical improvement was important, devitalized tissues delimited to the level marked by the bone scan study, so amputation was performed. CONCLUSION: Because the bone scan remained invariable, we believe that could help us to determine the amputation level early without delaying surgery.

Antecedentes: la congelación es el daño sufrido por los tejidos cuando se someten a temperaturas inferiores a su punto de congelación. La gravedad de las lesiones es variable, pero con frecuencia termina en amputación. El desbridamiento quirúrgico temprano está contraindicado en la mayoría de los casos porque la demarcación de los tejidos viables tarda en producirse. La gammagrafía ósea está indicada para la evaluación de las lesiones por congelación y ayuda a establecer el pronóstico temprano. Caso clínico: paciente varón de 42 años, con lesiones por congelación en los dedos de las manos y los pies, tras permanecer más de 24 horas a 8,000 metros de altitud. Durante seis semanas se administró tratamiento anticoagulante y se realizaron curas tópicas. En este periodo se practicaron dos estudios gammagráficos consecutivos, sin apreciarse cambios en la vascularización. Sin embargo, la mejoría clínica fue importante, delimitándose el tejido desvitalizado hasta el nivel marcado por el estudio gammagráfico, por lo que se realizó la amputación. Conclusión: puesto que la gammagrafía ósea permaneció invariable, consideramos que puede ayudar a determinar de forma temprana el nivel de amputación, sin tener que demorar la cirugía.

[Improved fixation of finger prostheses by means of intramedullary titanium anchors and magnets]. / Osseointegrierte Fingerprothetik -- Endomedulläre Titan-Implantatverankerungen und Titan-Magnete zur besseren Fixation von Fingerprothesen.

BACKGROUND: A small series of patients with traumatic amputation of fingers have undergone treatment with a new technique using endomedullar osseointegrated titanium implant device that magnetically holds the finger prosthesis. METHODS: A two-stage reconstruction procedure with endomedullar osseointegrated titanium implants was performed to attach a finger prosthesis to the proximal, middle and distal phalanx. The first stage included implantation of the titanium fixture into the medullary cavity canal of the phalanx. After a 2-month rest period to allow the fixture to firmly osseointegrate with the phalanx of the bone, a skin-penetrating titan-magnetic abutment was placed on top of the fixture, to which the prosthesis was firmly attached. RESULTS: Good stability could be achieved using an endomedullar osseointegrated prosthesis. Easy handling is possible with the magnetic connection between finger and prosthesis. In the clinical use were no complications observed. We observed no infections and no problems with the soft tissue. CONCLUSIONS: The combination of osseointegrated titanium implants and magnetics for finger prosthetics provides several advantages. Such as stable fixation of the prosthetic finger to the bone, restoration of some sensory feedback with better osseoperception as well as an excellent cosmetic result.

An open-label study to evaluate the safety and efficacy of tissue plasminogen activator in treatment of severe frostbite.

BACKGROUND: Severe frostbite can have devastating consequences with loss of limbs and digits. One of the mechanisms of cold injury to human tissue is vascular thrombosis. The effect of tissue plasminogen activator (tPA) and heparin in limb and digit preservation in severe frostbite patients has not been previously studied. METHODS: Intra-arterial (6 patients) or intravenous (i.v., 13 patients) tPA and IV heparin were used in patients with severe frostbite. All patients between January 1, 1989 and February 1, 2003 with severe frostbite not improved by rapid rewarming, with absent Doppler pulses in distal limb or digits, without perfusion by Technetium (Tc) 99m three-phase bone scan, and no contraindication to tPA use were eligible. Efficacy was assessed on the basis of predicted digit amputation before therapy, given the clinical and Tc-99m scan results, versus partial or complete digits removed. RESULTS: There were no complications with i.v. tPA. Two patients with intra-arterial TPA had bleeding complications. We know from historical Tc-99m scan data which digits were at risk for amputation. In this study, there were 174 digits at risk in 18 patients and only 33 were amputated. CONCLUSION: Intravenous tPA and heparin after rapid rewarming is safe and reduced predicted digit amputations considerably. Patients with no response to thrombolytic therapy were those with more than 24 hours of cold exposure, warm ischemia times greater than 6 hours, or evidence of multiple freeze-thaw cycles. Our algorithm for treatment of severe frostbite now includes use of i.v. tPA for patients without contraindications.