Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2019.

Vascular Surgery Workforce: Evaluation and Estimation of Future Demand in the United Kingdom.

BACKGROUND: Vascular disease is a common cause of death and disability in our growing elderly population and the demand for vascular procedures is increasing worldwide. Workforce planning is essential to meet future demand and provide safe vascular services. Our aim was to evaluate the current workforce in the United Kingdom and estimate future demand for vascular surgeons. METHODS: From November 2020 to January 2021, we surveyed UK vascular surgeons for information on their work patterns. We estimated current vascular surgery (VS) workforce using the National Vascular Registry (NVR) data and population data from the Office for National Statistics. To estimate future demand, we interrogated Hospital Episode Statistic (HES) data using Hospital Admitted Patient Care Activity (HAPCA) and linear trend analysis. RESULTS: NVR data estimate that currently there are 518 consultant VS in the United Kingdom, or 1 per 128,951 population, lower than international comparisons. HAPCA data (2012-2020) suggests VS Finished Consultant Episodes (FCE), admissions, and waiting lists are growing by approximately 2% per year, and we estimate the workforce will need to grow by more than 50% over the next 10 years to meet this demand and Vascular Society of Great Britain and Ireland recommendation. CONCLUSIONS: The UK has a shortage of vascular surgeons at a time when vascular activity is increasing. The VS workforce, both VS consultant and vascular surgeons in training numbers need to expand to address the ongoing shortage and maintain a safe level of service.

Revacept, an Inhibitor of Platelet Adhesion in Symptomatic Carotid Stenosis: A Multicenter Randomized Phase II Trial.

BACKGROUND: Patients with symptomatic internal carotid artery (ICA) stenosis are at high risk of recurrent ischemic stroke and require early interventional treatment and antiplatelet therapy. Increased bleeding rates might counterbalance the periprocedural efficacy of intensified platelet inhibition. We aim to investigate, whether Revacept, a competitive antagonist of glycoprotein VI, adjunct to standard antiplatelet therapy reduces the occurrence of ischemic lesions in patients with symptomatic ICA stenosis. METHODS: International, multicenter (16 sites), 3-arm, randomized (1:1:1), double-blind, and placebo-controlled study with parallel groups, including patients with symptomatic ICA stenosis. A single infusion over 20 minutes of either placebo, 40 mg or 120 mg Revacept in addition to guideline-conform antiplatelet therapy was evaluated with regard to the exploratory efficacy end point: Number of new ischemic lesions on diffusion-weighted magnetic resonance imaging after treatment initiation. Main clinical outcome was the combined safety and efficacy end point including any stroke or death, transient ischemic attack, myocardial infarction, coronary intervention, and bleeding complications during follow-up. RESULTS: Out of 160 randomized patients, 158 patients (68±10.1 years, 24% female) received study medication (51 patients placebo, 54 patients 40 mg Revacept and 53 patients 120 mg Revacept) and were followed for 11.2±2.3 months. A total of 1.16 (95% CI, 0.88-1.53)/1.05 (95% CI, 0.78-1.42; P=0.629)/0.63 (95% CI, 0.43-0.93) new diffusion-weighted magnetic resonance imaging lesions per patient were detected in the placebo/40 mg/120 mg Revacept groups, without statistical evidence of a difference. A reduction of the combined safety and efficacy end point during the study period was observed in patients who received 120 mg (HR, 0.46 [95% CI, 0.21-0.99]; P=0.047), but not 40 mg Revacept compared with placebo (HR, 0.72 [95% CI, 0.37-1.42]; P=0.343). CONCLUSIONS: Revacept 120 mg reduced the combined safety and efficacy end point in patients with symptomatic ICA stenosis. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique Identifier: NCT01645306.

Vascular Surgeon Burnout and Resilience in the United Kingdom: A Report from the Vascular Society Workforce Committee.

BACKGROUND: Occupational burnout is a growing concern in frontline roles such as vascular surgery, and is associated with medical errors and shortened careers. Our aim is to measure burnout, resilience, and associated risk factors among vascular surgeons (VS) in the United Kingdom (UK). METHODS: We carried out an electronic survey of active VS in the UK using validated self-report questionnaires, including the following: Copenhagen Burnout Inventory (CBI), Brief Resilience Scale (BRS), and information on job characteristics, health, and well-being. Univariate regression analysis looked at potential risk factors. RESULTS: One hundred forty-eight VS responded (49% participation rate), and after excluding retirees and nonconsultants, 133 VS practicing in the UK were analyzed. Mean age was 49.9 ± 7.19 years; the majority (83.5%) were male. In total, 81.3% recorded ethnic identity as White. In addition, 93.2% worked full time; 74.8% were contracted above 10 programmed activities and 87.9% worked more than 40 hr/week. On-call was 1 in 6, or above, for 87.4%. Overall, 38.4% of VS had high burnout on the CBI. Resilience was also high, with BRS mean (standard deviation) of 3.6 (0.69) and median (interquartile range) of 3.7 (3-4). Univariate regression analysis found no significant risk factor associated with high burnout or resilience. CONCLUSIONS: VS in the UK have high levels of burnout and work long hours. Resilience levels were also high, which may offer some protection. However, policymakers and our surgical leaders should address contributing factors and excessive working hours and establish measures to identify and support surgeon well-being for optimal surgeon and patient safety.

Early Use of Iloprost in Nonfreezing Cold Injury.

Nonfreezing cold injury (NFCI) is caused by prolonged exposure to cold, usually wet conditions and represents a separate pathological entity from frostbite. The pathophysiology of NFCI is characterized by vasoconstriction and microcirculatory disturbance. Iloprost, a synthetic prostaglandin analogue with vasodilatory properties is a recognized adjuvant treatment in frostbite; however, its role in NFCI is unclear. We present a case of a 29-y-old man with severe NFCI to both forefeet after prolonged immersion in cold seawater. Initial treatment with passive rewarming, analgesia and aspirin was initiated. Infusion of iloprost was used within 24 h from presentation and was well tolerated. This resulted in reduced tissue loss compared to the apparent tissue damage documented during the initial assessment. Delayed surgical intervention allowed minor debridement and minor toe amputations, maintaining the patient's ability to ambulate. This case demonstrates the safe use of iloprost in acute NFCI and highlights the importance of delayed surgical intervention in patients presenting with severe NFCI.

Allograft nephrectomy versus nonallograft nephrectomy after failed renal transplantation: a systematic review by updated meta-analysis.

There is limited evidence regarding the impact of allograft nephrectomy (AN) on the long-term outcome of subsequent kidney re-transplantation compared with no prior allograft nephrectomy. The aim of the present study was to conduct a systematic review and meta-analysis to estimate the accumulation of evidence over time. Primary outcomes were 5-year graft and patient survival. Cochrane library, Google scholar, PubMed, Medline and Embase were systematically searched. Meta-analysis was conducted using both fixed- and random-effects models. Study quality was assessed in duplicate using the Newcastle-Ottawa scale. Sixteen studies were included, with a total of 2256 patients. All included studies were retrospective and comparative. There was no significant difference in 5-year graft survival (GS) [Hazard Ratio (HR) = 1.11, 95% Confidence Intervals (CI): 0.89, 1.38, P = 0.37, I2  = 10%) or in 5-year patient survival (PS; HR = 0.70, 95% CI: 0.45, 1.10, P = 0.12, I2  = 0%]. Patients in the AN cohort were significantly younger than patients in the nonallograft nephrectomy (NAN) cohort by one year. Prior allograft nephrectomy was associated with a significantly higher risk of delayed graft function (DGF), acute rejection, primary nonfunction (PNF), per cent of panel reactive antibodies (% PRA) and allograft loss of the subsequent transplant. Although, DGF, % PRA, acute rejection and primary nonfunction rates were significantly higher in the AN cohort, allograft nephrectomy prior to re-transplantation had no significant association with five-year graft and patient survival.

Editor's Choice - Acute Kidney Injury (AKI) in Aortic Intervention: Findings From the Midlands Aortic Renal Injury (MARI) Cohort Study.

OBJECTIVES: The incidence of acute kidney injury (AKI) after open (OAR) or endovascular (EVAR) aortic repair is unknown. This research assessed the proportion of patients who develop AKI after aortic intervention using validated criteria, and explored AKI risk factors. METHODS: This was a multicentre national prospective cohort study. Eleven centres recruited patients undergoing EVAR or OAR (September 2017-December 2018). Serum creatinine (SCr) and urine outputs were measured over a minimum of 48 h or throughout the index inpatient stay to define post-operative AKI using the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Renal decline at 30 days was calculated using estimated glomerular filtration rate (eGFR) and the Major Adverse Kidney Events (MAKE) 30 day composite endpoint (consisting of: death, new dialysis, > 25% eGFR decline). RESULTS: 300 patients (mean age: 71 years, standard deviation [SD] 4 years; 9% females) were included, who underwent: infrarenal endovascular aneurysm repair (EVAR) 139 patients, fenestrated EVAR (fEVAR) 30, branched EVAR (bEVAR) seven, infrarenal open aneurysm repair (OAR) 98, juxtarenal OAR 26. Overall, 24% of patients developed stage 1 AKI (defined at 48 h as per KDIGO), 2.7% stage 2 AKI and 1% needed renal replacement therapy before discharge. AKI proportions per intervention were: infrarenal EVAR 18%; fEVAR 27%; bEVAR 71%; infrarenal OAR 41%; juxtarenal OAR 63%. Older age (odds ratio [OR] 1.44 for EVAR, 1.58 for OAR), lower baseline eGFR (OR 0.88 EVAR, 0.74 OAR), and ischaemic heart disease (OR 4.42 EVAR, 5.80 OAR) were the main predictors of AKI for infrarenal EVAR and OAR. Overall, 24% developed the MAKE30 endpoint. All patients who died (0.6%) or developed a major cardiac event (5.6%) at one year had developed AKI. CONCLUSION: AKI and short term renal decline after aortic intervention are common. Age, renal function, and cardiovascular disease are the main risk factors. Research should now focus on AKI prevention in this high risk group.

C3d-positive donor-specific antibodies have a role in pretransplant risk stratification of cross-match-positive HLA-incompatible renal transplantation: United Kingdom multicentre study.

Anti-HLA-antibody characteristics aid to risk-stratify patients and improve long-term renal graft outcomes. Complement activation by donor-specific antibody (DSA) is an important characteristic that may determine renal allograft outcome. There is heterogeneity in graft outcomes within the moderate to high immunological risk cases (cross-match-positive). We explored the role of C3d-positive DSAs in sub-stratification of cross-match-positive cases and relate to the graft outcomes. We investigated 139 cross-match-positive living-donor renal transplant recipients from four transplant centres in the United Kingdom. C3d assay was performed on serum samples obtained at pretreatment (predesensitization) and Day 14 post-transplant. C3d-positive DSAs were found in 52 (37%) patients at pretreatment and in 37 (27%) patients at Day 14 post-transplant. Median follow-up of patients was 48 months (IQR 20.47-77.57). In the multivariable analysis, pretreatment C3d-positive DSA was independently associated with reduced overall graft survival, the hazard ratio of 3.29 (95% CI 1.37-7.86). The relative risk of death-censored five-year graft failure was 2.83 (95% CI 1.56-5.13). Patients with both pretreatment and Day 14 C3d-positive DSAs had the worst five-year graft survival at 45.5% compared with 87.2% in both pretreatment and Day 14 C3d-negative DSA patients with the relative risk of death-censored five-year graft failure was 4.26 (95% CI 1.79, 10.09). In this multicentre study, we have demonstrated for the first time the utility of C3d analysis as a distinctive biomarker to sub-stratify the risk of poor graft outcome in cross-match-positive living-donor renal transplantation.

Nonfreezing Cold Injuries Among Long-Distance Polar Rowers.

INTRODUCTION: Nonfreezing cold injury (NFCI) is a peripheral cold injury that occurs when the extremities are exposed to cold temperatures, at or near the freezing point, for sustained periods of time (48-96 h at temperatures of usually around 0 to 6°C with associated wind chill). Although NFCI often goes unreported and may be underdiagnosed, it is a cause of significant morbidity in those working in cold conditions, particularly those in the military. Thus, further research into the prevention, recognition, and treatment of NFCI is warranted. METHODS: The height, body weight, and body composition of 6 rowers taking part in 1 or 2 legs of the 2017 Polar Row expedition were measured. The weather conditions of the 2 legs of the journey were recorded, and symptoms relating to NFCI were documented. RESULTS: All incidences of NFCI occurred during Leg 2 of the expedition, which was colder and wetter. Of the Leg 2 rowers, those who developed NFCI had a trend toward higher pre-row body weight and body mass index and a trends toward losing more weight and body water relative to those who did not. CONCLUSIONS: The main factor contributing to the incidence of NFCI appeared to be weather; NFCI only occurred during the colder and wetter leg of the expedition. We also tentatively suggest that nutrition and dehydration may be linked to the incidence of NFCI as predisposing factors. More work, with sample sizes greater than those reported here, is required to investigate these associations to further characterize risk factors.

Endovascular Aneurysm Repair May Provide a Survival Advantage in Patients Deemed Physiologically Ineligible for Open Abdominal Aortic Aneurysm Repair.

BACKGROUND: Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity and fitness. It can be used to guide decision making prior to major vascular surgery. The EVAR-2 trial suggested that endovascular aneurysm repair (EVAR) in patients unfit for open repair failed to provide a significant survival advantage over nonsurgical management. The aim of this study is to assess contemporary survival differences between patients with poor CPET measures who underwent EVAR or were not offered surgical intervention. METHODS: A prospectively maintained database of CPET results of patients considered for elective infrarenal aortic aneurysm repair were interrogated. Anaerobic threshold (AT) of <11 mL/min/kg was used to indicate poor physical fitness. Hospital electronic records were then reviewed for perioperative, reintervention, and long-term outcomes. RESULTS: Between November 2007 and October 2017, 532 aortic aneurysm repairs were undertaken, of which 376 underwent preoperative CPET. Seventy patients were identified as having an AT <11 mL/min/kg. Thirty-seven patients underwent EVAR and 33 were managed nonsurgically. All-cause survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 92%, and 81%, respectively. For those not offered surgical intervention survival at the same points was 72%, 48%, and 24% [hazard ratio, HR = 5.13 (1.67-15.82), P = 0.004]. Aneurysm-specific survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 94%, and 94%, respectively. Survival at the same time points for those not offered surgical intervention was 90%, 69%, and 39%, respectively [HR = 7.48 (1.37-40.82), P = 0.02]. CONCLUSIONS: In this small, retrospective, single-center, nonrandomized cohort, EVAR may provide a survival advantage in patients with poor physical fitness identified via CPET. Randomized studies with current generation EVAR are required to validate the results shown here.

Pedicled Abdominal Flaps for Enhanced Digital Salvage After Severe Frostbite Injury.

Extremities are the area of the body most commonly affected by frostbite, which can also affect the face, ears, perineum, or genitals. Optimum management has moved away from early amputation and debridement toward maximizing tissue preservation and delaying surgical intervention. Increasing length of digit amputation increases morbidity, in terms of loss of hand function, experienced by patients. Reconstruction of affected digits is limited by bone necrosis, which often leads to shortened residual stumps and limited functional outcomes. This case describes the management of a severe frostbite injury affecting both hands and feet in a 39-y-old man, sustained during descent of Mount Everest. The use of a pedicled abdominal flap to provide soft-tissue cover permitted optimized digit length and function and sensate digits. The case highlights the benefits of early multidisciplinary team involvement in the management of severe frostbite to optimize functional outcome.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2019 Update.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2014.

HYDration and Bicarbonate to Prevent Acute Renal Injury After Endovascular Aneurysm Repair With Suprarenal Fixation: Pilot/Feasibility Randomised Controlled Study (HYDRA Pilot Trial).

OBJECTIVE/BACKGROUND: Up to 25% of patients undergoing elective endovascular aneurysm repair (EVAR) develop acute kidney injury (AKI), which is associated with short and long-term morbidity and mortality. There is no high quality randomised evidence regarding prevention of EVAR related AKI. METHODS: A novel AKI prevention strategy for EVAR was devised, based on best evidence and an expert consensus group. This included a bolus of high dose sodium bicarbonate (NaHCO3) immediately before EVAR (1 mL/kg of 8.4% NaHCO3) and standardised crystalloid based hydration pre- and post-EVAR. A pilot/feasibility randomised controlled trial (RCT) was performed in two centres to assess the safety of the intervention, potential impact on AKI prevention, and feasibility of a national RCT; the primary end point was the proportion of eligible patients recruited into the study. AKI was defined using "Kidney Disease Improving Global Outcomes" and "Acute Kidney Injury Network" criteria based on National Institute for Health and Clinical Excellence AKI recommendations, using serum creatinine and hourly urine output. RESULTS: Fifty-eight patients (84% of those screened; median age 75 years [range 57-89 years], 10% female) were randomised to receive the standardised intravenous hydration with (intervention) or without (control) NaHCO3. Groups were comparable in terms of AKI risk factors; 56 of 58 participants had a device with suprarenal fixation. Overall, 33% of patients in the control arm developed AKI versus 7% in the intervention arm (as treated analysis). None of the patients receiving NaHCO3 developed a serious intervention related adverse event; five patients did not attend their 30 day follow-up. CONCLUSION: Bolus high dose NaHCO3 and hydration is a promising EVAR related AKI prevention method. This trial has confirmed the feasibility of delivering a definitive large RCT to confirm the efficacy of this novel intervention, in preventing EVAR related AKI.

Kidney retransplantation from HLA-incompatible living donors: A single-center study of 3rd/4th transplants.

BACKGROUND: The demand for kidney retransplantation following graft failure is rising. Repeat transplantation is often associated with poorer outcomes due to both immunological and surgical challenges. The aim of this study was to compare surgical and functional outcomes of kidney retransplantation in recipients that had previously had at least two kidney transplants with a focus on those with antibody incompatibility. METHODS: We analyzed 66 patients who underwent renal transplantation at a single center between 2003 and 2011. Consecutive patients receiving their 3rd or 4th kidney were case-matched with an equal number of 1st and 2nd transplants. RESULTS: Twenty-two 3rd and 4th kidney transplants were matched with 22 first and 22 seconds transplants. Operative times and length of stay were equivalent between the subgroups. Surgical complication rates were similar in all groups (22.7% in 1st and 2nd transplants, and 27.2% in 3rd/4th transplants). There was no significant difference in patient or graft survival over 5 years. Graft function was similar between transplant groups at 1, 3, and 5 years. CONCLUSIONS: Third and fourth kidney transplants can be performed safely with similar outcomes to 1st and 2nd transplants. Kidney retransplantation from antibody-incompatible donors may be appropriate for highly sensitized patients.

Blood purine measurements as a rapid real-time indicator of reversible brain ischaemia.

To preserve the disequilibrium between ATP and ADP necessary to drive cellular metabolism, enzymatic pathways rapidly convert ADP to adenosine and the downstream purines inosine and hypoxanthine. During ischaemia, these same pathways result in the production of purines. We performed a prospective observational study to test whether purine levels in arterial blood might correlate with brain ischaemia. We made real-time perioperative measurements, via microelectrode biosensors, of the purine levels in untreated arterial blood from 18 patients undergoing regional anaesthetic carotid endarterectomy. Pre-operatively, the median purine level was 2.4 µM (95% CI 1.3-4.0 µM); during the cross-clamp phase, the purines rose to 6.7 µM (95% CI 4.7-11.5 µM) and fell back to 1.9 µM (95% CI 1.4-2.7 µM) in recovery. Three patients became unconscious during carotid clamping, necessitating insertion of a temporary carotid shunt to restore cerebral blood flow. In these, the pre-operative median purine level was 5.4 µM (range 4.7-6.1 µM), on clamping, 9.6 µM (range 9.4-16.1 µM); during shunting, purines fell to below the pre-operative level (1.4 µM, range 0.4-2.9 µM) and in recovery 1.8 µM (range 1.8-2.6 µM). Our results suggest that blood purines may be a sensitive real-time and rapidly produced indicator of brain ischaemia, even when there is no accompanying neurological obtundation.

Potential new treatment for non-freezing cold injury: is Iloprost the way forward?

INTRODUCTION: Non-freezing cold injury (NFCI) remains largely under-reported, and is of particular importance in the armed forces where its prevalence is greatest. Iloprost, a synthetic prostaglandin I2 analogue, has previously been used with some success in the treatment of vasospastic and freezing cold injuries, although its role in NFCI remains unclear. CASE REPORT: An Iloprost infusion was used to treat the long-term sequelae of an ex-soldier suffering with ongoing pedal pain and loss of function 20 years after the initial NFCI insult sustained on military exercise. Following 5 days of iloprost infusion, he reported 4 weeks of markedly reduced pain and increased mobility before symptom relapse. A second infusion was thus given 3 months later, which resulted in increased pain and analgesic requirements. DISCUSSION: The use of iloprost in the treatment of NFCI is discussed and its use in a condition which physicians consistently struggle to treat effectively is considered. Careful counselling is recommended as symptoms may be worsened.

Extreme, expedition, and wilderness medicine.

Extreme, expedition, and wilderness medicine are modern and rapidly evolving specialties that address the spirit of adventure and exploration. The relevance of and interest in these specialties are changing rapidly to match the underlying activities, which include global exploration, adventure travel, and military deployments. Extreme, expedition, and wilderness medicine share themes of providing best available medical care in the outdoors, especially in austere or remote settings. Early clinical and logistics decision making can often have important effects on subsequent outcomes. There are lessons to be learned from out-of-hospital care, military medicine, humanitarian medicine, and disaster medicine that can inform in-hospital medicine, and vice-versa. The future of extreme, expedition, and wilderness medicine will be defined by both recipients and practitioners, and empirical observations will be transformed by evidence-based practice.

Acute Mountain Sickness (AMS) Knowledge Among High Altitude Marathon Runners Competing in the Everest Marathon.

OBJECTIVE: Although there are a number of studies on trekkers' knowledge of acute mountain sickness (AMS), there is little current literature on other groups at altitude, for example, marathon runners. Increased knowledge of AMS is associated with a lower incidence of AMS. The purpose of this study was to determine AMS knowledge of marathon runners with an aim to improve AMS information distribution. Incidence of AMS was also determined. METHODS: Participants completed a self-assessment AMS knowledge questionnaire in Kathmandu before starting the acclimatization trek for the Tenzing Hillary Everest Marathon in Nepal. Lake Louise Scoring questionnaires were completed every day of the 12-day acclimatization trek. RESULTS: The majority (86%; 43 of 50) of participants obtained information about AMS before the marathon, with the Internet providing the most common source (50%; 25 of 50). Ninety-two percent (46 of 50) of participants rated their knowledge as average or above, and self-assessment correlated with knowledge questionnaire scores (r = .479, P < .001). However, 48% (24 of 50) did not know it was unsafe to ascend with mild AMS symptoms, and 66% (33 of 50) thought it was safe to go higher with symptoms relieved by medication. Only 50% (25 of 50) knew AMS could occur from 2500 m. Thirty-eight percent (19 of 50) of participants had AMS during the acclimatization trek, and 6% (3 of 50) experienced it during the race. CONCLUSIONS: This study adds to previous literature regarding knowledge and incidence of AMS. It further highlights that more needs to be done to improve knowledge through better information dissemination, with inclusion of scenario-based information to aid application of this knowledge to practical situations.