Frequency and relevance of acute peritraumatic pulmonary thrombus diagnosed by computed tomographic imaging in combat casualties

Challenging Traditional Paradigms in Posttraumatic Pulmonary Thromboembolism

Importance

Pulmonary clots are seen frequently on chest computed tomography performed after trauma, but recent studies suggest that pulmonary thrombosis (PT) and pulmonary embolism (PE) after trauma are independent clinical events.

Objective

To assess whether posttraumatic PT represents a distinct clinical entity associated with the nature of the injury, different from the traditional venous thromboembolic paradigm of deep venous thrombosis (DVT) and PE.

Design, Setting, and Participants

This prospective, observational, multicenter cohort study was conducted by the Consortium of Leaders in the Study of Traumatic Thromboembolism (CLOTT) study group. The study was conducted at 17 US level I trauma centers during a 2-year period (January 1, 2018, to December 31, 2020). Consecutive patients 18 to 40 years of age admitted for a minimum of 48 hours with at least 1 previously defined trauma-associated venous thromboembolism (VTE) risk factor were followed up until discharge or 30 days.

Exposures

Investigational imaging, prophylactic measures used, and treatment of clots.

Main Outcomes and Measures

The main outcomes of interest were the presence, timing, location, and treatment of any pulmonary clots, as well as the associated injury-related risk factors. Secondary outcomes included DVT. We regarded pulmonary clots with DVT as PE and those without DVT as de novo PT.

Results

A total of 7880 patients (mean [SD] age, 29.1 [6.4] years; 5859 [74.4%] male) were studied, 277 with DVT (3.5%), 40 with PE (0.5%), and 117 with PT (1.5%). Shock on admission was present in only 460 patients (6.2%) who had no DVT, PT, or PE but was documented in 11 (27.5%) of those with PE and 30 (25.6%) in those with PT. Risk factors independently associated with PT but not DVT or PE included shock on admission (systolic blood pressure <90 mm Hg) (odds ratio, 2.74; 95% CI, 1.72-4.39; P < .001) and major chest injury with Abbreviated Injury Score of 3 or higher (odds ratio, 1.72; 95% CI, 1.16-2.56; P = .007). Factors associated with the presence of PT on admission included major chest injury (14 patients [50.0%] with or without major chest injury with an Abbreviated Injury Score >3; P = .04) and major venous injury (23 [82.1%] without major venous injury and 5 [17.9%] with major venous injury; P = .02). No deaths were attributed to PT or PE.

Conclusions and Relevance

To our knowledge, this CLOTT study is the largest prospective investigation in the world that focuses on posttraumatic PT. The study suggests that most pulmonary clots are not embolic but rather result from inflammation, endothelial injury, and the hypercoagulable state caused by the injury itself.

[Pulmonary artery thrombosis: strategy of anticoagulation]

This review is devoted to the management of primary artery thrombosis (PAT). This disease was always considered only as a part of other venous thromboembolic events, in particular isolated pulmonary embolism (PE). Various studies show that PAT can develop as an independent event without concomitant damage to extra-vessels. PAT is characterized by own typical signs as primary and recurrent event that can determine special strategies of treatment. However, there are no studies devoted to this problem. We can only make some assumptions about PAT anticoagulation (AC) considering data on isolated PE comprising PAT. These data are available in PADIS-PE, ASPIRE, EINSTEIN-PE, Hokusai-VTE studies underlying modern guidelines of various societies. In the absence of studies on PAT AC these guidelines should regulate PAT AC approaches. AC is recommended in all cases of PE except isolated subsegmental PAT in ambulatory patients. Duration of AC depends on risk factors (major or minor). Anticoagulation for PAT following chronic inflammatory diseases is still disputable.

[Explosion trauma part 1 : Physical principles and pathophysiology]

After explosions, various injury mechanisms lead to multiple injuries that can affect the entire body. While high pressure peaks and exposure to heat, especially in the vicinity of a detonation, can cause severe injuries and organ damage, fragments also pose a considerable threat to explosion victims even over long distances. The recognition and treatment of life-threatening disorders and the assessment of the severity of the injury are just as challenging for the entire treatment team as long-term operative management, reconstruction strategies and rehabilitation of the complex injuries. Knowledge of the injury mechanics and the pathophysiology of blast injuries should help the interdisciplinary team to master this challenge.

Chronic Thromboembolic Pulmonary Hypertension: the Bench

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH) is an uncommon complication of acute pulmonary embolism (PE), in which the red, platelet-rich thrombus does not resolve but forms into an organized yellow, fibrotic scar-like obstruction in the pulmonary vasculature. Here we review the pathobiology of CTEPH.

RECENT FINDINGS

Our current knowledge has predominantly been informed by studies of human samples and animal models that are inherently limited in their ability to recapitulate all aspects of the disease. These studies have identified alterations in platelet biology and inflammation in the formation of a scar-like thrombus that comprised endothelial cells, myofibroblasts, and immune cells, along with a small vessel pulmonary arterial hypertension-like vasculopathy. The development of CTEPH-specific therapies is currently hindered by a limited knowledge of its pathobiology. The development of new CTEPH medical therapies will require new insights into its pathobiology that bridge the gap from bench to bedside.

Trauma-induced coagulopathy

Uncontrolled haemorrhage is a major preventable cause of death in patients with traumatic injury. Trauma-induced coagulopathy (TIC) describes abnormal coagulation processes that are attributable to trauma. In the early hours of TIC development, hypocoagulability is typically present, resulting in bleeding, whereas later TIC is characterized by a hypercoagulable state associated with venous thromboembolism and multiple organ failure. Several pathophysiological mechanisms underlie TIC; tissue injury and shock synergistically provoke endothelial, immune system, platelet and clotting activation, which are accentuated by the 'lethal triad' (coagulopathy, hypothermia and acidosis). Traumatic brain injury also has a distinct role in TIC. Haemostatic abnormalities include fibrinogen depletion, inadequate thrombin generation, impaired platelet function and dysregulated fibrinolysis. Laboratory diagnosis is based on coagulation abnormalities detected by conventional or viscoelastic haemostatic assays; however, it does not always match the clinical condition. Management priorities are stopping blood loss and reversing shock by restoring circulating blood volume, to prevent or reduce the risk of worsening TIC. Various blood products can be used in resuscitation; however, there is no international agreement on the optimal composition of transfusion components. Tranexamic acid is used in pre-hospital settings selectively in the USA and more widely in Europe and other locations. Survivors of TIC experience high rates of morbidity, which affects short-term and long-term quality of life and functional outcome.

Pulmonary Artery Thrombosis: A Diagnosis That Strives for Its Independence

According to a widespread theory, thrombotic masses are not formed in the pulmonary artery (PA) but result from migration of blood clots from the venous system. This concept has prevailed in clinical practice for more than a century. However, a new technologic era has brought forth more diagnostic possibilities, and it has been shown that thrombotic masses in the PA could, in many cases, be found without any obvious source of emboli. Chronic obstructive pulmonary disease, asthma, sickle cell anemia, emergency and elective surgery, viral pneumonia, and other conditions could be complicated by PA thrombosis development without concomitant deep vein thrombosis (DVT). Different pathologies have different causes for local PA thrombotic process. As evidenced by experimental results and clinical observations, endothelial and platelet activation are the crucial mechanisms of this process. Endothelial dysfunction can impair antithrombotic function of the arterial wall through downregulation of endothelial nitric oxide synthase (eNOS) or via stimulation of adhesion receptor expression. Hypoxia, proinflammatory cytokines, or genetic mutations may underlie the procoagulant phenotype of the PA endothelium. Both endotheliocytes and platelets could be activated by protease mediated receptor (PAR)- and receptors for advanced glycation end (RAGE)-dependent mechanisms. Hypoxia, in particular induced by high altitudes, could play a role in thrombotic complications as a trigger of platelet activity. In this review, we discuss potential mechanisms of PA thrombosis in situ.

Pulmonary embolism following complex trauma: UK MTC observational study

OBJECTIVES

To describe the incidence of pulmonary embolism (PE) in a critically ill UK major trauma centre (MTC) patient cohort.

METHODS

A retrospective, multidataset descriptive study of all trauma patients requiring admission to level 2 or 3 care in the East of England MTC from 1 November 2014 to 1 May 2017. Data describing demographics, the nature and extent of injuries, process of care, timing of PE prophylaxis, tranexamic acid (TXA) administration and CT scanner type were extracted from the Trauma Audit and Research Network database and hospital electronic records. PE presentation was categorised as immediate (diagnosed on initial trauma scan), early (within 72 hours of admission but not present initially) and late (diagnosed after 72 hours).

RESULTS

Of the 2746 trauma patients, 1039 were identified as being admitted to level 2 or 3 care. Forty-eight patients (4.6%) were diagnosed with PE during admission with 14 immediate PEs (1.3%). Of 32.1% patients given TXA, 6.3% developed PE compared with 3.8% without TXA (p=0.08).

CONCLUSION

This is the largest study of the incidence of PE in UK MTC patients and describes the greatest number of immediate PEs in a civilian complex trauma population to date. Immediate PEs are a rare phenomenon whose clinical importance remains unclear. Tranexamic acid was not significantly associated with an increase in PE in this population following its introduction into the UK trauma care system.

The medical and operational impact of the deployment of a scanner within Role 2 in Mali for the French army

INTRODUCTION

According to the NATO classification, the difference between Role 2 and Role 2+ is the presence of extra diagnostic and therapeutic means, including the deployment of a scanner. The aim of this study is to analyze the impact of this deployment at the front, in the Gao French Role 2 (Mali). Our main hypothesis is that the presence of a scanner at the front improves the servicemen's diagnostic and therapeutic management abilities. Secondly that scanner holds strategic relevance by limiting the repatriation of servicemen on medical grounds.

MATERIALS AND METHODS

A prospective analytical observational study was conducted over 6 months within Gao's Role 2. All the French military patients who received a scanner were involved. The collected data was epidemiological, clinical and radiological in nature, and included the results from the scanner and data regarding the operational impact (repatriation). The principal judgment criterion was the rate of modification of the therapeutic decision. The secondary criterion was the modification of the repatriation decision on medical grounds.

RESULTS

Of the 45 patients examined, in 14 cases (31.1%), performing a scanner changed patients' therapeutic management in relation to the management, which would have been conducted in the scanner's absence. For 12 of these patients (85.7%), the indication of the scanner concerned visceral or cranium-spine pathologies. For 33 patients (73.3%), the scanner enabled diagnosis via the elimination of an organic injury or a severity criterion. The repatriation decision remained unchanged for many patients.

DISCUSSION

The scanner appears to be a significant factor in the initial therapeutic decision. Scanning made it possible to clarify the diagnosis and to better adapt the initial therapeutic decision. In contrast, the operational impact was null. The literature highlights the relevance of scanner in surgical abstention (limiting unnecessary operative procedures), and for the visceral, cranium-cerebral and spine pathologies in an emergency.

CONCLUSION

The scanner, a heavy logistic unit deployed within a forward surgical unit, holds therapeutic relevance for French servicemen's management with an important medical service provided for the therapeutic choices, although its operational impact has yet to be demonstrated.

Trauma Embolic Scoring System in military trauma: a sensitive predictor of venous thromboembolism

Introduction

Clinical decision support tools capable of predicting which patients are at highest risk for venous thromboembolism (VTE) can assist in guiding surveillance and prophylaxis decisions. The Trauma Embolic Scoring System (TESS) has been shown to model VTE risk in civilian trauma patients. No such support tools have yet been described in combat casualties, who have a high incidence of VTE. The purpose of this study was to evaluate the utility of TESS in predicting VTE in military trauma patients.

Methods

A retrospective cohort study of 549 combat casualties from October 2010 to November 2012 admitted to a military treatment facility in the USA was performed. TESS scores were calculated through data obtained from the Department of Defense Trauma Registry and chart reviews. Univariate analysis and multivariate logistic regression were performed to evaluate risk factors for VTE. Receiver operating characteristic (ROC) curve analysis of TESS in military trauma patients was also performed.

Results

The incidence of VTE was 21.7% (119/549). The median TESS for patients without VTE was 8 (IQR 4–9), and the median TESS for those with VTE was 10 (IQR 9–11). On multivariate analysis, Injury Severity Score (ISS) (OR 1.03, p=0.007), ventilator days (OR 1.05, p=0.02), and administration of tranexamic acid (TXA) (OR 1.89, p=0.03) were found to be independent risk factors for development of VTE. On ROC analysis, an optimal high-risk cut-off value for TESS was ≥7 with a sensitivity of 0.92 and a specificity of 0.53 (area under the curve 0.76, 95% CI 0.72 to 0.80, p<0.0001).

Conclusions

When used to predict VTE in military trauma, TESS shows moderate discrimination and is well calibrated. An optimal high-risk cut-off value of ≥7 demonstrates high sensitivity in predicting VTE. In addition to ISS and ventilator days, TXA administration is an independent risk factor for VTE development.

Level of evidence

Level III.

Military assistance to the civil authority: medical liaison with the Manchester clinicians after the Arena bombing

UK Defence Medical Services’ personnel have experienced an intense exposure to patients injured during war over the last decade and a half. As some bitter lessons of war surgery were relearned and innovative practices introduced, outcomes for patients impr oved consistently as experience accumulated. The repository of many of the enduring lessons learnt at the Role 4 echelon of care remain at the Queen Elizabeth Hospital Birmingham (QEHB), with the National Health Service and Defence Medical Services personnel who treated the returning casualties. On 22 May 2017, a terrorist detonated an improvised explosive device at the Manchester Arena, killing 22 and wounding 159 people. In the aftermath of the event, QEHB was requested to provide support to the Manchester clinicians and teleconferencing and then two clinical visits were arranged. This short report describes the nature of the visits, outlines the principles of Military Aid to the Civil Authority and looks to the future role of the Defence Medical Services in planning and response to UK terrorism events.

Primary Pulmonary Thrombus in Combat Casualties: Is Treatment Necessary?

The objective of this study was to describe the natural history of primary pulmonary thrombus (PPT) in combat casualties. This was a retrospective study of casualties treated at a major military treatment facility from 2010 to 2012. Patients with a downrange chest CTwere included. CTs were reviewed by two independent, blinded radiologists to confirm PPTon initial imaging. Follow-up CTs, if obtained, were also independently reviewed to determine the extent of clot burden. Two hundred and forty-nine casualties with a downrange, acceptable quality chest CT were included. 9 per cent (23/249) of patients sustained PPT. Thirty nine per cent (9/23) were initially treated with therapeutic anticoagulation (AC). Conversely, 61 per cent (14/23) arrived to our military treatment facility without AC. Seven arriving without AC-developed pulmonary symptoms during their hospitalization and had interval chest CTs. Of those, three had no evidence of pulmonary thrombus. The other four had subsegmental filling defects and three were started AC whereas one had an IVC (Inferior Vena Cava) filter inserted. In total, 11/23 (48%) PPT patients were managed without AC and discharged without complications. This is the first study attempting to look at PPT natural history. There were no adverse sequelae from managing PPT without AC. Further studies are warranted to further characterize PPT.

Preinjury statin use and thromboembolic events in trauma: a 10-year retrospective evaluation

BACKGROUND

Traumatic injury is well known to increase the risk of venous thromboembolic events (VTEs), occurring in up to 58% of trauma patients. Statin medications have significant anti-inflammatory properties and have been shown to reduce the risk of VTE. We hypothesized that trauma patients who received statin medication before injury would have a lower incidence of VTE after injury.

METHODS

A 10-y retrospective review identified all patients admitted to our trauma service with an injury severity score >9 and an intensive care unit stay of >3 d. This population was categorized as either "statin recipient" (SR) or "statin naïve," with subsequent categorical division by occurrence of VTE. Our primary outcome measure was the occurrence of documented VTE in both statin naïve and SR subjects.

RESULTS

A total of 2519 trauma patients were included with 97 (3.8%) developing VTE. Pretrauma statin use in males remained as an independent predictor of VTE (odds ratio = 2.25, 95% confidence interval = 1.25-4.04, P < 0.01). The median time to VTE onset was 3 d longer in SRs (10.0 d; confidence interval = 7.3-12.7, P < 0.05).

CONCLUSIONS

Pretrauma statin use does not appear to have a protective benefit of VTE prevention in trauma patients, as we have shown pretrauma SR male trauma patients to have a twofold increased incidence of VTE. However, when considering the 3 d longer median time to VTE onset found in SRs, we consider the protective benefit of statin use reported in the current literature as likely attributable to this observed delayed onset.

[Prevention of venous thromboembolic complications in firearm injury]

Prevention of venous thromboembolic complications in wounded is a complex problem which has not yet been fully resolved throughout the world. Current state of venous thrombosis prevention in wounded in different countries and certain ways of its improvement are analyzed in the article.

Manual aspiration thrombectomy with a Penumbra catheter for acute anterior cerebral artery occlusion

Purpose The purpose of this article is to assess the efficacy and safety of manual aspiration thrombectomy (MAT) using a Penumbra catheter in patients with anterior cerebral artery (ACA) occlusions. Materials and methods From January 2012 to March 2016, 16 patients underwent MAT with Penumbra catheters using a proximal and distal supporting technique to treat ACA occlusions. We evaluated immediate angiographic results and clinical outcomes by reviewing patient electrical medical records. Results Of these patients, 11 had a complete obstruction of the distal internal carotid artery (ICA) and five had ACA and middle cerebral artery (MCA) occlusions. All patients achieved successful recanalization of the distal ICA or MCA (Thrombolysis in Cerebral Infarction (TICI) grade ≥2b). Overall the recanalization rate for ACA occlusions (TICI grade≥2b) was 93.7% (15/16). The median procedure time was 45 minutes (range: 35-65 minutes). No patients were observed to have a procedure-related subarachnoid hemorrhage. Four patients (25.0%) died during hospitalization because of massive symptomatic hemorrhage, brain edema, or herniation. At discharge, the median NIHSS score for surviving patients was 6 (range: 1-17). Five patients had favorable clinical outcomes (modified Rankin scale ≤2). Conclusion MAT appears to be safe and successfully achieves recanalization in patients with ACA occlusions.

Current concepts in the pathogenesis of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by fibrotic obstruction of the proximal pulmonary arteries, and it is believed to result from incomplete thrombus resolution after acute pulmonary embolism. While treatment for this condition with surgery and medical therapy has improved outcomes, our understanding of the molecular mechanisms underlying CTEPH is incomplete. Numerous risk factors have been associated with the development of CTEPH, including but not limited to acquired thrombophilias and chronic inflammatory states. A minority of patients with CTEPH have an abnormal fibrin structure that may delay thrombus resolution. Recently, examination of resected scar material in patients with CTEPH has suggested that deficient angiogenesis may play a role in thrombus nonresolution, and there is increasing interest in factors that drive intravascular scar formation. An additional challenge in CTEPH research is understanding the etiology and implications of the small-vessel disease present in many patients. Future work will likely be directed at understanding the pathways important to disease pathogenesis through further examinations of resected tissue material, continued work on animal models, and genomic approaches to identify alterations in gene expression or gene variants that may distinguish CTEPH from other forms of pulmonary hypertension.

Scanning and War: Utility of FAST and CT in the Assessment of Battlefield Abdominal Trauma

OBJECTIVE

To determine utilization and accuracy of focused assessment with sonography for trauma (FAST) and computed tomography (CT) in a mature military trauma system to inform service provision for future conflicts.

BACKGROUND

FAST and CT scans undertaken by attending radiologists contribute to surgical decision making for battlefield casualties at the Joint Force, Role 3 Medical Treatment Facility at Camp Bastion (R3), Afghanistan.

METHODS

Registry data for abdominally injured casualties treated at R3 from July to November 2012 were matched to radiological and surgical records to determine diagnostic accuracy for FAST and CT and their influence on casualty management.

RESULTS

A total of 468 casualties met inclusion criteria, of whom 85.0% underwent FAST and 86.1% abdominal CT; 159 (34.0%) had abdominal injuries. For detection of intra-abdominal injury, FAST sensitivity (Sn) was 0.56, specificity (Sp) 0.98, positive predictive value (PPV) 0.87, negative predictive value (NPV) 0.90, and accuracy (Acc) 0.89. For CT, Sn was 0.99, Sp 0.99, PPV 0.96, NPV 1.00, and Acc 0.99. Forty-six solid organ injuries were identified in 38 patients by CT; 17 were managed nonoperatively. A further 61 patients avoided laparotomy after CT confirmed extra-abdominal wounds only. The negative laparotomy rate was 3.9%.

CONCLUSIONS

FAST and CT contribute to triage, guide surgical management, and reduce nontherapeutic laparotomy. When imaging is available, these data challenge current doctrine about inadvisability of nonoperative management of abdominal injury after combat trauma.

Deep vein thrombosis and pulmonary embolism in the military patient

OBJECTIVES

Venous thromboembolism (VTE), encompassing deep vein thrombosis and pulmonary embolism, is a common, potentially lethal condition and a cause of long-term morbidity and functional limitation. This paper is a clinical review focused on military epidemiology, evidence-based recommendations for prevention, diagnosis and management of VTE and occupational considerations in a military population.

METHODS

A literature review was conducted through Pubmed and Embase for systematic reviews, meta-analyses and clinical trials relating to VTE. Guidelines from the National Institute for Health and Care Excellence, British Thoracic Society and the American College of Chest Physicians were reviewed and recommendations considered.

RESULTS

Acute morbidity from VTE can range from limb pain and swelling to life-threatening cardiovascular compromise. Long-term sequelae include postthrombotic syndrome, chronic thrombosis and pulmonary hypertension. Diagnosis should follow a validated pathway depending on the patient's prerest probability. The management of the condition should vary with attention to risk stratification.

DISCUSSION

Prompt initiation of anticoagulation reduces symptoms, rates of recurrent VTE and death but treatment must be balanced against the risk of major haemorrhage. Military operations expose personnel to a unique combination of risk factors for VTE and operating in austere environments can increase the challenge of diagnosis, prognostication and management. Furthermore, there are implications for troop attrition, operational readiness and return to work.

Deployed research

The Role 3 Medical Treatment Facility (Field Hospital) in Camp Bastion (R3 Bastion) is acknowledged to be one of the busiest dedicated trauma facilities in the world. Casualties typically present with severe injuries and in physiological extremis. These casualties form a unique cohort representing the most relevant population to evaluate the effectiveness of treating battlefield injuries as academic clinicians and scientists interested in trauma seek to improve outcomes for such patients in the future. This article describes four separate but related research projects that have been undertaken in Camp Bastion, Afghanistan, over the last year. They traverse the spectrum of clinical research, ranging from data collection to a randomised control trial. The aim is to discuss some of the problems encountered and the solutions that made it possible to undertake research in a theatre of operations, thereby providing a starting point for others who may wish to initiate research in a similar environment.

Venous thromboembolism: reducing the risk in a Role 3 setting

BACKGROUND

Venous thromboembolism (VTE) represents a significant preventable cause of hospital mortality. VTE assessment and prophylaxis rates are key patient safety and quality of care indicators. The aim of this study was to audit low molecular weight heparin (LMWH) and graduated elasticated compression stockings (GECS) prescriptions compared with the current Clinical Guidelines for Operations.

METHODS

Complete audit loop in the Role 3 Hospital, Camp Bastion, Afghanistan. A multifaceted intervention programme incorporating physician and nurse education and pre-printed medication charts was introduced to improve VTE assessment and prophylaxis rates.

RESULTS

Only 111/301 (36.9%) of patients in the pre-intervention cohort had a VTE risk assessment performed; this improved to 142/155 (91.6%, p<0.0001) post-intervention. A total of 57/88 (64.8%) patients prescribed LMWH pre-intervention had a documented assessment of bleeding risk performed; this rose to 65/66 (98.5%, p=0.0003) post-intervention. In pre-intervention, only 63/213 (29.6%) patients had a documented reassessment of VTE and bleeding risk at 24 h; reassessment rates rose to 68.8% (66/96 patients, p<0.0001) post-intervention. Of those patients at risk of VTE without ongoing bleeding risk, 62/96 (64.6%) had LMWH prescribed pre-intervention; this rose to 57/62 (91.9%) post-intervention (p<0.0001). Inappropriate LMWH prescription rates fell from 26/190 (13.7%) to 4/85 (4.7%, p=0.035) post-intervention. In those patients in whom GECS were not contraindicated, prescription rates rose from 23/95 (24.2%) to 42/62 (67.7%, p<0.0001) post-intervention.

CONCLUSIONS

Inclusion of pre-printed LMWH/GECS prescriptions and risk assessment stickers in the mediction chart significantly improved rates of VTE risk assessment and prophylaxis. These easily reproducible and low-cost interventions could improve patient safety on deployment.