Corrigendum: Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies.

[This corrects the article DOI: 10.3389/fimmu.2023.1230049.].

Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies.

Iatrogenic vascular air embolism is a relatively infrequent event but is associated with significant morbidity and mortality. These emboli can arise in many clinical settings such as neurosurgery, cardiac surgery, and liver transplantation, but more recently, endoscopy, hemodialysis, thoracentesis, tissue biopsy, angiography, and central and peripheral venous access and removal have overtaken surgery and trauma as significant causes of vascular air embolism. The true incidence may be greater since many of these air emboli are asymptomatic and frequently go undiagnosed or unreported. Due to the rarity of vascular air embolism and because of the many manifestations, diagnoses can be difficult and require immediate therapeutic intervention. An iatrogenic air embolism can result in both venous and arterial emboli whose anatomic locations dictate the clinical course. Most clinically significant iatrogenic air emboli are caused by arterial obstruction of small vessels because the pulmonary gas exchange filters the more frequent, smaller volume bubbles that gain access to the venous circulation. However, there is a subset of patients with venous air emboli caused by larger volumes of air who present with more protean manifestations. There have been significant gains in the understanding of the interactions of fluid dynamics, hemostasis, and inflammation caused by air emboli due to in vitro and in vivo studies on flow dynamics of bubbles in small vessels. Intensive research regarding the thromboinflammatory changes at the level of the endothelium has been described recently. The obstruction of vessels by air emboli causes immediate pathoanatomic and immunologic and thromboinflammatory responses at the level of the endothelium. In this review, we describe those immunologic and thromboinflammatory responses at the level of the endothelium as well as evaluate traditional and novel forms of therapy for this rare and often unrecognized clinical condition.

Hemorrhagic Resuscitation Guided by Viscoelastography in Far-Forward Combat and Austere Civilian Environments: Goal-Directed Whole-Blood and Blood-Component Therapy Far from the Trauma Center.

Modern approaches to resuscitation seek to bring patient interventions as close as possible to the initial trauma. In recent decades, fresh or cold-stored whole blood has gained widespread support in multiple settings as the best first agent in resuscitation after massive blood loss. However, whole blood is not a panacea, and while current guidelines promote continued resuscitation with fixed ratios of blood products, the debate about the optimal resuscitation strategy-especially in austere or challenging environments-is by no means settled. In this narrative review, we give a brief history of military resuscitation and how whole blood became the mainstay of initial resuscitation. We then outline the principles of viscoelastic hemostatic assays as well as their adoption for providing goal-directed blood-component therapy in trauma centers. After summarizing the nascent research on the strengths and limitations of viscoelastic platforms in challenging environmental conditions, we conclude with our vision of how these platforms can be deployed in far-forward combat and austere civilian environments to maximize survival.

"Death Diamond" Tracing on Thromboelastography as a Marker of Poor Survival After Trauma.

BACKGROUND: Improvements in health care innovations have resulted in an enhanced ability to extend patient viability. As a consequence, resources are being increasingly utilized at an unsustainable level. As we implement novel treatments, identifying futility should be a focus. The "death diamond" (DD) is a unique thrombelastography (TEG) tracing that is indicative of failure of the coagulation system, with a mortality rate exceeding 90%. The purpose of this study was to determine if the DD was a consistent marker of poor survival in a multicenter study population. We hypothesize that the DD, while an infrequent occurrence, predicts poor survival and can be used to stratify patients in whom resuscitation efforts are futile. METHODS: A retrospective multi-institutional study of trauma patients presenting with TEG DDs between 8/2008 and 12/2018 at four American College of Surgeons trauma centers was completed. Demographics, injury mechanisms, TEG results, management, and survival were examined. RESULTS: A total of 50 trauma patients presented with DD tracings, with a 94% (n = 47) mortality rate. Twenty-six (52%) patients received a repeat TEG with 10 patients re-demonstrating the DD tracing. There was 100% mortality in patients with serial DD tracings. The median use of total blood products was 18 units (interquartile range 6, 34.25) per patient. DISCUSSION: The DD is highly predictive of trauma-associated mortality. This multicenter study highlights that serial DDs may represent a possible biomarker of futility.

Whole Blood, Fixed Ratio, or Goal-Directed Blood Component Therapy for the Initial Resuscitation of Severely Hemorrhaging Trauma Patients: A Narrative Review.

This narrative review explores the pathophysiology, geographic variation, and historical developments underlying the selection of fixed ratio versus whole blood resuscitation for hemorrhaging trauma patients. We also detail a physiologically driven and goal-directed alternative to fixed ratio and whole blood, whereby viscoelastic testing guides the administration of blood components and factor concentrates to the severely bleeding trauma patient. The major studies of each resuscitation method are highlighted, and upcoming comparative trials are detailed.

Viscoelastic testing in oncology patients (including for the diagnosis of fibrinolysis): Review of existing evidence, technology comparison, and clinical utility.

The quantification of the coagulopathic state associated with oncologic and hematologic diseases is imperfectly assessed by common coagulation tests such as prothrombin time, activated partial thromboplastin time, fibrinogen levels, and platelet count. These tests provide a static representation of a component of hemostatic integrity, presenting an incomplete picture of coagulation in these patients. Viscoelastic tests (VETs), such as rotational thromboelastometry (ROTEM) and thromboelastography (TEG), as whole blood analyses, provide data related to the cumulative effects of blood components and all stages of the coagulation and fibrinolytic processes. The utility of VETs has been demonstrated since the late 1960s in guiding blood component therapy for patients undergoing liver transplantation. Since then, the scope of viscoelastic testing has expanded to become routinely used for cardiac surgery, obstetrics, and trauma. In the past decade, VETs' expanded usage has been most significant in trauma resuscitation. However, use of VETs for patients with malignancy-associated coagulopathy (MAC) and hematologic malignancies is increasing. For the purposes of this narrative review, we discuss the similarities between trauma-induced coagulopathy (TIC) and MAC. These similarities center on the thrombomodulin-thrombin complex as it switches between the thrombin-activatable fibrinolysis inhibitor coagulation pathway and activating the protein C anticoagulation pathway. This produces a spectrum of coagulopathy and fibrinolytic alterations ranging from shutdown to hyperfibrinolysis that are common to TIC, MAC, and hematologic malignancies. There is expanding literature regarding the utility of TEG and ROTEM to describe the hemostatic integrity of patients with oncologic and hematologic conditions, which we review here.

Diagnosis and Treatment of Trauma-Induced Coagulopathy by Viscoelastography.

This article explores the application of viscoelastic tests (VETs) in trauma-induced coagulopathy and trauma resuscitation. We describe the advantages of VETs over conventional coagulation tests in the trauma setting and refer to previous disciplines in which VET use has reduced blood product utilization, guided prohemostatic agents, and improved clinical outcomes such as the mortality of critically bleeding patients. We describe different VETs and provide guidance for blood component therapy and prohemostatic therapy based on specific VET parameters. Because the two most commonly used VET systems, rotational thromboelastometry and thromboelastography, use different activators and have different terminologies, this practical narrative review will directly compare and contrast these two VETs to help the clinician easily interpret either and use the interpretation to determine hemostatic integrity in the bleeding trauma patient. Finally, we anticipate the future of new viscoelastic technologies that can be used in this setting.

Whole Blood for Civilian Urban Trauma Resuscitation: Historical, Present, and Future Considerations.

Whole blood (WB) has been used for more than a century for far-forward combat resuscitation. Following the Iraq/Afghanistan combat, maritime, and austere environment use of WB for the resuscitation of severely hemorrhaging patients, there has been an increasing use of WB for the civilian urban resuscitation environment population. The impetus for this was not just improved outcomes in far-forward hospitals, which had different populations and different needs than the civilian urban population, but also an application of the lessons suggested by recent 1:1:1 plasma:platelets:packed red cells fixed-ratio studies for patients with massive transfusion needs. Mechanistic, logistic, and standardization concerns have been addressed and are evolving as the WB project advances. A small number of studies have been published on WB in the civilian urban trauma population. In addition, European experience with viscoelastic testing and resuscitation with fibrinogen and prothrombin complex concentrate has provided another viewpoint regarding the choice of resuscitation strategies for severely bleeding trauma patients in urban civilian environments. There are randomized controlled trials in process, which are testing the hypothesis that WB may be beneficial for the civilian urban population. Whether WB will improve mortality significantly is now a matter of intense study, and this commentary reviews the history, mechanistic foundations, and logistical aspects for the use of WB in the civilian trauma population.

Universal Anesthesia Machine: Clinical Application in an Austere, Resource-Limited Environment.

INTRODUCTION: In austere environments, the safe administration of anesthesia becomes challenging because of unreliable electrical sources, limited amounts of compressed gas, and insufficient machine maintenance capabilities. Such austere environments exist in battlefield medicine, in low- and middle-income countries (LMICs), and in areas struck by natural disasters. Whether in military operations or civilian settings, the Universal Anesthesia Machine (UAM) (Gradian Health Systems, New York, New York) is a draw-over device capable of providing safe and effective general anesthesia when external oxygen supplies or reliable electrical sources are limited. This brief report discusses a proof-of-concept observational study demonstrating the clinical utility of the UAM in a resource-limited area. MATERIALS AND METHODS: This observational study of 20 patients in Haiti who underwent general anesthesia using the UAM highlights the device's capability to deliver anesthesia intraoperatively in a resource-limited LMIC clinical setting. Preoxygenation was achieved with the UAM's draw-over oxygen supply. Patients received acetaminophen for analgesia, dexmedetomidine for preinduction anesthesia, and succinylcholine for paralysis. After induction, the UAM provided a mixture of oxygen and isoflurane for maintenance of anesthesia. Manual ventilation was performed using draw-over bellows until spontaneous ventilation recurred, when clinically appropriate, artificial airways were removed. Intraoperative medication was administered at the anesthesiologist's discretion. The institutional review board at the U.S. anesthesiologists' affiliated institution and the Haitian hospital approved this study; patients were consented in their native language. RESULTS: Two anesthesiologists used the UAM to deliver general anesthesia to 20 patients in a Haitian hospital without access to an external oxygen supply, reliable power grid, or opioids. The patients' average age was ~40 years, and 90% of them were male. Most of the cases were herniorrhaphy (50%) and hydrocelectomy (25%) surgeries. The median American Society of Anesthesiologists (ASA) score was 2; 45% of the patients had an ASA score of 1, and none had an ASA score >3. Of the 20 cases, 55% of patients received an endotracheal tube, and 40% received a laryngeal mask airway; for one patient, only a masked airway was used. Every patient was discharged on the day of the surgery. No complications occurred in the perioperative or 1-month follow-up period. CONCLUSION: The UAM can be used where a lack of resources and training exist because of its simple design, built-in oxygen concentrator, and capacity to revert from continuous-flow to draw-over anesthesia in the event of a power failure or if external oxygen supplies are unavailable. We believe the UAM addresses some of the shortcomings of modern anesthesia machines and has the potential to improve the delivery of safe general anesthesia in combat and austere scenarios. Further studies could consider different types of surgeries than those reported here and involve more complex patients. Studies involving alternative anesthetic agents and non-anesthesiologist personnel are also needed. Overall, this brief report detailing the use of the UAM following a natural disaster in a LMIC is proof of concept that the machine can provide reliable anesthesia for surgical procedures in austere and resource-limited environments, including disaster areas and modern combat zones.