Successful treatment for disseminated intravascular coagulation (DIC) corresponding to phenotype changes in a heat stroke patient

Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally-occurring heatstroke

BACKGROUND

Thromboelastometry (TEM) provides a comprehensive overview of the entire coagulation process and has not been evaluated in heatstroke-induced coagulopathies in dogs.

OBJECTIVES

To determine the diagnostic and prognostic utility of TEM in dogs with heatstroke.

ANIMALS

Forty-two client-owned dogs with heatstroke.

METHODS

Prospective observational study. Blood samples for intrinsic and extrinsic TEM (INTEM and EXTEM, respectively) were collected at presentation and every 12 to 24 hours for 48 hours. Coagulation phenotype (hypo-, normo-, or hypercoagulable) was defined based on TEM area under the 1st derivative curve (AUC).

RESULTS

Case fatality rate was 31%. Median TEM variables associated with death (P < .05 for all) included longer INTEM clotting time, lower AUC at presentation and at 12 to 24 hours postpresentation (PP), lower INTEM alpha angle, maximum clot firmness, and maximum lysis (ML) at 12 to 24 hours PP, and lower EXTEM ML at 12 to 24 hours PP. Most dogs were normo-coagulable on presentation (66% and 63% on EXTEM and INTEM, respectively), but hypo-coagulable 12 to 24 PP (63% for both EXTEM and INTEM). A hypo-coagulable INTEM phenotype was more frequent at presentation and 12 to 24 PP among nonsurvivors compared to survivors (55% vs 15% and 100% vs 50%, P = .045 and .026, respectively). AKI was more frequent (P = .015) in dogs with hypo-coagulable INTEM tracings at 12 to 24 hours. Disseminated intravascular coagulation was more frequent (P < .05) in dogs with a hypo-coagulable INTEM phenotype and in nonsurvivors at all timepoints.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypocoagulability, based on INTEM AUC, is predictive of worse prognosis and occurrence of secondary complications.

Risk factors for and outcomes of heatstroke-related intracerebral hemorrhage

Some patients with heatstroke also experience intracerebral hemorrhage (ICH). However, clinical case reports of heatstroke-induced ICH are rare. The risk factors for cerebral hemorrhage after heatstroke remain unknown. The present study evaluated the clinical characteristics and risk factors of patients with heatstroke-related ICH. In this retrospective observational study, we collected data on all ICHs after heatstroke occurred between 2012 and 2022. The characteristics of patients with heatstroke-induced ICH were described. The risk factors for cerebral hemorrhage after heatstroke were examined using logistic regression analysis. In total, 177 patients were included in this study, and 11 patients with ICH secondary to heatstroke were identified. Variables with P values of <.05 in univariate models, comparing the cerebral hemorrhage and control groups, included heatstroke cause, temperature, heart rate, respiratory rate, vasopressor use, mechanical ventilation use, Acute Physiology and Chronic Health Evaluation II, total bilirubin, creatinine, platelet count, prothrombin time, procalcitonin, creatine kinase, disseminated intravascular coagulation (DIC) occurrence, and DIC score. Multivariate logistic regression showed that heatstroke patients with higher DIC scores (odds ratio, 18.402, 95% confidence interval, 1.384-244.763, P = .027) and higher creatine kinase levels (odds ratio, 1.021, 95% confidence interval, 1.002-1.041, P = .033) were at a higher risk of developing ICH. The death rate was higher in the cerebral hemorrhage group than in the control group (P = .042). Heatstroke-related cerebral hemorrhage may be associated with elevated creatinine levels and DIC severity (International Society on Thrombosis and Hemostasis score) after heatstroke, and heatstroke with cerebral hemorrhage may accelerate death.

Thromboinflammation and microcirculation damage in heatstroke

Rising temperatures associated with climate change have significantly increased the risk of heatstroke. Unfortunately, the trend is anticipated to persist and increasingly threaten vulnerable populations, particularly older adults. According to Japan's environment ministry, over 1000 people died from heatstroke in 2021, and 86% of deaths occurred in those above 65. Since the precise mechanism of heatstroke is not fully understood, we examined the pathophysiology by focusing on the microcirculatory derangement. Online search of published medical literature through MEDLINE and Web of Science using the term "heatstroke," "heat-related illness," "inflammation," "thrombosis," "coagulation," "fibrinolysis," "endothelial cell," and "circulation." Articles were chosen for inclusion based on their relevance to heatstroke, inflammation, and thrombosis. Reference lists were reviewed to identify additional relevant articles. Other than preexisting conditions (genetic background, age, etc.), factors such as hydration status, acclimatization, dysregulated coagulation, and inflammation are the additional major factors that promote tissue malcirculation in heatstroke. The fundamental pathophysiologic mechanisms significantly overlap with those seen in the systemic inflammatory response to sepsis, and as a result, coagulation-predominant coagulopathy develops during heat stress. Although a bleeding tendency is not common, bleeding frequently occurs in the microcirculation, causing additional injury. Sterile inflammation is mediated by proinflammatory cytokines, chemokines, and other humoral mediators in concert with cellular factors, including monocytes, neutrophils, platelets, and endothelial cells. Excess inflammation results in inflammatory cell death, including pyroptosis and necroptosis, and the release of danger signals that further propagate systemic inflammation and coagulopathy. Consequently, thromboinflammation is the critical factor that induces microcirculatory disturbance in heatstroke.

A newly proposed heatstroke-induced coagulopathy score in patients with heat illness: A multicenter retrospective study in China

PURPOSE

In patients with heatstroke, disseminated intravascular coagulation (DIC) is associated with greater risk of in-hospital mortality. However, time-consuming assays or a complex diagnostic system may delay immediate treatment. Therefore, the present study proposes a new heatstroke-induced coagulopathy (HIC) score in patients with heat illness as an early warning indicator for DIC.

METHODS

This retrospective study enrolled patients with heat illness in 24 Chinese hospitals from March 2021 to May 2022. Patients under 18 years old, with a congenital clotting disorder or liver disease, or using anticoagulants were excluded. Data were collected on demographic characteristics, routine blood tests, conventional coagulation assays and biochemical indexes. The risk factors related to coagulation function in heatstroke were identified by regression analysis, and used to construct a scoring system for HIC. The data of patients who met the diagnostic criteria for HIC and International Society on Thrombosis and Haemostasis defined-DIC were analyzed. All statistical analyses were performed using SPSS 26.0.

RESULTS

The final analysis included 302 patients with heat illness, of whom 131 (43.4%) suffered from heatstroke, including 7 death (5.3%). Core temperature (OR = 1.681, 95% CI 1.291 - 2.189, p < 0.001), prothrombin time (OR = 1.427, 95% CI 1.175 - 1.733, p < 0.001) and D-dimer (OR = 1.242, 95% CI 1.049 - 1.471, p = 0.012) were independent risk factors for heatstroke, and therefore used to construct an HIC scoring system because of their close relation with abnormal coagulation. A total score ≥ 3 indicated HIC, and HIC scores correlated with the score for International Society of Thrombosis and Hemostasis -DIC (r = 0.8848, p < 0.001). The incidence of HIC (27.5%) was higher than that of DIC (11.2%) in all of 131 heatstroke patients. Meanwhile, the mortality rate of HIC (19.4%) was lower than that of DIC (46.7%). When HIC developed into DIC, parameters of coagulation dysfunction changed significantly: platelet count decreased, D-dimer level rose, and prothrombin time and activated partial thromboplastin time prolonged (p < 0.05).

CONCLUSIONS

The newly proposed HIC score may provide a valuable tool for early detection of HIC and prompt initiation of treatment.

Phenotypes of Disseminated Intravascular Coagulation

Two phenotypes of disseminated intravascular coagulation (DIC) are systematically reviewed. DIC is classified into thrombotic and fibrinolytic phenotypes characterized by thrombosis and hemorrhage, respectively. Major pathology of DIC with thrombotic phenotype is the activation of coagulation, insufficient anticoagulation with endothelial injury, and plasminogen activator inhibitor-1-mediated inhibition of fibrinolysis, leading to microvascular fibrin thrombosis and organ dysfunction. DIC with fibrinolytic phenotype is defined as massive thrombin generation commonly observed in any type of DIC, combined with systemic pathologic hyperfibrinogenolysis caused by underlying disorder that results in severe bleeding due to excessive plasmin formation. Three major pathomechanisms of systemic hyperfibrinogenolysis have been considered: (1) acceleration of tissue-type plasminogen activator (t-PA) release from hypoxic endothelial cells and t-PA-rich storage pools, (2) enhancement of the conversion of plasminogen to plasmin due to specific proteins and receptors that are expressed on cancer cells and endothelial cells, and (3) alternative pathways of fibrinolysis. DIC with fibrinolytic phenotype can be diagnosed by DIC diagnosis followed by the recognition of systemic pathologic hyperfibrin(ogen)olysis. Low fibrinogen levels, high fibrinogen and fibrin degradation products (FDPs), and the FDP/D-dimer ratio are important for the diagnosis of systemic pathologic hyperfibrin(ogen)olysis. Currently, evidence-based treatment strategies for DIC with fibrinolytic phenotypes are lacking. Tranexamic acid appears to be one of the few methods to be effective in the treatment of systemic pathologic hyperfibrin(ogen)olysis. International cooperation for the elucidation of pathomechanisms, establishment of diagnostic criteria, and treatment strategies for DIC with fibrinolytic phenotype are urgent issues in the field of thrombosis and hemostasis.

The role of platelets in heat-related illness and heat-induced coagulopathy

Heat-related illness is becoming more problematic due to ongoing global warming. Heat-related injury causes systemic inflammation and coagulopathy, due to leukocyte, platelet, and vascular endothelial cell activation and injury. Hyperthermia directly modulates platelet function and can induce cellular damage. Meanwhile, heat also affects platelet function via activated coagulation, excess inflammation, production of cytokines, and heat shock proteins. Aberrant hyperthermia-induced interactions between leukocytes and endothelial cells are also involved in platelet regulation. Heat-induced coagulopathy commonly progresses to disseminated intravascular coagulation (DIC), leading to multiple organ failure and in some cases enhanced bleeding. Consequently, platelet count, prothrombin time, and DIC score are useful for evaluating the severity of heat-related illness in addition to other organ damage markers such as Glasgow Coma Scale, creatinine, and bilirubin. Despite the increasing risk, therapeutic modalities targeting platelets are limited and no established therapy exists. In this review, we summarize the current knowledge about the role of platelets in the pathogenesis, diagnosis, and management of heat-related illness.

Inflammation, coagulation, and cellular injury in heat-induced shock

BACKGROUND

The number of heatstroke victims hit record numbers in 2022 as global warming continues. In heat-induced injuries, circulatory shock is the most severe and deadly complication. This review aims to examine the mechanisms and potential approaches to heat-induced shock and the life-threatening complications of heatstroke.

METHODS

A computer-based online search was performed using the PubMed database and Web of Science database for published articles concerning heatstroke, shock, inflammation, coagulopathy, endothelial cell, cell death, and heat shock proteins.

RESULTS

Dehydration and heat-induced cardiomyopathy were reported as the major causes of heat-induced shock, although other heat-induced injuries are also involved in the pathogenesis of circulatory shock. In addition to dehydration, the blood volume decreases considerably due to the increased vascular permeability as a consequence of endothelial damage. Systemic inflammation is induced by factors that include elevated cytokine and chemokine levels, dysregulated coagulation/fibrinolytic responses, and the release of damage-associated molecular patterns (DAMPs) from necrotic cell death that cause distributive shock. The cytoprotective heat shock proteins can also facilitate circulatory disturbance under excess heat stress.

CONCLUSIONS

Multiple mechanisms are involved in the pathogenesis of heat-induced shock. In addition to dehydration, heat stress-induced cardiomyopathy due to the thermal damage of mitochondria, upregulated inflammation via damage-associated molecular patterns released from oncotic cells, unbalanced coagulation/fibrinolysis, and endothelial damage are the major factors that are related to circulatory shock.

ZBP1 and heatstroke

Heatstroke, which is associated with circulatory failure and multiple organ dysfunction, is a heat stress-induced life-threatening condition characterized by a raised core body temperature and central nervous system dysfunction. As global warming continues to worsen, heatstroke is expected to become the leading cause of death globally. Despite the severity of this condition, the detailed mechanisms that underlie the pathogenesis of heatstroke still remain largely unknown. Z-DNA-binding protein 1 (ZBP1), also referred to as DNA-dependent activator of IFN-regulatory factors (DAI) and DLM-1, was initially identified as a tumor-associated and interferon (IFN)-inducible protein, but has recently been reported to be a Z-nucleic acid sensor that regulates cell death and inflammation; however, its biological function is not yet fully understood. In the present study, a brief review of the main regulators is presented, in which the Z-nucleic acid sensor ZBP1 was identified to be a significant factor in regulating the pathological characteristics of heatstroke through ZBP1-dependent signaling. Thus, the lethal mechanism of heatstroke is revealed, in addition to a second function of ZBP1 other than as a nucleic acid sensor.

Plasmin Inhibitor in Health and Diabetes: Role of the Protein as a Therapeutic Target

The vascular obstructive thrombus is composed of a mesh of fibrin fibers with blood cells trapped in these networks. Enhanced fibrin clot formation and/or suppression of fibrinolysis are associated with an increased risk of vascular occlusive events. Inhibitors of coagulation factors and activators of plasminogen have been clinically used to limit fibrin network formation and enhance lysis. While these agents are effective at reducing vascular occlusion, they carry a significant risk of bleeding complications. Fibrin clot lysis, essential for normal hemostasis, is controlled by several factors including the incorporation of antifibrinolytic proteins into the clot. Plasmin inhibitor (PI), a key antifibrinolytic protein, is cross-linked into fibrin networks with higher concentrations of PI documented in fibrin clots and plasma from high vascular risk individuals. This review is focused on exploring PI as a target for the prevention and treatment of vascular occlusive disease. We first discuss the relationship between the PI structure and antifibrinolytic activity, followed by describing the function of the protein in normal physiology and its role in pathological vascular thrombosis. Subsequently, we describe in detail the potential use of PI as a therapeutic target, including the array of methods employed for the modulation of protein activity. Effective and safe inhibition of PI may prove to be an alternative and specific way to reduce vascular thrombotic events while keeping bleeding risk to a minimum. Key Points Plasmin inhibitor (PI) is a key protein that inhibits fibrinolysis and stabilizes the fibrin network.This review is focused on discussing mechanistic pathways for PI action, role of the molecule in disease states, and potential use as a therapeutic target.

Thromboelastography maximum amplitude as an early predictor of disseminated intravascular coagulation in patients with heatstroke

OBJECTIVES

The aim of this study was to investigate the ability of TEG to predict DIC associated with heatstroke.

METHODS

We carried out a retrospective, single-center study of 67 patients with heatstroke admitted to an intensive care unit (ICU) at a comprehensive hospital between July 2016 and August 2021. Conventional coagulation tests (CCTs) and TEG were performed within 2 h of admission in ICU. Patients were diagnosed with DIC based on International Society of Thrombosis and Hemostasis criteria, and those with or without DIC were compared in terms of CCTs and TEG findings. The ability of individual parameters to predict DIC was assessed based on logistic regression and the area under receiver operating characteristic curves (AUC).

RESULTS

Of the 67 patients, 19 (28.4%) were diagnosed with DIC. Compared to patients without DIC, those with DIC had significantly longer reaction time [14.5(10.6-26.0) vs. 6.2(5.1-10.1)min](p < 0.001) and kinetic time [10.9(5.9-25.0) vs. 2.7(2.2-4.7) min](p < 0.001). Conversely, those with DIC had significantly lower alpha angle [22(9.1-43.3) vs. 55.0(44.8-61.7)°](p < 0.001), maximum amplitude (MA) [(26.9(17.7-41.4) vs. 52.2(45.8-58.1) mm)] (p < 0.001) and coagulation index [-17.3(-39 to -7.9）vs. -2.4(-6.2to-0.6)](p < 0.001). MA at a cutoff value of 45.4 mm gave an AUC of 0.9 for predicting DIC, with sensitivity of 77.1%, specificity of 89.5%, positive predictive value of 10.5% and negative predictive value of 22.9%. Multifactorial logistic regression identified MA < 45.4 mm as an independent predictor of DIC (odds ratio 9, 95% confidence interval 1.2-69.2, p = 0.035). MA decreased significantly as DIC score increased and was significantly lower in the non-survivors on admission.

CONCLUSIONS

MA < 45.4 mm in patients with heatstroke may predict elevated risk of DIC. HighlightsPatients with heatstroke-induced disseminated intravascular coagulation (DIC) has high mortality.A retrospective, single-center study was performed to investigate the ability of thromboelastography (TEG) to predict DIC associated with heatstroke.The maximum amplitude (MA) value of TEG decreased significantly with the increase of DIC score.MA < 45.4 mm was firstly demonstrated to an independent predictor of heatstroke-induced DIC.

Heatstroke-induced coagulopathy: Biomarkers, mechanistic insights, and patient management

Heatstroke is increasingly becoming a significant concern due to global warming. Systemic inflammation and coagulopathy are the two major factors that provoke life-threatening organ dysfunction in heatstroke. Dysregulated thermo-control induces cellular injury, damage-associated molecular patterns release, hyperinflammation, and hypercoagulation with suppressed fibrinolysis to produce heatstroke-induced coagulopathy (HSIC). HSIC can progress to disseminated intravascular coagulation and multiorgan failure if severe enough. Platelet count, D-dimer, soluble thrombomodulin, and inflammation biomarkers such as interleukin-6 and histone H3 are promising markers for HSIC. In exertional heatstroke, the measurement of myoglobin is helpful to anticipate renal dysfunction. However, the optimal cutoff for each biomarker has not been determined. Except for initial cooling and hydration, effective therapy continues to be explored, and the use of antiinflammatory and anticoagulant therapies is under investigation. Despite the rapidly increasing risk, our knowledge is limited, and further study is warranted. In this review, we examine current information and what future efforts are needed to better understand and manage HSIC.

Therapeutic Strategies for Disseminated Intravascular Coagulation Associated with Aortic Aneurysm

Aortic aneurysms are sometimes associated with enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). In enhanced-fibrinolytic-type DIC, both coagulation and fibrinolysis are markedly activated. Typical cases show decreased platelet counts and fibrinogen levels, increased concentrations of fibrin/fibrinogen degradation products (FDP) and D-dimer, and increased FDP/D-dimer ratios. Thrombin-antithrombin complex or prothrombin fragment 1 + 2, as markers of coagulation activation, and plasmin-α₂ plasmin inhibitor complex, a marker of fibrinolytic activation, are all markedly increased. Prolongation of prothrombin time (PT) is not so obvious, and the activated partial thromboplastin time (APTT) is rather shortened in some cases. As a result, DIC can be neither diagnosed nor excluded based on PT and APTT alone. Many of the factors involved in coagulation and fibrinolysis activation are serine proteases. Treatment of enhanced-fibrinolytic-type DIC requires consideration of how to control the function of these serine proteases. The cornerstone of DIC treatment is treatment of the underlying pathology. However, in some cases surgery is either not possible or exacerbates the DIC associated with aortic aneurysm. In such cases, pharmacotherapy becomes even more important. Unfractionated heparin, other heparins, synthetic protease inhibitors, recombinant thrombomodulin, and direct oral anticoagulants (DOACs) are agents that inhibit serine proteases, and all are effective against DIC. Inhibition of activated coagulation factors by anticoagulants is key to the treatment of DIC. Among them, DOACs can be taken orally and is useful for outpatient treatment. Combination therapy of heparin and nafamostat allows fine-adjustment of anticoagulant and antifibrinolytic effects. While warfarin is an anticoagulant, this agent is ineffective in the treatment of DIC because it inhibits the production of coagulation factors as substrates without inhibiting activated coagulation factors. In addition, monotherapy using tranexamic acid in cases of enhanced-fibrinolytic-type DIC may induce fatal thrombosis. If tranexamic acid is needed for DIC, combination with anticoagulant therapy is of critical importance.

Exertional heat stroke: pathophysiology and risk factors

Exertional heat stroke, the third leading cause of mortality in athletes during physical activity, is the most severe manifestation of exertional heat illnesses. Exertional heat stroke is characterised by central nervous system dysfunction in people with hyperthermia during physical activity and can be influenced by environmental factors such as heatwaves, which extend the incidence of exertional heat stroke beyond athletics only. Epidemiological data indicate mortality rates of about 27%, and survivors display long term negative health consequences ranging from neurological to cardiovascular dysfunction. The pathophysiology of exertional heat stroke involves thermoregulatory and cardiovascular overload, resulting in severe hyperthermia and subsequent multiorgan injury due to a systemic inflammatory response syndrome and coagulopathy. Research about risk factors for exertional heat stroke remains limited, but dehydration, sex differences, ageing, body composition, and previous illness are thought to increase risk. Immediate cooling remains the most effective treatment strategy. In this review, we provide an overview of the current literature emphasising the pathophysiology and risk factors of exertional heat stroke, highlighting gaps in knowledge with the objective to stimulate future research.

Lessons From Heat Stroke for Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

We here provide an overview of the pathophysiological mechanisms during heat stroke and describe similar mechanisms found in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Both conditions are characterized by disturbed homeostasis in which inflammatory pathways play a central role. Splanchnic vasoconstriction, increased gut permeability, gut-related endotoxemia, systemic inflammatory response, central nervous system dysfunction, blood coagulation disorder, endothelial-cell injury, and mitochondrial dysfunction underlie heat stroke. These mechanisms have also been documented in ME/CFS. Moreover, initial transcriptomic studies suggest that similar gene expressions are altered in both heat stroke and ME/CFS. Finally, some predisposing factors for heat stroke, such as pre-existing inflammation or infection, overlap with those for ME/CFS. Notwithstanding important differences - and despite heat stroke being an acute condition - the overlaps between heat stroke and ME/CFS suggest common pathways in the physiological responses to very different forms of stressors, which are manifested in different clinical outcomes. The human studies and animal models of heat stroke provide an explanation for the self-perpetuation of homeostatic imbalance centered around intestinal wall injury, which could also inform the understanding of ME/CFS. Moreover, the studies of novel therapeutics for heat stroke might provide new avenues for the treatment of ME/CFS. Future research should be conducted to investigate the similarities between heat stroke and ME/CFS to help identify the potential treatments for ME/CFS.

Sonoclot Signature Analysis: A New Point-of-Care Testing Method for Defining Heat Stroke-Induced Coagulopathy

Purpose

Data regarding the incidence of a coagulable state following heat stroke as assessed by Sonoclot signature analysis are limited. Our purpose was to appraise coagulopathy using a dynamic test capable of analyzing the entire coagulation cascade and to characterize coagulation in patients with heat stroke prior to transfusion.

Materials and Methods

The data of 106 patients were collected prospectively from the Critical Care Center of the General Hospital of Guangzhou Military Command. Coagulable state was defined as normal. Both hyper- and hypo-coagulable states were defined as coagulation defects. Hypercoagulability was defined as an activated clotting time (ACT) ≦195s and a clot rate (CR) >23, and hypocoagulability was defined as an ACT ≧119s and a CR < 7. The Sonoclot signature t examination was performed at the time of admission. Conventional tests, such as the prothrombin time (PT) and activated partial thromboplastin time (aPTT), were compared with Sonoclot monitoring to identify coagulation defects.

Results

The average age of the 106 patients was 23.2±2.5 years. There were 102 males (96.3%) and 4 females (3.7%). Thirty-four patients (32.1%) were hypercoagulable and 44 patients (41.5%) were hypocoagulable at the time of admission; 28 patients (26.4%) had no evidence of a coagulopathy. Patients with hypocoagulability, unlike patients with hypercoagulability, had a higher sequential Organ Failure Assessment score, indicating a more severe multiple organ dysfunction score. Mortality was 5.9% in patients with hypercoagulability compared with 3.5% in patients with normal coagulation, and 18.1% in patients with a hypocoagulable state (P < 0.05). ACT was a predictor of mortality, while the CR and platelet function did not show statistical significance.

Conclusion

This study determined the clinical outcomes and prognostic value of coagulability in patients with heat stroke, as defined by Sonoclot signature analysis at the time of admission.