Changes in coagulation during therapeutic hypothermia in cardiac arrest patients

Dual Cardiac Arrests Leading to Hypercoagulability and Extensive Upper Extremity Deep Vein Thrombosis: A Hematological Case Report

Upper extremity (UE) deep vein thrombosis (DVT) is a rare yet significant complication that can occur following cardiac arrest (CA). CA initiates a prothrombotic state via various processes, including stasis, endothelial damage, and an impaired balance between thrombogenesis and fibrinolysis, which may contribute to UE DVT formation. Inadequate cardiopulmonary resuscitation (CPR) in the field may further exacerbate blood stasis and clot formation. This case report describes an 80-year-old male with a history of bladder cancer who experienced two cardiac arrest events and subsequently developed an extensive left UE DVT. Despite treatment with a heparin drip and other supportive measures, the patient's condition deteriorated, and he passed away on the tenth day of hospitalization. This case is the first to describe UE DVT post-CA. It underscores the importance of recognizing and proactively managing hypercoagulable states post-CA, which can lead to significant DVTs in atypical locations that may evolve into life-threatening conditions.

Analysis of risk factors for early-onset ventilator-associated pneumonia in a neurosurgical intensive care unit

Background

Ventilator-associated pneumonia (VAP) is a severe infection among patients in the neurosurgery intensive care unit (NICU).

Methods

We retrospectively evaluated risk factors for early-onset ventilator-associated pneumonia (EOVAP) from January 2019 to December 2019 at a NICU. A total of 89 NICU patients who were intubated within 48 h of onset and whose mechanical ventilation time was at least 7 days were enrolled. We evaluated EOVAP that occurred within the first 7 days after the onset of mechanical ventilation. The enrolled patients had no history of chronic lung disease and no clinical manifestations of infection before intubation. Clinical data of patients were recorded, and the incidence of and risk factors for EOVAP were analyzed. Patients were also grouped by age (≥ 65 vs. < 65 years) and whether they had received hypothermia treatment or not.

Results

Among 89 mechanically ventilated patients (49 men and 40 women; the mean age ± SD was 60.1 ± 14.3 years), 40 patients (44.9%) developed EOVAP within 7 days and 14 patients (15.7%) had a multidrug resistant bacterial infection. Binary logistic regression analysis indicated that older age (≥ 65 years) (odds ratio [OR]:3.53, 95% confidence interval [CI]:1.27–9.79, P = 0.015) and therapeutic hypothermia (OR:3.68, CI:1.10–12.31, p = 0.034) were independent predictors of EOVAP. Levels of peripheral blood leukocytes, neutrophils and platelets were lower in the therapeutic hypothermia group than those who did not receive hypothermia treatment.

Conclusions

This study found that older age (≥ 65 years) and therapeutic hypothermia were independently associated with the risk of EOVAP in NICU patients.

Topical Neck Cooling Prolongs Survival of Rats with Intra-Abdominal Feculent Sepsis by Activation of the Vagus Nerve

Global hypothermia prolongs survival in rats with intraabdominal feculent sepsis by inhibiting inflammatory responses. We hypothesized that topical neck cooling (TNC) has similar benefits. Septic shock was induced by cecal ligation and incision (CLI) in Sprague Dawley rats. Rats were randomized to sham laparotomy, control with CLI, CLI with TNC, or vagotomy at the gastroesophageal junction before CLI and TNC. Two more groups underwent peritoneal washout with and without TNC two hours after CLI. TNC significantly lowered neck skin temperature (16.7 ± 1.4 vs. 30.5 ± 0.6 °C, p < 0.05) while maintaining core body normothermia. TNC rats recovered from anesthesia 70 min earlier than the control (p < 0.05). Three hours following CLI, the control and vagotomy with TNC groups had significantly more splenic contraction, fewer circulating leukocytes and higher plasma IL-1β, IL-10 and TNF-α levels than TNC rats (p < 0.05). TNC prolonged survival duration after CLI by a median of four hours vs. control (p < 0.05), but no benefit was seen if vagotomy preceded TNC. Peritoneal washout alone increased survival by 3 h (9.2 (7.8–10.5) h). Survival duration increased dramatically with TNC preceding washout, to a 56% survival rate (>10 days). TNC significantly prolonged the survival of rats with severe intraabdominal sepsis by inhibiting systemic proinflammatory responses by activating vagal anti-inflammatory pathways.

Mild Therapeutic Hypothermia Alters Hemostasis in ST Elevation Myocardial Infarction Patients

Background and Rationale: Mild therapeutic hypothermia (MTH) is a concept to reduce infarct size and improve outcome after ST-segment elevation myocardial infarction (STEMI). In the STATIM trial, we investigated MTH as an additional therapy for STEMI patients. In the intention-to-treat set, 101 patients were included. No difference in primary and secondary endpoints measured by cardiac magnetic resonance imaging was found. Platelet activation and plasmatic coagulation are key in the pathophysiology of STEMI. In the present study, we investigated the effect of MTH on primary and secondary hemostasis in STEMI patients.

Methods and Results: Platelet function and morphology were assessed by routine blood count, aggregometry testing, and flow cytometry. Soluble platelet markers were determined by enzyme-linked immunosorbent assay (ELISA) testing. Plasmatic coagulation was measured throughout the study. Platelet count remained unchanged, irrespective of treatment, whereas platelet size decreased in both patient groups. Platelet aggregometry indicated increased platelet reactivity in the MTH group. Furthermore, higher adenosine diphosphate (ADP) plasma levels were found in MTH patients. Expression of glycoprotein IIb/IIIa was increased on platelets of STEMI patients treated with MTH. Lower patient temperatures correlated with longer clotting times and resulted in reduced pH. Lower pH values were positively correlated with longer clotting times.

Conclusion: Present data indicate longer clotting times and higher platelet reactivity in STEMI patients treated with MTH. These changes did not correspond to clinical bleeding events or larger infarct size.

Investigation of myocardial protection during pediatric CPB: Practical experience in 100 Chinese hospitals

Many measures have been proposed for myocardial protection in pediatric congenital heart surgeries, but little data is available for China. This study investigates myocardial protection strategies in pediatric cardiopulmonary bypass (CPB) throughout China. Online questionnaires were delivered to 100 hospitals in 27 provinces. The number of yearly on-pump pediatric cardiovascular surgeries in these hospitals varied greatly. About 91.0% of respondents believe that each surgery should have at least two perfusionists, while only 64.0% of hospitals actually met this requirement. For pediatric patients, crystalloid cardioplegia was more prevalent than blood-based cardioplegia. Histidine-tryptophan-ketoglutarate solution and St. Thomas crystalloid solution were dominant among crystalloid cardioplegia. Del Nido cardioplegia and St. Thomas blood-based cardioplegia ranked the top two in the popularity of blood-based cardioplegia. Dosages varied among different kinds of cardioplegia. In the choice of different cardioplegia, perfusionists mainly focused on myocardial protective effect and cost. Hypothermia of cardioplegia solution was maintained by ice buckets in 3/4 of the hospitals in this survey. In conclusion, the essence of myocardial protection management during pediatric CPB was cardiac arrest induced by cardioplegia under systemic hypothermia. However, there is no uniform standard for the type of cardioplegia, or dosages. Therefore, well-designed multicenter randomized controlled trials are warranted to provide tangible evidence for myocardial protection of cardioplegia in pediatric CPB.

Prognostic value of repeated thromboelastography measurement for favorable neurologic outcome during targeted temperature management in out-of-hospital cardiac arrest survivors

BACKGROUND

Cardiac arrest can activate blood coagulation, which clinically manifests as obstruction of the microcirculation and multiple organ dysfunction. Thromboelastography (TEG) provides a rapid and comprehensive assessment of hemostatic processes, but there are limited data on the use of sequential TEG values during targeted temperature management (TTM) in out-of-hospital cardiac arrest (OHCA) survivors. The aim of this study was to investigate the prognostic value of coagulopathy assessed by repeated TEG to predict neurologically intact survival.

METHODS

A prospective cohort of consecutive non-trauma OHCA patients who were successfully resuscitated and treated with TTM. Patients with a target temperature of 36 ℃, no TEG data, and who declined appropriate treatment were excluded. TEG was measured at three time points of TTM (initial phase, target phase, and rewarming phase). The primary outcome was 28 day favorable neurologic function, defined as a Cerebral Performance Category of 1 or 2.

RESULTS

A total of 125 patients (mean age, 61 years; 63.2% male) were analyzed. A favorable neurologic outcome at 28 days was seen in 40 patients (32.0%). TEG values of R and LY30 in the initial phase were significantly lower in the favorable neurologic outcome group than in the unfavorable group (5.8 vs. 8.1 and 0.1 vs. 0.7, respectively; p < 0.01). TEG values of R < 5 or LY30 < 7.5 in the initial phase were more frequently seen in the favorable outcomes group than in the unfavorable group (37.5% vs. 12.9%, p = 0.002 and 95.0% vs. 72.9%, p = 0.004, respectively). However, no significant differences were seen between the two groups in other TEG values (R, K, alpha, and MA) in the target and rewarming phases (p > 0.05 for all). Univariate analysis showed higher D-dimer levels, prothrombin time, and activated partial thromboplastin time in the unfavorable outcome group. In the multivariable analysis, TEG values of combination of R < 5 and LY30 < 7.5 in the initial phase were the only coagulation profiles seen to be independently associated with favorable neurologic outcome (OR, 4.508, 95% CI, 1.254-16.210).

CONCLUSION

TEG results are available within minutes, and shorted R values or the absence of prolonged LY30 values in the initial phase are an early predictor of neurologically intact survival in successfully resuscitated OHCA patients.

Use of therapeutic hypothermia among patients with coagulation disorders - A Nationwide analysis

OBJECTIVES

The study aimed to assess the impact of therapeutic hypothermia (TH) on bleeding and in-hospital mortality among patients with coagulation disorders (CD).

BACKGROUND

TH affects coagulation factors and platelets putting patients at risk for bleeding and worse outcomes. Effect of TH among patients with CD remains understudied.

METHODS

Between 2009 and 2014, a total of 6469 cases of TH were identified using the National Inpatient Sample out of which 1036 (16.02%) had a CD. The incidence of bleeding events, blood product transfusion and in-hospital mortality was compared between patients with and without CD using one to one propensity score matching.

RESULTS

Proportion of patients with CD increased during study duration from 13.0% to 17.4% from 2009 to 2014. Propensity matching was performed to adjust for baseline differences with 799 patients in both groups depending on presence or absence of CD. Patients with CD had a higher rate of bleeding events (13% vs. 8.5%; adjusted odds ratio 1.60; 95% confidence interval 1.16-2.23; P = 0.004), and blood product transfusion (25.0% vs. 14.1%; aOR 2.03; 95% CI 1.56-2.63; p < 0.001) compared to those without CD. There was no difference in rate of intracranial bleeding or hemorrhagic strokes between those with and without CD (3.3% vs. 3.2%; p = 0.88). There was no difference in mortality between patients with CD and those without (74.5% vs. 74.8%, aOR 0.98, 95% CI 0.78-1.23; P = 0.86).

CONCLUSIONS

Use of TH with CD resulted in more bleeding events and blood product transfusion but there was no difference in hospital mortality.

Accidental hypothermia

Accidental hypothermia causes profound changes to the body's physiology. After an initial burst of agitation (e.g., 36-37°C), vital functions will slow down with further cooling, until they vanish (e.g. <20-25°C). Thus, a deeply hypothermic person may appear dead, but may still be able to be resuscitated if treated correctly. The hospital use of minimally invasive rewarming for nonarrested, otherwise healthy patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionized the management of hypothermic cardiac arrest, with survival rates approaching 100%. Hypothermic patients with risk factors for imminent cardiac arrest (i.e., temperature <28°C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS center. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanic CPR can be helpful. Intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern postresuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimize prehospital triage, transport, and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and postresuscitation care.

Coagulofibrinolytic Changes in Patients with Post-cardiac Arrest Syndrome

Whole-body ischemia and reperfusion due to cardiac arrest and subsequent return of spontaneous circulation constitute post-cardiac arrest syndrome (PCAS), which consists of four syndromes including systemic ischemia/reperfusion responses and post-cardiac arrest brain injury. The major pathophysiologies underlying systemic ischemia/reperfusion responses are systemic inflammatory response syndrome and increased coagulation, leading to disseminated intravascular coagulation (DIC), which clinically manifests as obstruction of microcirculation and multiple organ dysfunction. In particular, thrombotic occlusion in the brain due to DIC, referred to as the "no-reflow phenomenon," may be deeply involved in post-cardiac arrest brain injury, which is the leading cause of mortality in patients with PCAS. Coagulofibrinolytic changes in patients with PCAS are characterized by tissue factor-dependent coagulation, which is accelerated by impaired anticoagulant mechanisms, including antithrombin, protein C, thrombomodulin, and tissue factor pathway inhibitor. Damage-associated molecular patterns (DAMPs) accelerate not only tissue factor-dependent coagulation but also the factor XII- and factor XI-dependent activation of coagulation. Inflammatory cytokines are also involved in these changes via the expression of tissue factor on endothelial cells and monocytes, the inhibition of anticoagulant systems, and the release of neutrophil elastase from neutrophils activated by inflammatory cytokines. Hyperfibrinolysis in the early phase of PCAS is followed by inadequate endogenous fibrinolysis and fibrinolytic shutdown by plasminogen activator inhibitor-1. Moreover, cell-free DNA, which is also a DAMP, plays a pivotal role in the inhibition of fibrinolysis. DIC diagnosis criteria or fibrinolysis markers, including d-dimer and fibrin/fibrinogen degradation products, which are commonly tested in patients and easily accessible, can be used to predict the mortality or neurological outcome of PCAS patients with high accuracy. A number of studies have explored therapy for this unique pathophysiology since the first report on "no-reflow phenomenon" was published roughly 50 years ago. However, the optimum therapeutic strategy focusing on the coagulofibrinolytic changes in cardiac arrest or PCAS patients has not yet been established. The elucidation of more precise pathomechanisms of coagulofibrinolytic changes in PCAS may aid in the development of novel therapeutic targets, leading to an improvement in the outcomes of PCAS patients.

Adaptation of global hemostasis to therapeutic hypothermia in patients with out-of-hospital cardiac arrest: Thromboelastography study

BACKGROUND

The use of mild therapeutic hypothermia (MTH) in patients after out-of-hospital cardiac arrest (OHCA) who are undergoing primary percutaneous coronary intervention (pPCI) can protect patients from thromboembolic complications. The aim of the study was to evaluate the adaptive mecha- nisms of the coagulation system in MTH-treated comatose OHCA survivors.

METHODS

Twenty one comatose OHCA survivors with acute coronary syndrome undergoing imme- diate pPCI were treated with MTH. Quantitative and qualitative analyses of physical clot properties were performed using thromboelastography (TEG). Two analysis time points were proposed: 1) during MTH with in vitro rewarming conditions (37°C) and 2) after restoration of normothermia (NT) under normal (37°C) and in vitro cooling conditions (32°C).

RESULTS

During MTH compared to NT, reaction time (R) was lengthened, clot kinetic parameter (a) was significantly reduced, but no effect on clot strength (MA) was observed. Finally, the coagulation index (CI) was significantly reduced with clot fibrinolysis attenuated during MTH. The clot lysis time (CLT) was shortened, and clot stability (LY60) was lower compared with those values during NT. In vitro cooling generally influenced clot kinetics and reduced clot stability after treatment.

CONCLUSIONS

Thromboelastography is a useful method for evaluation of coagulation system dysfunc- tion in OHCA survivors undergoing MTH. Coagulation impairment in hypothermia was associated with a reduced rate of clot formation, increased weakness of clot strength, and disturbances of fibrinoly- sis. Blood sample analyses performed at 32°C during MTH, instead of the standard 37°C, seems to enhance the accuracy of the evaluation of coagulation impairment in hypothermia.

Influence of temperature on thromboelastometry and platelet aggregation in cardiac arrest patients undergoing targeted temperature management

BACKGROUND

Coagulation can be visualised using whole blood coagulation analyses such as thromboelastometry and platelet aggregation tests; however, the role of temperature in the analyses is ambiguous. The aim was to examine whether temperature influences the whole blood coagulation tests.

METHODS

We included 40 patients treated with targeted temperature management (33 ± 1 °C) after out-of-hospital cardiac arrest. The blood samples were obtained on hypothermia and normothermia. Each blood sample was analysed simultaneously at 33 °C and 37 °C by thromboelastography (ROTEM®) employing the assays EXTEM®, INTEM®, FIBTEM® and HEPTEM®, and by Multiplate®Analyzer, using COLtest®, ADPtest®, ASPItest® and TRAPtest® as agonists. Data on antithrombotic drugs were collected systematically from medical records, and data were analysed using repeated measurement analysis of variance (ANOVA).

RESULTS

The ROTEM® analyses showed increased clotting time, lower maximum velocity and increased time to maximum velocity (all p values <0.02) when performed at 33 °C compared with 37 °C, irrespective of the patients being hypothermic (median 33.1 °C) or normothermic (median 37.5 °C). However, EXTEM® time to maximum velocity showed no difference between the analyses performed at 33 °C and 37 °C when the patients were hypothermic (p = 0.83). No differences were found in maximum clot firmness (all p values >0.09) analysed at 33 °C and 37 °C, independent of the body temperature. In the hypothermic blood sample, no difference was found when using the COLtest®, ASPItest® or TRAPtest® to compare platelet aggregation analysed at 33 °C and 37 °C (all p values >0.19), but platelet aggregation was significantly higher using the ADPtest® (p < 0.001) when analysed at 33 °C. In the normothermic blood sample, the TRAPtest® showed no difference (p = 0.73) when performed at 33 °C; however, significantly lower aggregation was found using the COLtest® and ASPItest® (all p values <0.001), while a higher aggregation at 33 °C was found using the ADPtest® (p = 0.003).

CONCLUSION

ROTEM® analyses seemed not to be dependent on body temperature but showed a slower initiation of coagulation when analysed at 33 °C compared with 37 °C. The Multiplate®Analyzer results were dependent on the temperature used in the analyses and the body temperature. In whole blood coagulation tests, the temperature used in the analyses should be kept at 37 °C irrespective of the patient's body temperature being 33 °C or 37 °C.