Tissue plasminogen activator in cardiac arrest with pulseless electrical activity

Fibrinolytic uses in the emergency department: a narrative review

INTRODUCTION

Several life-threatening conditions associated with thrombosis include acute ischemic stroke (AIS), acute myocardial infarction (AMI), and acute pulmonary embolism (PE). Fibrinolytics are among the treatment algorithms for these conditions.

OBJECTIVE

This narrative review provides emergency clinicians with an overview of fibrinolytics for AIS, AMI, and PE in the emergency department (ED) setting.

DISCUSSION

Pathologic thrombosis can result in vascular occlusion and embolism, ultimately leading to end-organ injury. Fibrinolytics are medications utilized to lyse a blood clot, improving vascular flow. One of the first agents utilized was streptokinase, though this is not as often used with the availability of fibrin-specific agents including alteplase (tPA), tenecteplase (TNK), and reteplase (rPA). These agents are integral components in the management of several conditions, including AIS, AMI, and PE. Patients with AIS who present within 3-4.5 h of measurable neurologic deficit with no evidence of intracerebral hemorrhage (ICH) or other contraindications may be eligible to receive tPA or TNK. In the absence of percutaneous coronary intervention (PCI), fibrinolytics should be considered in patients with AMI presenting with chest pain for at least 30 min but less than 12 h, though it may be considered up to 24 h. Unlike in AIS and PE, anticoagulation and antiplatelet medications should be administered in those with AMI receiving fibrinolytics. Following fibrinolytics, PCI is typically necessary. Fibrinolytics are recommended in patients with high-risk PE (hemodynamic instability), as they reduce the risk of mortality. The most significant complication following fibrinolytic administration includes major bleeding such as ICH, which occurs most frequently in those with AIS compared to AMI and PE. Thus, close patient monitoring is necessary following fibrinolytic administration.

CONCLUSIONS

An understanding of fibrinolytics in the ED setting is essential, including the indications, contraindications, and dosing.

Outcome of massive pulmonary embolism treated only with extracorporeal membrane oxygenation and anticoagulation without thrombolytic therapy or surgical embolectomy

INTRODUCTION

Although thrombolytic therapy is the standard treatment for massive pulmonary thromboembolism (PTE), it is often ineffective in patients with circulatory collapse. Surgical embolectomy is another treatment option, but whether it is absolutely necessary is controversial. We sought to evaluate the outcomes of patients with massive PTE treated with intensive critical care including extracorporeal membrane oxygenation (ECMO) without thrombolytic therapy or surgical embolectomy.

METHODS

We analyzed 39 patients who were treated for massive PTE from January 2011 to June 2019. Massive PTE was treated with anticoagulation and hemodynamic support at an intensive care unit. ECMO was applied in patients with circulatory collapse. The computed tomography (CT) obstruction index and the ratio of the right ventricle to left ventricle short-axis diameters (RV/LV) were measured using serial CT angiography to confirm changes in pulmonary emboli and RV strain.

RESULTS

Twenty-one patients were in cardiogenic shock, and 15 of them needed cardiopulmonary resuscitation (CPR). Fifteen patients were treated with ECMO and nine of them were weaned successfully. The overall in-hospital mortality was 23% (9/39). On the follow-up CT scan after 6 months, residual PTE was observed in 10 patients and their median CT obstruction index was 6.25 % (range 2.5-35). The initial mean RV/LV ratio was 1.8 ± 0.47 and the value measured at follow-up CT decreased to less than 1 (0.9 ± 0.1).

CONCLUSIONS

Intensive critical care with heparin alone and timely ECMO support without thrombolytic therapy could be an effective treatment option in patients with acute massive PTE.

The Pharmacologic Management of Cardiac Arrest

The effectiveness of pharmacologic management of cardiac arrest patients is widely debated; however, several studies published in the past 5 years have begun to clarify some of these issues. This article covers the current state of evidence for the effectiveness of the vasopressor epinephrine and the combination of vasopressin-steroids-epinephrine and antiarrhythmic medications amiodarone and lidocaine and reviews the role of other medications such as calcium, sodium bicarbonate, magnesium, and atropine in cardiac arrest care. We additionally review the role of β-blockers for refractory pulseless ventricular tachycardia/ventricular fibrillation and thrombolytics in undifferentiated cardiac arrest and suspected fatal pulmonary embolism.

Thrombolytics in Cardiac Arrest from Pulmonary Embolism: A Systematic Review and Meta Analysis

BACKGROUND

During cardiopulmonary resuscitation, intravenous thrombolytics are commonly used for patients whose underlying etiology of cardiac arrest is presumed to be related to pulmonary embolism (PE).

METHODS

We performed a systematic review and meta-analysis of the existing literature that focused on the use of thrombolytics for cardiac arrest due to presumed or confirmed PE. Outcomes of interest were return of spontaneous circulation (ROSC), survival to hospital discharge, neurologically-intact survival, and bleeding complications.

RESULTS

Thirteen studies with a total of 803 patients were included in this review. Most studies included were single-armed and retrospective. Thrombolytic agent and dose were heterogeneous between studies. Among those with control groups, intravenous thrombolysis was associated with higher rates of ROSC (OR 2.55, 95% CI = 1.50-4.34), but without a significant difference in survival to hospital discharge (OR 1.41, 95% CI = 0.79-2.41) or bleeding complications (OR 2.21, 0.95-5.17).

CONCLUSIONS

Use of intravenous thrombolytics in cardiac arrest due to confirmed or presumed PE is associated with increased ROSC but not survival to hospital discharge or change in bleeding complications. Larger randomized studies are needed. Currently, we recommend continuing to follow existing consensus guidelines which support use of thrombolytics for this indication.

Management of high-risk pulmonary embolism in the emergency department: A narrative review

BACKGROUND

High-risk pulmonary embolism (PE) is a complex, life-threatening condition, and emergency clinicians must be ready to resuscitate and rapidly pursue primary reperfusion therapy. The first-line reperfusion therapy for patients with high-risk PE is systemic thrombolytics (ST). Despite consensus guidelines, only a fraction of eligible patients receive ST for high-risk PE.

OBJECTIVE

This review provides emergency clinicians with a comprehensive overview of the current evidence regarding the management of high-risk PE with an emphasis on ST and other reperfusion therapies to address the gap between practice and guideline recommendations.

DISCUSSION

High-risk PE is defined as PE that causes hemodynamic instability. The high mortality rate and dynamic pathophysiology of high-risk PE make it challenging to manage. Initial stabilization of the decompensating patient includes vasopressor administration and supplemental oxygen or high-flow nasal cannula. Primary reperfusion therapy should be pursued for those with high-risk PE, and consensus guidelines recommend the use of ST for high-risk PE based on studies demonstrating benefit. Other options for reperfusion include surgical embolectomy and catheter directed interventions.

CONCLUSIONS

Emergency clinicians must possess an understanding of high-risk PE including the clinical assessment, pathophysiology, management of hemodynamic instability and respiratory failure, and primary reperfusion therapies.

The Pharmacologic Management of Cardiac Arrest

The effectiveness of pharmacologic management of cardiac arrest patients is widely debated; however, several studies published in the past 5 years have begun to clarify some of these issues. This article covers the current state of evidence for the effectiveness of the vasopressor epinephrine and the combination of vasopressin-steroids-epinephrine and antiarrhythmic medications amiodarone and lidocaine and reviews the role of other medications such as calcium, sodium bicarbonate, magnesium, and atropine in cardiac arrest care. We additionally review the role of β-blockers for refractory pulseless ventricular tachycardia/ventricular fibrillation and thrombolytics in undifferentiated cardiac arrest and suspected fatal pulmonary embolism.

Coagulation measures after cardiac arrest (CMACA)

BACKGROUND

During cardiac arrest (CA) and after cardiopulmonary resuscitation, activation of blood coagulation and inadequate endogenous fibrinolysis occur. The aim of this study was to describe the time course of coagulation abnormalities after out-of-hospital CA (OHCA) and to examine the association with clinical outcomes in patients undergoing targeted temperature management (TTM) after OHCA.

METHODS

This prospective, multicenter, observational cohort study was performed in eight emergency departments in Korea between September 2018 and September 2019. Laboratory findings from hospital admission and 24 hours after return of spontaneous circulation (ROSC) were analyzed. The primary outcome was cerebral performance category (CPC) at discharge, and the secondary outcome was in-hospital mortality.

RESULTS

A total of 170 patients were included in this study. The lactic acid, prothrombin time (PT), activated partial thrombin time (aPTT), international normalized ratio (INR), and D-dimer levels were higher in patients with poor neurological outcomes at admission and 24 h after ROSC. The lactic acid and D-dimer levels decreased over time, while fibrinogen increased over time. PT, aPTT, and INR did not change over time. The PT at admission and D-dimer levels 24 h after ROSC were associated with neurological outcomes at hospital discharge. Coagulation-related factors were moderately correlated with the duration of time from collapse to ROSC.

CONCLUSION

The time-dependent changes in coagulation-related factors are diverse. Among coagulation-related factors, PT at admission and D-dimer levels 24 h after ROSC were associated with poor neurological outcomes at hospital discharge in patients treated with TTM.

Pulmonary embolism management in the emergency department: part 2

Pulmonary embolism (PE) can present with a range of severity. Prognostic risk stratification is important for efficacious and safe management. This second of two review articles discusses the management of high-, intermediate- and low-risk PE. We discuss strategies to identify patients suitable for urgent outpatient care in addition to identification of patients who would benefit from thrombolysis. We discuss specific subgroups of patients where optimal treatment differs from the usual approach and identify emerging management paradigms exploring new therapies and subgroups.

Thrombolytic therapy in cardiac arrest caused by cardiac etiologies or presumed pulmonary embolism: An updated systematic review and meta-analysis

Background

Many cardiac arrest cases are encountered annually worldwide, with poor survival. The use of systemic thrombolysis during cardiopulmonary resuscitation for the treatment of cardiac arrest remains controversial.

Objectives

Evaluate the safety and efficacy of systemic thrombolysis in patients with cardiac arrest due to presumed or confirmed pulmonary embolism or cardiac etiology.

Methods

We searched the PubMed and Cochrane databases from inception through April 2021 to identify relevant randomized controlled trials and observational studies. The primary efficacy and safety outcomes were survival to hospital discharge and reported bleeding, respectively. Sensitivity analysis was performed on the basis of study design and etiology of cardiac arrest.

Results

Eleven studies were included, with 4696 patients (1178 patients received systemic thrombolysis, and 3518 patients received traditional therapy). There was a higher rate of survival to hospital discharge in patients who received systemic thrombolysis versus no systemic thrombolysis (risk ratio [RR], 1.35; 95% confidence interval [CI], 0.95-1.91). There were also higher rates of survival at 24 hours (RR, 1.24; 95% CI, 0.97-1.59) and hospital admission (RR, 1.53; 95% CI, 1.04-2.24), and return of spontaneous circulation (ROSC) (RR, 1.34; 95% CI, 1.05-1.71) with the use of systemic thrombolysis. Impacts on survival to discharge and survival at 24 hours were not statistically significant. Patients receiving systemic thrombolysis had a 65% increase in bleeding events compared with no systemic thrombolysis (RR, 1.65; 95% CI, 1.20-2.27).

Conclusion

Systemic thrombolysis in cardiac arrest did not improve survival to hospital discharge and led to more bleeding events. However, it increased the rates of hospital admission and ROSC achievement.

Accelerated treatment with rtPA for pulmonary embolism induced circulatory arrest

Patients with circulatory arrest due to pulmonary embolism (PE) should be treated with fibrinolytics. Current guidelines do not specify which regimen to apply, and it has been suggested that the regimen of 100 mg rtPA/2 h should be used, because this is recommended for hemodynamic instable PE in the ESC/ERS Guideline. This two hour regimen, however, is incompatible with key principles of cardiopulmonary resuscitation (CPR), such as employment of interventions that allow fast evaluation of effectiveness, and limitation of the total duration of CPR to avoid poor neurological outcomes. Additionally, the low flow-state during CPR has important consequences for the pharmacokinetic properties of rtPA. Arguably, the volume of distribution is lower, the metabolism reduced and the half life time longer. Therefore, these changes largely discard the rationale to use high dosages of rtPA over a prolonged period of time. More importantly, these changes highlight that the guideline recommendations, based on studies in patients without circulatory arrest, cannot be easily translated to the situation of circulatory arrest. An accelerated regimen of rtPA (0.6 mg/kg/15 min., max 50 mg) is mentioned by the 2019 ESC/ERS Guideline. However, empirical support or a rationale is not provided. Due to the rarity of the situation and ethical difficulties associated with randomizing unconscious patients, a randomized head-to-head comparison between the two regimens is unlikely to ever be performed. With this comprehensive overview of the pharmacokinetics of rtPA and current literature, a strong rationale is provided that the accelerated protocol is the regimen of choice for patients with PE-induced circulatory arrest.

Usefulness of thrombolysis in cardiac arrest secondary to suspected or confirmed pulmonary embolism

Acute pulmonary embolism (PE) is a form of venous thromboembolism associated with significant morbidity and mortality. Massive PE, characterized by hemodynamic instability, has been reported as a common cause of cardiac arrest. Thrombolytic agents have therefore been identified as a potential rescue therapy to restore circulatory perfusion. This study describes use patterns of systemic thrombolysis in cardiac arrest and corresponding patient outcomes. A multicenter retrospective chart review was conducted to evaluate adult patients who received rescue thrombolysis during cardiac arrest for suspected or confirmed PE. A total of 27 patients were included. PE was confirmed in 4 patients (15%). Pulseless electrical activity was the initial rhythm in 21 patients (78%), with a median cardiac arrest duration of 23 minutes in patients with return of spontaneous circulation (ROSC) vs 42.5 minutes in patients without ROSC. Among the 11 patients (41%) with ROSC, two (7%) survived to hospital discharge. Notable characteristics of the two survivors included a confirmed PE, an initial presenting rhythm of pulseless electrical activity, and administration of alteplase within 5 minutes of cardiac arrest. We recommend early administration of rescue thrombolysis when there is a high clinical index of suspicion that PE is the cause of the arrest.

Neuroprotective Treatment of Postanoxic Encephalopathy: A Review of Clinical Evidence

Postanoxic encephalopathy is the key determinant of death or disability after successful cardiopulmonary resuscitation. Animal studies have provided proof-of-principle evidence of efficacy of divergent classes of neuroprotective treatments to promote brain recovery. However, apart from targeted temperature management (TTM), neuroprotective treatments are not included in current care of patients with postanoxic encephalopathy after cardiac arrest. We aimed to review the clinical evidence of efficacy of neuroprotective strategies to improve recovery of comatose patients after cardiac arrest and to propose future directions. We performed a systematic search of the literature to identify prospective, comparative clinical trials on interventions to improve neurological outcome of comatose patients after cardiac arrest. We included 53 studies on 21 interventions. None showed unequivocal benefit. TTM at 33 or 36°C and adrenaline (epinephrine) are studied most, followed by xenon, erythropoietin, and calcium antagonists. Lack of efficacy is associated with heterogeneity of patient groups and limited specificity of outcome measures. Ongoing and future trials will benefit from systematic collection of measures of baseline encephalopathy and sufficiently powered predefined subgroup analyses. Outcome measurement should include comprehensive neuropsychological follow-up, to show treatment effects that are not detectable by gross measures of functional recovery. To enhance translation from animal models to patients, studies under experimental conditions should adhere to strict methodological and publication guidelines.

Translation from animal studies of novel pharmacological therapies to clinical trials in cardiac arrest: A systematic review

BACKGROUND

There is a lack of new promising therapies to improve the dismal outcomes from cardiac arrest. The objectives of this study were: (1) To identify novel pharmacological therapies investigated in experimental animal studies and (2) to identify pharmacological therapies translated from experimental animal studies to clinical trials.

METHODS

PubMed was searched to first identify relevant experimental cardiac arrest animal models published within the last 20 years. Based on this, a list of interventions was created and a second search was performed to identify clinical trials testing one of these interventions. Data extraction was performed using standardised data extraction forms.

RESULTS

We identified 415 animal studies testing 190 different pharmacological interventions. The most commonly tested interventions were classified as vasopressors, anaesthetics/gases, or interventions aimed at molecular targets. We found 43 clinical trials testing 26 different interventions identified in the animal studies. Of these, 13 trials reported positive findings and 30 trials reported neutral findings with regards to the primary endpoint. No study showed harm of the intervention. Some interventions tested in human clinical trials, had previously been tested in animal studies without a positive effect on outcomes. A large number of animal studies was performed after publication of a clinical trial.

CONCLUSION

Numerous different pharmacological interventions have been tested in experimental animal models. Despite this only a limited number of these interventions have advanced to clinical trials, however several of the clinical trials tested interventions that were first tested in experimental animal models.

Intraoperative Cardiac Arrest

Cardiac arrest in the operating room and in the immediate postoperative period is a potentially catastrophic event that is almost always witnessed and is frequently anticipated. Perioperative crises and perioperative cardiac arrest, although often catastrophic, are frequently managed in a timely and directed manner because practitioners have a deep knowledge of the patient's medical condition and details of recent procedures. It is hoped that the approaches described here, along with approaches for the rapid identification and management of specific high-stakes clinical scenarios, will help anesthesiologists continue to improve patient outcomes.

Fibrinolytics for the treatment of pulmonary embolism

The use of fibrinolytic agents in acute pulmonary embolism (PE), first described over 50 years ago, hastens the resolution of RV stain, leading to earlier hemodynamic improvement. However, this benefit comes at the increased risk of bleeding. The strongest indication for fibrinolysis is in high-risk PE, or that characterized by sustained hypotension, while its use in patients with intermediate-risk PE remains controversial. Fibrinolysis is generally not recommended for routine use in intermediate-risk PE, although most guidelines advise that it may be considered in patients with signs of acute decompensation and an overall low bleeding risk. The efficacy of fibrinolysis often varies significantly between patients, which may be at least partially explained by several factors found to promote resistance to fibrinolysis. Ultimately, treatment decisions should carefully weigh the risks and benefits of the individual clinical scenario at hand, including the overall severity, the patient's bleeding risk, and the presence of factors known to promote resistance to fibrinolysis. This review aims to further explore the use of fibrinolytic agents in the treatment of PE including specific indications, outcomes, and special considerations.

“Real-World” Application of Thrombolysis in Cardiac Arrest

Background:

Current guidelines recommend consideration of thrombosis as a reversible cause of cardiac arrest. The use of thrombolytic therapy during cardiac arrest, however, is controversial.

Objective:

We sought to characterize the use of thrombolytic therapy during cardiac arrest and to evaluate the rate of return of spontaneous circulation (ROSC) in a “real-word” setting.

Methods:

A single-center, retrospective, cohort study of adult patients who received alteplase during cardiac arrest between 2010 and 2015 were performed at a tertiary academic medical center.

Results:

Twenty-six patients were identified. Patients were predominantly male (65%) and Caucasian (89%) and were a median age of 64 years. Five patients had a history of preexisting venous thromboembolism, and eight patients were receiving systemic anticoagulation. Pulmonary embolism was confirmed prior to the administration of alteplase in 5 patients. The median dose of alteplase administered was 100 mg. ROSC was achieved in 65% of patients, 2 of whom survived to hospital discharge. Both surviving patients experienced a bleeding event.

Conclusion:

In a single center’s experience, thrombolytic therapy is used infrequently for the management of cardiac arrest. Thrombolysis during cardiac arrest should be considered on a case-by-case basis and should be utilized only when there is a high suspicion for pulmonary embolism as the cause of arrest and when thrombolytic therapy is readily available.

Frequency of Medical Reversal Among Published Randomized Controlled Trials Assessing Cardiopulmonary Resuscitation (CPR)

OBJECTIVE

To characterize what proportion of all randomized controlled trials (RCTs) among patients experiencing cardiac arrest find that an established practice is ineffective or harmful, that is, a medical reversal.

METHODS

We reviewed a database of all published RCTs of cardiac arrest patient populations between 1995 and 2014. Articles were classified on the basis of whether they tested a new or existing therapy and whether results were positive or negative. A reversal was defined as a negative RCT of an established practice. Further review and categorization were performed to confirm that reversals were supported by subsequent systematic review, as well as to identify the type of medical practice studied in each reversal. This study was conducted from October 2017 to June 17, 2019.

RESULTS

We reviewed 92 original articles, 76 of which could be conclusively categorized. Of these, 18 (24%) articles examined a new medical practice, whereas 58 (76%) tested an established practice. A total of 18 (24%) studies had positive findings, whereas 58 (76%) reached a negative conclusion. Of the 58 articles testing existing standard of care, 44 (76%) reversed that practice, whereas 14 (24%) reaffirmed it.

CONCLUSION

Reversal of cardiopulmonary resuscitation practices is widespread. This investigation sheds new light on low-value practices and patterns of medical research and suggests that novel resuscitation practices have low pretest probability and should be empirically tested with rigorous trials before implementation.

Can Systemic Thrombolysis Improve Prognosis of Cardiac Arrest Patients During Cardiopulmonary Resuscitation? A Systematic Review and Meta-Analysis

BACKGROUND

Cardiac arrests are caused in most cases by thromboembolic diseases, such as acute myocardial infarction (AMI) and pulmonary embolism (PE).

OBJECTIVE

We aimed to ascertain the associations of thrombolytic therapy with potential benefits among cardiac arrest patients during cardiopulmonary resuscitation (CPR).

METHODS

We searched PubMed, Embase, and Cochrane databases for studies that evaluated systemic thrombolysis in cardiac arrest patients. The primary outcome was survival to hospital discharge, and secondary outcomes included return of spontaneous circulation (ROSC), 24-h survival rate, hospital admission rate, and bleeding complications.

RESULTS

Nine studies with a total of 4384 cardiac arrest patients were pooled in the meta-analysis, including 1084 patients receiving systemic thrombolysis and 3300 patients receiving traditional treatments. Compared with conventional therapies, the use of systemic thrombolysis did not significantly improve survival to hospital discharge (13.5% vs. 10.8%; risk ratio [RR] 1.13; 95% confidence interval [CI] 0.92-1.39; p = 0.24, I² = 35%), ROSC (50.9% vs. 44.3%; RR 1.29; 95% CI 1.00-1.66; p = 0.05, I² = 73%), and 24-h survival (28.1% vs. 25.6%; RR 1.25; 95% CI 0.88-1.77; p = 0.22, I² = 63%). We observed higher hospital admission rates for patients receiving systemic thrombolysis (43.4% vs. 30.6%; RR 1.53; 95% CI 1.04-2.24; p = 0.03, I² = 87%). In addition, higher risk of bleeding was observed in the thrombolysis group (8.8% vs. 5.0%; RR 1.65; 95% CI 1.16-2.35; p = 0.005, I² = 7%).

CONCLUSIONS

Systemic thrombolysis during CPR did not improve hospital discharge rate, ROSC, and 24-h survival for cardiac arrest patients. Patients receiving thrombolytic therapy have a higher risk of bleeding. More high-quality studies are needed to confirm our results.

Characterization of alteplase therapy for presumed or confirmed pulmonary embolism during cardiac arrest

PURPOSE

The dosing and administration of alteplase in cardiac arrest due to suspected or confirmed pulmonary embolism (PE) are characterized.

METHODS

This multicenter, retrospective, cohort study evaluated adult patients who received alteplase during PE-induced cardiac arrest at 16 medical centers. Outcomes analyzed included alteplase dosing characteristics, cardiopulmonary resuscitation survival, time to return of spontaneous circulation (ROSC), documented occurrence of major or minor bleeding, intensive care unit and hospital length of stay, and survival to discharge.

RESULTS

A total of 35 patients were included in the analysis. Forty-six percent of patients received alteplase by a bolus-only dosing strategy. The most common bolus-only alteplase dose was 50 mg. Patients in the bolus-only group had a significantly shorter mean time from cardiac arrest onset to alteplase administration (15.1 minutes) compared with both the infusion-only group (46.4 minutes) and the bolus-with-infusion group (48.0 minutes) (p = 0.006). The mean cumulative alteplase dose was significantly higher in patients who had ROSC than those who did not (90.6 and 69.4 mg, respectively; p = 0.03). Although there was a significant difference in the cardiac arrest survival between groups, there was no difference between dosing strategies and the attainment of ROSC, and survival to hospital discharge.

CONCLUSION

Among patients receiving alteplase for presumed or confirmed PE during cardiac arrest, the most common treatment was administration of a single 50-mg bolus of the thrombolytic agent. This treatment was received by all survivors of cardiac arrest.

Evolving Strategies in Cardiac Arrest Management

Cardiac arrest is a leading cause of death in the United States, with a hospital discharge rate of approximately 10%. International resuscitation guidelines offer standardized cardiac arrest management approaches, but beyond the guidelines, are promising innovations to improve resuscitative care. Although clinical data do not yet support the routine use of mechanical chest compressions, corticosteroids, thrombolytics, and adjunctive ventilation devices during arrest, these therapies may have an important role in select patients. Extracorporeal membrane oxygenation during cardiopulmonary resuscitation is a promising advancement and may have survival benefit in select patients. The evidence for standard therapies and these innovations is discussed.

Double Bolus Alteplase Therapy during Cardiopulmonary Resuscitation for Cardiac Arrest due to Massive Pulmonary Embolism Guided by Focused Bedside Echocardiography

Massive pulmonary embolism (PE) frequently leads to cardiac arrest (CA) which carries an extremely high mortality rate. Although available, randomized trials have not shown survival benefits from thrombolytic use. Thrombolytics however have been used successfully during resuscitation in clinical practice in multiple case reports and in retrospective studies. Recent resuscitation guidelines recommend using alteplase for PE related CA; however they do not offer a standardized treatment regimen. The most consistently applied approach is an intravenous bolus of 50 mg tissue plasminogen activator (t-PA) early during cardiopulmonary resuscitation (CPR). There is no consensus on the subsequent dosing. We present a case in which two 50 mg boluses of t-PA were administered 20 minutes apart during CPR due to persistent hemodynamic compromise guided by bedside echocardiogram. The patient had an excellent outcome with normalization of cardiac function and no neurologic sequela. This case demonstrates the benefit of utilizing bedside echocardiography to guide administration of a second bolus of alteplase when there is persistent hemodynamic compromise despite achieving return of spontaneous circulation after the initial bolus, and there is evidence of persistent right ventricle dysfunction. Future trials are warranted to help establish guidelines for thrombolytic use in cardiac arrest to maximize safety and efficacy.

Thrombolysis as a Therapeutic Modality in Cardiac Arrest

Introduction

In recent years, thrombolysis has emerged as a potentially promising treatment for cardiac arrest. Patients with cardiac arrests from myocardial infarction or pulmonary embolism, as well as out-of-hospital cardiac arrests, were reported to have improvement in both survival and neurologic outcome after being treated with thrombolysis. This paper aims to review the available literature on the use of thrombolysis in cardiac arrest.

Method

Study of papers from PubMed literature search for all articles with terms related to thrombolysis and cardiac arrest in title or abstract.

Results

Thrombolytics are thought to act by lysing both macroscopic clots and microthrombi, particularly in the cerebral microcirculation, thus alleviating or reversing post-arrest cerebral no-reflow. Their use in cardiac arrest has been restrained by concerns over their safety after cardiopulmonary resuscitation, in particular bleeding-related complications, although these concerns seem to have been misplaced.

Conclusions

Thrombolysis for cardiac arrest is likely to be most efficacious in a pre-hospital environment, and future research should be directed to this setting.

Interventional Treatment of Pulmonary Embolism

Pulmonary embolism (PE) is a serious and prevalent cause of vascular disease. Nevertheless, optimal treatment for many phenotypes of PE remains uncertain. Treating PE requires appropriate risk stratification as a first step. For the highest-risk PE, presenting as shock or arrest, emergent systemic thrombolysis or embolectomy is reasonable, while for low-risk PE, anticoagulation alone is often chosen. Normotensive patients with PE but with indicia of right heart dysfunction (by biomarkers or imaging) constitute an intermediate-risk group for whom there is controversy on therapeutic strategy. Some intermediate-risk patients with PE may require urgent stabilization, and ≈10% will decompensate hemodynamically and suffer high mortality, though identifying these specific patients remains challenging. Systemic thrombolysis is a consideration, but its risks of major and intracranial hemorrhages rival overall harms from intermediate PE. Multiple hybrid pharmacomechanical approaches have been devised to capture the benefits of thrombolysis while reducing its risks, but there is limited aggregate clinical experience with such novel interventional strategies. One method to counteract uncertainty and generate a consensus multidisciplinary prognostic and therapeutic plan is through a Pulmonary Embolism Response Team, which combines expertise from interventional cardiology, interventional radiology, cardiac surgery, cardiac imaging, and critical care. Such a team can help determine which intervention-catheter-directed fibrinolysis, ultrasound-assisted thrombolysis, percutaneous mechanical thrombus fragmentation, or percutaneous or surgical embolectomy-is best suited to a particular patient. This article reviews these various modalities and the background for each.

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.

Systemic Thrombolysis for Pulmonary Embolism: Who and How

Anticoagulation has been shown to improve mortality in acute pulmonary embolism (PE). Initiation of anticoagulation should be considered when PE is strongly suspected and the bleeding risk is perceived to be low, even if acute PE has not yet been proven. Low-risk patients with acute PE are simply continued on anticoagulation. Severely ill patients with high-risk (massive) PE require aggressive therapy, and if the bleeding risk is acceptable, systemic thrombolysis should be considered. However, despite clear evidence that parenteral thrombolytic therapy leads to more rapid clot resolution than anticoagulation alone, the risk of major bleeding including intracranial bleeding is significantly higher when systemic thrombolytic therapy is administered. It has been demonstrated that right ventricular dysfunction, as well as abnormal biomarkers (troponin and brain natriuretic peptide) are associated with increased mortality in acute PE. In spite of this, intermediate-risk (submassive) PE comprises a fairly broad clinical spectrum. For several decades, clinicians and clinical trialists have worked toward a more aggressive, yet safe solution for patients with intermediate-risk PE. Standard-dose thrombolysis, low-dose systemic thrombolysis, and catheter-based therapy which includes a number of devices and techniques, with or without low-dose thrombolytic therapy, have offered potential solutions and this area has continued to evolve. On the basis of heterogeneity within the category of intermediate-risk as well as within the high-risk group of patients, we will focus on the use of systemic thrombolysis in carefully selected high- and intermediate-risk patients. In certain circumstances when the need for aggressive therapy is urgent and the bleeding risk is acceptable, this is an appropriate approach, and often the best one.

Long-Term Outcomes in Critically Ill Septic Patients Who Survived Cardiopulmonary Resuscitation

OBJECTIVE

To evaluate the long-term survival rate of critically ill sepsis survivors following cardiopulmonary resuscitation on a national scale.

DESIGN

Retrospective and observational cohort study.

SETTING

Data were extracted from Taiwan's National Health Insurance Research Database.

PATIENTS

A total of 272,897 ICU patients with sepsis were identified during 2000-2010. Patients who survived to hospital discharge were enrolled. Post-discharge survival outcomes of ICU sepsis survivors who received cardiopulmonary resuscitation were compared with those of patients who did not experience cardiopulmonary arrest using propensity score matching with a 1:1 ratio.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Only 7% (n = 3,207) of sepsis patients who received cardiopulmonary resuscitation survived to discharge. The overall 1-, 2-, and 5-year postdischarge survival rates following cardiopulmonary resuscitation were 28%, 23%, and 14%, respectively. Compared with sepsis survivors without cardiopulmonary arrest, sepsis survivors who received cardiopulmonary resuscitation had a greater risk of all-cause mortality after discharge (hazard ratio, 1.38; 95% CI, 1.34-1.46). This difference in mortality risk diminished after 2 years (hazard ratio, 1.11; 95% CI, 0.96-1.28). Multivariable analysis showed that independent risk factors for long-term mortality following cardiopulmonary resuscitation were male sex, older age, receipt of care in a nonmedical center, higher Charlson Comorbidity Index score, chronic kidney disease, cancer, respiratory infection, vasoactive agent use, and receipt of renal replacement therapy during ICU stay.

CONCLUSION

The long-term outcome was worse in ICU survivors of sepsis who received in-hospital cardiopulmonary resuscitation than in those who did not, but this increased risk of mortality diminished at 2 years after discharge.

Outcome of out-of-hospital cardiac arrest after fibrinolysis with reteplase in comparison to the return of spontaneous circulation after cardiac arrest score in a geographic region without emergency coronary intervention

Coronary occlusion and pulmonary embolism are responsible for the majority of cases of out-of-hospital cardiac arrest (OHCA). Despite previous favourable results of pre-hospital fibrinolysis in cases of OHCA, the benefit could not be confirmed in a large controlled study using the fibrinolytic tenecteplase. For reteplase (r-PA), there are hardly any data regarding pre-hospital fibrinolysis during ongoing resuscitation. The present study reported results using r-PA therapy in a German physician-supported Emergency Medical Services system. The data of OHCA patients who received pre-hospital fibrinolytic treatment with r-PA after an individual risk/benefit assessment were retrospectively analysed. To assess the effectiveness of this approach, the rate of patients with a return of spontaneous circulation (ROSC) was compared with the corresponding figure that was calculated with the help of the RACA (ROSC after cardiac arrest) score. The RACA algorithm predicts the probability of ROSC based on data from the German Resuscitation Registry. Further outcome data comprised hospital discharge rate and neurologic status at discharge. From 2001 to 2009, 43 patients (mean age, 58.5 years; 65.1% male; 58.1% ventricular fibrillation) received r-PA. Of these, 20 patients (46.5%) achieved ROSC, compared to a probability of 49.8% according to the RACA score (P=0.58). A total of 8 patients (18.6%) were discharged alive, including 5 (11.2%) with a good neurological outcome. For the analysed small patient collective, pre-hospital r-PA did not offer any benefits with regard to the ROSC rate. Further analyses of larger patient numbers on a nationwide registry basis are recommended.

Thromboelastometric analysis of the risk factors for return of spontaneous circulation in adult patients with out-of-hospital cardiac arrest

It is well known that coagulopathy is observed in patients with out-of-hospital cardiac arrest (OHCA). Thrombolytic therapy for those patients has been controversial until now. The purpose of this study was to identify a significant predictor for return of spontaneous circulation (ROSC) of OHCA patients in the emergency department (ED) using whole blood viscoelastic testing. Adult non-trauma OHCA patients transported to our hospital that underwent thromboelastometry (ROTEM) during cardiopulmonary resuscitation between January 2013 and December 2015 were enrolled in this study. We divided patients into two groups based on the presence or absence of ROSC, and performed statistical analysis utilizing patient characteristics, prehospital data, laboratory data, and ROTEM data. Seventy-five patients were enrolled. The ROSC group and non-ROSC group included 23 and 52 patients, respectively. The logistic regression analysis, utilizing significant parameters by univariate analysis, demonstrated that lactate level [odds ratio (OR) 0.880, 95% confidence interval (CI) 0.785-0.986, p = 0.028] and A30 of EXTEM test [OR 1.039, 95% CI 1.010-1.070, p = 0.009] were independent risk factors for ROSC. The cut-off values of lactate and A30 in EXTEM were 12.0 mmol/L and A 48.0 mm, respectively. We defined a positive prediction for ROSC if the patient presented lower lactate level (<12.0 mmol/L) and higher A30 of EXTEM (≥48.0 mm) with high specificity (94.7%) and accuracy (75.0%). The present study showed that lactate level and ROTEM parameter of clot firmness were reliable predictors of ROSC in the ED for adult patients with OHCA.

Thrombolytic Therapy for Massive Pulmonary Embolism in a Patient With a Known Intracranial Tumor

The objective was to describe and review the use of thrombolytic therapy in a patient with an intracranial tumor and massive pulmonary embolism. This is the first reported case of a patient with a known glioblastoma multiforme and massive pulmonary embolism who was successfully treated with alteplase. Pulmonary embolism was demonstrated by a ventilation-perfusion scan and transthoracic echocardiogram with repeat studies demonstrating resolution of the thromboembolism and reperfusion of pulmonary vasculature. A review of the literature revealed that the incidence of intracranial hemorrhage with thrombolysis is <3% and compares favorably with the much higher mortality rate of 25% to ≥50% in patients with hemodynamically unstable pulmonary emboli. The benefit of thrombolysis may outweigh the risks of intracranial hemorrhage in these patients, and careful consideration for its use in these patients is warranted.

Pulseless electrical activity in pulmonary embolism treated with thrombolysis (from the "PEAPETT" study)

OBJECTIVE

Pulseless electrical activity (PEA) during cardiac arrest portends a poor prognosis. There is a paucity of data in the use of thrombolytic therapy in PEA and cardiopulmonary arrest due to confirmed pulmonary embolism (PE). We evaluated the outcome of low-dose systemic thrombolysis with tissue plasminogen activator (tPA) in patients presenting with PEA due to PE.

METHODS

During a 34-month period, we treated 23 patients with PEA and cardiopulmonary arrest due to confirmed massive PE. All patients received 50 mg of tPA as intravenous push in 1 minute while cardiopulmonary resuscitation was ongoing. The time from initiation of cardiopulmonary resuscitation to administration of tPA was 6.5 ± 2.1 minutes.

RESULTS

Return of spontaneous circulation occurred in 2 to 15 minutes after tPA administration in all but 1 patient. There was no minor or major bleeding despite chest compression. Of the 23 patients, 2 died in the hospital, and at 22 ± 3 months of follow-up, 20 patients (87%) were still alive. The right ventricular/left ventricular ratio and pulmonary artery systolic pressure dropped from 1.79 ± 0.27 and 58.10 ± 7.99 mm Hg on admission to 1.16 ± 0.13 and 40.25 ± 4.33 mm Hg within 48 hours, respectively (P< .001 for both comparisons). There was no recurrent venous thromboembolism or bleeding during hospitalization or at follow-up.

CONCLUSION

Rapid administration of 50 mg of tPA is safe and effective in restoration of spontaneous circulation in PEA due to massive PE leading to enhanced survival and significant reduction in pulmonary artery pressures.

[Inhospital resuscitation : Decisive measures for the outcome]

BACKGROUND

Approximately 18 million patients are treated in German hospitals annually. On the basis of internationally published data the number of in-hospital cardiac arrests can be estimated as 54,000 per year. A structured treatment of in-hospital resuscitation according to the current scientific evidence is essential.

AIM

In-hospital resuscitation shows some special characteristics in comparison to resuscitation in emergency services, which are highlighted in this article.

MATERIAL AND METHODS

This article is based on the international guidelines for cardiopulmonary resuscitation (CPR) first published in 1992 by the European Resuscitation Council (ERC) and the American Heart Association (AHA) as well as the amendments (current version 2010). Some current studies are also presented, which could not be taken into consideration for the guidelines from 2010.

RESULTS

High quality chest compressions with as few interruptions as possible are of utmost importance. Patients with cardiac rhythms which can be defibrillated should be defibrillated within less than 2 min after the collapse. There is no evidence that equipping hospitals with automated external defibrillators is an advantage for survival after in-hospital cardiac arrest. Endotracheal intubation represents the gold standard of airway management during CPR. During in-hospital resuscitation experienced anesthesiologists are mostly involved; however, the use of supraglottic airway devices may help to minimize interruptions in chest compressions especially before the medical emergency team arrives at the scene. Feedback devices may improve the quality of manual chest compressions; however, most devices overestimate the compression depth if the patient is resuscitated when lying in bed. There is no evidence that mechanical chest compression devices improve the outcome after cardiac arrest. Mild therapeutic hypothermia is still recommended for neuroprotection after successful in-hospital resuscitation.

CONCLUSION

The prevention of cardiac arrest is of special importance. Uniform and low threshold criteria for alarming the medical emergency team have to be defined to be able to identify and treat critically ill patients in time before cardiac arrest occurs.

Double Bolus Thrombolysis for Suspected Massive Pulmonary Embolism during Cardiac Arrest

More than 70% of cardiac arrest cases are caused by acute myocardial infarction (AMI) or pulmonary embolism (PE). Although thrombolytic therapy is a recognised therapy for both AMI and PE, its indiscriminate use is not routinely recommended during cardiopulmonary resuscitation (CPR). We present a case describing the successful use of double dose thrombolysis during cardiac arrest caused by pulmonary embolism. Notwithstanding the relative lack of high-level evidence, this case suggests a scenario in which recombinant tissue Plasminogen Activator (rtPA) may be beneficial in cardiac arrest. In addition to the strong clinical suspicion of pulmonary embolism as the causative agent of the patient's cardiac arrest, the extremely low end-tidal CO2 suggested a massive PE. The absence of dilatation of the right heart on subxiphoid ultrasound argued against the diagnosis of PE, but not conclusively so. In the context of the circulatory collapse induced by cardiac arrest, this aspect was relegated in terms of importance. The second dose of rtPA utilised in this case resulted in return of spontaneous circulation (ROSC) and did not result in haemorrhage or an adverse effect.

Neurologically normal survival after fibrinolysis during prolonged cardiac arrest: case report and discussion

Cardiac arrest secondary to pulmonary embolism is a devastating condition with a high mortality rate. It is currently unclear whether fibrinolysis (thrombolysis) is beneficial in this setting. We report the case of a 28-year-old woman with a pulmonary embolism who developed return of pulses following the administration of tissue plasminogen activator after 38 minutes of pulseless electrical activity cardiac arrest. She went on to make a full neurologic and cardiopulmonary recovery. This case is discussed with reference to the current literature on the subject.

Ethical challenges of informed consent in prehospital research

Informed consent to participation in research is an important protector of potential subjects’ rights and autonomy. Ethical research involving critically ill people is challenging because their medical condition often makes obtaining informed consent impossible. This is especially true in the prehospital setting, where additional barriers to obtaining informed consent exist. A recently published Canadian policy (Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans) specifies circumstances under which an exception to the requirement for informed consent may be granted so that vulnerable individuals are not denied the potential benefits of participating in research. This article reviews the rationale for theTri-Council Policy Statementand illustrates some problems with its application in the context of a Canadian prehospital study on continuous positive airway pressure. A new risk analysis model and a national research ethics board are discussed as possible ways to facilitate interpretation and application of the current exception of informed consent policy.

Prolonged chest compressions during cardiopulmonary resuscitation for in-hospital cardiac arrest due to acute pulmonary embolism

Patients with hemodynamic collapse due to acute pulmonary embolism have a dismal prognosis if not treated rapidly. Therapeutic options include systemic thrombolytic therapy, rheolytic thrombectomy, and surgical embolectomy. However, the efficacy of thrombolytic therapy is diminished because the low-output state hinders effective delivery of the lytic agent to the thrombus. In the absence of any form of mechanical circulatory support, such as extracorporeal membrane oxygenation or cardiac surgery on site, we think that prolonged vigorous manual compressions might be the only way to support the circulation during the initial critical state, when thrombolytic therapy has been administered. We report the results of prolonged manual chest compressions (exceeding 30 minutes) on 6 patients who received tenecteplase in treatment of acute pulmonary embolism that induced in-hospital cardiopulmonary arrest. Four of 6 patients survived and were discharged from the hospital. In an era of increasing technologic complexity for patients with hemodynamic instability, we emphasize the importance of prolonged chest compressions, which can improve systemic perfusion, counteract the prothrombotic state associated with cardiopulmonary arrest, and give the lytic agent time to act.

[Clinical practice of systemic lysis in prehospital resuscitation. Success and complication rates]

BACKGROUND

Systemic thrombolysis was introduced as the sole prehospital treatment option in patients with cardiac arrest in the setting of acute myocardial ischemia or pulmonary embolism; however, it remains the subject of discussion.

PATIENTS AND METHODS

A total of 194 patients with sudden prehospital cardiac arrest were included in this retrospective case control study. Of these patients, 96 in whom circulatory arrest due to cardiac disease (pulmonary artery embolism or myocardial ischemia) was suspected underwent thrombolytic treatment and were compared to the remaining 98 patients that did not undergo thrombolytic therapy. In addition to the circumstances of circulatory arrest, the course and success of resuscitation, as well as in-hospital course (including bleeding complications), overall survival and neurological outcomes were compared.

RESULTS

There were no significant differences between patients with or without thrombolysis in terms of the circumstances of cardiac arrest. Patients that received thrombolytic treatment were significantly younger and were more frequently treated with anticoagulants, platelet aggregation inhibitors and amiodarone. They also received higher doses of epinephrine and arrived at hospital under ongoing resuscitation significantly more frequently. A trend toward more prehospital return of spontaneous circulation (ROSC) following thrombolytic treatment was seen in the entire cohort. However, patients pre-treated with acetylsalicylic acid and heparin did not show better prehospital ROSC rates as a result of additional thrombolytic therapy. Significant differences in terms of bleeding complications or the need for blood transfusion could not be seen due to the small number of patients.

DISCUSSION

The indication for systemic thrombolysis in the context of prehospital resuscitation should remain restricted to patients with clear symptoms of acute pulmonary embolism or recurrent episodes of ventricular fibrillation in the setting of acute myocardial infarction. Due to a lack of evidence, systemic thrombolysis should not be used as a treatment of last resort in younger patients with persistent ventricular fibrillation.