International multicentre trial protocol to assess the efficacy and safety of tenecteplase during cardiopulmonary resuscitation in patients with out-of-hospital cardiac arrest: the Thrombolysis in Cardiac Arrest (TROICA) Study

Coagulofibrinolytic effects of recombinant soluble thrombomodulin in prolonged porcine cardiac arrest

Aim

To evaluate coagulofibrinolytic abnormalities and the effects of ART-123 (recombinant human thrombomodulin alpha) in a porcine model of cardiac arrest and prolonged cardiopulmonary resuscitation (CA/CPR).

Methods

Fifteen pigs (n = 5 per group) underwent 8 minutes of no-flow CA followed by 50 minutes of mechanical CPR, while 2 pigs underwent sham arrest. CA/CPR animals were randomized to receive saline or 1 mg/kg ART-123 pre-arrest (5 minutes prior to ventricular fibrillation) or post-arrest (2 minutes after initiation of CPR). Arterial and venous blood samples were drawn at multiple time points for blood gas analysis and measurement of plasma and whole blood markers of coagulation and fibrinolysis.

Results

In saline-treated CA/CPR, but not sham animals, robust and persistent activation of coagulation and fibrinolysis was observed throughout resuscitation. After 50 minutes of CPR, plasma tests and thromboelastography indicated a mix of hypercoagulability and consumptive coagulopathy. ART-123 had a robust anticoagulant effect, reducing both thrombin-antithrombin (TAT) complexes and d-dimer (p < 0.05 for each). The duration of anticoagulant effect varied depending on the timing of ART-123 administration. Similarly, ART-123 when given prior to cardiac arrest was found to have pro-fibrinolytic effects, increasing free tissue plasminogen activator (tPA, p = 0.02) and decreasing free plasminogen activator inhibitor-1 (PAI-1, p = 0.04).

Conclusion

A porcine model of prolonged CA/CPR reproduces many of the coagulofibrinolytic abnormalities observed in human cardiac arrest patients. ART-123 demonstrates a combination of anticoagulant and profibrinolytic effects, depending on the timing of its administration relative to cardiac arrest.

Percutaneous Coronary Intervention After Return of Spontaneous Circulation Reduces the In-Hospital Mortality in Patients with Acute Myocardial Infarction Complicated by Cardiac Arrest

Background and Objective

The role of percutaneous coronary intervention (PCI) after return of spontaneous circulation (ROSC) in patients with acute myocardial infarction (AMI) complicated by cardiac arrest (CA) is controversial. This study aimed to evaluate the effects of PCI on the in-hospital mortality after ROSC in patients with AMI complicated by CA.

Methods

The clinical data of 66 consecutive patients with ROSC after CA caused by AMI from January 2006 to December 2015 at the First Affiliated Hospital of Sun Yat-sen University were collected. Among these patients, 21 underwent urgent PCI. We analyzed the clinical characteristics of the patients during hospitalization.

Results

The patients who underwent PCI had a higher rate of ST-segment elevation, and their initial recorded heart rhythms were more likely to have a shockable rhythm. Further, they had a high PCI success rate of 100%. The in-hospital mortality in the patients who did not undergo PCI was significantly higher than that in the patients who underwent PCI (68.9% vs 9.5%, P<0.05). Multivariate logistic regression analysis showed that cardiogenic shock (odds ratio [OR], 3.537; 95% CI, 1.047–11.945; P=0.042) and Glasgow Coma Scale score of ≤8 after ROSC (OR, 14.992; 95% CI, 2.815–79.843; P=0.002) were the independent risk factors for in-hospital mortality among the patients. Meanwhile, PCI was a protective factor against in-hospital mortality (OR, 0.063; 95% CI, 0.012–0.318; P=0.001). After propensity matching analysis, the results still showed that PCI (OR, 0.226; 95% CI, 0.028–1.814; P=0.0162) was a protective factor for in-hospital death.

Conclusion

The patients with ROSC after CA caused by AMI who underwent PCI had a lower in-hospital mortality than those who did not undergo PCI.

Oxygen administration in patients recovering from cardiac arrest: a narrative review

High oxygen tension in blood and/or tissue affects clinical outcomes in several diseases. Thus, the optimal target PaO₂ for patients recovering from cardiac arrest (CA) has been extensively examined. Many patients develop hypoxic brain injury after the return of spontaneous circulation (ROSC); this supports the need for oxygen administration in patients after CA. Insufficient oxygen delivery due to decreased blood flow to cerebral tissue during CA results in hypoxic brain injury. By contrast, hyperoxia may increase dissolved oxygen in the blood and, subsequently, generate reactive oxygen species that are harmful to neuronal cells. This secondary brain injury is particularly concerning. Although several clinical studies demonstrated that hyperoxia during post-CA care was associated with poor neurological outcomes, considerable debate is ongoing because of inconsistent results. Potential reasons for the conflicting results include differences in the definition of hyperoxia, the timing of exposure to hyperoxia, and PaO₂ values used in analyses. Despite the conflicts, exposure to PaO₂ > 300 mmHg through administration of unnecessary oxygen should be avoided because no obvious benefit has been demonstrated. The feasibility of titrating oxygen administration by targeting SpO₂ at approximately 94% in patients recovering from CA has been demonstrated in pilot randomized controlled trials (RCTs). Such protocols should be further examined.

Association of antiplatelet therapy with patient outcomes after out-of-hospital cardiac arrest

BACKGROUND

Cessation of blood flow during out-of-hospital cardiac arrest (OHCA) results in microvascular thrombosis, protracted hypoperfusion after return of spontaneous circulation and damage to vital organs. We tested the hypothesis that pre-arrest antiplatelet and anticoagulant medication use would be associated with less post-arrest organ dysfunction and better outcomes.

METHODS

We included OHCA patients treated from January 2005 to October 2014 at a single academic medical center. We combined our prospective OHCA registry of clinical and demographic data with a structured chart review to abstract home antiplatelet and anticoagulant medications. We fit unadjusted and adjusted regression models to test the association of antiplatelet and anticoagulant medication use with early post-arrest illness severity, survival and functionally favorable recovery.

RESULTS

Of 1054 subjects, 295 (28%) were prescribed an antiplatelet agent and 147 (14%) were prescribed an anticoagulant prior to arrest. In adjusted models, antiplatelet agents were associated with lower post-arrest illness severity (adjusted OR 0.50 95% CI 0.33-0.77), greater odds of survival to discharge (adjusted OR 1.74 95% CI 1.08-2.80) and greater odds favorable functional outcome (adjusted OR 2.11 95% CI 1.17-3.79). By contrast, anticoagulation via any agent was not associated with illness severity, survival to discharge or favorable outcome.

CONCLUSION

Preventing intra-arrest and post-arrest microvascular thrombosis via antiplatelet agents could represent a novel therapeutic target to improve outcomes after OHCA.

Clinical pathophysiology of hypoxic ischemic brain injury after cardiac arrest: a "two-hit" model

Hypoxic ischemic brain injury (HIBI) after cardiac arrest (CA) is a leading cause of mortality and long-term neurologic disability in survivors. The pathophysiology of HIBI encompasses a heterogeneous cascade that culminates in secondary brain injury and neuronal cell death. This begins with primary injury to the brain caused by the immediate cessation of cerebral blood flow following CA. Thereafter, the secondary injury of HIBI takes place in the hours and days following the initial CA and reperfusion. Among factors that may be implicated in this secondary injury include reperfusion injury, microcirculatory dysfunction, impaired cerebral autoregulation, hypoxemia, hyperoxia, hyperthermia, fluctuations in arterial carbon dioxide, and concomitant anemia.Clarifying the underlying pathophysiology of HIBI is imperative and has been the focus of considerable research to identify therapeutic targets. Most notably, targeted temperature management has been studied rigorously in preventing secondary injury after HIBI and is associated with improved outcome compared with hyperthermia. Recent advances point to important roles of anemia, carbon dioxide perturbations, hypoxemia, hyperoxia, and cerebral edema as contributing to secondary injury after HIBI and adverse outcomes. Furthermore, breakthroughs in the individualization of perfusion targets for patients with HIBI using cerebral autoregulation monitoring represent an attractive area of future work with therapeutic implications.We provide an in-depth review of the pathophysiology of HIBI to critically evaluate current approaches for the early treatment of HIBI secondary to CA. Potential therapeutic targets and future research directions are summarized.

Use of computed tomography and mechanical CPR in cardiac arrest to confirm pulmonary embolism: a case study

Precise therapeutic decision-making is vital in managing out-of-hospital cardiac arrest. We present an interesting approach where suspected pulmonary embolism could be confirmed by early computed tomography in cardiac arrest. Chest compressions were performed automatically by mechanical devices also during the acquisition of computed tomography data and subsequent thrombolysis.

[Comments on the 2010 guidelines on cardiopulmonary resuscitation of the European Resuscitation Council]

ADULTS

Administer chest compressions (minimum 100/min, minimum 5 cm depth) at a ratio of 30:2 with ventilation (tidal volume 500-600 ml, inspiration time 1 s, F(I)O₂ if possible 1.0). Avoid any interruptions in chest compressions. After every single defibrillation attempt (initially biphasic 120-200 J, monophasic 360 J, subsequently with the respective highest energy), chest compressions are initiated again immediately for 2 min independent of the ECG rhythm. Tracheal intubation is the optimal method for securing the airway during resuscitation but should be performed only by experienced airway management providers. Laryngoscopy is performed during ongoing chest compressions; interruption of chest compressions for a maximum of 10 s to pass the tube through the vocal cords. Supraglottic airway devices are alternatives to tracheal intubation. Drug administration routes for adults and children: first choice i.v., second choice intraosseous (i.o.). Vasopressors: 1 mg epinephrine every 3-5 min i.v. After the third unsuccessful defibrillation amiodarone (300 mg i.v.), repetition (150 mg) possible. Sodium bicarbonate (50 ml 8.4%) only for excessive hyperkaliemia, metabolic acidosis, or intoxication with tricyclic antidepressants. Consider aminophylline (5 mg/kgBW). Thrombolysis during spontaneous circulation only for myocardial infarction or massive pulmonary embolism; during on-going cardiopulmonary resuscitation (CPR) only when indications of massive pulmonary embolism. Active compression-decompression (ACD-CPR) and inspiratory threshold valve (ITV-CPR) are not superior to good standard CPR.

CHILDREN

Most effective improvement of outcome by prevention of full cardiorespiratory arrest. Basic life support: initially five rescue breaths, followed by chest compressions (100-120/min depth about one third of chest diameter), compression-ventilation ratio 15:2. Foreign body airway obstruction with insufficient cough: alternate back blows and chest compressions (infants), or abdominal compressions (children >1 year). Treatment of potentially reversible causes: ("4 Hs and 4 Ts") hypoxia and hypovolaemia, hypokalaemia and hyperkalaemia, hypothermia, and tension pneumothorax, tamponade, toxic/therapeutic disturbances, thrombosis (coronary/pulmonary). Advanced life support: adrenaline (epinephrine) 10 µg/kgBW i.v. or i.o. every 3-5 min. Defibrillation (4 J/kgBW; monophasic or biphasic) followed by 2 min CPR, then ECG and pulse check. NEWBORNS: Initially inflate the lungs with bag-valve mask ventilation (p(AW) 20-40 cmH₂O). If heart rate remains <60/min, start chest compressions (120 chest compressions/min) and ventilation with a ratio 3:1. Maintain normothermia in preterm babies by covering them with foodgrade plastic wrap or similar. POSTRESUSCITATION PHASE: Early protocol-based intensive care stabilization; initiate mild hypothermia early regardless of initial cardiac rhythm [32-34°C for 12-24 h (adults) or 24 h (children); slow rewarming (<0.5°C/h)]. Consider percutaneous coronary intervention (PCI) in patients with presumed cardiac ischemia. Prediction of CPR outcome is not possible at the scene, determine neurological outcome <72 h after cardiac arrest with somatosensory evoked potentials, biochemical tests and neurological examination. ACUTE CORONARY SYNDROME: Even if only a weak suspicion of an acute coronary syndrome is present, record a prehospital 12-lead ECG. In parallel to pain therapy, administer aspirin (160-325 mg p.o. or i.v.) and clopidogrel (75-600 mg depending on strategy); in ST-elevation myocardial infarction (STEMI) and planned PCI also prasugrel (60 mg p.o.). Antithrombins, such as heparin (60 IU/kgBW, max. 4000 IU), enoxaparin, bivalirudin or fondaparinux depending on the diagnosis (STEMI or non-STEMI-ACS) and the planned therapeutic strategy. In STEMI define reperfusion strategy depending on duration of symptoms until PCI, age and location of infarction. TRAUMA: In severe hemorrhagic shock, definitive control of bleeding is the most important goal. For successful CPR of trauma patients a minimal intravascular volume status and management of hypoxia are essential. Aggressive fluid resuscitation, hyperventilation and excessive ventilation pressure may impair outcome in patients with severe hemorrhagic shock.

TRAINING

Any CPR training is better than nothing; simplification of contents and processes is the main aim.

Mechanisms of action, physiological effects, and complications of hypothermia

BACKGROUND

Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood.

OBJECTIVE

To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (<or=30 degrees C), moderate hypothermia does not induce arrhythmias; indeed, the evidence suggests that arrhythmias can be prevented and/or more easily treated under hypothermic conditions.

CONCLUSIONS

Therapeutic hypothermia is a highly promising treatment, but the potential side effects need to be properly managed particularly if prolonged treatment periods are required. Understanding the underlying mechanisms, awareness of physiological changes associated with cooling, and prevention of potential side effects are all key factors for its effective clinical usage.

Consequence and factors related to not offering reperfusion therapy in STEMI

INTRODUCTION

Varied reasons existed for not offering reperfusion therapy in ST elevation myocardial infarction and results in poor outcomes, and if related factors could be delineated, corrective measures can be attempted.

METHOD

We compared variables between participants not receiving reperfusion therapy and those receiving single reperfusion therapy. Multivariate analysis examined the contribution of non-reperfusion therapy to death and factors related to it.

RESULTS

Non-reperfusion therapy was older and had a lower frequency of typical chest pain, but more dyspnea, and post cardiac resuscitation. They had more heart failure and death. Non-reperfusion therapy was an independent factor related to cardiac death, and factors related to non-reperfusion therapy were age, type of hospital, presenting features on admission (dyspnea and post cardiac resuscitation), lack of typical chest pain, and not being referred to.

CONCLUSION

Non-reperfusion therapy had 2 to 3 times higher in-hospital mortality. Factors related to not offering reperfusion therapy, aside from age, appeared to be amendable to better management.

Percutaneous cardiopulmonary support for the treatment of acute pulmonary embolism: summarized review of the literature in Japan including our own experience

BACKGROUND

Acute pulmonary embolism (APE) has high mortality. Some APEs with circulatory collapse or cardiopulmonary arrest have been treated by percutaneous cardiopulmonary support (PCPS) in Japan. But there have been no reports with a large number of series of APE treated with the use of PCPS.

METHODS AND RESULTS

We collected all the reported cases with acute thrombotic pulmonary embolism treated with PCPS before surgical embolectomy or those without surgical embolectomy in Japan, and assessed the effectiveness of PCPS. PCPS was combined with surgical embolectomy in 35% (68 of 193), thrombolytic therapy in 62% (120/193), and catheter therapy in 24% (46/193). The survival rate treated with PCPS was 73% (80% in surgical embolectomy, 71% in thrombolytic therapy, and 76% in catheter therapy). Logistic regression analysis showed that the mortality rate was elevated in cases with cardiopulmonary arrest (odds ratio [OR], 3.41; 95% confidence interval [CI], 1.52-7.67; p-value, 0.003) but not by surgical embolectomy (OR, 0.99; 95% CI, 0.39-2.53; p-value, 0.98), catheter therapy (OR, 0.71; 95% CI, 0.30-1.72; p-value, 0.45), and thrombolysis (OR, 1.60; 95% CI, 0.64-3.99; p-value, 0.31) as regards to the concomitant therapies with PCPS.

CONCLUSION

PCPS might improve the survival rate in APE patients with circulatory collapse or cardiopulmonary arrest, but there was no differences in outcome among cases treated by surgical embolectomy, catheter therapy, and thrombolysis as the concomitant therapies.

Pronounced platelet hyperfunction in patients with cardiac arrest achieving restoration of spontaneous circulation

OBJECTIVE

Markers of platelet activation are increased in patients undergoing cardiopulmonary resuscitation. Hyperfunctional platelets may contribute to impairment of microcirculatory function and overall poor outcome despite restoration of spontaneous circulation (ROSC). Patients with myocardial infarction have hyperfunctional platelets, which predict the degree of myocardial necrosis. Thus, we hypothesized that platelets may be even more activated in patients whose myocardial infarction leads to cardiac arrest and compared them with patients whose cardiac arrest was due to a noncardiac origin.

DESIGN

Prospective observational study.

SETTING

Emergency department of a tertiary care hospital.

PATIENTS

One hundred four patients with witnessed cardiac arrest who achieved ROSC.

INTERVENTIONS

Blood sampling.

MEASUREMENTS AND MAIN RESULTS

We assessed collagen adenosine diphosphate closure time with the platelet function analyzer-100, and measured plasma levels of von Willebrand factor: ristocetin cofactor activity levels by turbidometry. Independent physicians diagnosed the origin of cardiac arrest. The majority of cardiac arrests were caused by myocardial ischemia. Invariably, collagen adenosine diphosphate closure time values (55 seconds; 95% confidence interval: 52-58 seconds) were much shorter in these patients compared with patients with other causes of cardiac arrest (110 seconds; 95% confidence interval: 84-135 seconds, p < 0.001). von Willebrand factor: ristocetin cofactor activity plasma levels were more than three-fold above normal values in both groups.

CONCLUSIONS

Patients with myocardial ischemia-triggered cardiac arrest had the highest degree of platelet hyperfunction under high shear rates, which was not solely due to increased von Willebrand factor. Future trials are necessary to clarify whether rapid, more aggressive antiplatelet therapy improves outcome after cardiac arrest.

Emergency percutaneous coronary intervention in patients with ST-elevation myocardial infarction complicated by out-of-hospital cardiac arrest: early and medium-term outcome

BACKGROUND

The role of emergency reperfusion therapy in patients with ST-elevation myocardial infarction (STEMI) resuscitated after an out-of-hospital cardiac arrest (OHCA) has not been clearly established yet. The aim of this study was to evaluate the in-hospital and postdischarge outcomes of STEMI patients surviving OHCA and undergoing emergency angioplasty (percutaneous coronary intervention [PCI]) within an established regional network.

METHODS

We prospectively collected data on 2,617 consecutive patients with STEMI treated with emergency PCI in 2005; in-hospital and 6-month outcomes of 99 patients who had experienced OHCA were compared with those of 2,518 patients without OHCA. The OHCA patients also underwent a cerebral performance evaluation after 12 months.

RESULTS

OHCA patients were at higher clinical risk at presentation (cardiogenic shock 26% vs 5%, P < .0001). Percutaneous coronary intervention was successful in 80% of the OHCA and 89% of the non-OHCA patients (P = NS). In-hospital mortality rates were 22% and 3%, respectively (P < .0001). Independent predictors of in-hospital mortality among OHCA patients were longer delay between the call to the emergency medical system and the start of cardiopulmonary resuscitation (odds ratio [OR] 3.5, P = .03), nonshockable initial rhythms (OR 10.5, P = .002), cardiogenic shock (OR 3.05, P = .035), and a Glasgow Coma Scale score of 3 on admission (OR 2.9, P = .032). The 6-month composite rate of death, myocardial infarction, and revascularization among OHCA patients surviving the acute phase was comparable to that of non-OHCA patients (16% vs 13.9%, P = NS), and 87% of them showed a favorable neurologic recovery after 1 year.

CONCLUSIONS

Resuscitated OHCA patients undergoing emergency PCI for STEMI have worse clinical presentation and higher in-hospital mortality compared to those without OHCA. However, subsequent cardiac events are similar, and neurologic recovery is more favorable than reported in most previous series.

Prognostic value of selected presenting features of acute coronary syndrome in predicting in-hospital adverse events: insight from the Thai Acute Coronary Syndrome Registry

OBJECTIVE

To evaluate the relationship of the presenting features of acute coronary syndrome (ACS) to in-hospital adverse events (total and cardiac deaths, heart failure and serious dysrhythmia) and the effects of coronary intervention.

BACKGROUND

Patients with ACS may present with dyspnea, shock and/or cardiac arrest with or without accompanying chest pain.

METHODS

We evaluated 9,373 patients (age 65+/-12 years and 60% males) enrolled in the Thai ACS Registry. Cardiac dyspnea included shortness of breath on exertion, and/or at rest, orthopnea, or paroxysmal nocturnal dyspnea presumed from cardiac sources. Shock was present if systolic blood pressure was <90 mmHg for >30 min with symptoms of end-organ hypoperfusion. Post cardiac arrest was identified if cardiopulmonary resuscitation was required. We calculated the frequencies of these presenting features and assessed their contribution toward in-hospital adverse events (total and cardiac deaths, heart failure and serious arrhythmias) for the whole ACS and each entity of ACS and the effects of in-hospital interventions, both coronary and medicinal.

RESULTS

Cardiac dyspnea, shock and post cardiac arrest were seen in 32.7%, 9.3%, and 4.2% of patients, respectively. In-hospital adverse events occurred more frequently in patients with these presenting features than those without (p<0.05). Cardiac dyspnea and shock were independent predictors of heart failure and death, respectively, while post cardiac arrest independently identified patients at risk of arrhythmia, total and cardiac death, regardless of the subgroup of ACS. Coronary revascularization significantly reduced the risk of total and cardiac death.

CONCLUSION

These 3 presenting features of ACS portend a poor prognosis, regardless of the subgroup of ACS and should be considered as important early indicators for early intervention.

Thrombolysis during resuscitation for out-of-hospital cardiac arrest

BACKGROUND

Approximately 70% of persons who have an out-of-hospital cardiac arrest have underlying acute myocardial infarction or pulmonary embolism. Therefore, thrombolysis during cardiopulmonary resuscitation may improve survival.

METHODS

In a double-blind, multicenter trial, we randomly assigned adult patients with witnessed out-of-hospital cardiac arrest to receive tenecteplase or placebo during cardiopulmonary resuscitation. Adjunctive heparin or aspirin was not used. The primary end point was 30-day survival; the secondary end points were hospital admission, return of spontaneous circulation, 24-hour survival, survival to hospital discharge, and neurologic outcome.

RESULTS

After blinded review of data from the first 443 patients, the data and safety monitoring board recommended discontinuation of enrollment of asystolic patients because of low survival, and the protocol was amended. Subsequently, the trial was terminated prematurely for futility after enrolling a total of 1050 patients. Tenecteplase was administered to 525 patients and placebo to 525 patients; the two treatment groups had similar clinical profiles. We did not detect any significant differences between tenecteplase and placebo in the primary end point of 30-day survival (14.7% vs. 17.0%; P=0.36; relative risk, 0.87; 95% confidence interval, 0.65 to 1.15) or in the secondary end points of hospital admission (53.5% vs. 55.0%, P=0.67), return of spontaneous circulation (55.0% vs. 54.6%, P=0.96), 24-hour survival (30.6% vs. 33.3%, P=0.39), survival to hospital discharge (15.1% vs. 17.5%, P=0.33), or neurologic outcome (P=0.69). There were more intracranial hemorrhages in the tenecteplase group.

CONCLUSIONS

When tenecteplase was used without adjunctive antithrombotic therapy during advanced life support for out-of-hospital cardiac arrest, we did not detect an improvement in outcome, in comparison with placebo. (ClinicalTrials.gov number, NCT00157261.)

Current and future therapies of pediatric cardiopulmonary arrest

OBJECTIVE

To review contemporary guidelines and therapies for pediatric cardiac arrest and discuss potential novel therapies.

METHODS

Key articles and guidelines in the field were reviewed along with recent publications in the fields of neurointensive care and neuroscience germane to cerebral resuscitation.

RESULTS

A total of 45 articles were reviewed. The majority of arrests in the pediatric population are asphyxial in origin--which differs importantly from the adult population. The International Consensus on CPR guidelines are discussed, including good quality CPR, chest compressions without interruptions, resuscitation with 100% oxygen and subsequent titration of oxygen to normal oxygen saturations, correct dose of epinephrine, and use of hypothermia in the first 12-24 hours. Novel therapies that showed success in animal studies, such as hypertensive reperfusion, thrombolytics, hemodilution and extracorporeal CPR are also discussed.

CONCLUSION

With only 30% return of spontaneous circulation, 12% survival to hospital discharge and 4% intact neurologic survival, pediatric cardiac arrest remains an area of intense research for therapies to improve its outcomes. In addition to the rapid implementation of basic and advanced life support interventions, new therapies that may have value include mild hypothermia, extracorporeal support, promotion of cerebral blood flow and other more novel therapies targeting oxidative stress, excitotoxicity, neuronal death, and rehabilitation.

Out-of-hospital thrombolysis during cardiopulmonary resuscitation in patients with high likelihood of ST-elevation myocardial infarction

Up to 90% of cardiac arrests are due to acute myocardial infarction or severe myocardial ischaemia. Thrombolysis is an effective treatment for ST-elevation myocardial infarction (STEMI), but there is no evidence or guideline to put forward a thrombolysis strategy during cardiopulmonary resuscitation (CPR). In two physician-manned emergency medical service (EMS) units in Berlin, Germany, using thrombolysis is based on an individual judgment of the EMS physician managing the CPR attempt. In this retrospective analysis over 3 years (total 22.164 scene calls), thrombolysis was started at the scene in 50 patients during brief intermittent phases of spontaneous circulation, and in 3 patients during ongoing CPR. On-scene diagnosis of myocardial infarction was established in 45 patients (85%) by a 12-lead ECG, 5 (9%) patients had a left bundle branch block. Sixteen patients (30%) died at the scene, 37 patients (70%) were admitted to a hospital. In-hospital mortality was 35% (13 of 37 patients), with cause of death being cardiogenic shock in nine patients, hypoxic cerebral coma in two and acute haemorrhage in two other patients. All 24 of 53 (45%) survivors were discharged with an excellent neurological recovery. CPR was started by an EMS physician in 18 of the 24 survivals (75%) and emergency medical technicians who arrived first in six (25%). Duration of CPR until return of spontaneous circulation was <10 min in 13 of 24 (54%) of the survivors. Thrombolysis was initiated during intermittent phases of spontaneous circulation in 50 (94%) of all patients and in 23 (96%) of the 24 survivors. In conclusion, this retrospective analysis shows excellent survival rates and neurological outcome in selected patients with a high likelihood of myocardial infarction, who develop cardiac arrest and are treated with thrombolysis.

Low-dose tenecteplase during cardiopulmonary resuscitation due to massive pulmonary embolism: a case report and review of previously reported cases

The case of a 29 year-old man who suffered a cardiac arrest due to a massive pulmonary embolism while he was undergoing surgical repair of a complex tibial plateau fracture is presented. After 70 min of unsuccessful cardiopulmonary resuscitation a bolus of 20 mg tenecteplase was given, with a return of spontaneous circulation 2 min after administration of the drug. Pulmonary embolism was subsequently demonstrated on a pulmonary angiogram. To our knowledge this is the first report to show that the use of a low dose of tenecteplase might be useful to achieve the return of spontaneous circulation in the resuscitation of patients with cardiac arrest secondary to massive pulmonary embolism. Previously reported cases are reviewed.

Informed consent in emergency research: a contradiction in terms

Improving the treatment of life threatening emergency illness or disease requires that new or novel therapies be assessed in clinical trials. As most subjects for these trials will be incapacitated there is some controversy about they might best protected whilst still allowing research to continue. Recent European and UK clinical trials legislation, which has effectively stopped research into emergency conditions, is discussed. Possible changes to these regulations are proposed.

Modelling the effect of laminar axially directed blood flow on the dissolution of non-occlusive blood clots

Axially directed blood plasma flow can significantly accelerate thrombolysis of non-occlusive blood clots. Viscous forces caused by shearing of blood play an essential role in this process, in addition to biochemical fibrinolytic reactions. An analytical mathematical model based on the hypothesis that clot dissolution dynamics is proportional to the power of the flowing blood plasma dissipated along the clot is presented. The model assumes cylindrical non-occlusive blood clots with the flow channel in the centre, in which the flow is assumed to be laminar and flow rate constant at all times during dissolution. Effects of sudden constriction on the flow and its impact on the dissolution rate are also considered. The model was verified experimentally by dynamic magnetic resonance (MR) microscopy of artificial blood clots dissolving in an in vitro circulation system, containing plasma with a magnetic resonance imaging contrast agent and recombinant tissue-type plasminogen activator (rt-PA). Sequences of dynamically acquired 3D low resolution MR images of entire clots and 2D high resolution MR images of clots in the axial cross-section were used to evaluate the dissolution model by fitting it to the experimental data. The experimental data fitted well to the model and confirmed our hypothesis.

Design and implementation of resuscitation research: special challenges and potential solutions

Evaluation of the effectiveness of resuscitation interventions is challenging. We describe these challenges, which include design, enrolment and analysis issues. Randomized trials establish if interventions work in predefined populations. "Efficacy" trials determine whether interventions work under ideal conditions. "Effectiveness" trials determine whether interventions work under usual practice conditions. These trials represent a trade-off between internal validity versus external validity. Randomized trials use random allocation of participants to interventions to produce study groups that are similar with respect to known and unknown risk factors, reduce bias in the allocation of participants, and assure that statistical tests have valid significance levels. In the emergency setting, there is a risk that treatment offered to control patients will be contaminated by providers' experiences of applying the intervention to patients receiving the experimental intervention. Frequently there is not time to obtain consent from a patient in an emergency setting. Exception from consent can be applied if certain conditions are met. Enrolment in a research study must be initiated quickly in an emergency setting or the patient will die or become disabled. In any trial, data can be used to explore different aspects of response to treatment: multiple treatments, subgroups, events; and interim analyses. We propose solutions to these challenges to help potential investigators through the myriad of difficulties in initiating trials in a complex environment. Design of simple trials that have adequate power enhances their external validity. Allocating groups of episodes to interventions by randomizing by clusters, rather than by individual patients reduces provider noncompliance. Waiver from consent for emergency research and use of novel technologies could facilitate enrolment despite time constraints. Rigorous statistical methods can be used to analyze multiple data without an excessive increase in the chance of a false-positive result.

[The new 2005 resuscitation guidelines of the European Resuscitation Council: comments and supplements]

The new CPR guidelines are based on a scientific consensus which was reached by 281 international experts. Chest compressions (100/min, 4-5 cm deep) should be performed in a ratio of 30:2 with ventilation (tidal volume 500 ml, Ti 1 s, FIO2 if possible 1.0). After a single defibrillation attempt (initially biphasic 150-200 J, monophasic 360 J, subsequently with the respective highest energy), chest compressions are initiated again immediately for 2 min. Endotracheal intubation is the gold standard; other airway devices may be employed as well depending on individual skills. Drug administration routes for adults and children: first choice IV, second choice intraosseous, third choice endobronchial [epinephrine dose 2-3x (adults) or 10x (pediatric patients) higher than IV]. Vasopressors: 1 mg epinephrine every 3-5 min IV. After the third unsuccessful defibrillation attempt amiodarone IV (300 mg); repetition (150 mg) possible. Sodium bicarbonate (1 ml/kg 8.4%) only in excessive hyperkalemia, metabolic acidosis, or intoxication with tricyclic antidepressants. Consider atropine (3 mg) and aminophylline (5 mg/kg). Thrombolysis during spontaneous circulation only in myocardial infarction or massive pulmonary embolism; during CPR only during massive pulmonary embolism. Cardiopulmonary bypass only after cardiac surgery, hypothermia or intoxication. Pediatrics: best improvement in outcome by preventing cardiocirculatory collapse. Alternate chest thumps and chest compression (infants), or abdominal compressions (>1-year-old) in foreign body airway obstruction. Initially five breaths, followed by chest compressions (100/min; approximately 1/3 of chest diameter): ventilation ratio 15:2. Treatment of potentially reversible causes (4 "Hs", "HITS": hypoxia, hypovolemia, hypo- and hyperkaliemia, hypothermia, cardiac tamponade, intoxication, thrombo-embolism, tension pneumothorax). Epinephrine 10 microg/kg IV or intraosseously, or 100 microg (endobronchially) every 3-5 min. Defibrillation (4 J/kg; monophasic oder biphasic) followed by 2 min CPR, then ECG and pulse check. Newborns: inflate the lungs with bag-valve mask ventilation. If heart rate<60/min chest compressions:ventilation ratio 3:1 (120 chest compressions/min). Postresuscitation phase: initiate mild hypothermia [32-34 degrees C for 12-24 h; slow rewarming (<0.5 degrees C/h)]. Prediction of CPR outcome is not possible at the scene; determining neurological outcome within 72 h after cardiac arrest with evoked potentials, biochemical tests and physical examination. Even during low suspicion for an acute coronary syndrome, record a prehospital 12-lead ECG. In parallel to pain therapy, aspirin (160-325 mg PO or IV) and in addition clopidogrel (300 mg PO). As antithrombin, heparin (60 IU/kg, max. 4000 IU) or enoxaparine. In ST-segment elevation myocardial infarction, define reperfusion strategy depending on duration of symptoms until PCI (prevent delay>90 min until PCI). Stroke is an emergency and needs to be treated in a stroke unit. A CT scan is the most important evaluation, MRT may replace a CT scan. After hemorrhage exclusion, thrombolysis within 3 h of symptom onset (0.9 mg/kg rt-PA IV; max 90 mg within 60 min, 10% of the entire dosage as initial bolus, no aspirin, no heparin within the first 24 h). In severe hemorrhagic shock, definite control of bleeding is the most important goal. For successful CPR of trauma patients, a minimal intravascular volume status and management of hypoxia are essential. Aggressive fluid resuscitation, hyperventilation, and excessive ventilation pressure may impair outcome in severe hemorrhagic shock. Despite bad prognosis, CPR in trauma patients may be successful in select cases. Any CPR training is better than nothing; simplification of contents and processes remains important.

Paramedics and pre-hospital management of acute myocardial infarction: diagnosis and reperfusion

In this paper, we discuss and critically analyse pre-hospital management of acute myocardial infarction (AMI). It is clear from several large studies that rapid diagnosis and application of thrombolysis reduces morbidity and mortality rates. Strategies that improve time to treatment in the pre-hospital setting are therefore of fundamental importance in the management of this fatal disease. The advantage of 12 lead electrocardiography use by paramedics to diagnose AMI and reduce time to treatment is discussed. Moreover, paramedic application of thrombolysis in the pre-hospital environment is examined. Several studies conducted worldwide support the notion that ambulance services can play a role in minimising time to treatment for patients with AMI. The contribution of early intervention by paramedics trained in critical care is potentially considerable, particularly in the important chain of survival that is often initiated by pre-hospital intervention.

Bolus thrombolytic infusion during prolonged refractory cardiac arrest of undiagnosed cause

Acute myocardial infarction (AMI) and pulmonary embolism (PE) account for about 70% of cardiac arrest. Although thrombolytic therapy is an effective therapy for both AMI and PE, it is not routinely recommended during cardiopulmonary resuscitation (CPR) for fear of life threatening bleeding complications. Numerous case reports and retrospective studies have suggested a beneficial effect of thrombolytics in cardiac arrest secondary to AMI and PE; however, we present a case of successful use of bolus thrombolytics during CPR in a patient with undifferentiated cardiac arrest (undiagnosed cause) after prolonged conventional resuscitation without success.

Drug treatment and thrombolytics during cardiopulmonary resuscitation

PURPOSE OF REVIEW

During cardiopulmonary resuscitation, no specific drug therapy has been shown to improve survival to hospital discharge after cardiac arrest, and only few drugs have a proven benefit for short-term survival. This article reviews recent experimental and clinical data about vasopressor, antiarrhythmic and thrombolytic agents.

RECENT FINDINGS

General use of high-dose epinephrine (>1 mg) can not be recommended, whereas it should be considered during prolonged cardiopulmonary resuscitation. No catecholamine superior to epinephrine has been identified. Arginine vasopressin has been shown to be as effective as epinephrine in patients with ventricular fibrillation and pulseless electrical activity, and may be more effective in patients presenting with asystole or as the second vasopressor (after epinephrine) in refractory cardiac arrest. Sodium bicarbonate should not be 'blindly' administered during cardiopulmonary resuscitation unless an arterial blood gas analysis can be obtained, or after prolonged unsuccessful cardiopulmonary resuscitation. Amiodarone should be preferred over lidocaine, since it may improve short-term survival. Thrombolytic therapy during cardiopulmonary resuscitation may be beneficial if a pulmonary embolism or acute myocardial infarction is suggested to be the cause of the cardiac arrest.

SUMMARY

Epinephrine still represents the first-line vasopressor during cardiopulmonary resuscitation. Arginine vasopressin may be considered in patients presenting with asystole or who are unresponsive to initial treatment with epinephrine. Amiodarone should be preferred to other antiarrythmic agents in patients with cardiac arrest. Thrombolytic therapy during cardiopulmonary resuscitation is a promising new therapeutic option, but its general use in cardiac arrest cannot be recommended until the results of a large multicentre trial become available.

Thrombolysis with streptokinase during cardiopulmonary resuscitation: a single center experience and review of the literature

OBJECTIVE

To report our experience with use of thrombolysis with streptokinase during cardiopulmonary resuscitation of patients with cardiac arrest due to myocardial infarction.

DESIGN

A case series.

METHODS

Thrombolytic therapy (streptokinase) was administered during cardiopulmonary resuscitation of 4 patients with suspected myocardial infarction as the cause of cardiac arrest.

RESULTS

3 of the 4 patients survived and were discharged from the hospital without any major complications or neurological sequela.

CONCLUSION

Thrombolysis with streptokinase during cardiopulmonary resuscitation of patients with suspected acute myocardial infarction is associated with reduced mortality and favorable neurological outcome.