Therapeutic hypothermia after cardiac arrest. An advisory statement by the Advancement Life support Task Force of the International Liaison committee on Resuscitation

Prearrest signs of shock and respiratory insufficiency in out-of-hospital cardiac arrests witnessed by crew of the emergency medical service

AIM

The objective of this study is to determine whether prearrest shock and respiratory insufficiency influence outcome in patients with emergency medical service-witnessed out-of-hospital cardiac arrest.

METHODS

Analysis of data from a cardiac arrest database and data from the ambulance charts was performed. For the purpose of the study, shock was defined as prearrest heart rate below 40 or above 140/min, systolic blood pressure as below 90 mm Hg, and respiratory insufficiency as respiratory rate above 36 or oxygen saturation below 90%. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

Of a total of 303 patients, 81% had prearrest shock or respiratory insufficiency. Mortality was higher in these patients indicated by fewer with return of spontaneous circulation (43% vs 75%, P < .001), and lower survival to hospital admission (31% vs 71%, P < .001) and to discharge (13% vs 59%, P < .001). Independent predictors of mortality were age (OR, 1.04; CI, 1.0-1.06), initial rhythm other than ventricular fibrillation or ventricular tachycardia (OR, 32.9; CI, 10.9-99.0), and respiratory insufficiency (OR, 4.2; CI, 1.4-12.5).

CONCLUSIONS

Shock and respiratory depression are common among patients with out-of-hospital cardiac arrest witnessed by the emergency medical service, and these patients have a high mortality when compared with patients without shock or respiratory failure.

Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication: A scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke (Part 1)

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the postcardiac arrest syndrome are potentially treatable.

Methods of cooling: practical aspects of therapeutic temperature management

OBJECTIVES

To review traditional and newer means of inducing, maintaining, and withdrawing therapeutic hypothermia and normothermia. To suggest treatment algorithms for temperature modulation and review neuromonitoring options.

DESIGN

A review of current literature describing methods of performing therapeutic temperature management and neuromonitoring during the cooling, maintenance, and decooling periods. Algorithms for performing therapeutic temperature management are suggested.

RESULTS

Temperature management can be safely and effectively performed using traditional or newer modalities. Although traditional means of cooling are feasible and efficacious, modern devices utilizing feedback loops to maintain steady body temperature and prevent overcooling have advantages in ease of application, patient safety, maintenance of target temperature, and control of decooling. Neuromonitoring options should be adapted to an individual patient and situation.

CONCLUSIONS

Intensivists should be familiar with techniques to induce, maintain, and withdraw therapeutic temperature management, and select the most appropriate method for a given patient and situation.

Development and implementation of a therapeutic hypothermia protocol

Two randomized controlled trials published in 2002 demonstrated that mild hypothermia induced after resuscitation from cardiac arrest decreased mortality and improved neurologic outcomes. Although therapeutic hypothermia is relatively easy to implement, side effects and special nursing considerations are associated with this therapy. This article discusses the process of developing and implementing a therapeutic hypothermia protocol. Patients resuscitated after cardiac arrest are cooled to 32 degrees C-34 degrees C for 12-24 hrs. Discussion highlights include patient selection, physiologic effects of hypothermia, routes of induction, nursing implications, protocol development and implementation, and review of current literature related to this topic. An established hypothermia protocol, order set, and education program can be successfully implemented in any institution providing standardized care of post-cardiac arrest patients.

A qualitative study to identify barriers to local implementation of prehospital termination of resuscitation protocols

BACKGROUND

Despite the existence of national American Heart Association guidelines and 2 termination-of-resuscitation (TOR) rules for ceasing efforts in refractory out-of-hospital cardiac arrest, many emergency medical services agencies in the United States have adopted their own local protocols. Public policies and local perceptions may serve as barriers or facilitators to implementing national TOR guidelines at the local level.

METHODS AND RESULTS

Three focus groups, lasting 90 to 120 minutes, were conducted at the National Association of Emergency Medical Services Physicians meeting in January 2008. Snowball sampling was used to recruit participants. Two reviewers analyzed the data in an iterative process to identify recurrent and unifying themes. We identified 3 distinct groups whose current policies or perceptions may impede efforts to adopt national TOR guidelines: payers who incentivize transport; legislators who create state mandates for transport and allow only narrow use of do-not-resuscitate orders; and communities where cultural norms are perceived to impede termination of resuscitation. Our participants suggested that national organizations, such as the American Heart Association and American College of Emergency Physicians, may serve as potential facilitators in addressing these barriers by taking the lead in asking payers to change reimbursement structures; encouraging legislators to revise laws to reflect the best available medical evidence; and educating the public that rapid transport to the hospital cannot substitute for optimal provision of prehospital care.

CONCLUSIONS

We have identified 3 influential groups who will need to work with national organizations to overcome current policies or prevailing perceptions that may impede implementing national TOR guidelines.

Factors associated with a change in functional outcome between one month and six months after cardiac arrest: a retrospective cohort study

AIM OF THE STUDY

The appropriate time point of evaluation of functional outcome in cardiac arrest survivors remains a matter of debate. In this cohort study we posed the hypothesis that there are no significant changes in Cerebral Performance Categories (CPC) between one month and six months after out-of hospital cardiac arrest. If changes were present we aimed to identify reasons for these changes.

METHODS

Based on a cardiac arrest registry, a potential change in CPC and mortality between one month and six months after cardiac arrest was analysed. Variables that were associated with these changes were identified.

RESULTS

Thirty percent of 681 patients showed a significant change in functional outcome and mortality between one month and six months after out-of hospital cardiac arrest, 12% improved in CPC, 1% deteriorated, 17% died. The only factor that was associated with an improvement in CPC in the multivariate analysis was time to restoration of spontaneous circulation (ROSC) (RRR 1.04, 95% CI 1.01-1.06, per minute). We could not find any significant factors associated with a deterioration of CPC. Factors that were associated with mortality were age (RRR 1.03, 95% CI 1.01-1.06) and ventricular fibrillation as initial cardiac rhythm (RRR 0.34, 95% CI 0.16-0.71).

CONCLUSIONS

There is a relevant change of functional outcome even one month after out-of hospital cardiac arrest. Especially when studies compare patient groups with unequal arrest times, and an unequal distribution of initial cardiac rhythms a follow-up period longer than one month should be considered for the final outcome evaluation after cardiac arrest.

Using the American Heart Association's National Registry of Cardiopulmonary Resuscitation for performance improvement

BACKGROUND

Data suggest that the overall quality of inhospital resuscitation is suboptimal and contributes to poor patient outcomes. In 2000 the American Heart Association created the National Registry of Cardiopulmonary Resuscitation (NRCPR) as an evidence-based hospital safety program. Participating hospitals voluntarily join the registry and pay an annual fee that includes data support and report generation. The primary purpose of NRCPR is to support local facility efforts in practice management and performance improvement (PI).

CHAIN OF SURVIVAL

The Chain of Survival illustrates the series of critical, interdependent actions necessary to maximize patient outcome from sudden cardiac arrest--early access to the emergency response system, early cardiopulmonary resuscitation (CPR), early defibrillation, and early advanced cardiovascular care. NRCPR specifically addresses each link and helps hospitals develop, implement, and monitor their resuscitation processes in a manner that builds on available evidence.

PARTICIPATION IN NRCPR

On enrollment into NRCPR, each hospital identifies an onsite coordinator who is instructed on a standardized method for abstracting data from patient charts and how to enter data into the NRCPR database. The NRCPR database is managed centrally and provides participating organizations with ongoing, quarterly, and annual reports related to their resuscitation events.

DISCUSSION

NRCPR is used as both a local PI tool as well as a source of data that scientists are analyzing to further the understanding of inhospital resuscitation processes and outcomes. Over time, researchers have recognized the need to refine the Chain of Survival to reflect the unique aspects of inhospital resuscitation. A rapid response system provides a new link at the beginning, and postresuscitation care provides a new link at the end of the Chain of Survival.

Protection and repair of the injured spinal cord: a review of completed, ongoing, and planned clinical trials for acute spinal cord injury

Over the past 2 decades, advances in understanding the pathophysiology of spinal cord injury (SCI) have stimulated the recent emergence of several therapeutic strategies that are being examined in Phase I/II clinical trials. Ten randomized controlled trials examining methylprednisolone sodium succinate, tirilizad mesylate, monosialotetrahexosylganglioside, thyrotropin releasing hormone, gacyclidine, naloxone, and nimodipine have been completed. Although the primary outcomes in these trials were laregely negative, a secondary analysis of the North American Spinal Cord Injury Study II demonstrated that when administered within 8 hours of injury, methylprednisolone sodium succinate was associated with modest clinical benefits, which need to be weighed against potential complications. Thyrotropin releasing hormone (Phase II trial) and monosialotetrahexosylganglioside (Phase II and III trials) also showed some promise, but we are unaware of plans for future trials with these agents. These studies have, however, yielded many insights into the conduct of clinical trials for SCI. Several current or planned clinical trials are exploring interventions such as early surgical decompression (Surgical Treatment of Acute Spinal Cord Injury Study) and electrical field stimulation, neuroprotective strategies such as riluzole and minocycline, the inactivation of myelin inhibition by blocking Nogo and Rho, and the transplantation of various cellular substrates into the injured cord. Unfortunately, some experimental and poorly characterized SCI therapies are being offered outside a formal investigational structure, which will yield findings of limited scientific value and risk harm to patients with SCI who are understandably desperate for any intervention that might improve their function. Taken together, recent advances suggest that optimism for patients and clinicians alike is justified, as there is real hope that several safe and effective therapies for SCI may become available over the next decade.

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.

Thermoregulatory management for mild therapeutic hypothermia

In recent years the use of mild therapeutic hypothermia as a means of neuroprotection has become an important concept for treatment after cerebral ischemic hypoxic injury. Mild therapeutic hypothermia has been shown to improve outcome after out-of-hospital cardiac arrest, and many studies suggest a beneficial effect of mild therapeutic hypothermia on patient outcome after traumatic brain injury, cerebrovascular damage and neonatal asphyxia. This review article explores the numerous possibilities and methods for the induction of mild therapeutic hypothermia, reviews thermoregulatory management during maintenance and discusses associated risks and complications.

A rare case of neuroleptic malignant syndrome presenting with serious hyperthermia treated with a non-invasive cooling device: a case report

INTRODUCTION

A rare side effect of antipsychotic medication is neuroleptic malignant syndrome, mainly characterized by hyperthermia, altered mental state, haemodynamic dysregulation, elevated serum creatine kinase and rigor. There may be multi-organ dysfunction including renal and hepatic failure as well as serious rhabdomyolysis, acute respiratory distress syndrome and disseminated intravascular coagulation. The prevalence of neuroleptic malignant syndrome is between 0.02% and 2.44% for patients taking neuroleptics and it is not necessary to fulfil all cardinal features characterizing the syndrome to be diagnosed with neuroleptic malignant syndrome. Because of other different life-threatening diseases matching the various clinical findings, the correct diagnosis can sometimes be hard to make. A special problem of intensive care treatment is the management of severe hyperthermia. Lowering of body temperature, however, may be a major clinical problem because hyperthermia in neuroleptic malignant syndrome is typically unresponsive to antipyretic agents while manual cooling proves difficult due to peripheral vasoconstriction.

CASE PRESENTATION

A 22-year-old Caucasian man was admitted unconscious with a body temperature of 42 degrees C, elevated serum creatine phosphokinase, tachycardia and hypotonic blood pressure. In addition to intensive care standard therapy for coma and shock, a non-invasive cooling device (Arctic Sun 2000((R)), Medivance Inc., USA), originally designed to induce mild therapeutic hypothermia in patients after cardiopulmonary resuscitation, was used to lower body temperature. After successful treatment it became possible to obtain information from the patient about his recent ambulant treatment with Olanzapin (Zyprexa(R)) for schizophrenia.

CONCLUSION

Numerous case reports have been published about patients who developed neuroleptic malignant syndrome due to Olanzapin (Zyprexa(R)) medication. Frequently hyperthermia has been observed in these cases with varying outcomes. In our case the only residual impairment for the patient is dysarthria with corresponding symmetric cerebellar pyramidal cell destruction demonstrated by increased signal intensity in T2-weighted magnetic resonance imaging, most likely caused by the excessive hyperthermia.

[Therapeutic hypothermia in neurocritical patients]

Induced hypothermia in neurocritical patients is one of the most promising neuroprotective therapies in the last decade. Unfortunately, the promising results obtained in experimental studies have had an unequal reflection in the different diseases that affect the neurocritical patient. The use of therapeutic hypothermia is clearly established in patients with neurological deterioration after cardiac arrest. On the contrary, its use in patients with traumatic brain injury is highly controversial. There is not enough evidence in stroke and hemorrhagic patients to support its use except in clinical trials. Nowadays, the greater understanding of the pathophysiology of secondary brain damage, the go od clinical results obtained in randomized clinical trials in patients with cerebral anoxia after ventricular fibrillation and the new cooling methods that have appeared have improved the interest of hypothermia in neurocritical patients. Induced hypothermia has a role in the intensive care unit. Critical care physicians should be familiar with the physiologic effects, current indications, techniques, and complications of induced hypothermia. This review elaborates on the clinical implications of hypothermia research in traumatic brain injury, anoxic, brain injury, stroke and intracerebral hemorrhage.

Influences of hypothermia on the cortical blood supply by laser speckle imaging

Induced hypothermia has been broadly applied in neurological intensive care unit (NICU). Meanwhile, accidental hypothermia is also a threatening condition in daily life. It is meaningful to investigate the influences of temperature change on the cerebral blood flow (CBF). In the present study, temporal laser speckle image contrast analysis (tLASCA) was implemented to study the relative CBF change in cerebral artery, vein and capillary level under mild (35 degrees C) and moderate (32 degrees C) hypothermia. Twelve male Sprague-Dawley rats (300 +/-50 g) were anesthetized with sodium pentobarbital and randomly assigned to mild and moderate hypothermia groups (n=9 each). Laser speckle imaging (LSI) trials were acquired from baseline (37 degrees C), hypothermia (35 degrees C or 32 degrees C), and post-rewarming (37 degrees C) phases. In the mild group, mean CBF in different vessels all increased throughout the hypothermic and post-rewarming phases. On the contrary, mean CBF reduced by 10%-20% at 32 degrees C and returned to approximately 95% of the baseline level during the post-rewarming session in the moderate group. Besides, in the moderate group, a CBF rebound in vein was found in the post-rewarming phase. Our results suggested that the CBF changed differently between mild and moderate hypothermia, which may be worth for further study in clinic. And we demonstrated LSI as a promising method to achieve high spatiotemporal resolution CBF change with minimal invasion.

Advanced life support update

INTRODUCTION

Cardiac arrest is a common emergency in acute hospitals. The Resuscitation Council (UK) Advanced Life Support Guidelines provide a systematic approach to cardiac arrest recognition, treatment and aftercare. This review provides an update on the current treatment guidelines and identifies areas where these may be strengthened.

METHODS

The evidence informing the 2005 Resuscitation Guidelines is reviewed. New evidence since the publication of the guidelines was identified by searching Medline (December 2005-December 2008) with the term heart arrest or advanced life support.

RESULTS

Opportunities for strengthening the chain of survival exist for each link. These include better recognition of critically ill patients at risk of cardiac arrest, improved quality of cardiopulmonary resuscitation, defibrillation strategies, which minimize pre- and post-shock pauses and development of post-resuscitation care bundles.

CONCLUSION

Emerging evidence suggests opportunities where Resuscitation Guidelines could be strengthened by focusing on specific aspects of the chain of survival.

Therapeutic hypothermia for cardiac arrest: a practical approach

Therapeutic hypothermia (TH), which prevents and ameliorates the cascade of secondary neurologic injury after the return of spontaneous circulation, is the most effective neuroprotective therapy for encephalopathic survivors of cardiac arrest. Acute management of patients with severe hypoxic-ischemic encephalopathy requires rapid and well-coordinated efforts involving emergency medicine, neurology, cardiology, critical care medicine, and palliative care. This effort is complex, and broad implementation of TH has been slow in the United States and Europe. This review summarizes recent developments in the practical application of TH, reviews the role of the neurologist, and suggests an algorithm for coordination of care of cardiac arrest survivors by physicians of divergent subspecialties, with the goals of maximizing neurologic and cardiac recovery.

GABA agonists fail to protect the retina from ischemia-reperfusion injury

The purpose of this study was to test the hypothesis that ischemia/reperfusion injury in the rat retina may be ameliorated by reducing retinal metabolism with either hypothermia or inhibitory GABA agonists. The intraocular pressure of each right eye in rats was raised to 130 mm Hg for 60 min with the left eye serving as normal control. The rats were divided into four groups in terms of drug and hypothermia treatment: (1) Untreated ischemia, (2) Hypothermia, (3) Baclofen/midazolam and (4) Baclofen/muscimol. Electroretinogram was recorded before ischemia and again after 10-day reperfusion. Histological analysis with H&E staining and cell counts was performed. Untreated ischemia/reperfusion resulted in severely reduced ERG responses. The ERG b-wave was reduced from 423+/-144 microV to 130+/-91 microV (mean+/-SD, n=5). With hypothermia the ERG b-wave was reduced from 499+/-80 microV to 237+/-111 microV (n=4). With combinations of baclofen and midazolam the ERG b-wave was reduced from 432+/-96 microV to 104+/-67 microV (n=7). In baclofen/muscimol treated eyes the ERG b-wave went from 426+/-101 microV to 148+/-118 microV (n=6). The histological tissue damage was severe in untreated ischemia and the baclofen/midazolam and baclofen/muscimol groups, but less severe in the hypothermia group. The GABA agonists do not provide any protection in our ischemia/reperfusion model. Our results are consistent with earlier reports that hypothermia may be helpful in ischemic conditions in the retina.

[Therapeutic hypothermia]

The use of therapeutic hypothermia has been shown to improve survival and neurological outcome following cardiac arrest. Patients with traumatic brain injury or ischemic stroke also responded positively to therapeutic hypothermia, which may be induced by various procedures including surface cooling, endovascular cooling catheter and cold infusion. Possible side effects include infection and hemorrhage, as well as changes in water and electrolyte levels. It is the aim of this article to provide an overview of studies to date, as well as practical guidance for the application of therapeutic hypothermia.

Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the post-cardiac arrest syndrome are potentially treatable.

Induced hypothermia in acute ischemic stroke

BACKGROUND

Induced hypothermia is a promising neuroprotective treatment for acute ischemic stroke. Data from both global and focal ischemia animal models have been encouraging. However, only a few small clinical studies have investigated its use in humans.

OBJECTIVE

To review the background, possible mechanisms of action, and the preclinical and clinical data supporting the neuroprotective role of induced hypothermia following acute ischemic stroke.

METHODS

A literature search was performed using the PubMed database. Only papers in English were reviewed.

RESULTS/CONCLUSIONS

Induced hypothermia is effective as a neuroprotectant in animal models of acute ischemic stroke. Its multimodal mechanism of action makes it a very attractive method of neuroprotection. Although human studies suggest it is safe and feasible, larger randomized controlled trials are necessary to address clinical efficacy and to refine the methods and parameters of induced hypothermia protocols.

Temperature management in acute neurologic disorders

Temperature management in acute neurologic disorders has received considerable attention in the last 2 decades. Numerous trials of hypothermia have been performed in patients with head injury, stroke, and cardiac arrest. This article reviews the physiology of thermoregulation and mechanisms responsible for hyperpyrexia. Detrimental effects of fever and benefits of normalizing elevated temperature in experimental models are discussed. This article presents a detailed analysis of trials of induced hypothermia in patients with acute neurologic insults and describes methods of fever control.

The influence of body composition on therapeutic hypothermia: a prospective observational study of patients after cardiac arrest

Introduction

Patients after out-of-hospital cardiac arrest (OHCA) benefit from therapeutic hypothermia for 24 hours. The time needed to reach hypothermia (target temperature of 32°C to 34°C) varies widely. In this study, we explore the relation between measures of body composition and the time needed to reach target temperature with hypothermia.

Method

We conducted a prospective observational study in patients treated with hypothermia after OHCA. Data collected included weight and height, body composition by anthropometric measures and by single-frequency body impedance, and waist-to-hip ratio. Analysis of concordance between impedance and anthropometric measures and hazard ratios of achieving target temperature (event) corrected for different body composition measures.

Results

Twenty-seven patients were included. The median (interquartile range) time to reach target temperature after admission to the intensive care unit was 191 (105 to 382) minutes. Intraclass correlation for total body fat (TBF) measures was 0.94 (95% confidence interval [CI] 0.89 to 0.97). Only TBF percentage (anthropometrics by the Durnin's table) appeared to be associated with time to reach target temperature: 0.93 (95% CI 0.87 to 0.99; P = 0.03).

Conclusion

The body composition measures from single-frequency impedance and anthropometrics appear to be very concordant. Only TBF percentage (anthropometrics) showed a significant but clinically irrelevant influence on time needed to achieve target temperature with hypothermia. We conclude that there are no indications to adjust current cooling practice toward the body composition of patients.

Therapeutic hypothermia: past, present, and future

Cardiac arrest causes devastating neurologic morbidity and mortality. The preservation of the brain function is the final goal of resuscitation. Therapeutic hypothermia (TH) has been considered as an effective method for reducing ischemic injury of the brain. The therapeutic use of hypothermia has been utilized for millennia, and over the last 50 years has been routinely employed in the operating room. TH gained recognition in the past 6 years as a neuroprotective agent in victims of cardiac arrest after two large, randomized, prospective clinical trials demonstrated its benefits in the postresuscitation setting. Extensive research has been done at the cellular and molecular levels and in animal models. There are a number of proposed applications of TH, including traumatic brain injury, acute encephalitis, stroke, neonatal hypoxemia, and near-drowning, among others. Several devices are being designed with the purpose of decreasing temperature at a fast and steady rate, and trying to avoid potential complications. This article reviews the historical development of TH, and its current indications, methods of induction, and potential future.

Early electrophysiologic markers predict functional outcome associated with temperature manipulation after cardiac arrest in rats

OBJECTIVE

Therapeutic hypothermia after cardiac arrest improves survival and functional outcomes, whereas hyperthermia is harmful. The optimal method of tracking the effect of temperature on neurologic recovery after cardiac arrest has not been elucidated. We studied the recovery of cortical electrical function by quantitative electroencephalography after 7-min asphyxial cardiac arrest, using information quantity (IQ).

DESIGN

Laboratory investigation.

SETTING

University medical school and animal research facility.

SUBJECTS

A total of 28 male Wistar rats.

INTERVENTIONS

Using an asphyxial cardiac arrest rodent model, we tracked quantitative electroencephalography of 6-hr immediate postresuscitation hypothermia (at 33 degrees C), normothermia (37 degrees C), or hyperthermia (39 degrees C) (n = 8 per group). Neurologic recovery was evaluated using the Neurologic Deficit Score. Four rats were included as a sham control group.

MEASUREMENTS AND MAIN RESULTS

Greater recovery of IQ was found in rats treated with hypothermia (IQ = 0.74), compared with normothermia (IQ = 0.60) and hyperthermia (IQ = 0.56) (p < .001). Analysis at different intervals demonstrated a significant separation of IQ scores among the temperature groups within the first 2 hrs postresuscitation (p < .01). IQ values of >0.523 at 60 mins postresuscitation predicted good neurologic outcome (72-hr Neurologic Deficit Score of > or = 60), with a specificity of 100% and sensitivity of 81.8%. IQ was also significantly lower in rats that died prematurely compared with survivors (p < .001). IQ values correlated strongly with 72-hr Neurologic Deficit Score as early as 30 mins post-cardiac arrest (Pearson's correlation 0.735, p < .01) and maintained a significant association throughout the 72-hr experiment. No IQ difference was noted in sham rats with temperature manipulation.

CONCLUSIONS

The enhanced recovery provided by hypothermia and the detrimental effect by hyperthermia were robustly detected by early quantitative electroencephalographic markers. IQ values during the first 2 hrs after cardiac arrest accurately predicted neurologic outcome at 72 hrs.

Mild therapeutic hypothermia in patients after out-of-hospital cardiac arrest due to acute ST-segment elevation myocardial infarction undergoing immediate percutaneous coronary intervention

OBJECTIVE

Mild therapeutic hypothermia (MTH) has been integrated into international resuscitation guidelines. In the majority of patients, sudden cardiac arrest is caused by myocardial infarction. This study investigated whether a combination of MTH with primary percutaneous coronary intervention (PCI) is feasible, safe, and potentially beneficial in patients after cardiac arrest due to acute myocardial infarction.

DESIGN

Single-center observational study with a historical control group.

SETTING

University clinic.

PATIENTS

Thirty-three patients after cardiac arrest with ventricular fibrillation as initial rhythm and restoration of spontaneous circulation who remained unconscious at admission and presented with acute ST elevation myocardial infarction (STEMI).

INTERVENTIONS

In 16 consecutive patients (2005-2006), MTH was initiated immediately after admission and continued during primary PCI. Seventeen consecutive patients who were treated in a similar 2-yr observation interval before implementation of MTH (2003-2004) served as a control group. Feasibility, safety, mortality, and neurologic outcome were documented.

MEASUREMENTS AND MAIN RESULTS

Initiation of MTH did not result in longer door-to-balloon times compared with the control group (82 vs. 85 mins), indicating that implementation of MTH did not delay the onset of primary PCI. Target temperature (32-34 degrees C) in the MTH group was reached within 4 hrs, consistent with previous trials and suggesting that primary PCI did not affect the velocity of cooling. Despite a tendency to increased bleeding complications and infections, patients treated with MTH tended to have a lower mortality after 6 months (25% vs. 35%, p = .71) and an improved neurologic outcome as determined by a Glasgow-Pittsburgh Cerebral Performance Scale score of 1 or 2 (69% vs. 47% in the control group, p = .30).

CONCLUSIONS

MTH in combination with primary PCI is feasible and safe in patients resuscitated after cardiac arrest due to acute myocardial infarction. A combination of these therapeutic procedures should be strongly considered as standard therapy in patients after out-of-hospital cardiac arrest due to STEMI.

Prehospital cooling with hypothermia caps (PreCoCa): a feasibility study

BACKGROUND

Animal studies suggest that the induction of therapeutic hypothermia in patients after cardiac arrest should be initiated as soon as possible after ROSC to achieve optimal neuroprotective benefit. A "gold standard" for the method of inducing hypothermia quickly and safely has not yet been established. In order to evaluate the feasibility of a hypothermia cap we conducted a study for the prehospital setting.

METHODS AND RESULTS

The hypothermia cap was applied to 20 patients after out-of-hospital cardiac arrest with a median of 10 min after ROSC (25/75 IQR 8-15 min). The median time interval between initiation of cooling and hospital admission was 28 min (19-40 min). The median tympanic temperature before application of the hypothermia cap was 35.5 degrees C (34.8-36.3). Until hospital admission we observed a drop of tympanic temperature to a median of 34.4 degrees C (33.6-35.4). This difference was statistically significant (P < 0.001). We could not observe any side effects related to the hypothermia cap. 25 patients who had not received prehospital cooling procedures served as a control group. Temperature at hospital admission was 35.9 degrees C (35.3-36.4). This was statistically significant different compared to patients treated with the hypothermia cap (P < 0.001).

CONCLUSIONS

In summary we demonstrated that the prehospital use of hypothermia caps is a safe and effective procedure to start therapeutic hypothermia after cardiac arrest. This approach is rapidly available, inexpensive, non-invasive, easy to learn and applicable in almost any situation.

Management of brain injury after resuscitation from cardiac arrest

The devastating neurologic injury in survivors of cardiac arrest has been recognized since the development of modern resuscitation techniques. After numerous failed clinical trials, two trials showed that induced mild hypothermia can ameliorate brain injury and improve survival and functional neurologic outcome in comatose survivors of out-of-hospital cardiac arrest. This article provides a comprehensive review of the advances in the care of brain injury after cardiac arrest, with updates on the process of prognostication, the use of therapeutic hypothermia and adjunctive intensive care unit care for cardiac arrest survivors.