Induction of mild hypothermia in cardiac arrest survivors presenting with cardiogenic shock syndrome

Therapeutic hypothermia after cardiac arrest during living-donor liver transplant surgery: A case report

RATIONALE

Therapeutic hypothermia is an effective medical treatment for neurological recovery after cardiac arrest. Here, we describe a case of successful mild therapeutic hypothermia after cardiac arrest during living-donor liver transplantation.

PATIENT CONCERNS

A 54-year-old woman with alcoholic liver cirrhosis was admitted for living-donor liver transplantation. Cardiac arrest occurred during the anhepatic phase. After cardiopulmonary resuscitation, spontaneous circulation returned, but the bispectral index level remained below 10 until the end of surgery.

DIAGNOSES

Neurological injury caused by global cerebral hypoperfusion was suspected.

INTERVENTIONS

The patient was treated with mild therapeutic hypothermia for 24hours after resuscitation targeting a core body temperature of 34°C with surface cooling using ice bags.

OUTCOMES

The patient recovered consciousness about 22 hours after the event. However, she showed symptoms of delirium even when discharged. At the 3-month follow-up exam, she showed no specific neurological complications. The transplanted liver showed no problems with regeneration.

LESSONS

Mild therapeutic hypothermia may be safely adopted in cases of cardiac arrest in liver transplant patients and is beneficial for neurological recovery.

State-of-the-art considerations in post-arrest care

Cardiac arrest has a high rate of morbidity and mortality. Several advances in post-cardiac arrest management can improve outcome, but are time-dependent, placing the emergency physician in a critical role to both recognize the need for and initiate therapy. We present a novel perspective of both the workup and therapeutic interventions geared toward the emergency physician during the first few hours of care. We describe how the immediate care of a post-cardiac arrest patient is resource intensive and requires simultaneous evaluation for the underlying cause and intensive management to prevent further end organ damage, particularly of the central nervous system. The goal of the initial focused assessment is to rapidly determine if any reversible causes of cardiac arrest are present and to intervene when possible. Interventions performed in this acute period are aimed at preventing additional brain injury through optimizing hemodynamics, providing ventilatory support, and by using therapeutic hypothermia when indicated. After the initial phase of care, disposition is guided by available resources and the clinician's judgment. Transfer to a specialized cardiac arrest center is prudent in centers that do not have significant support or experience in the care of these patients.

Effect of sub-hypothermia blood purification technique in cardiac shock after valvular disease surgery

To observe the effect of sub-hypothermia (HT) blood purification technique in the treatment of cardiac shock after heart valve disease.The patients were randomly divided into normothermic (NT) continuous blood purification (CBP) group (NT group) and HT CBP group (HT group). Observe the cardiac index (CI), the oxygen delivery (DO2) and oxygen consumption (VO2) ratio, Acute Physiology and Chronic Health Evaluation III(APACHE III) score, multiple organ dysfunction syndrome (MODS) score, dynamic monitoring of electrocardiograph, blood loss with or without muscle tremors, intensive care unit stay, mechanical ventilation time, CBP time, and the cases of infection and mortality at 0 day, 1 day, 2 day, 3 day; all above indicators were compared between 2 groups.Ninety-five patients were randomly assigned into HT group (48 cases) and NT group (47 cases); there were no significant differences between the 2 groups for age, gender, pre-operative cardiac function, cardiothoracic ratio, and type of valve replacement (P > .05). There were no significant differences among the 1 day, 2 day, 3 day after recruited for CI, DO2/VO2 ratio, APACHE III score, MODS score (P > .05). But in HT group, DO2/VO2 ratio had been significantly improved after treatment for 1 day (2.5 ± 0.7 vs 1.8 ± 0.4, P = .024), and CI (3.0 ± 0.5 vs 1.9 ± 0.7, P = .004), APACHE III score (50.6 ± 6.2 vs 77.5 ± 5.5 P = .022), MODS score (6.0 ± 1.5 vs 9.3 ± 3.4, P = .013) also had been significantly improved after treatment for 3 days. In clinical outcomes, there were no significant differences between 2 groups for blood loss (617.0 ± 60.7 ml vs 550.9 ± 85.2 ml, P = .203), infection ratio (54.17% vs 53.19%, P = .341), the incidence of ventricular arrhythmia (31.25% vs 36.17%, P = .237), and muscle tremors (14.58% vs 8.51%, P = .346), while there were significant differences between 2 groups for intensive care unit stay (6.9 ± 3.4 days vs 12.5 ± 3.5 days, P = .017,), mechanical ventilation time (4.2 ± 1.3 days vs 7.5 ± 2.7 days, P = .034,), CBP time (4.6 ± 1.4 days vs 10.5 ± 4.0 days, P = .019), mortality (12.50% vs 23.40%, P = .024). But the incidence of bradycardia in HT group was much higher than the NT group (29.16% vs 14.89%, P = .029).HT blood purification is a safer and more effective treatment than NT blood purification for patients who suffered from cardiac shock after valve surgery.

Invasive Hemodynamics and Outcomes in Cardiac Arrest Survivors Undergoing Targeted Temperature Management

Most important prognostic factors in the postcardiac arrest patients who underwent targeted temperature management (TTM) derive from the periarrest period. Whether early invasive hemodynamics predict survival or neurologic outcomes remains unknown. We retrospectively reviewed all comatose survivors of cardiac arrest who underwent TTM at the Coronary Intensive Care Unit of a Quaternary Center between January 2015 and June 2017. Patients were required to have a set of invasive hemodynamics available at initiation of TTM to be included. Those with cooling initiated before admission and temperature of <36°C before obtaining hemodynamics were excluded. Univariate logistic and multivariate regression were conducted to test whether cardiac index (Fick-cardiac index ≥2.2 vs <2.2 L/min/m²), pulmonary capillary wedge pressure (PCWP ≥18 vs <18 mm Hg), systemic vascular resistance (SVR >1200 vs 800 to 1200 vs <800 dynes⋅s/cm⁵) or Forrester hemodynamic profiles were predictive of survival and favorable neurologic outcomes at hospital discharge. Total of 52 consecutive arrest survivors who underwent TTM were studied demonstrating a wide variability in invasive hemodynamic parameters. There was no association between cardiac index (p = 0.45 and p = 0.10), PCWP (p = 0.90 and p = 0.60), SVR (0.95 and p = 0.17) or Forrester hemodynamic profiles (p = 0.40 and p = 0.42) and survival or favorable neurologic outcome at discharge. In conclusion, comatose arrest survivors who underwent TTM presents with a wide spectrum of invasive hemodynamics highlighting the heterogeneity of the postcardiac arrest syndrome. Early invasive hemodynamics did not predict survival or favorable neurologic outcomes at hospital discharge.

Successful Re-Initiation of Therapeutic Hypothermia as Adjunctive Salvage Therapy in a Case of Refractory Cardiogenic Shock Due to Acute Myocardial Infarction

BACKGROUND Acute myocardial infarction (AMI) complicated by cardiogenic shock has a high mortality rate, despite prompt revascularization, advanced medical therapy and the use of mechanical circulatory support devices. Therapeutic hypothermia is associated with physiological cellular changes in the ischemic myocardium, and a trend towards improved hemodynamics in patients with AMI and cardiogenic shock, but is currently not considered to be a therapeutic modality. A case is presented that supports the role of therapeutic hypothermia as salvage therapy in patients with cardiogenic shock following AMI. CASE REPORT A 37-year-old man who presented with cardiac arrest following an anterior wall AMI due to occlusion of the left anterior descending coronary artery complicated by cardiogenic shock, underwent emergent percutaneous revascularization with placement of a stent, a percutaneous left ventricular-assist device (LVAD), and a pulmonary artery catheter. Therapeutic hypothermia was initiated to achieve a target core body temperature of between 32-34°C for 24 hours, followed by slow re-warming. However, after rewarming, the patient developed refractory cardiogenic shock, despite revascularization, pharmacological and mechanical circulatory support. A second cycle of therapeutic hypothermia was initiated as salvage therapy, leading to clinical improvement. The patient had a favorable outcome, was discharged from hospital and was able to return to work. CONCLUSIONS The first successful case is described in which therapeutic hypothermia was re-initiated as salvage therapy for cardiogenic shock where no other hemodynamic support resources were available.

Successful Therapeutic Hypothermia in a Propofol-Related Cardiac Arrest Case: A Case Report and Literature Review

Targeted temperature management (therapeutic hypothermia) is a treatment method used to prevent potential complications that can develop in relation to the increased temperature in the brain as a result of cardiac arrest. Due to costs and various health policies there is no comprehensive study in the world that has been able to guide the relevant literature on therapeutic hypothermia. We have presented a 25-year-old female patient in our study who developed cardiac arrest after the administration of propofol for sedation before undergoing a diagnostic upper gastroscopy procedure and received a successful therapeutic hypothermia therapy following a resuscitation of 19 minutes.

Moderate Hypothermia Improves Cardiac and Vascular Function in a Pig Model of Ischemic Cardiogenic Shock Treated With Veno-Arterial ECMO

Cardiogenic shock (CS) patients treated with extracorporeal membrane oxygenation (ECMO) have severe cardiac failure, associated with ischemia-reperfusion. The use of moderate hypothermia during ischemia-reperfusion syndrome is supported by experimental data. We therefore studied the effects of moderate hypothermia on cardiac and vascular function in pig ischemic CS treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). CS was induced in 12 anesthetized pigs by coronary ligation. After 1 h of CS, VA-ECMO was initiated and pigs were randomized to normothermia (38°C) or moderate hypothermia (34°C) during 8 h. Intrinsic cardiac function was measured using a left ventricular conductance catheter. At the end of the experiment, tissues were harvested for Western blotting. ECMO associated with norepinephrine infusion and volume resuscitation increased mean arterial pressure, mixed venous oxygen saturation as well as carotid, renal, and coronary blood flow without any differences between normothermia and hypothermia. Hypothermia was associated with less fluid and less norepinephrine infusion, lower lactate level, and higher urinary output. Vascular reactivity was superior in hypothermia comparatively to normothermia as expressed using norepinephrine dose-response curves. Pressure development during isovolumic contraction, left ventricular ejection fraction, and prerecruitable stroke work index were higher in the hypothermia group. There were no differences between normothermia and hypothermia with regard to carotid and mesenteric protein expression for iNOs, eNOS, and phospho AKt/AKt measured at the end of the experimentation. The incidence of surgical bleeding and coagulation disorders was the same in both groups. In conclusion, moderate and rapid hypothermia improves hemodynamics and cardiac and vascular function in a pig model of ischemic CS treated with ECMO.

Optimal course of treatment in acute cardiogenic shock complicating myocardial infarction

INTRODUCTION

About 5% of patients with myocardial infarction suffer from cardiogenic shock as a complication, with a mortality of ≥30%. Primary percutaneous coronary intervention as soon as possible is the most successful therapeutic approach. Prognosis depends not only on the extent of infarction, but also - and even more - on organ hypoperfusion with consequent development of multiple organ dysfunction syndrome. Areas covered: This review covers diagnostic, monitoring and treatment concepts relevant for caring patients with cardiogenic shock complicating myocardial infarction. All major clinical trials have been selected for review of the recent data. Expert commentary: For optimal care, not only primary percutaneous intervention of the occluded coronary artery is necessary, but also best intensive care medicine avoiding the development of multiple organ dysfunction syndrome and finally death. On contrary, intra-aortic balloon pump - though used for decades - is unable to reduce mortality of patients with cardiogenic shock complicating myocardial infarction.

Targeted temperature management in the ICU: Guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term "targeted temperature management" (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de réanimation de langue française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société française de médecine d'urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe francophone de réanimation et urgences pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association nationale de neuro-anesthésie réanimation française [ANARLF]), and the French Neurovascular Society (Société française neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts' opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

Targeted temperature management in the ICU: guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term “targeted temperature management” (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de Réanimation de Langue Française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société Francaise d’Anesthésie Réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société Française de Médecine d’Urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe Francophone de Réanimation et Urgences Pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association Nationale de Neuro-Anesthésie Réanimation Française [ANARLF]), and the French Neurovascular Society (Société Française Neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts’ opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

An inspection of therapeutic hypothermia preceding coronary reperfusion in patients with a cardiogenic shock complicating anterior ST-segment elevation myocardial infarction

Background

We retrospectively investigated our hypothesis that pre-percutaneous coronary intervention (PCI) procedural therapeutic hypothermia may have clinical advantages in patients with a profound cardiogenic shock complicating anterior ST-segment elevation myocardial infarction (STEMI).

Methods

Of 483 consecutive patients treated with PCI for a first anterior STEMI including 31 patients with aborted sudden cardiac arrest between 2009 and 2013, a total of 37 consecutive patients with an anterior STEMI complicated with profound cardiogenic shock defined as the presence of hyperlactic acidemia (serum levels of lactate > 4 mmol/L) with mechanical circulatory support were identified. An impaired myocardial tissue-level reperfusion (angiographic myocardial blush grade 0 or 1) and in-hospital mortality were evaluated in accordance with the presence or absence of pre-PCI procedural therapeutic hypothermia.

Results

Thirteen patients were treated with pre-PCI procedural therapeutic hypothermia and 24 were not inducted with therapeutic hypothermia. Five patients with and 18 without pre-PCI procedural therapeutic hypothermia impaired myocardial tissue-level reperfusion (38% vs. 75%, p = 0.037). A total of 26 patients with in-hospital death (overall in-hospital mortality 70%) were composed of 6 with and 20 without therapeutic hypothermia (in-hospital mortality 46% vs. 83%, p = 0.028). A multivariate analysis demonstrated a significant association of pre-PCI procedural therapeutic hypothermia (p = 0.021) with in-hospital survival benefit. Adverse events associated with therapeutic hypothermia were not found in 12 patients who completed this treatment.

Conclusions

The present study may imply a crucial possibility of clinical benefits of pre-PCI procedural therapeutic hypothermia in patients with a cardiogenic shock complicating anterior STEMI.

Postcardiac Arrest Management

Cardiac arrest afflicts more than 300,000 persons annually in North America alone. Advances in systematic, regimented postresuscitation care have lowered mortality and improved neurologic outcomes in select cohorts of patients over the last decade. Postcardiac arrest care now comprises its own link in the chain of survival. For most patients, high-quality postcardiac arrest care begins in the Emergency Department. This article reviews the evidence and offers treatment strategies for the key components of postcardiac arrest care.

Improving neurological outcome after cardiac arrest: Therapeutic hypothermia the best treatment

Cardiac arrest, irrespective of its etiology, has a high mortality. This event is often associated with brain anoxia which frequently causes severe neurological damage and persistent vegetative state. Only one out of every six patients survives to discharge following in-hospital cardiac arrest, whereas only 2-9% of patients who experience out of hospital cardiac arrest survive to go home. Functional outcomes of survival are variable, but poor quality survival is common, with only 3-7% able to return to their previous level of functioning. Therapeutic hypothermia is an important tool for the treatment of post-anoxic coma after cardiopulmonary resuscitation. It has been shown to reduce mortality and has improved neurological outcomes after cardiac arrest. Nevertheless, hypothermia is underused in critical care units. This manuscript aims to review the mechanism of hypothermia in cardiac arrest survivors and to propose a simple protocol, feasible to be implemented in any critical care unit.

Therapeutic temperature management after cardiac arrest and the risk of bleeding: systematic review and meta-analysis

AIM

Prognosis after cardiac arrest in the era of modern critical care is still poor with a high mortality of approximately 90%. Around 30% of the survivors have neurological impairments. Targeted temperature management (TTM) is the only treatment option which can improve mortality and neurological outcome. It is so far unclear if bleeding complications occur more often in patients undergoing TTM treatment.

METHODS

We conducted a systematic literature research in September 2013 including three major databases i.e. MEDLINE, EMBASE and CENTRAL. All studies were rated in respect to the ILCOR Guidelines and concerning their level of evidence and quality. We then performed a meta-analysis on bleeding disposition under TTM.

RESULTS

We initially found 941 studies out of which 34 matched our requirements and were thus included in our overview. Five studies including 599 patients were summarized in a meta-analysis concerning bleeding complications of all severities. There was a trend toward higher bleeding in patients treated with TTM (RR: 1.30, 95% CI: 0.97-1.74) which did not reach significance (p=0.085). Seven studies with an overall 599 patients were included in our meta-analysis on bleeding requiring transfusion. There was no significant difference in the incidence of severe bleeding with a risk ratio of 0.97 (95% CI: 0.61-1.56, p=0.909).

CONCLUSIONS

The data included in our meta-analysis indicate that, concerning the risk of bleeding, TTM is a safe method for patients after cardiac arrest. We did not observe a significantly higher risk for bleeding in patients undergoing TTM.

SOPs and the right hospitals to improve outcome after cardiac arrest

Approximately 400,000 Europeans are yearly resuscitated from out-of-hospital cardiac arrest (OHCA).(1,2) Despite evolving evidence based guidelines for cardiopulmonary resuscitation (CPR), survival rates after OHCA has not improved much in several places around the world. However, a potential for improved survival is absolutely present, based on the huge spread in worldwide survival; some cities with survival over 20-30% and some cities with just a few percent.(1,2) These survival differences can partly be explained by different definitions of OHCA,(2) but mainly due to the overall quality of the local Chain of Survival (COS)(3); early arrest recognition and call for help, early CPR, early defibrillation and early post resuscitation care. By identifying and thereafter improving weak links in the local COS, survival can indeed increase. This review will focus on the quality of the last link in the COS, the hospital treatment after return of spontaneuous circulation (ROSC), and how good quality post resuscitation care can improve not only survival, but survival with neurologically intact outcome.

Managing the Complications of Mild Therapeutic Hypothermia in the Cardiac Arrest Patient

Mild therapeutic hypothermia (MTH) is used to lower the core body temperature of cardiac arrest (CA) patients to 32°C from 34°C to provide improved survival and neurologic outcomes after resuscitation from in-hospital or out-of-hospital CA. Despite the improved benefits of MTH, there are potentially unforeseen complications associated during management. Although the adverse effects are transient, the clinician should be aware of the associated complications when managing the patient receiving MTH. We aim to provide the medical community comprehensive information related to the potential complications of survivors of CA receiving MTH, as it is imperative for the clinician to understand the physiologic changes that take place in the patient receiving MTH and how to prepare for them and manage them if they do occur. We hope to provide information of how to manage these potential complications through both a review of the current literature and a reflection of our own experience.

Intensive care unit mortality after cardiac arrest: the relative contribution of shock and brain injury in a large cohort

OBJECTIVE

Brain injury is well established as a cause of early mortality after out-of-hospital cardiac arrest (OHCA), but postresuscitation shock also contributes to these deaths. This study aims to describe the respective incidence, risk factors, and relation to mortality of post-cardiac arrest (CA) shock and brain injury.

DESIGN

Retrospective analysis of an observational cohort.

SETTING

24-bed medical intensive care unit (ICU) in a French university hospital.

PATIENTS

All consecutive patients admitted following OHCA were considered for analysis. Post-CA shock was defined as a need for infusion of vasoactive drugs after resuscitation. Death related to brain injury included brain death and care withdrawal for poor neurological evolution.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Between 2000 and 2009, 1,152 patients were admitted after OHCA. Post-CA shock occurred in 789 (68%) patients. Independent factors associated with its onset were high blood lactate and creatinine levels at ICU admission. During the ICU stay, 269 (34.8%) patients died from post-CA shock and 499 (65.2%) from neurological injury. Age, raised blood lactate and creatinine values, and time from collapse to restoration of spontaneous circulation increased the risk of ICU mortality from both shock and brain injury, whereas a shockable rhythm was associated with reduced risk of death from these causes. Finally, bystander cardiopulmonary resuscitation (CPR) decreased the risk of death from neurological injury.

CONCLUSIONS

Brain injury accounts for the majority of deaths, but post-CA shock affects more than two-thirds of OHCA patients. Mortality from post-CA shock and brain injury share similar risk factors, which are related to the quality of the rescue process.

The effect of hypothermia "dose" on vasopressor requirements and outcome after cardiac arrest

OBJECTIVES

We evaluated the association between TH use and "dose" and cumulative vasopressor and inotrope requirement, survival, and neurologic outcome.

BACKGROUND

Therapeutic hypothermia (TH) improves outcome after cardiac arrest, but may increase vasopressor and inotrope requirements.

METHODS

Chart review of in- and out-of-hospital cardiac arrests between 1/1/2005 and 3/15/2010. Data included demographic information, category of post-cardiac arrest illness severity ((I) awake, (II) coma (not following commands but intact brainstem responses)+mild cardiopulmonary dysfunction (SOFA [Sequential Organ Failure Assessment] cardiac+respiratory score<4), (III) coma+moderate-severe cardiopulmonary dysfunction (SOFA cardiac+respiratory score≥4), and (IV) coma without brainstem reflexes), cumulative vasopressor index (CVI), inotrope use, survival, and neurologic outcome. The "dose" of TH (hours*temperature below threshold) was calculated using thresholds of ≤34 °C and ≤35 °C. Data were analyzed using descriptive statistics, Student's t-test, Wilcoxon test, and chi-squared analysis. Linear and logistic regression evaluated the effect of hypothermia "dose" on total CVI, survival and neurologic outcome.

RESULTS

Among 361 comatose patients, 233 (65%) received TH. Vasopressor administration (measured by CVI) was higher in normothermic subjects (60.2% vs. 46.4%; p=0.016). Using a 34 °C threshold, SOFA respiratory subscore and PEA arrest predicted total CVI. Using a 35 °C threshold, severity of coma, SOFA respiratory subscore, PEA arrest and use of inotropic agents in addition to vasopressors predicted total CVI. Initial motor examination predicted survival and neurologic outcome, while TH "dose" did not.

CONCLUSIONS

TH delivery is not associated with vasopressor requirement. TH "dose" is not associated with total CVI, survival, or good outcome. Vasopressor or inotropic requirement should not contraindicate TH use.

Therapeutic hypothermia and vasopressor dependency after cardiac arrest

OBJECTIVE

Clinical trials of therapeutic hypothermia (TH) after cardiac arrest excluded patients with persistent hemodynamic instability after return of spontaneous circulation (ROSC), and thus equipoise may exist regarding use of TH in these patients. Our objective was to determine if TH is associated with worsening hemodynamic instability among patients who are vasopressor-dependent after ROSC.

METHODS

We performed a prospective observational study in vasopressor-dependent post-cardiac arrest patients. Inclusion criteria were age >17, non-trauma cardiac arrest, comatose after ROSC, and persistent vasopressor dependence. The decision to initiate TH (33-34 ° C) was made by the treating physician. We measured cumulative vasopressor index (CVI) and mean arterial pressure (MAP) every 15 min during the first 6h after ROSC. The outcome measures were change in CVI (primary outcome) and MAP (secondary outcome) over time. We graphed median CVI and MAP over time for the treated and not treated cohorts, and used propensity adjusted repeated measures mixed models to test for an association between TH induction and change in CVI or MAP over time.

RESULTS

Seventy-five post-cardiac arrest patients were included (35 treated; 40 not treated). We observed no major differences in CVI or MAP over time between the treated and not treated cohorts. In the mixed models we found no statistically significant association between TH induction and changes in CVI or MAP.

CONCLUSION

In patients with vasopressor-dependency after cardiac arrest, the induction of hypothermia was not associated with a decrease in mean arterial pressure or increase in vasopressor requirement.

Neurologic and cardiac benefits of therapeutic hypothermia

Numerous studies have shown the favorable effects of lowering the core temperature of the body in various conditions such as acute myocardial infarction, acute cerebrovascular disease, acute lung injury, and acute spinal cord injury. Therapeutic hypothermia (TH) works at different molecular and cellular levels. TH improves oxygen supply to ischemic areas and increases blood flow by decreasing vasoconstriction, as well as oxygen consumption, glucose utilization, lactate concentration, intracranial pressure, heart rate, cardiac output, and plasma insulin levels. TH has been shown to improve neurologic outcome in acute cerebrovascular accidents. Furthermore, recent studies revealed that TH is a useful method of neuroprotection against ischemic neuronal injury after cardiac arrest. TH in out-of-hospital cardiac arrest is becoming a standard practice nationwide. Further studies need to be performed to develop a better understanding of the benefits and detrimental effects of TH, to identify the most efficacious TH strategy, and the candidates most likely to derive benefit from the procedure. Although many animal studies have demonstrated benefit, larger human clinical trials are recommended to investigate the beneficial effect of TH on reducing myocardial infarction size and coronary reperfusion injuries.

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. Despite the compelling efficacy of TH, most patients who survive cardiac arrest long enough to be hospitalized will nonetheless suffer a poor neurologic outcome. Attention to the details of therapy and an integrated approach involving emergency medicine, neurology, cardiology, critical care medicine, and palliative care are likely to yield the best results. This effort is complex, and broad implementation of TH has been slow in the United States and Europe. Given that most cardiac arrest mortality in patients who survive long enough to be hospitalized is due to brain injury rather than circulatory collapse, neurologists should recognize their primary role as advocates for neuroprotective therapy at all stages of the evaluation. In the emergency department, hemodynamic stabilization must be achieved and a rapid neurologic and cardiac evaluation performed, with patients efficiently triaged to hypothermia and cardiac revascularization. Cardiologists should be aware that it is safe and desirable to induce TH, even when urgent coronary angiography and percutaneous revascularization procedures are required. In the intensive care unit, cerebral perfusion must be optimized, metabolic homeostasis achieved, and neuromonitoring used during the dangerous decooling phase. Cardiac arrest is always a life-altering event for patients and their families. Even after cardiac arrest survivors have been stabilized and treated, physicians must recogonize and embrace their role in facilitating a variety of difficult transitions: to organ donation, end-of-life care, nursing or rehabilitation placement, or home.

Therapeutic hypothermia for out-of-hospital cardiac arrest: an update for neurosurgeons

BACKGROUND

Neurosurgeons have been familiar with the idea that hypothermia is protective against various types of brain injuries, including traumatic brain injury (TBI). Recent randomized controlled trials, however, have failed to demonstrate the efficacy of therapeutic hypothermia (TH) in patients with TBI. On the other hand, TH becomes popular in the treatment of out-of-hospital cardiac arrest (OHCA) survivors, after randomized controlled trials have shown that survival rate and functional outcome is improved with the use of TH in selected patients. We believe that knowledge on the recent progress in TH for OHCA is useful for neurosurgeons, because feedback of information obtained in the treatment of OHCA may revitalize the interest in TH for neurosurgical disorders, particularly TBI.

METHODS

A review of the literature was conducted with the use of PubMed.

RESULTS

Various cooling techniques and devices have been developed and trialed in the treatment of OHCA survivors, including prehospital cooling with bolus ice-cold saline, endovascular cooling catheters, and new generation surface cooling devices, some of which have already been known to neurosurgeons. The efficacy of these new methods and devices has been demonstrated in many preliminary studies, and phase III trials are also expected.

CONCLUSIONS

Neurosurgeons and critical care medicine physicians pursue the same goal of rescuing the brain from the secondary injury despite the difference in etiology (focal trauma vs. global ischemia), with the presumption that earlier and faster implementation of TH will result in better outcome. Thoughtful application of knowledge and techniques obtained in OHCA to TBI under a rigorously controlled situation will make a small, but significant difference in the outcome of TBI victims.

The role of hypothermia in post-cardiac arrest patients with return of spontaneous circulation: a systematic review

OBJECTIVES

To update a comprehensive systematic review of the use of therapeutic hypothermia after cardiac arrest that was undertaken initially as part of the 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. The specific question addressed was: 'in post-cardiac arrest patients with a return of spontaneous circulation, does the induction of mild hypothermia improve morbidity or mortality when compared with usual care?'

METHODS

Pubmed was searched using ("heart arrest" or "cardiopulmonary resuscitation") AND "hypothermia, induced" using 'Clinical Queries' search strategy; EmBASE was searched using (heart arrest) OR (cardiopulmonary resuscitation) AND hypothermia; The Cochrane database of systematic reviews; ECC EndNote Library for "hypothermia" in abstract OR title. Excluded were animal studies, reviews and editorials, surveys of implementation, analytical models, reports of single cases, pre-arrest or during arrest cooling and group where the intervention was not hypothermia alone.

RESULTS

77 studies met the criteria for further review. Of these, four were meta-analyses (LOE 1); seven were randomised controlled trials (LOE 1), although six of these were from the same set of patients; nine were non-randomised, concurrent controls (LOE 2); 15 were trials with retrospective controls (LOE 3); 40 had no controls (LOE 4); and one was extrapolated from a non-cardiac arrest group (LOE 5).

CONCLUSION

There is evidence supporting the use of mild therapeutic hypothermia to improve neurological outcome in patients who remain comatose following the return of spontaneous circulation after a cardiac arrest; however, much of the evidence is from low-level, observational studies. Of seven randomised controlled trials, six use data from the same patients.

Therapeutic hypothermia

Pioneer works on therapeutic hypothermia (TH) half a century ago already showed promising results but clinical application was limited by a lack of understanding of the underlying pathophysiology, lack of reliable method for temperature control and lack of intensive care facilities to deal with possible complications. More recently, 2 studies in 2002 supported the application of moderate TH (32.0-34.0℃) in post-cardiac arrest patients. Although the studies included only patients suffering from out-of-hospital VF, many ICUs world-wide are applying the therapy to all post-cardiac arrest patients irrespective of site or presenting rhythm. While primary coagulopathy and cardiogenic shock are usually stated as relative contraindications, evidences are accumulating to support the application of TH in patients with cardiogenic shock. TH can be divided into 4 phases: Induction, maintenance, de-cooling and normothermia. Induction is usually achieved by infusion of cold isotonic fluid. The precautions included avoidance of over-cooling, hypokalaemia, hyperglycaemia, and shivering. TH can be maintained by many different methods, varying in their level of invasiveness, cost and effectiveness. Issues including changes in pharmacokinetics and haemodynamics, and susceptibility to infection need to the addressed. The optimal duration of maintenance is unknown but the usual practice is 12-24 hours. De-cooling and rewarming is especially challenging because complications can be serious if temperature rise by more than 1℃ every 3-5 hours. Life-theatening hyperkalaemia can occur especially if patient suffers from renal insufficiency. Fever is a frequent complication either due to infection or post-cardiac arrest syndrome but patient must be kept normothermic for 72 hours.