Hypothermia after cardiac arrest: expanding the therapeutic scope. Crit Care Med. 2009;37:S227-S233. [PMID: 19535951 DOI: 10.1097/ccm.0b013e3181aa5d0c]

Hypothermic preconditioning attenuates hypobaric hypoxia induced spatial memory impairment in rats

Hypobaric Hypoxia (HH) is known to cause oxidative stress in the brain that leads to spatial memory deficit and neurodegeneration. For decades therapeutic hypothermia is used to treat global and focal ischemia in preserving brain functions that proved to be beneficial in humans and rodents. Considering these previous reports, the present study was designed to establish the therapeutic potential of hypothermia preconditioning on HH induced spatial memory, biochemical and morphological changes in adult rats. Male Sprague Dawley rats were exposed to HH (7620 m, ~ 282 mmHg) for 1, 3 and 7 days with and without hypothermic preconditioning. Spatial learning memory was assessed by Morris water maze (MWM) test along with evaluation of hippocampal pyramidal neuron damage by histological study. Oxidative stress was measured by studying the levels of nitric oxide (NO), reactive oxygen species (ROS), lipid peroxidation (LPO), oxidized and reduced glutathione (GSSG and GSH). Results of MWM test indicated prolonged path length and latency to reach the platform in HH groups that regained to normal in cold pre-treated groups. A likely neurodegeneration was evident in HH groups that lessen in the cold pre-treated groups. Hypothermic preconditioning prevented spatial memory impairment and neurodegeneration in animals subjected to HH via decreasing the NO, ROS and LPO compared to control animals. The GSH level and GSH/GSSG ratio was found to be higher in preconditioned animals as compared to respective HH exposed animals, indicative of redox scavenging and restoration of hippocampal neuronal structure as well as spatial memory. Therefore, hypothermic preconditioning improves spatial memory deficit by reducing HH induced oxidative stress and hippocampal neurodegeneration, hence can be used as a multi-target prophylactic measure to combat HH induced neurodegeneration.

Therapeutic hypothermia after out of hospital cardiac arrest improve 1-year survival rate for selective patients

Background

Therapeutic Hypothermia (TH) is a standard of care after out-of-hospital cardiac arrest (OHCA). Previous reports failed to prove a significant benefit for survival or neurological outcomes. We examined whether the proper selection of patients would enhance treatment efficacy.

Method

We conducted a retrospective cohort study. Data was collected from January 2000 and August 2018. Patients were enrolled after OHCA and classified into two groups, patients treated with TH and patients who were not treated with TH.

Results

A total of 92 patients were included in the study. 57 (63%) patients were in the TH Group and 34 (37%) in the Non-TH group. There was no statistical difference in favorable neurological outcomes between the groups. Patients presenting with ventricular fibrillation had a higher 1-year survival rate from TH, while patients with asystole were found to benefit only if they were younger than 65 years (p < .007, p < .02, respectively).

Conclusion

Therapeutic Hypothermia patients failed to demonstrate a significant benefit in terms of improved neurological outcomes. Patients treated with TH following ventricular fibrillation experienced the most benefit in terms of 1-year survival, while patients who had suffered from asystole experienced a modest benefit only if they were younger than 65 years of age. Guidelines should address age and primary arrhythmia for proper treatment selection.

Hypothermia post-cardiopulmonary resuscitation with low inputs: an experience report

OBJECTIVE

to report the experience of conducting directed temperature control of a post-cardiopulmonary resuscitation patient, with reduced and basic inputs available at the institution.

METHOD

an experience report of directed temperature control in patient (age 15 years), after four hours of cardiopulmonary resuscitation in an Intensive Care Unit of a hospital in São Paulo State countryside in 2016, according to the protocol suggested by the American Heart Association, in 2015. There were applications of cold compresses, plastic bags with crushed ice and rectal temperature control.

RESULTS

after eight hours, temperature had reached 93.2 ºF. Body cooling was maintained for 24 hours. However, bags with crushed ice were used in the first 6 hours.

CONCLUSION

conduct of nurses to obtain the body cooling with reduced and basic inputs was effective during the stay at the Intensive Care Unit.

Therapeutic hypothermia in children: Which indications remain in 2018?

Experimental studies on therapeutic hypothermia in acute brain injury reported positive outcomes and identified two potential benefits, namely, reduction in seizure incidence and in intracranial pressure. Translating this evidence to humans is challenging, especially for conditions in pediatric patients, such as cardiac arrest, traumatic brain injury, and status epilepticus, among others. This narrative review aimed to discuss the current indications and benefits of therapeutic hypothermia in acute brain injury in the pediatric population (i.e., beyond the neonatal period) by analyzing the neurologic outcome and mortality data obtained from previous studies.

New Developments in the Treatment of Acute Myocardial Infarction Associated with Out-of-Hospital Cardiac Arrest. A Review

Out-of-hospital cardiac arrest (OHCA) occurring as the first manifestation of an acute myocardial infarction is associated with very high mortality rates. As in comatose patients the etiology of cardiac arrest may be unclear, especially in cases without ST-segment elevation on the surface electrocardiogram, the decision to perform or not to perform urgent coronary angiography can have a significant impact on the prognosis of these patients. This review summarises the current knowledge and recommendations for treating patients with acute myocardial infarction presenting with OHCA. New therapeutic measures for the post-resuscitation phase are presented, such as hypothermia or extracardiac life support, together with strategies aiming to restore the coronary flow in the resuscitation phase using intra-arrest percutaneous revascularization performed during resuscitation. The role of regional networks in providing rapid access to the hospital facilities and to a catheterization laboratory for these critical cardiovascular emergencies is described.

Editor's Choice- Inside the cold heart: A review of therapeutic hypothermia cardioprotection

Targeted temperature management has been originally used to reduce neurological injury and improve outcome in patients after out-of-hospital cardiac arrest. Myocardial infarction remains a major cause of death in the world and several investigators are studying the effect of mild therapeutic hypothermia during an acute cardiac ischemic injury. A search on MEDLINE, Scopus and EMBASE databases was conducted to obtain data regarding the cardioprotective properties of therapeutic hypothermia. Preclinical studies have shown that therapeutic hypothermia provides a cardioprotective effect in animals. The proposed pathways for the cardioprotective effects of therapeutic hypothermia include stabilization of mitochondrial permeability, production of nitric oxide, equilibration of reactive oxygen species, and calcium channels homeostasis. Clinical trials in humans have yielded controversial results. Current trials are therefore seeking to combine therapeutic hypothermia with other treatment modalities in order to improve the outcomes of patients with acute ischemic injury. This article provides a review of the hypothermia effects on the cardiovascular system, from the basic science of physiological changes in the human body and molecular mechanisms of cardioprotection to the bench of clinical trials with therapeutic hypothermia in patients with acute ischemic injury.

Therapeutic hypothermia after cardiac arrest: A systematic review/meta-analysis exploring the impact of expanded criteria and targeted temperature

AIMS OF THE STUDY

We aimed to determine the benefit of an expanded use of TH. We also described the impact of a targeted temperature management on outcomes at discharge.

DATA SOURCES

We identified studies by searching MEDLINE, EMBASE and Cochrane Library databases. We included RCTs and observational studies restricted to those reporting achieved temperature during TH after OHCA. No other patient, cardiac arrest or hypothermia protocol restrictions were applied. Outcomes of interest were hospital mortality and neurological outcome at discharge. Appropriate risk of bias assessment for meta-analyzed studies was conducted. Studies contrasting hypothermia and normothermia outcomes were meta-analyzed using a random-effect model. Outcomes of cooling arms, obtained from enrolled studies, were pooled and compared across achieved temperatures.

RESULTS

Search strategy yielded 32,275 citations of which 24 articles met inclusion criteria. Eleven studies were meta-analyzed. The use of TH after OHCA, even within an expanded use, decreased the mortality (OR 0.51, 95%CI [0.41-0.64]) and improved the odds of good neurological outcome (OR 2.48, 95%CI [1.91-3.22]). No statistical heterogeneity was found for either mortality (I²=4.0%) or neurological outcome (I²=0.0%). No differences in hospital mortality (p=0.86) or neurological outcomes at discharge (p=0.32) were found when pooled outcomes of 34 hypothermia arms grouped by cooling temperature were compared.

CONCLUSION

The use of TH after OHCA is associated with a survival and neuroprotective benefit, even when including patients with non-shockable rhythms, more lenient downtimes, unwitnessed arrest and/or persistent shock. We found no evidence to support one specific temperature over another during hypothermia.

Prognostic factors associated with hospital survival in comatose survivors of cardiac arrest

AIM: To identify patient, cardiac arrest and management factors associated with hospital survival in comatose survivors of cardiac arrest.

METHODS: A retrospective, single centre study of comatose patients admitted to our intensive care unit (ICU) following cardiac arrest during the twenty year period between 1993 and 2012. This study was deemed by the Human Research Ethics Committee (HREC) of Monash Health to be a quality assurance exercise, and thus did not require submission to the Monash Health HREC (Research Project Application, No. 13290Q). The study population included all patients admitted to our ICU between 1993 and 2012, with a discharge diagnosis including “cardiac arrest”. Patients were excluded if they did not have a cardiac arrest prior to ICU admission (i.e., if their primary arrest was during their admission to ICU), or were not comatose on arrival to ICU. Our primary outcome measure was survival to hospital discharge. Secondary outcome measures were ICU and hospital length of stay (LOS), and factors associated with survival to hospital discharge.

RESULTS: Five hundred and eighty-two comatose patients were admitted to our ICU following cardiac arrest, with 35% surviving to hospital discharge. The median ICU and hospital LOS was 3 and 5 d respectively. There was no survival difference between in-hospital and out-of-hospital cardiac arrests. Males made up 62% of our cardiac arrest population, were more likely to have a shockable rhythm (56% vs 37%, P < 0.001), and were more likely to survive to hospital discharge (40% vs 28%, P = 0.006). On univariate analysis, therapeutic hypothermia, regardless of method used (e.g., rapid infusion of ice cold fluids, topical ice, “Arctic Sun”, passive rewarming, “Bair Hugger”) and location initiated (e.g., pre-hospital, emergency department, intensive care) was associated with increased survival. There was however no difference in survival associated with target temperature, time at target temperature, location of initial cooling, method of initiating cooling, method of maintaining cooling or method of rewarming. Patients that survived were more likely to have a shockable rhythm (P < 0.001), shorter time to return of spontaneous circulation (P < 0.001), receive therapeutic hypothermia (P = 0.03), be of male gender (P = 0.006) and have a lower APACHE II score (P < 0.001). After multivariate analysis, only a shockable initial rhythm (OR = 6.4, 95%CI: 3.95-10.4; P < 0.01) and a shorter time to return of spontaneous circulation (OR = 0.95, 95%CI: 0.93-0.97; P < 0.01) was found to be independently associated with survival to hospital discharge.

CONCLUSION: In comatose survivors of cardiac arrest, shockable rhythm and shorter time to return of spontaneous circulation were independently associated with increased survival to hospital discharge.

Electrocardiographic changes during induced therapeutic hypothermia in comatose survivors after cardiac arrest

AIM: To assess the safety of therapeutic hypothermia (TH) concerning arrhythmias we analyzed serial electrocardiograms (ECG) during TH.

METHODS: All patients recovered from a cardiac arrest with Glasgow < 9 at admission were treated with induced mild TH to 32-34 °C. TH was obtained with cool fluid infusion or a specific intravascular device. Twelve-lead ECG before, during, and after TH, as well as ECG telemetry data was recorded in all patients. From a total of 54 patients admitted with cardiac arrest during the study period, 47 patients had the 3 ECG and telemetry data available. ECG analysis was blinded and performed with manual caliper by two independent cardiologists from blinded copies of original ECG, recorded at 25 mm/s and 10 mm/mV. Coronary care unit staff analyzed ECG telemetry for rhythm disturbances. Variables measured in ECG were rhythm, RR, PR, QT and corrected QT (QTc by Bazett formula, measured in lead v2) intervals, QRS duration, presence of Osborn’s J wave and U wave, as well as ST segment displacement and T wave amplitude in leads II, v2 and v5.

RESULTS: Heart rate went down an average of 19 bpm during hypothermia and increased again 16 bpm with rewarming (P < 0.0005, both). There was a non-significant prolongation of the PR interval during TH and a significant decrease with rewarming (P = 0.041). QRS duration significantly prolonged (P = 0.041) with TH and shortened back (P < 0.005) with rewarming. QTc interval presented a mean prolongation of 58 ms (P < 0.005) during TH and a significant shortening with rewarming of 22.2 ms (P = 0.017). Osborn or J wave was found in 21.3% of the patients. New arrhythmias occurred in 38.3% of the patients. Most frequent arrhythmia was non-sustained ventricular tachycardia (19.1%), followed by severe bradycardia or paced rhythm (10.6%), accelerated nodal rhythm (8.5%) and atrial fibrillation (6.4%). No life threatening arrhythmias (sustained ventricular tachycardia, polymorphic ventricular tachycardia or ventricular fibrillation) occurred during TH.

CONCLUSION: A 38.3% of patients had cardiac arrhythmias during TH but without life-threatening arrhythmias. A concern may rise when inducing TH to patients with long QT syndrome.

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 hypothermia in children after cardiac arrest: a systematic review and meta-analysis

BACKGROUND

Therapeutic hypothermia (TH) has been shown to be effective in resuscitation of some adults following cardiac arrest and infants with hypoxic ischemic encephalopathy, but has not been well studied in children.

OBJECTIVES

The purpose of this systematic review/meta-analysis was to examine mortality, neurologic outcomes, and adverse events in children following use of TH.

RESULTS

A search of PubMed, the Cumulative Index to Nursing and Allied Health Literature, and the Institute for Scientific Information's Web of Knowledge from 1946 to 2014 yielded 6 studies (3 retrospective and 3 prospective cohort studies) that met our inclusion criteria. Quantitative synthesis of mortality following TH (136 subjects) was 44% (95% confidence interval, 32-57) with 28% (95% confidence interval, 11-53) of survivors (42 subjects) demonstrating poor neurologic outcome. The most frequently reported adverse events were electrolyte imbalances and pneumonia.

CONCLUSIONS

Evidence is insufficient to support the advantage of TH compared with normothermia in pediatric resuscitation. The adverse event profile appears to be different than that reported in adults. Further studies are needed before TH may be considered a standard protocol for children after cardiac arrest.

Impact of presenting rhythm on short- and long-term neurologic outcome in comatose survivors of cardiac arrest treated with therapeutic hypothermia

OBJECTIVES

To compare short- and long-term neurologic outcomes in comatose survivors of out-of-hospital cardiac arrest treated with mild therapeutic hypothermia presenting with nonshockable versus shockable initial rhythms.

DESIGN

Retrospective cohort study.

SETTING

Emergency department and ICU of an academic hospital.

PATIENTS

One hundred twenty-three consecutive post-out-of-hospital cardiac arrest adults (57 nonshockable rhythms, 66 shockable rhythms) treated with therapeutic hypothermia between 2006 and 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data were collected from electronic health records. Neurologic outcomes were dichotomized by Cerebral Performance Category at discharge and 6- to 12-month follow-up and analyzed via multivariable logistic regressions. Groups were similar, except nonshockable rhythm patients were more likely to have a history of diabetes mellitus (p = 0.01), be dialysis dependent (p = 0.01), and not have bystander cardiopulmonary resuscitation (p = 0.05). At discharge, 3 of 57 patients (5%) with nonshockable rhythm versus 28 of 66 (42%) with shockable rhythm had a favorable outcome (unadjusted odds ratio, 0.08; 95% CI, 0.02-0.3; adjusted odds ratio, 0.1; 95% CI, 0.03-0.4). At follow-up, 4 of 55 patients (7%) versus 29 of 60 (48%) with nonshockable rhythm and shockable rhythm, respectively, had a favorable Cerebral Performance Category (odds ratio, 0.08; 95% CI, 0.03-0.3; adjusted odds ratio, 0.09; 95% CI, 0.09-0.3). Among those surviving hospitalization, favorable neurologic outcome was more likely at long-term follow-up than at hospital discharge for both groups (odds ratio, 2.5; 95% CI, 1.3-4.7; adjusted odds ratio, 2.9; 95% CI, 1.4-6.2). No significant interaction between changes in neurologic status over time and presenting rhythm was seen (p = 0.93).

CONCLUSIONS

These data indicate an association between initial nonshockable rhythm and significantly worse short- and long-term outcomes in patients treated with mild therapeutic hypothermia. Among survivors, neurologic status significantly improved over time for all patients and shockable rhythm patients and tended to improve over time for the small number of nonshockable rhythm patients who survived beyond hospitalization. No significant interaction between changes in neurologic status over time and presenting rhythm was seen.

Outcomes of asphyxial cardiac arrest patients who were treated with therapeutic hypothermia: a multicentre retrospective cohort study

INTRODUCTION

While therapeutic hypothermia (TH) is in clinical use, its efficacy in certain patient groups is unclear. This study was designed to describe the characteristics and outcomes of patients with out-of-hospital cardiac-arrest (OHCA) caused by asphyxia, who were treated with TH.

PATIENTS AND METHODS

A multicentre, retrospective, registry-based study was performed using data from the period 2007-2012. Comatose patients who were treated with TH after asphyxial cardiac arrest were included, while those who with cardiac arrest attributed to hanging, drowning or gas intoxication were excluded.

RESULTS

Of a total of 932 OHCA patients in the registry, 111 were enrolled in this study. The mean age was 65.8±16.3 years with individuals who were ≥65 years of age accounted for 61.3% of the cohort. Foreign-body airway obstruction was the most common cause (70.3%) of the cardiac arrest. Eighty patients (72.1%) presented with an initial non-shockable rhythm. In all institutions target TH temperatures were 32-34°C, but TH maintenance times varied. A total of 52 patients (46.8%) survived, of whom six patients (5.4%) showed a good neurologic outcome (cerebral performance category scale 1-2). The pupil light reflex, corneal reflex and time to return of spontaneous circulation (p=0.012, 0.015 and 0.032, respectively) were associated with survival. Witnessed arrest, age, previous lung disease, bystander basic life support and time factors were not associated with survival.

CONCLUSION

About half of patients who underwent TH after asphyxial cardiac arrest survived, but a very small number showed a good neurologic outcome. The TH maintenance times were not uniform in these patients. Additional research regarding both the appropriate TH guidelines for patients with asphyxial cardiac arrest and improvement of their neurologic outcome is needed.

A systematic review of neuroprotective strategies after cardiac arrest: from bench to bedside (Part I - Protection via specific pathways)

Neurocognitive deficits are a major source of morbidity in survivors of cardiac arrest. Treatment options that could be implemented either during cardiopulmonary resuscitation or after return of spontaneous circulation to improve these neurological deficits are limited. We conducted a literature review of treatment protocols designed to evaluate neurologic outcome and survival following cardiac arrest with associated global cerebral ischemia. The search was limited to investigational therapies that were utilized to treat global cerebral ischemia associated with cardiac arrest. In this review we discuss potential mechanisms of neurologic protection following cardiac arrest including actions of several medical gases such as xenon, argon, and nitric oxide. The 3 included mechanisms are: 1. Modulation of neuronal cell death; 2. Alteration of oxygen free radicals; and 3. Improving cerebral hemodynamics. Only a few approaches have been evaluated in limited fashion in cardiac arrest patients and results show inconclusive neuroprotective effects. Future research focusing on combined neuroprotective strategies that target multiple pathways are compelling in the setting of global brain ischemia resulting from cardiac arrest.

The evidence base for nursing care and monitoring of patients during therapeutic temperature management

Therapeutic temperature management (TTM) is fast becoming a primary management strategy for a variety of medical conditions treated in critical care settings throughout the world. Nurses who provide direct care and who are tasked with developing multidisciplinary protocols and pathways are struggling to collate evidence from which to support specific nursing interventions. The aim of this project was to create the first comprehensive set of evidence-based guidelines specific to nursing care of the patient for whom TTM is medically necessary. Evidence-based nursing practice summaries are provided for nine nursing content areas: interventions to manage temperature, monitoring temperature, neurologic, cardiac, pulmonary, skin care, gastrointestinal/endocrine, laboratory findings, and general considerations for nursing care.

Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.

Blood pH is a useful indicator for initiation of therapeutic hypothermia in the early phase of resuscitation after comatose cardiac arrest: a retrospective study

BACKGROUND

Therapeutic hypothermia (TH) is one of the key treatments after cardiac arrest (CA). Selection of post-CA patients for TH remains problematic, as there are no clinically validated tools to determine who might benefit from the therapy.

OBJECTIVE

The aim of this study was to investigate retrospectively whether laboratory findings or other patient data obtained during the early phase of hospital admission could be correlated with neurological outcome after TH in comatose survivors of CA.

METHODS

Medical charts of witnessed CA patients admitted between June 2003 and July 2009 who were treated with TH were reviewed retrospectively. The subjects were grouped based on their cerebral performance category (CPC) 6 months after CA, as either good recovery (GR) for CPC 1-2 or non-good recovery (non-GR) for CPC 3-5. The following well-known determinants of outcome obtained during the early phase of hospital admission were evaluated: age, gender, body mass index, cardiac origin, presence of ventricular fibrillation (VF), time from collapse to cardiopulmonary resuscitation, time from collapse to return of spontaneous circulation, body temperature, arterial blood gases, and blood test results.

RESULTS

We analyzed a total of 50 (25 GR and 25 non-GR) patients. Multivariate logistic analysis showed that initial heart rhythm and pH levels were significantly higher in the GR group than in the non-GR group (ventricular tachycardia/VF rate: p = 0.055, 95% confidence interval [CI] 0.768-84.272, odds ratio [OR] 8.047; pH: 7.155 ± 0.139 vs. 6.895 ± 0.100, respectively, p < 0.001, 95% CI 1.838-25.827; OR 6.89).

CONCLUSION

These results imply that in addition to initial heart rhythm, pH level may be a good candidate for neurological outcome predictor even though previous research has found no correlation between initial pH value and neurological outcome.

Therapeutic hypothermia application vs standard support care in post resuscitated out-of-hospital cardiac arrest patients

INTRODUCTION

Survival after cardiac arrest remains poor, especially when it occurs outside of hospital. In recent years, therapeutic hypothermia has been used to improve outcomes in patients who have experienced cardiac arrest, however, application to out-of-hospital cardiac arrest (OHCA) patients remains controversial.

METHODS

A total of 175 OHCA patients underwent therapeutic hypothermia (TH), which was performed using large volume ice crystalloid fluid (LVICF) infusions after ICU admission. Ice packs and conventional cooling blankets were used to maintain a core body temperature of 33°C, according to standard protocol for 36 hours. Patients in the control group received standard supportive care without TH. Hospital survival and neurologic outcomes were compared.

RESULTS

There was no significant difference between the groups with regards to patient characteristics, underlying etiologies, and length of hospital stays. The duration of cardiac pulmonary resuscitation (CPR) was also similar. In the 51 patients that received TH, 14 were alive at hospital discharge. In the 124 patients belonging to the supportive care group, only 15 were alive at hospital discharge (27.5% vs. 12.1%, p = 0.013). Approximately 7.9% of patients in the TH group had good neurologic outcomes (4 of 51) compared with the 1.7% (2 of 124) of patients in the supportive group (p = 0.04). There were no specific treatment-related complications.

CONCLUSION

Therapeutic hypothermia can be safely applied to OHCA patients and can improve their outcome. Further large scale studies are needed to verify our results.

The effects of levosimendan on brain metabolism during initial recovery from global transient ischaemia/hypoxia

BACKGROUND

Neuroprotective strategies after cardiopulmonary resuscitation are currently the focus of experimental and clinical research. Levosimendan has been proposed as a promising drug candidate because of its cardioprotective properties, improved haemodynamic effects in vivo and reduced traumatic brain injury in vitro. The effects of levosimendan on brain metabolism during and after ischaemia/hypoxia are unknown.

METHODS

Transient cerebral ischaemia/hypoxia was induced in 30 male Wistar rats by bilateral common carotid artery clamping for 15 min and concomitant ventilation with 6% O2 during general anaesthesia with urethane. After 10 min of global ischaemia/hypoxia, the rats were treated with an i.v. bolus of 24 μg kg-1 levosimendan followed by a continuous infusion of 0.2 μg kg-1 min-1. The changes in the energy-related metabolites lactate, the lactate/pyruvate ratio, glucose and glutamate were monitored by microdialysis. In addition, the effects on global haemodynamics, cerebral perfusion and autoregulation, oedema and expression of proinflammatory genes in the neocortex were assessed.

RESULTS

Levosimendan reduced blood pressure during initial reperfusion (72 ± 14 vs. 109 ± 2 mmHg, p = 0.03) and delayed flow maximum by 5 minutes (p = 0.002). Whereas no effects on time course of lactate, glucose, pyruvate and glutamate concentrations in the dialysate could be observed, the lactate/pyruvate ratio during initial reperfusion (144 ± 31 vs. 77 ± 8, p = 0.017) and the glutamate release during 90 minutes of reperfusion (75 ± 19 vs. 24 ± 28 μmol·L-1) were higher in the levosimendan group. The increased expression of IL-6, IL-1ß TNFα and ICAM-1, extend of cerebral edema and cerebral autoregulation was not influenced by levosimendan.

CONCLUSION

Although levosimendan has neuroprotective actions in vitro and on the spinal cord in vivo and has been shown to cross the blood-brain barrier, the present results showed that levosimendan did not reduce the initial neuronal injury after transient ischaemia/hypoxia.

Therapeutic hypothermia after exsanguination

Therapeutic hypothermia has been shown to be effective in out-of-hospital cardiac arrest, and use of this therapy has been expanded to involve in-hospital cardiac arrest. The utility of hypothermia in cardiac arrest after hemorrhage is not known. We describe a case of successful neurological and functional outcome after in-hospital pulseless electrical activity arrest secondary to exsanguination from an internal carotid artery rupture. Therapeutic hypothermia by surface cooling was initiated after acute control of the bleeding source, restoration of circulating blood volume, and hemodynamic stabilization. We believe therapeutic hypothermia use will continue to increase for in-hospital cardiac arrests.

Induction of prehospital therapeutic hypothermia after resuscitation from nonventricular fibrillation cardiac arrest*

OBJECTIVE

To evaluate the effects on temperature and outcome at hospital discharge of a pre-hospital rapid infusion of large volume, ice-cold intravenous Hartmann's solution in patients with out-of-hospital cardiac arrest and an initial cardiac rhythm of asystole or pulseless electrical activity.

DESIGN

Prospective, randomized, controlled clinical trial.

SETTING

Pre-hospital emergency medical service and 12 critical care units in Melbourne, Australia.

PATIENTS

One hundred and sixty three patients who had been resuscitated from cardiac arrest with an initial cardiac rhythm of asystole or pulseless electrical activity.

INTERVENTIONS

: Patients were randomized to either pre-hospital cooling using a rapid infusion of up to two litres ice-cold Hartmann's solution (82 patients) or cooling after hospital admission (81 patients). The planned duration of therapeutic hypothermia (32 °C-34 °C) in both groups was 24 hrs.

MEASUREMENTS AND MAIN RESULTS

Patients allocated to pre-hospital cooling received a median of 1500 ml of ice-cold fluid. This resulted in a mean decrease in core temperature of 1.4 °C compared with 0.2 °C in hospital cooled patients (p < .001). The time to therapeutic hypothermia (<34 °C) was 3.2 hrs in the pre-hospital cooled group compared with 4.8 hrs in the hospital cooled group (p = .0328). Both groups received a mean of 15 hrs cooling in the hospital and only 7 patients in each group were cooled for 24 hrs. Overall, there was no difference in outcomes at hospital discharge with favorable outcome (discharge from hospital to home or rehabilitation) in 10 of 82 (12%) in the pre-hospital cooled patients, compared with 7 of 81 (9%) in the hospital cooled patients (p = .50). In the patients with a cardiac cause of the arrest, 8 of 47 patients (17%) who received pre-hospital cooling had a favorable outcome at hospital discharge compared with 3 of 43 (7%) in the hospital cooled group (p = .146).

CONCLUSIONS

In adults who have been resuscitated from out-of-hospital cardiac arrest with an initial cardiac rhythm of asystole or pulseless electrical activity, pre-hospital cooling using a rapid infusion of large-volume, ice cold intravenous Hartmann's solution decreases core temperature at hospital arrival and decreases the time to therapeutic hypothermia. In patients with a cardiac cause of the arrest, this treatment may increase the rate of favorable outcome at hospital discharge. Further larger studies should evaluate the effects of pre-hospital cooling when the initial cardiac rhythm is asystole or pulseless electrical activity, particularly in patients with a cardiac cause of the arrest.

Early findings on brain computed tomography and the prognosis of post-cardiac arrest syndrome: application of the score for stroke patients

AIM

To examine whether early findings of the brain computed tomography (CT) evaluated by the modified Alberta stroke programme early CT (m-ASPECT) score is useful for determining the prognosis of post-cardiac arrest syndrome (PCAS) patients or not.

MATERIALS

From 2003 through 2010, 149 consecutive PCAS patients: (1) with various aetiologies but neither from haemorrhagic stroke nor trauma, (2) who were 15 years old or older and (3) whose brain CT was available were admitted to our intensive care unit. Early findings on all of their CT images were rated with the m-ASPECT scoring system by three raters, and an inter-rater comparison was conducted. Next, the images within 24 h from arrest were collected from 133 patients (89 males, age 60.2±17.6 years), and a relation of the scores with outcome at day 30 of the patients was analysed.

RESULTS

According to the inter-rater comparison based on a linear regression analysis, agreement between the raters was good (correlation coefficient 0.76-0.88). A receiver operating curve analysis revealed that the m-ASPECT scores within 24 h were a good predictor of poor outcome (dead or vegetative state) with an area under the curve of 0.905. An m-ASPECT score ≤13 was 100% predictive of a poor outcome, with a negative predictive value of 0.57. The m-ASPECT score was the best predictor of poor outcome (odds ratio 45.62) among various factors including cause or duration of arrest.

CONCLUSION

The m-APSECT score evaluated within 24 h from arrest was found to be the most predictive factor for outcome at day 30.

Postresuscitation care

Caring in the emergency department for the patient with return of spontaneous circulation after cardiac arrest is challenging. A coordinated and systematic approach to post-cardiac arrest care can improve the mortality and the chance of meaningful neurologic recovery. By achieving appropriate targets for oxygenation, ventilation, and hemodynamic parameters, along with initiating therapeutic hypothermia and arranging early percutaneous coronary intervention, the emergency physician can have the most significant impact on patients who have just been revived from death.

Therapeutic hypothermia: benefits, mechanisms and potential clinical applications in neurological, cardiac and kidney injury

Therapeutic hypothermia involves the controlled reduction of core temperature to attenuate the secondary organ damage which occurs following a primary injury. Clinicians have been increasingly using therapeutic hypothermia to prevent or ameliorate various types of neurological injury and more recently for some forms of cardiac injury. In addition, some recent evidence suggests that therapeutic hypothermia may also provide benefit following acute kidney injury. In this review we will examine the potential mechanisms of action and current clinical evidence surrounding the use of therapeutic hypothermia. We will discuss the ideal methodological attributes of future studies using hypothermia to optimise outcomes following organ injury, in particular neurological injury. We will assess the importance of target hypothermic temperature, time to achieve target temperature, duration of cooling, and re-warming rate on outcomes following neurological injury to gain insights into important factors which may also influence the success of hypothermia in other organ injuries, such as the heart and the kidney. Finally, we will examine the potential of therapeutic hypothermia as a future kidney protective therapy.

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.

Induction of therapeutic hypothermia requires modulation of thermoregulatory defenses

Hypothermia has been linked to beneficial neurologic outcomes in different clinical situations and its therapeutic value is considered important. For example, in asphyctic neonates and in patients with out-of-hospital cardiac arrest (with ventricular fibrillation as the initial cardiac rhythm), rapid installation of hypothermia has been reported to add substantial therapeutic benefits over nonthermal standard treatments. Yet, in other groups of patients in which the application of therapeutic hypothermia may be applied with clinical benefits, the optimization of therapy remains less straightforward, as the body possesses vigorous defense mechanisms to protect it from inducing hypothermia, that is, especially in conscious patients and/or in those in which the hypothalamus remains intact, such as stroke patients or patients who suffer a myocardial infarction or spinal cord injury. This overview summarizes the body's primary reactions to hypothermia and the defense mechanisms available or evoked. Then, clinically applicable ways to overcome these forceful cold defenses of the body are described to ensure both an optimal induction process for therapeutic hypothermia and maximal subjective comfort for these conscious patients.

Vascular procedures in the critically ill obese patient

The increasing societal prevalence of obesity is consequential to the increasing number of critically ill obese patients. Vascular procedures are an essential aspect of care in these patients. This article reviews the general, anatomic, and physiologic considerations pertaining to vascular procedures in critically ill obese patients. In addition, the use of ultrasonography for these procedures is discussed.

Influence of prophylactic, endovascularly based normothermia on inflammation in patients with severe cerebrovascular disease: a prospective, randomized trial

BACKGROUND AND PURPOSE

We analyzed the impact of long-term endovascularly based prophylactic normothermia versus conventional temperature management on inflammatory parameters in patients with severe cerebrovascular disease.

METHODS

This was a prospective, randomized, controlled trial comparing the course of inflammatory parameters between the 2 treatment arms: (1) prophylactically endovascular long-term normothermia; and (2) conventional, stepwise fever management with antiinflammatory drugs and surface cooling. Inclusion criteria were (1) spontaneous subarachnoid hemorrhage with Hunt-Hess grade between 3 and 5; (2) spontaneous intracerebral hemorrhage with a Glasgow Coma Scale score of ≤ 10; or (3) complicated cerebral infarction requiring intensive care unit treatment with a NIH Stroke Scale score of ≥ 15. Treatment period was 336 hours in subarachnoid hemorrhage patients and 168 hours in patients with complicated stroke or intracerebral hemorrhage patients.

RESULTS

A total of 102 patients (56 female) were enrolled during a 3.5-year period. Overall median total fever burden during the course of treatment was 0.0°C hour and 4.3°C hours in the catheter and conventional group, respectively (P < 0.0001). C-reactive protein and interleukin-6 were significantly elevated in the endovascular group (P < 0.05). Nonsteroidal antiinflammatory drugs, used as additional treatment of fever, significantly reduced mean C-reactive protein in endovascular treated patients (P < 0.01).

CONCLUSIONS

The proinflammatory cytokines C-reactive protein and interleukin-6 were significantly elevated in patients receiving prophylactic endovascularly based long-term normothermia. Nonsteroidal antiinflammatory drugs significantly affected the course of proinflammatory parameters; thus, future trials should investigate the role of nonsteroidal antiinflammatory drugs in severe cerebrovascular disease patients and their interaction with temperature management. Clinical Trial Registration-Trial not registered; enrollment began before July 2005.

Hypothermia and rapid rewarming is associated with worse outcome following traumatic brain injury

PURPOSE

The purpose of the present study was to determine (1) the prevalence and degree of hypothermia in patients on emergency department admission and (2) the effect of hypothermia and rate of rewarming on patient outcomes.

METHODS

Secondary data analysis was conducted on patients admitted to a level I trauma center following severe traumatic brain injury (n = 147). Patients were grouped according to temperature on admission according to hypothermia status and rate of rewarming (rapid or slow). Regression analyses were performed.

FINDINGS

Hypothermic patients were more likely to have lower postresuscitation Glasgow Coma Scale scores and a higher initial injury severity score. Hypothermia on admission was correlated with longer intensive care unit stays, a lower Glasgow Coma Scale score at discharge, higher mortality rate, and lower Glasgow outcome score-extended scores up to 6 months postinjury (P < .05). When controlling for other factors, rewarming rates more than 0.25°C/h were associated with lower Glasgow Coma Scale scores at discharge, longer intensive care unit length of stay, and higher mortality rate than patients rewarmed more slowly although these did not reach statistical significance.

CONCLUSION

Hypothermia on admission is correlated with worse outcomes in brain-injured patients. Patients with traumatic brain injury who are rapidly rewarmed may be more likely to have worse outcomes. Trauma protocols may need to be reexamined to include controlled rewarming at rates 0.25°C/h or less.

Postresuscitation care: entering a new era

PURPOSE OF REVIEW

The purpose of this study is to discuss recent data relating to the treatment of cardiac arrest survivors. This is a rapidly evolving component of resuscitation medicine that impacts significantly on the quality of survival after cardiac arrest.

RECENT FINDINGS

The postcardiac arrest syndrome comprises postcardiac arrest brain injury, postcardiac arrest myocardial dysfunction, the systemic ischaemia/reperfusion response, and the persistent precipitating disease. Primary percutaneous coronary intervention is the preferred method for restoring coronary perfusion when cardiac arrest has been caused by an ST-elevation myocardial infarction. Many cardiac arrest survivors with non-ST-elevation myocardial infarction may also benefit from urgent percutaneous coronary intervention. Comatose cardiac arrest survivors should be managed with a moderate blood glucose target range of below 10 mmol/l (180 mg/dl). Therapeutic hypothermia is now generally accepted as part of a treatment strategy for comatose survivors of cardiac arrest, but its use may render conventional methods of prognostication unreliable.

SUMMARY

Survivors from cardiac arrest develop a postcardiac arrest syndrome. Postresuscitation care, including primary percutaneous coronary intervention, therapeutic hypothermia, and control of blood sugar, improves survival and neurological outcome in cardiac arrest survivors. Completely reliable prognostication in comatose survivors of cardiac arrest is difficult to achieve.

Reversal of intractable hypoxemia with exogenous surfactant (calfactant) facilitating complete neurological recovery in a pediatric drowning victim

OBJECTIVE

To report the successful reversal of intractable hypoxemia after exogenous surfactant (calfactant) administration, facilitating neurological recovery in a toddler cold-water drowning victim with significant circulatory arrest time.

METHODS

Case report and review of literature.

RESULTS

A 2(1/2)-year-old girl cold-water drowning victim with severe, intractable hypoxemia after submersion time of approximately 15 minutes and arrest time of approximately 45 minutes was given 80 mL/m of calfactant endotracheally with reversal of her hypoxemia and eventual neurologically intact survival.

CONCLUSIONS

Surfactant replacement with calfactant is a rational, useful, and potentially lifesaving treatment for acute hypoxemic respiratory failure due to drowning.

Successful use of therapeutic hypothermia in an opiate induced out-of-hospital cardiac arrest complicated by severe hypoglycaemia and amphetamine intoxication: a case report

The survival to discharge rate after unwitnessed, non-cardiac out-of-hospital cardiac arrest (OHCA) is dismal. We report the successful use of therapeutic hypothermia in a 26-year old woman with OHCA due to intentional poisoning with heroin, amphetamine and insulin.The cardiac arrest was not witnessed, no bystander CPR was initiated, the time interval from the call to ambulance arrival was 9 minutes and the initial cardiac rhythm was asystole. Eight minutes of advanced cardiac life support resulted in ROSC.Upon hospital admission, the patient's pupils were dilated. Her arterial lactate was 17 mmol/l, base excess -20, pH 6.9 and serum glucose 0.2 mmol/l. During the first 24 hours in the ICU, the patient developed maximally dilated pupils not reacting to light and became increasingly haemodynamically unstable, requiring both inotropic support and massive fluid resuscitation. After 1 week in the ICU, however, she made an uneventful recovery with a Cerebral Performance Category of 1 at hospital discharge and at a follow up examination at 6 months.

CONCLUSION

According to most prognostic factors, the patient had a statistical chance for survival of less than 1%, not taking into account her severe state of hypoglyaemia. We suggest that this case exemplifies the need for more studies on the use of TH in non-coronary causes of OHCA.