Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation

Neuroprotective body hypothermia among newborns with hypoxic ischemic encephalopathy: three-year experience in a tertiary university hospital. A retrospective observational study

CONTEXT AND OBJECTIVE

Neonatal hypoxic-ischemic encephalopathy is associated with high morbidity and mortality. Studies have shown that therapeutic hypothermia decreases neurological sequelae and death. Our aim was therefore to report on a three-year experience of therapeutic hypothermia among asphyxiated newborns.

DESIGN AND SETTING

Retrospective study, conducted in a university hospital.

METHODS

Thirty-five patients with perinatal asphyxia undergoing body cooling between May 2009 and November 2012 were evaluated.

RESULTS

Thirty-nine infants fulfilled the hypothermia protocol criteria. Four newborns were removed from study due to refractory septic shock, non-maintenance of temperature and severe coagulopathy. The median Apgar scores at 1 and 5 minutes were 2 and 5. The main complication was infection, diagnosed in seven mothers (20%) and 14 newborns (40%). Convulsions occurred in 15 infants (43%). Thirty-one patients (88.6%) required mechanical ventilation and 14 of them (45%) were extubated within 24 hours. The duration of mechanical ventilation among the others was 7.7 days. The cooling protocol was started 1.8 hours after birth. All patients showed elevated levels of creatine phosphokinase, creatine phosphokinase- MB and lactate dehydrogenase. There was no severe arrhythmia; one newborn (2.9%) presented controlled coagulopathy. Four patients (11.4%) presented controlled hypotension. Twenty-nine patients (82.9%) underwent cerebral ultrasonography and 10 of them (34.5%) presented white matter hyper-echogenicity. Brain magnetic resonance imaging was performed on 33 infants (94.3%) and 11 of them (33.3%) presented hypoxic-ischemic changes. The hospital stay was 23 days. All newborns were discharged. Two patients (5.8%) needed gastrostomy.

CONCLUSION

Hypothermia as therapy for asphyxiated newborns was shown to be safe.

Early EEG contributes to multimodal outcome prediction of postanoxic coma

OBJECTIVES

Early identification of potential recovery of postanoxic coma is a major challenge. We studied the additional predictive value of EEG.

METHODS

Two hundred seventy-seven consecutive comatose patients after cardiac arrest were included in a prospective cohort study on 2 intensive care units. Continuous EEG was measured during the first 3 days. EEGs were classified as unfavorable (isoelectric, low-voltage, burst-suppression with identical bursts), intermediate, or favorable (continuous patterns), at 12, 24, 48, and 72 hours. Outcome was dichotomized as good or poor. Resuscitation, demographic, clinical, somatosensory evoked potential, and EEG measures were related to outcome at 6 months using logistic regression analysis. Analyses of diagnostic accuracy included receiver operating characteristics and calculation of predictive values.

RESULTS

Poor outcome occurred in 149 patients (54%). Single measures unequivocally predicting poor outcome were an unfavorable EEG pattern at 24 hours, absent pupillary light responses at 48 hours, and absent somatosensory evoked potentials at 72 hours. Together, these had a specificity of 100% and a sensitivity of 50%. For the remaining 203 patients, who were still in the "gray zone" at 72 hours, a predictive model including unfavorable EEG patterns at 12 hours, absent or extensor motor response to pain at 72 hours, and higher age had an area under the curve of 0.90 (95% confidence interval 0.84-0.96). Favorable EEG patterns at 12 hours were strongly associated with good outcome. EEG beyond 24 hours had no additional predictive value.

CONCLUSIONS

EEG within 24 hours is a robust contributor to prediction of poor or good outcome of comatose patients after cardiac arrest.

[Therapeutic hypothermia in 2015 : Influence of the TTM study on the intensive care procedure after cardiac arrest]

BACKGROUND

In the 1960s, Peter Safar et al. postulated the benefit of postcardiac arrest hypothermia after successful cardiopulmonary resuscitation (CPR). However, therapeutic hypothermia postCPR did not become a standard procedure until the first few years of the new millennium. Various noninvasive and invasive cooling methods are available. Generally, more invasive cooling methods are more effective-but also tend to involve more complications. Furthermore, invasive measures need more time and thus may be instituted late in the postCPR process, delaying the cooling efforts in the initial phase. There is ongoing controversy about when best to commence cooling.

CURRENT SITUATION

Recent studies of initial out-of-hospital cooling did not show any benefit for the patients compared to starting cooling in the hospital. The exact target temperature is the subject of multiple ongoing discussions. A recent study showed no disadvantage of cooling to 36 ℃ compared to 33 ℃, which is in the widely accepted standard target temperature range of 32-34 ℃. Nevertheless, cooling to 32-34 ℃ according to the 2010 guidelines is still the accepted standard procedure unless and until new studies generate more evidence. The European Resuscitation Council has given advance notice of a statement on the optimal target temperature in the near future. Finally, large registry studies have demonstrated the benefit of combining postCPR hypothermia with early percutaneous cardiac interventions (PCI) in acute coronary syndromes, which are often a cause of cardiac arrest.

OUTLOOK

Transport of patients after CPR to specialized postcardiac arrest centres with the possibility of acute PCI and cooling, comparable to the transfer of multiple trauma patients to trauma centres, may be beneficial.

Therapeutic hypothermia after nonshockable cardiac arrest: the HYPERION multicenter, randomized, controlled, assessor-blinded, superiority trial

BACKGROUND

Meta-analyses of nonrandomized studies have provided conflicting data on therapeutic hypothermia, or targeted temperature management (TTM), at 33°C in patients successfully resuscitated after nonshockable cardiac arrest. Nevertheless, the latest recommendations issued by the International Liaison Committee on Resuscitation and by the European Resuscitation Council recommend therapeutic hypothermia. New data are available on the adverse effects of therapeutic hypothermia, notably infectious complications. The risk/benefit ratio of therapeutic hypothermia after nonshockable cardiac arrest is unclear.

METHODS

HYPERION is a multicenter (22 French ICUs) trial with blinded outcome assessment in which 584 patients with successfully resuscitated nonshockable cardiac arrest are allocated at random to either TTM between 32.5 and 33.5°C (therapeutic hypothermia) or TTM between 36.5 and 37.5°C (therapeutic normothermia) for 24 hours. Both groups are managed with therapeutic normothermia for the next 24 hours. TTM is achieved using locally available equipment. The primary outcome is day-90 neurological status assessed by the Cerebral Performance Categories (CPC) Scale with dichotomization of the results (1 + 2 versus 3 + 4 + 5). The primary outcome is assessed by a blinded psychologist during a semi-structured telephone interview of the patient or next of kin. Secondary outcomes are day-90 mortality, hospital mortality, severe adverse events, infections, and neurocognitive performance. The planned sample size of 584 patients will enable us to detect a 9% absolute difference in day-90 neurological status with 80% power, assuming a 14% event rate in the control group and a two-sided Type 1 error rate of 4.9%. Two interim analyses will be performed, after inclusion of 200 and 400 patients, respectively.

DISCUSSION

The HYPERION trial is a multicenter, randomized, controlled, assessor-blinded, superiority trial that may provide an answer to an issue of everyday relevance, namely, whether TTM is beneficial in comatose patients resuscitated after nonshockable cardiac arrest. Furthermore, it will provide new data on the tolerance and adverse events (especially infectious complications) of TTM at 32.5-33.5°C.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01994772 .

Special considerations in infants and children

Head injury in children is one of the most common causes of death and disability in the US and, increasingly, worldwide. This chapter reviews the causes, patterns, pathophysiology, and treatment of head injury in children across the age spectrum, and compares pediatric head injury to that in adults. Classification of head injury in children can be organized according to severity, pathoanatomic type, or mechanism. Response to injury and repair mechanisms appear to vary at different ages, and these may influence optimal treatment; however, much work is still needed before investigation leads to clearly effective clinical interventions. This is true both for the more severe injuries as well as those at the milder end of the injury spectrum, the latter of which have received increasing attention. In this chapter, neuroassessment tools for each age, newer imaging modalities including magnetic resonance imaging (MRI), and specific pediatric management issues, including intracranial pressure (ICP) monitoring and seizure prophylaxis, are reviewed. Finally, specific head injury patterns and functional outcomes relevant to pediatric patients are discussed. While head injury is common, the number of head-injured children is significantly smaller than the corresponding adult head-injured population. When divided further by specific ages, injury types, and other sources of heterogeneity, properly powered clinical research is likely to require large data sets that will allow for stratification across variables, including age. While much has been learned in the past several decades, further study will be required to determine the best management practices for optimizing recovery in individual pediatric patients. This approach is likely to depend on collaborative international head injury databases that will allow researchers to better understand the nuanced evolution of different types of head injury in patients at each age, and the pathophysiologic, treatment-related, and genetic factors that influence recovery.

Cardiac arrest survivors treated with or without mild therapeutic hypothermia: performance status and quality of life assessment

BACKGROUND

Hypoxic-ischaemic encephalopathy is the main determinant of clinical outcome after cardiac arrest. The study was designed to determine long-term neurological and psychological status in cardiac arrest survivors, as well as to compare neuropsychological outcomes between patients treated with mild therapeutic hypothermia (MTH) and patients who did not undergo hypothermia treatment.

METHODS

The article describes a single-center, retrospective, observational study on 28 post-cardiac arrest adult patients treated in the cardiac intensive care unit who qualified for MTH vs. 37 control group patients, hospitalized at the same center following cardiac arrest in the preceding years and fulfilling criteria for induced hypothermia, but who were not treated due to unavailability of the method at that time. Disability Rating Scale (DRS), Barthel Index and RAND-36 were used to assess performance status and quality of life in both study groups after hospital discharge.

RESULTS

There were no statistically significant differences in physical functioning found between groups either at the end of hospital treatment or at long-term follow-up (DRS: p = 0.11; Barthel Index: p = 0.83). In long-term follow-up, MTH patients showed higher vitality (p = 0.02) and reported fewer complaints on role limitations due to emotional problems (p = 0.04) compared to the control group. No significant differences were shown between study groups in terms of physical capacity and independent functioning.

CONCLUSION

To conclude, in long-term follow-up, MTH patients showed higher vitality and reported fewer complaints on role limitations due to emotional problems compared to the control group. This suggest that MTH helps to preserve global brain function in cardiac arrest survivors. However, the results can be biased by a small sample size and variable observation periods.

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.

Monitoring of cerebral oxygen saturation during resuscitation in out-of-hospital cardiac arrest: a feasibility study in a physician staffed emergency medical system

Background

Despite recent advances in resuscitation algorithms, neurological injury after cardiac arrest due to cerebral ischemia and reperfusion is one of the reasons for poor neurological outcome. There is currently no adequate means of measuring cerebral perfusion during cardiac arrest. It was the aim of this study to investigate the feasibility of measuring near infrared spectroscopy (NIRS) as a potential surrogate parameter for cerebral perfusion in patients with out-of-hospital resuscitations in a physician-staffed emergency medical service.

Methods

An emergency physician responding to out-of-hospital emergencies was equipped with a NONIN cerebral oximetry device. Cerebral oximetry values (rSO₂) were continuously recorded during resuscitation and transport. Feasibility was defined as >80% of total achieved recording time in relation to intended recording time.

Results

10 patients were prospectively enrolled. In 89.8% of total recording time, rSO₂ values could be recorded (213 minutes and 20 seconds), thus meeting feasibility criteria. 3 patients experienced return of spontaneous circulation (ROSC). rSO₂ during manual cardiopulmonary resuscitation (CPR) was lower in patients who did not experience ROSC compared to the 3 patients with ROSC (31.6%, ± 7.4 versus 37.2% ± 17.0). ROSC was associated with an increase in rSO₂. Decrease of rSO₂ indicated occurrence of re-arrest in 2 patients. In 2 patients a mechanical chest compression device was used. rSO₂ values during mechanical compression were increased by 12.7% and 19.1% compared to manual compression.

Conclusions

NIRS monitoring is feasible during resuscitation of patients with out-of-hospital cardiac arrest and can be a useful tool during resuscitation, leading to an earlier detection of ROSC and re-arrest. Higher initial rSO₂ values during CPR seem to be associated with the occurrence of ROSC. The use of mechanical chest compression devices might result in higher rSO₂. These findings need to be confirmed by larger studies.

MicroRNA-155 potentiates the inflammatory response in hypothermia by suppressing IL-10 production

Therapeutic hypothermia is commonly used to improve neurological outcomes in patients after cardiac arrest. However, therapeutic hypothermia increases sepsis risk and unintentional hypothermia in surgical patients increases infectious complications. Nonetheless, the molecular mechanisms by which hypothermia dysregulates innate immunity are incompletely understood. We found that exposure of human monocytes to cold (32°C) potentiated LPS-induced production of TNF and IL-6, while blunting IL-10 production. This dysregulation was associated with increased expression of microRNA-155 (miR-155), which potentiates Toll-like receptor (TLR) signaling by negatively regulating Ship1 and Socs1. Indeed, Ship1 and Socs1 were suppressed at 32°C and miR-155 antagomirs increased Ship1 and Socs1 and reversed the alterations in cytokine production in cold-exposed monocytes. In contrast, miR-155 mimics phenocopied the effects of cold exposure, reducing Ship1 and Socs1 and altering TNF and IL-10 production. In a murine model of LPS-induced peritonitis, cold exposure potentiated hypothermia and decreased survival (10 vs. 50%; P < 0.05), effects that were associated with increased miR-155, suppression of Ship1 and Socs1, and alterations in TNF and IL-10. Importantly, miR-155-deficiency reduced hypothermia and improved survival (78 vs. 32%, P < 0.05), which was associated with increased Ship1, Socs1, and IL-10. These results establish a causal role of miR-155 in the dysregulation of the inflammatory response to hypothermia.

Therapeutic induced hypothermia does not improve the prognosis of out-of-hospital cardiac arrest patients

Unconscious patients admitted to critical care units after out-of-hospital cardiac arrest are at high risk for death, and neurologic deficits are common among those who survive. The target temperature management (TTM), 33 vs. 36 °C, after out-of-hospital cardiac arrest trial was conducted to assess the benefits and harms of two targeted temperature regimens after out-of-hospital cardiac arrest of presumed cardiac cause. The study randomized 950 unconscious survivors of out-of-hospital cardiac arrest with presumed cardiac cause to a target temperature of 33 vs. 36 °C following return of spontaneous circulation (ROSC), irrespective of the initial rhythm. At the end of the trial, 50% of the patients in the 33 °C group (235 of 473 patients) had died, as compared to 48% of the patients in the 36 °C group (225 of 466 patients) [hazard ratio with a temperature of 33 °C 1.06; 95% confidence interval (CI) 0.89-1.28; p = 0.51]. In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33 °C does not confer a survival benefit as compared to a targeted temperature of 36 °C.

Brain resuscitation and prognosis after cardiac arrest

Brain injury represents the major cause of long-term disability and mortality among patients resuscitated from cardiac arrest. Brain-directed therapies include maintenance of normal oxygenation, hemodynamic support to optimize cerebral perfusion, glycemic control, and targeted temperature management. Pertinent guidelines and recommendations are reviewed for brain-directed treatment. The latest clinical trial data regarding targeted temperature management are also reviewed. Contemporary prognostication among initially comatose cardiac arrest survivors uses a combination of clinical and electrophysiologic tests. The most recent guidelines for prognostication after cardiac arrest are reviewed. Ongoing research regarding the effects of induced hypothermia on prognostic algorithms is also reviewed.

Hypothermia after cardiac arrest as a novel approach to increase survival in cardiopulmonary cerebral resuscitation: a review

Context:

The aim of this review study was to evaluate therapeutic mild hypothermia, its complications and various methods for induced mild hypothermia in patients following resuscitation after out-of-hospital cardiac arrest.

Evidence Acquisition:

Studies conducted on post-cardiac arrest cares, history of induced hypothermia, and therapeutic hypothermia for patients with cardiac arrest were included in this study. We used the valid databases (PubMed and Cochrane library) to collect relevant articles.

Results:

According to the studies reviewed, induction of mild hypothermia in patients after cardiopulmonary resuscitation would lead to increased survival and better neurological outcome; however, studies on the complications of hypothermia or different methods of inducing hypothermia were limited and needed to be studied further.

Conclusions:

This study provides strategic issues concerning the induction of mild hypothermia, its complications, and different ways of performing it on patients; using this method helps to increase patients’ neurological survival rate.

Extracranial hypothermia during cardiac arrest and cardiopulmonary resuscitation is neuroprotective in vivo

There is increasing evidence that ischemic brain injury is modulated by peripheral signaling. Peripheral organ ischemia can induce brain inflammation and injury. We therefore hypothesized that brain injury sustained after cardiac arrest (CA) is influenced by peripheral organ ischemia and that peripheral organ protection can reduce brain injury after CA and cardiopulmonary resuscitation (CPR). Male C57Bl/6 mice were subjected to CA/CPR. Brain temperature was maintained at 37.5°C ± 0.0°C in all animals. Body temperature was maintained at 35.1°C ± 0.1°C (normothermia) or 28.8°C ± 1.5°C (extracranial hypothermia [ExHy]) during CA. Body temperature after resuscitation was maintained at 35°C in all animals. Behavioral testing was performed at 1, 3, 5, and 7 days after CA/CPR. Either 3 or 7 days after CA/CPR, blood was analyzed for serum urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, and interleukin-1β; mice were euthanized; and brains were sectioned. CA/CPR caused peripheral organ and brain injury. ExHy animals experienced transient reduction in brain temperature after resuscitation (2.1°C ± 0.5°C for 4 minutes). Surprisingly, ExHy did not change peripheral organ damage. In contrast, hippocampal injury was reduced at 3 days after CA/CPR in ExHy animals (22.4% ± 6.2% vs. 45.7% ± 9.1%, p=0.04, n=15/group). This study has two main findings. Hypothermia limited to CA does not reduce peripheral organ injury. This unexpected finding suggests that after brief ischemia, such as during CA/CPR, signaling or events after reperfusion may be more injurious than those during the ischemic period. Second, peripheral organ hypothermia during CA reduces hippocampal injury independent of peripheral organ protection. While it is possible that this protection is due to subtle differences in brain temperature during early reperfusion, we speculate that additional mechanisms may be involved. Our findings add to the growing understanding of brain-body cross-talk by suggesting that peripheral interventions can protect the brain even if peripheral organ injury is not altered.

Benefits of thrombolytics in prolonged cardiac arrest and hypothermia over its bleeding risk

A 52-year-old non-smoking Caucasian male, who was admitted to our emergency room after he was found unconscious in the bathroom, went into cardiac arrest requiring prolonged cardiopulmonary resuscitation (CPR) and hypothermia therapy. Cardiac catheterization showed non-obstructive coronary arteries and further bedside echocardiogram suggested probable pulmonary embolism (PE) as an underlying cause of cardiac arrest. Although thrombolytic therapy is an effective therapy for PE, it is not routinely given during prolonged CPR for its life- threatening bleeding complications. Many reported cases have suggested a beneficial effect of empiric thrombolytic in cardiac arrest, but unrelated to duration of resuscitation and adjuvant treatments that imposes bleeding risk. We suspect that tissue plasminogen activator (tPA) should be promptly given to prolonged cardiac arrest patients, even when bleeding risk is high with the concurrent hypothermia treatment, keeping the benefits over risk strategy. Our patient received thrombolytic, tPA and showed remarkable clinical, physiological and radiographical improvement.

Comparative Effectiveness of Therapeutic Hypothermia After Out-of-Hospital Cardiac Arrest: Insight from a Large Data Registry

This study was done to determine the effectiveness of therapeutic hypothermia (TH) after out-of-hospital cardiac arrest (OHCA) among a large cohort of adults in the Cardiac Arrest Registry to Enhance Survival (CARES), with an emphasis on subgroups with a nonshockable first documented rhythm. This was an IRB approved retrospective cohort study. All adult index events at participating sites from November 2010 to December 2013 were study eligible. All patient data elements were provided. Summary statistics were calculated for all patients with and without TH. For multivariate adjustment, a multilevel (i.e., hierarchical), mixed-effects logistic regression (MLR) model was used with hospitals treated as random effects. Propensity score matching (PSM) on both shockable and nonshockable patients was done as a sensitivity analysis. After predefined exclusions, our final sample size was 6369 records for analysis: shockable=2992 (47.0%); asystole=1657 (26.0%); pulseless electrical activity=1249 (19.6%); other unspecified nonshockable=471 (7.4%). Unadjusted differences in neurological status at hospital discharge with and without TH were similar (p=0.295). After multivariate adjustment, TH had either no association with good neurological status at hospital discharge or that TH was actually associated with worse neurological outcome, particularly in patients with a nonshockable first documented rhythm (i.e., for NS patients, MLR odds ratio for TH=1.444; 95% CI [1.039, 2.006] p=0.029, and OR=1.017, p=0.927 via PSM). Highlighting our limitations, we conclude that when TH is indiscriminately provided to a large population of OHCA survivors with a nonshockable first documented rhythm, evidence for its effectiveness is diminished. We suggest more uniform and rigid guidelines for application.

Successful treatment of a young woman with acute complicated myocardial infarction

Therapeutic hypothermia is method used to improve the neurological status of patients who are at risk of ischaemia after myocardial infarction. We report a case of a 28-year-old woman who suffered acute myocardial infarction complicated by ventricular fibrillation. The patient was successfully resuscitated. Invasive and non-invasive medical treatment was applied including therapeutic hypothermia. Success was achieved due to adequate public reaction, fast transportation, blood vessel revascularization and application of therapeutic hypothermia. The patient was successfully discharged after one week of treatment, and just minor changes in heart function were present.

Imaging of temperature dependent hemodynamics in the rat sciatic nerve by functional photoacoustic microscopy

Background

Vascular hemodynamics is central to the regulation of neuro-metabolism and plays important roles in peripheral nerves diseases and their prevention. However, at present there are only a few techniques capable of directly measuring peripheral nerve vascular hemodynamics.

Method

Here, we investigate the use of dark-field functional photoacoustic microscopy (fPAM) for intrinsic visualizing of the relative hemodynamics of the rat sciatic nerve in response to localized temperature modulation (i.e., cooling and rewarming).

Results and conclusion

Our main results show that the relative functional total hemoglobin concentration (HbT) is more significantly correlated with localized temperature changes than the hemoglobin oxygen saturation (SO₂) changes in the sciatic nerve. Our study also indicates that the relative HbT changes are better markers of neuronal activation than SO₂ during nerve temperature changes. Our results show that fPAM is a promising candidate for in vivo imaging of peripheral nerve hemodynamics without the use of contrast agents. Additionally, this technique may shed light on the neuroprotective effect of hypothermia on peripheral nerves by visualizing their intrinsic hemodynamics.

A novel mouse model of pediatric cardiac arrest and cardiopulmonary resuscitation reveals age-dependent neuronal sensitivities to ischemic injury

BACKGROUND

Pediatric sudden cardiac arrest (CA) is an unfortunate and devastating condition, often leading to poor neurologic outcomes. However, little experimental data on the pathophysiology of pediatric CA is currently available due to the scarcity of animal models.

NEW METHOD

We developed a novel experimental model of pediatric cardiac arrest and cardiopulmonary resuscitation (CA/CPR) using postnatal day 20-25 mice. Adult (8-12 weeks) and pediatric (P20-25) mice were subjected to 6min CA/CPR. Hippocampal CA1 and striatal neuronal injury were quantified 3 days after resuscitation by hematoxylin and eosin (H&E) and Fluoro-Jade B staining, respectively.

RESULTS

Pediatric mice exhibited less neuronal injury in both CA1 hippocampal and striatal neurons compared to adult mice. Increasing ischemia time to 8 min CA/CPR resulted in an increase in hippocampal injury in pediatric mice, resulting in similar damage in adult and pediatric brains. In contrast, striatal injury in the pediatric brain following 6 or 8 min CA/CPR remained extremely low. As observed in adult mice, cardiac arrest causes delayed neuronal death in pediatric mice, with hippocampal CA1 neuronal damage maturing at 72 h after insult. Finally, mild therapeutic hypothermia reduced hippocampal CA1 neuronal injury after pediatric CA/CPR.

COMPARISON WITH EXISTING METHOD

This is the first report of a cardiac arrest and CPR model of global cerebral ischemia in mice.

CONCLUSIONS

Therefore, the mouse pediatric CA/CPR model we developed is unique and will provide an important new tool to the research community for the study of pediatric brain injury.

Two cases of asystolic cardiac arrests managed with therapeutic hypothermia

Poor neurological outcome is a common sequel of prolonged cardiac arrest. Although Therapeutic Hypothermia (TH) for neuroprotection has been a subject for research for over Half a century, its use has been limited because of many controversies and lack of clear guidelines. However for over two decades there has been a revival of interest in mild therapeutic hypothermia (32-34°C) for neuroprotection. However its use after primary asystolic cardiac arrest has been questioned.

Herein presenting two cases of prolonged asystolic arrest (39 minutes and 25 minutes); where therapeutic hypothermia was successfully used in following prolonged cardio pulmonary resuscitation. On patients who were in deep coma after resuscitation, TH was applied for 24 hours as per institutional protocol with full neurological recovery in both the cases. Therapeutic hypothermia might have a potential role in even in non-shockable arrests and should be considered in every successful cardiopulmonary resuscitation with poor neurological status.

Employment status 1 year after out-of-hospital cardiac arrest in comatose patients treated with therapeutic hypothermia

BACKGROUND

Therapeutic hypothermia for comatose survivors of out-of-hospital cardiac arrest (OHCA) has improved survival and neurologic outcome. This study focused on return to work 1 year after therapeutic hypothermia.

METHODS

From June 2004 to June 2009, patients between 18 and 65 years of age with OHCA, who were treated with hypothermia from two regions, representing one third of the national population, were identified from the Danish National Patient Registry, and from hospital and ambulance records. The patients' employment status was obtained from the Danish Ministry of Employment.

RESULTS

One hundred thirty-three comatose patients after OHCA treated with hypothermia were identified. One hundred and four (78%) patients were employed, or able to work, at the time of cardiac arrest. This particular group of patients showed significant lower in-hospital mortality compared to the group of patients who were not able to work before cardiac arrest; 13% vs. 48%, respectively (P < 0.001). The workable group had a lower Charlson comorbidity score (P = 0.004), a higher incidence of witnessed cardiac arrest (P = 0.004) and a higher incidence of shockable heart rhythm (P < 0.001). Eighty-seven patients (84%), who were able to work prior to cardiac arrest, survived, and 55 (65%) of these patients were employed or able to work at 1 year follow-up.

CONCLUSION

The majority of patients employed, or able to work prior to OHCA, had returned to work at one year follow-up. Predictors of return to work in comatose patients treated with hypothermia have to be identified in a larger-scale study.

Mesenchymal stem cells transplantation suppresses inflammatory responses in global cerebral ischemia: contribution of TNF-α-induced protein 6

AIM

To investigate the effects of mesenchymal stem cells (MSCs) transplantation on rat global cerebral ischemia and the underlying mechanisms.

METHODS

Adult male SD rats underwent asphxial cardiac arrest to induce global cerebral ischemia, then received intravenous injection of 5×10(6) cultured MSCs of SD rats at 2 h after resuscitation. In another group of cardiac arrest rats, tumor necrosis factor-α-induced protein 6 (TSG-6, 6 μg) was injected into the right lateral ventricle. Functional outcome was assessed at 1, 3, and 7 d after resuscitation. Donor MSCs in the brains were detected at 3 d after resuscitation. The level of serum S-100B and proinflammatory cytokines in cerebral cortex were assayed using ELISA. The expression of TSG-6 and proinflammatory cytokines in cerebral cortex was assayed using RT-PCR. Western blot was performed to determine the levels of TSG-6 and neutrophil elastase in cerebral cortex.

RESULTS

MSCs transplantation significantly reduced serum S-100B level, and improved neurological function after global cerebral ischemia compared to the PBS-treated group. The MSCs injected migrated into the ischemic brains, and were observed mainly in the cerebral cortex. Furthermore, MSCs transplantation significantly increased the expression of TSG-6, and reduced the expression of neutrophil elastase and proinflammatory cytokines in the cerebral cortex. Intracerebroventricular injection of TSG-6 reproduced the beneficial effects of MSCs transplantation in rats with global cerebral ischemia.

CONCLUSION

MSCs transplantation improves functional recovery and reduces inflammatory responses in rats with global cerebral ischemia, maybe via upregulation of TSG-6 expression.

ACS network-based implementation of therapeutic hypothermia for the treatment of comatose out-of-hospital cardiac arrest survivors improves clinical outcomes: the first European experience

Background

There is a paucity of data regarding clinical outcomes associated with the integration of a mild therapeutic hypothermia (MTH) protocol into a regional network dedicated to treatment of patients with acute coronary syndromes (ACS). Additionally, a recent report suggests that the neurological benefits of MTH therapy in interventionally managed ACS patients resuscitated from out-of-hospital cardiac arrest (OHCA) may be potentially offset by the catastrophic occurrence of stent thrombosis. The goal of this study was to share our experience with the implementation of an MTH program using a previously established ACS network in consecutive comatose OHCA survivors undergoing interventional management due to an initial diagnosis of ACS and to assess the clinical effectiveness and safety of MTH.

Methods

We conducted a retrospective historically controlled single centre study. Hospital survival with a favourable neurological outcome (Cerebral Performance Category of 1 or 2) and all-cause in-hospital mortality were the primary and secondary efficacy end points, respectively. Occurrence of definite stent thrombosis was the primary safety end point while the development of pneumonia, presence of positive blood cultures, occurrence of probable stent thrombosis, any bleeding complications, need for red blood cell transfusion and presence of rhythm and conductions disorders during hospitalisation constituted secondary safety end points.

Results

Comatose OHCA survivors (n = 32) were referred to our Department based on ECG recording transmissions and/or phone consultations or admitted from the Emergency Department. Compared with controls (n = 33), they were significantly more likely to be discharged from hospital with a favourable neurological outcome (59 vs. 27%; p < 0.05; number needed to treat [NNT] = 3.11) and experienced lower all-cause in-hospital mortality (13 vs. 55%; p < 0.05; NNT = 2.38). Rates of all safety end points were similar in patients treated with and without MTH.

Conclusions

Our study indicates that a regional system of care for OHCA survivors may be successfully implemented based on an ACS network, leading to an improvement in neurological status and to a reduction of in-hospital mortality in patients treated with MTH, without any excess of complications. However, our findings should be verified in large, prospective trials.

Hypothermia for neuroprotection in children after cardiopulmonary arrest

BACKGROUND

Cardiopulmonary arrest in paediatric patients often results in death or survival with severe brain injury. Therapeutic hypothermia, lowering of the core body temperature to 32°C to 34°C, may reduce injury to the brain in the period after the circulation has been restored. This therapy has been effective in neonates with hypoxic ischaemic encephalopathy and adults after witnessed ventricular fibrillation cardiopulmonary arrest. The effect of therapeutic hypothermia after cardiopulmonary arrest in paediatric patients is unknown.

OBJECTIVES

To assess the clinical effectiveness of therapeutic hypothermia after paediatric cardiopulmonary arrest.

SEARCH METHODS

We searched the Cochrane Anaesthesia Review Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 11); Ovid MEDLINE (1966 to December 2011); Ovid EMBASE (1980 to December 2011); Ovid CINAHL (1982 to December 2011); Ovid BIOSIS (1923 to December 2011); and Web of Science (1945 to December 2011). We searched the trials registry databases for ongoing trials. We also contacted international experts in therapeutic hypothermia and paediatric critical care to locate further published and unpublished studies.

SELECTION CRITERIA

We planned to include randomized and quasi-randomized controlled trials comparing therapeutic hypothermia with normothermia or standard care in children, aged 24 hours to 18 years, after paediatric cardiopulmonary arrest.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed articles for inclusion.

MAIN RESULTS

We found no studies that satisfied the inclusion criteria. We found four on-going randomized controlled trials which may be available for analysis in the future. We excluded 18 non-randomized studies. Of these 18 non-randomized studies, three compared therapeutic hypothermia with standard therapy and demonstrated no difference in mortality or the proportion of children with a good neurological outcome; a narrative report was presented.

AUTHORS' CONCLUSIONS

Based on this review, we are unable to make any recommendations for clinical practice. Randomized controlled trials are needed and the results of on-going trials will be assessed when available.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal studies and pilot studies in humans suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae without adverse effects.

OBJECTIVES

To determine the effect of therapeutic hypothermia in encephalopathic asphyxiated newborn infants on mortality, long-term neurodevelopmental disability and clinically important side effects.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group as outlined in The Cochrane Library (Issue 2, 2007). Randomised controlled trials evaluating therapeutic hypothermia in term and late preterm newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2007, Issue 2), MEDLINE (1966 to June 2007), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal handsearching. We updated this search in May 2012.

SELECTION CRITERIA

We included randomised controlled trials comparing the use of therapeutic hypothermia with standard care in encephalopathic term or late preterm infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Four review authors independently selected, assessed the quality of and extracted data from the included studies. Study authors were contacted for further information. Meta-analyses were performed using risk ratios (RR) and risk differences (RD) for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals (CI).

MAIN RESULTS

We included 11 randomised controlled trials in this updated review, comprising 1505 term and late preterm infants with moderate/severe encephalopathy and evidence of intrapartum asphyxia. Therapeutic hypothermia resulted in a statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age (typical RR 0.75 (95% CI 0.68 to 0.83); typical RD -0.15, 95% CI -0.20 to -0.10); number needed to treat for an additional beneficial outcome (NNTB) 7 (95% CI 5 to 10) (8 studies, 1344 infants). Cooling also resulted in statistically significant reductions in mortality (typical RR 0.75 (95% CI 0.64 to 0.88), typical RD -0.09 (95% CI -0.13 to -0.04); NNTB 11 (95% CI 8 to 25) (11 studies, 1468 infants) and in neurodevelopmental disability in survivors (typical RR 0.77 (95% CI 0.63 to 0.94), typical RD -0.13 (95% CI -0.19 to -0.07); NNTB 8 (95% CI 5 to 14) (8 studies, 917 infants). Some adverse effects of hypothermia included an increase sinus bradycardia and a significant increase in thrombocytopenia.

AUTHORS' CONCLUSIONS

There is evidence from the 11 randomised controlled trials included in this systematic review (N = 1505 infants) that therapeutic hypothermia is beneficial in term and late preterm newborns with hypoxic ischaemic encephalopathy. Cooling reduces mortality without increasing major disability in survivors. The benefits of cooling on survival and neurodevelopment outweigh the short-term adverse effects. Hypothermia should be instituted in term and late preterm infants with moderate-to-severe hypoxic ischaemic encephalopathy if identified before six hours of age. Further trials to determine the appropriate techniques of cooling, including refinement of patient selection, duration of cooling and method of providing therapeutic hypothermia, will refine our understanding of this intervention.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal and human pilot studies suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae, without adverse effects.

OBJECTIVES

To determine whether therapeutic hypothermia in encephalopathic asphyxiated newborn infants reduces mortality and long-term neurodevelopmental disability, without clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library (Issue 2, 2003) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue Issue 2, 2003), MEDLINE (1966 to July 2003), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.

SELECTION CRITERIA

Randomised controlled trials comparing the use of therapeutic hypothermia with normothermia in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta-analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Two randomised controlled trials were included in this review, comprising 50 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. There was no significant effect of therapeutic hypothermia on the combined outcome of death or major neurodevelopmental disability in survivors followed. No adverse effects of hypothermia on short term medical outcomes or on some 'early' indicators of neurodevelopmental outcome were detected.

REVIEWER'S CONCLUSIONS

Although two small randomised controlled trials demonstrated neither evidence of benefit or harm, current evidence is inadequate to assess either safety or efficacy of therapeutic hypothermia in newborn infants with hypoxic ischaemic encephalopathy. Therapeutic hypothermia for encephalopathic asphyxiated newborn infants should be further evaluated in well designed randomised controlled trials.