EuroHYP-1-Studie: EU-geförderte Therapiestudie zur Effektivität milder therapeutischer Hypothermie beim akuten ischämischen Schlaganfall

The Clinical Usefulness of Targeted Temperature Management in Acute Ischemic Stroke with Malignant Trait After Endovascular Thrombectomy

BACKGROUND/OBJECTIVE

Targeted temperature management (TTM) may be more beneficial after endovascular treatment (EVT) in patients with a large ischemic core. Therefore, we assessed the usefulness of TTM for such patients from a multicenter endovascular registry.

METHODS

Anterior circulation stroke patients who underwent endovascular recanalization were included; acute ischemic stroke with malignant traits was designated as (1) baseline Alberta Stroke Program Early CT Score (ASPECTS) below 6 and (2) diffusion-weighted imaging (DWI) lesion volume measurement (> 82 ml) or National Institutes of Health Stroke Scale score > 20 and item Ia > 0. TTM (34.5 °C) was maintained for at least 48 h.

RESULTS

We evaluated baseline demographics, risk factors, EVT parameters, and clinical outcomes between the TTM and non-TTM groups. Among the 548 patients, the TTM group (n = 91) significantly had a lower baseline ASPECTS (p < 0.001) and a higher DWI volume (p < 0.001) than the non-TTM group (n = 457). TTM group had a lower prevalence of favorable outcome (0-2 of modified Rankin Scale at 3 months; p = 0.008) than the non-TTM group. In a subgroup analysis of malignant trait patients (n = 80), TTM patients (n = 28) had more favorable outcome (32.1% vs. 7.7% p = 0.009) and less hemorrhagic transformation (none vs. any hemorrhage, p = 0.007) than non-TTM patients (n = 52). After adjusting for potential outcome predictors, TTM (odds ratio [OR] 4.63; confidence interval [CI] 1.20-17.89; p = 0.026) and hypertension (OR 0.18; CI 0.04-0.74; p = 0.018) were found to be independent determinants.

CONCLUSIONS

Our data suggest that TTM attenuates impending hemorrhagic transformation and leads to favorable clinical outcomes in EVT patients with malignant trait.

Novel method for inducing rapid, controllable therapeutic hypothermia in rats using a perivascular implanted closed-loop cooling circuit

BACKGROUND

Hypothermia is the most potent protective therapy available for cerebral ischemia. In experimental models, cooling the brain even a single degree Celsius alters outcome after global and focal ischemia. Difficulties translating therapeutic hypothermia to patients with stroke or after cardiac arrest include: uncertainty as to the optimal treatment duration; best target-depth temperature; and longest time delay after which therapeutic hypothermia won't benefit. Recent results from human clinical trials suggest that cooling with surface methods provides insufficient cooling speed or control over target temperature.

COMPARISON WITH EXISTING METHODS

Available animal models incorporate surface cooling methods that are slow, and do not allow for precise control of the target temperature.

NEW METHOD

To address this need, we developed a rapid, simple, inexpensive model for inducing hypothermia using a perivascular implanted closed-loop cooling circuit. The method allows precise control of the target temperature.

RESULTS

Using this method, target temperature for therapeutic hypothermia was reached within 13±1.07min (Mean±SE). Once at target, the temperature was maintained within 0.09°C for 4h.

CONCLUSIONS

This method will allow future experiments to determine under what conditions therapeutic hypothermia is effective, determine the optimal relationship among delay, duration, and depth, and provide the research community with a new model for conducting further research into mechanistic questions underlying the efficacy of therapeutic hypothermia.

Dantrolene enhances the protective effect of hypothermia on cerebral cortex neurons

Therapeutic hypothermia is the most promising non-pharmacological neuroprotective strategy against ischemic injury. However, shivering is the most common adverse reaction. Many studies have shown that dantrolene is neuroprotective in in vitro and in vivo ischemic injury models. In addition to its neuroprotective effect, dantrolene neutralizes the adverse reaction of hypothermia. Dantrolene may be an effective adjunctive therapy to enhance the neuroprotection of hypothermia in treating ischemic stroke. Cortical neurons isolated from rat fetuses were exposed to 90 minutes of oxygen-glucose deprivation followed by reoxygenation. Neurons were treated with 40 μM dantrolene, hypothermia (at 33°C), or the combination of both for 12 hours. Results revealed that the combination of dantrolene and hypothermia increased neuronal survival and the mitochondrial membrane potential, and reduced intracellular active oxygen cytoplasmic histone-associated DNA fragmentation, and apoptosis. Furthermore, improvements in cell morphology were observed. The combined treatment enhanced these responses compared with either treatment alone. These findings indicate that dantrolene may be used as an effective adjunctive therapy to enhance the neuroprotective effects of hypothermia in ischemic stroke.

[News and perspectives in neurocritical care]

Neurocritical care is an ever-evolving discipline and its implementation in intensive care leads to reduction in mortality and to improvement of functional outcome in patients with devastating injuries to the nervous system. However, the decisive elements of the complete field of neurocritical care remain relatively unclear, as well as the exact ways to optimize them. During recent years new insights have been gained and new exciting studies have been initiated from which results are soon to be expected. This review focuses on the following management aspects: neuromonitoring, airway and ventilation, endovascular therapy, cerebrospinal fluid drainage, decompressive craniectomy, hematoma evacuation, blood pressure, and targeted temperature management. The application of these measures to brain diseases and injuries frequently treated in neurointensive care units will be addressed in the context of current studies.

Targeted temperature management in brain protection: An evidence-based review

Targeted temperature management (TTM) for neuroprotection involves maintaining the temperature of the brain at predetermined levels by various techniques. It is aimed at avoiding the harmful effects of hyperthermia on the brain and at exploiting the protective effects of lower tissue temperature. There has been an explosion in the use of TTM for neuroprotection in a variety of clinical scenarios apart from the commonly accepted fields of resuscitation and ischaemic, hypoxic encephalopathy. This review briefly discusses the evidence base for TTM. The focus is on various areas of application for neuroprotection, the practical issues pertaining to TTM implementation, the recent data that support it and the present areas of controversy.

Critical care for patients with massive ischemic stroke

Malignant cerebral edema following ischemic stroke is life threatening, as it can cause inadequate blood flow and perfusion leading to irreversible tissue hypoxia and metabolic crisis. Increased intracranial pressure and brain shift can cause herniation syndrome and finally brain death. Multiple randomized clinical trials have shown that preemptive decompressive hemicraniectomy effectively reduces mortality and morbidity in patients with malignant middle cerebral artery infarction. Another life-saving decompressive surgery is suboccipital craniectomy for patients with brainstem compression by edematous cerebellar infarction. In addition to decompressive surgery, cerebrospinal fluid drainage by ventriculostomy should be considered for patients with acute hydrocephalus following stroke. Medical treatment begins with sedation, analgesia, and general measures including ventilatory support, head elevation, maintaining a neutral neck position, and avoiding conditions associated with intracranial hypertension. Optimization of cerebral perfusion pressure and reduction of intracranial pressure should always be pursued simultaneously. Osmotherapy with mannitol is the standard treatment for intracranial hypertension, but hypertonic saline is also an effective alternative. Therapeutic hypothermia may also be considered for treatment of brain edema and intracranial hypertension, but its neuroprotective effects have not been demonstrated in stroke. Barbiturate coma therapy has been used to reduce metabolic demand, but has become less popular because of its systemic adverse effects. Furthermore, general medical care is critical because of the complex interactions between the brain and other organ systems. Some challenging aspects of critical care, including ventilator support, sedation and analgesia, and performing neurological examinations in the setting of a minimal stimulation protocol, are addressed in this review.

Hypothermia protects human neurons

BACKGROUND AND AIMS

Hypothermia provides neuroprotection after cardiac arrest, hypoxic-ischemic encephalopathy, and in animal models of ischemic stroke. However, as drug development for stroke has been beset by translational failure, we sought additional evidence that hypothermia protects human neurons against ischemic injury.

METHODS

Human embryonic stem cells were cultured and differentiated to provide a source of neurons expressing β III tubulin, microtubule-associated protein 2, and the Neuronal Nuclei antigen. Oxygen deprivation, oxygen-glucose deprivation, and H2 O2 -induced oxidative stress were used to induce relevant injury.

RESULTS

Hypothermia to 33°C protected these human neurons against H2 O2 -induced oxidative stress reducing lactate dehydrogenase release and Terminal deoxynucleotidyl transferase dUTP nick end labeling-staining by 53% (P ≤ 0·0001; 95% confidence interval 34·8-71·04) and 42% (P ≤ 0·0001; 95% confidence interval 27·5-56·6), respectively, after 24 h in culture. Hypothermia provided similar protection against oxygen-glucose deprivation (42%, P ≤ 0·001, 95% confidence interval 18·3-71·3 and 26%, P ≤ 0·001; 95% confidence interval 12·4-52·2, respectively) but provided no protection against oxygen deprivation alone. Protection (21%) persisted against H2 O2 -induced oxidative stress even when hypothermia was initiated six-hours after onset of injury (P ≤ 0·05; 95% confidence interval 0·57-43·1).

CONCLUSION

We conclude that hypothermia protects stem cell-derived human neurons against insults relevant to stroke over a clinically relevant time frame. Protection against H2 O2 -induced injury and combined oxygen and glucose deprivation but not against oxygen deprivation alone suggests an interaction in which protection benefits from reduction in available glucose under some but not all circumstances.

Therapeutic hypothermia for neuroprotection: history, mechanisms, risks, and clinical applications

The earliest recorded application of therapeutic hypothermia in medicine spans about 5000 years; however, its use has become widespread since 2002, following the demonstration of both safety and efficacy of regimens requiring only a mild (32°C-35°C) degree of cooling after cardiac arrest. We review the mechanisms by which hypothermia confers neuroprotection as well as its physiological effects by body system and its associated risks. With regard to clinical applications, we present evidence on the role of hypothermia in traumatic brain injury, intracranial pressure elevation, stroke, subarachnoid hemorrhage, spinal cord injury, hepatic encephalopathy, and neonatal peripartum encephalopathy. Based on the current knowledge and areas undergoing or in need of further exploration, we feel that therapeutic hypothermia holds promise in the treatment of patients with various forms of neurologic injury; however, additional quality studies are needed before its true role is fully known.

In cold blood: intraarteral cold infusions for selective brain cooling in stroke

Hypothermia is a promising therapeutic option for stroke patients and an established neuroprotective treatment for global cerebral ischemia after cardiac arrest. While whole body cooling is a feasible approach in intubated and sedated patients, its application in awake stroke patients is limited by severe side effects: Strong shivering rewarms the body and potentially worsens ischemic conditions because of increased O2 consumption. Drugs used for shivering control frequently cause sedation that increases the risk of aspiration and pneumonia. Selective brain cooling by intraarterial cold infusions (IACIs) has been proposed as an alternative strategy for patients suffering from acute ischemic stroke. Preclinical studies and early clinical experience indicate that IACI induce a highly selective brain temperature decrease within minutes and reach targeted hypothermia 10 to 30 times faster than conventional cooling methods. At the same time, body core temperature remains largely unaffected, thus systemic side effects are potentially diminished. This review critically discusses the limitations and side effects of current cooling techniques for neuroprotection from ischemic brain damage and summarizes the available evidence regarding advantages and potential risks of IACI.

Neuroprotection in stroke: past, present, and future

Stroke is a devastating medical condition, killing millions of people each year and causing serious injury to many more. Despite advances in treatment, there is still little that can be done to prevent stroke-related brain damage. The concept of neuroprotection is a source of considerable interest in the search for novel therapies that have the potential to preserve brain tissue and improve overall outcome. Key points of intervention have been identified in many of the processes that are the source of damage to the brain after stroke, and numerous treatment strategies designed to exploit them have been developed. In this review, potential targets of neuroprotection in stroke are discussed, as well as the various treatments that have been targeted against them. In addition, a summary of recent progress in clinical trials of neuroprotective agents in stroke is provided.

Endovascular therapeutic hypothermia for acute ischemic stroke: ICTuS 2/3 protocol

Therapeutic hypothermia improves neurological outcome after out-of-hospital cardiac arrest or neonatal hypoxic-ischemic injury. Although supported by preclinical evidence, therapeutic hypothermia for acute stroke remains under study. In the Intravascular Cooling in the Treatment of Stroke (ICTuS) trial, awake stroke patients were successfully cooled using an endovascular cooling catheter and a novel antishivering regimen. In the ICTuS-L study, the combination of endovascular hypothermia and thrombolysis proved feasible; while hypothermia was associated with no increased risk of bleeding complications, there was an increased association with pneumonia. Despite efforts to expedite, cooling began on average six-hours after stroke onset. We designed a novel Phase 2/3 trial to further test the safety of combined thrombolysis and endovascular hypothermia and to determine if the combination shows superiority compared with thrombolysis alone. ICTuS 2 (n = 400) will assess four hypotheses, and if milestones are met, ICTuS 3 (n = 1200) will begin as a seamless continuation for a total sample of 1600 patients. The ICTuS 2 milestones include (1) target temperature reached within six-hours of symptom onset; (2) no increased risk of pneumonia; (3) no increase in signs/symptoms of fluid overload due to chilled saline infusions; and (4) sufficient recruitment to complete the trial on time. The ICTuS 2/3 protocol contains novel features - based on the previous ICTuS and ICTuS-L trials - designed to achieve these milestones. Innovations include scrupulous pneumonia surveillance, intravenous chilled saline immediately after randomization to induce rapid cooling, and a requirement for catheter placement within two-hours of thrombolysis. An Investigational Device Exemption has been obtained and an initial group of sites initiated.

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.