Adjuvant High-Flow Normobaric Oxygen After Mechanical Thrombectomy for Anterior Circulation Stroke: a Randomized Clinical Trial

Association of oxygenation levels after successful mechanical thrombectomy under general anesthesia and 3-month functional outcome in patients with acute ischemic stroke: A prospective observational study

BACKGROUND

This study aimed to evaluate whether oxygenation levels (PaO2 <150 mmHg vs. PaO2 ≥150 mmHg) in mechanically ventilated patients with acute ischemic stroke (AIS) after successful endovascular treatment (EVT) under general anesthesia are associated with functional outcomes at three months.

METHODS

We prospectively collected data over 30 mo from patients with proximal occlusion of the anterior circulation treated with successful EVT under general anesthesia. After the procedure, patients were admitted to the ICU for delayed extubation. Two groups were established based on the partial pressure of oxygen (PaO2 <150 mmHg vs. PaO2 ≥150 mmHg), measured in arterial blood gas analysis within the first hour of ICU admission. Demographics, clinical factors, and neurological status were compared. The primary outcome was the proportion of patients achieving a favorable functional outcome (mRS ≤ 2) at 3 mo.

RESULTS

During the study period, 271 patients were admitted to our ICU after EVT for AIS. Of these, 210 patients met the inclusion criteria. No significant differences were found between the groups in demographics, clinical factors, neurological status, or functional outcomes at 3 mo. The primary outcome showed no significant difference: 48 of 100 patients (48%) in the PaO2 <150 mmHg group achieved a favorable functional outcome (mRS 0-2) compared to 56 of 108 patients (51.9%) in the PaO2 ≥150 mmHg group (p = 0.579).

CONCLUSION

No association was found between 3-mo functional outcomes and post-procedure oxygenation levels in patients with AIS treated successfully with EVT under general anesthesia.

Assessing Practice Variation of Anesthetic Management for Endovascular Thrombectomy in Acute Ischemic Stroke: A Comprehensive Multicenter Survey

OBJECTIVE

This study explored the current global landscape of periprocedural care of acute ischemic stroke patients undergoing endovascular thrombectomy (EVT).

METHODS

An anonymous, 54-question electronic survey was sent to 354 recipients in hospitals worldwide. The responses were stratified by World Bank country income level into high-income (HICs) and low/middle-income (LMICs) countries.

RESULTS

A total of 354 survey invitations were issued. Two hundred twenty-three respondents started the survey, and 87 fully completed surveys were obtained from centers in which anesthesiologists were routinely involved in EVT care (38 in HICs; 49 in LMICs). Respondents from 35 (92.1%) HICs and 14 (28.6%) LMICs reported that their centers performed >50 EVTs annually. Respondents from both HICs and LMICs reported low rates of anesthesiologist involvement in pre-EVT care, though a communication system was in place in 100% of HIC centers and 85.7% of LMIC centers to inform anesthesiologists about potential EVTs. Respondents from 71.1% of HIC centers and 51% of LMIC centers reported following a published guideline during EVT management, though the use of cognitive aids was low in both (28.9% and 24.5% in HICs and LMICs, respectively). Variability in multiple areas of practice, including choice of anesthetic techniques, monitoring and management of physiological variables during EVT, and monitoring during intrahospital transport, were reported. Quality metrics were rarely tracked or reported to the anesthesiology teams.

CONCLUSIONS

This study demonstrated variability in anesthesiology involvement and in clinical care during and after EVT. Centers may consider routinely involving anesthesiologists in pre-EVT care, using evidence-based recommendations for EVT management, and tracking adherence to published guidelines and other quality metrics.

Is Reperfusion Injury a Largely Intra-Ischemic Injury?

Reperfusion injury (RI) refers to an array of detrimental cellular and biochemical processes that are widely believed to be triggered by reperfusion following focal cerebral ischemia and to contribute to infarct extension and poor outcome despite complete recanalization. Accordingly, it is widely recommended that therapies targeting RI be administered after recanalization. The present topical review demonstrates, however, that the vast majority of, and possibly all, processes considered part of RI are not actually provoked by reperfusion but develop during the ischemic phase. This notion has significant implications for clinical trials. Thus, for optimal efficacy, treatments targeting RI should accordingly be started before recanalization. Conversely, interventions aimed at protecting the ischemic penumbra, either pharmacological or nonpharmacological, during arterial occlusion are likely to also benefit RI-related processes and should probably be continued after recanalization. Overall, that RI is largely an intra-ischemic process has important ramifications for drug development as well as clinical trials, and more broadly for the management of hyperacute ischemic stroke patients prior to, and following, recanalization.

Normobaric hyperoxia combined with endovascular treatment for acute ischaemic stroke in China (OPENS-2 trial): a multicentre, randomised, single-blind, sham-controlled trial

BACKGROUND

Endovascular treatment improves the recanalisation rate for patients with acute ischaemic stroke; however, even with endovascular treatment, approximately half of patients do not have a favourable functional outcome. We aimed to evaluate the effect of normobaric hyperoxia combined with endovascular treatment on functional outcomes up to 90 days after treatment in patients who had an acute ischaemic stroke with large-vessel occlusion.

METHODS

In this multicentre, randomised, single-blind, sham-controlled trial, patients aged 18-80 years presenting within 6 h of acute ischaemic stroke attributed to large-vessel occlusion in anterior circulation, who were candidates for endovascular treatment, were recruited from 26 comprehensive stroke centres in China. Eligible patients were randomly assigned (1:1), with an Interactive Web Response System on the basis of a minimisation process to balance assignment at each participating site both overall and according to age, sex, occlusion location, and use of intravenous thrombolytics, to receive either normobaric hyperoxia combined with endovascular treatment or sham normobaric hyperoxia combined with endovascular treatment. Participants and assessors were blinded to treatment assignment. Normobaric hyperoxia treatment involved inhaling 100% oxygen at a flow rate of 10 L/min through a non-rebreather mask for 4 h, or an inspiratory oxygen fraction (FiO2) of 1·0 in participants for whom intubation was necessary. Sham treatment was 100% oxygen delivered at a flow rate of 1 L/min or an FiO2 of 0·3. The primary outcome was the comparison of the ordinal scores on the modified Rankin Scale (mRS) at 90 days assessed in the intention-to-treat population (including all patients randomly assigned to treatment). Safety was assessed in all patients who received any oxygen therapy. This trial is registered with ClinicalTrials.gov, NCT04681651, and is now complete.

FINDINGS

Between April 22, 2021, and Feb 5, 2023, 473 patients were screened, of whom 282 were randomly assigned to either normobaric hyperoxia plus endovascular treatment (n=140) or sham normobaric hyperoxia plus endovascular treatment (n=142; intention-to-treat population). The median age was 65 years (IQR 57-71), 75 (27%) of 282 participants were female, 207 (73%) were male, and 282 (100%) of participants were of Chinese Han ethnicity. At 90 days, the median score on the mRS for the normobaric hyperoxia group was 2 (IQR 1-4) and it was 3 (1-4) in the sham normobaric hyperoxia group (adjusted common odds ratio 1·65 [95% CI 1·09-2·50]; p=0·018). At 90 days, 14 (10%) of 140 patients in the normobaric hyperoxia group and 17 (12%) of 142 in the sham normobaric hyperoxia group died (adjusted risk difference -0·02 [95% CI -0·09 to 0·06]) and 28 (20%) and 33 (23%) had serious adverse events (adjusted risk difference -0·03 [-0·12 to 0·07]).

INTERPRETATION

In patients with acute ischaemic stroke caused by large-vessel occlusion in the anterior circulation who were candidates for endovascular treatment, normobaric hyperoxia yielded superior functional outcomes at 90 days compared with the sham normobaric hyperoxia, without raising safety concerns.

FUNDING

Beijing Municipal Education Commission, Beijing Municipal Finance Bureau, and National Natural Science Foundation of China.

Multi-Target and Multi-Phase Adjunctive Cerebral Protection for Acute Ischemic Stroke in the Reperfusion Era

Stroke remains the leading cause of death and disability in some countries, predominantly attributed to acute ischemic stroke (AIS). While intravenous thrombolysis and endovascular thrombectomy are widely acknowledged as effective treatments for AIS, boasting a high recanalization rate, there is a significant discrepancy between the success of revascularization and the mediocre clinical outcomes observed among patients with AIS. It is now increasingly understood that the implementation of effective cerebral protection strategies, serving as adjunctive treatments to reperfusion, can potentially improve the outcomes of AIS patients following recanalization therapy. Herein, we reviewed several promising cerebral protective methods that have the potential to slow down infarct growth and protect ischemic penumbra. We dissect the underlying reasons for the mismatch between high recanalization rates and moderate prognosis and introduce a novel concept of "multi-target and multi-phase adjunctive cerebral protection" to guide our search for neuroprotective agents that can be administered alongside recanalization therapy.

Evaluating high-flow oxygen therapy after mechanical thrombectomy under general anesthesia in acute ischemic stroke: A retrospective single-center study

BACKGROUND

The use of mechanical thrombectomy for acute intracranial vascular occlusion under general anesthesia with endotracheal intubation is well-established as a safe and effective method. However, the process of extubation post-surgery presents challenges for certain patients. This retrospective study assesses the safety and efficacy of combining mechanical ventilation with high-flow oxygen inhalation as an interim strategy, while also examining its impact on long-term clinical outcomes.

METHODS

This research enrolled 119 patients with acute intracranial large vessel occlusion who underwent mechanical thrombectomy under general anesthesia with tracheal intubation between January 2020 and November 2023. Participants were categorized into two groups: Group 1 (n=55), which received high-flow oxygen (HFO) post-extubation, and Group 2 (n=64), which was treated with routine oxygen supplementation (RO). The study compared reintubation and tracheotomy rates between these groups to determine safety and effectiveness. Additionally, it analyzed long-term clinical outcomes by comparing NIHSS and mRS scores before treatment and at 90-day follow-up.

RESULTS

The reintubation rate post-extubation was significantly lower in the HFO group (12.7 %, n=7) compared to the RO group (31.2 %, n=20, p=0.016). The incidence of tracheotomy within 7 days was also reduced in the HFO group compared to the RO group (7.3 %, n=4 vs 20.3 %, n=13, p=0.043). Moreover, a greater proportion of patients in the HFO group achieved mRS scores of 0-2 at 90 days post-stroke than those in the RO group (60 %, n=33 vs 40.6 %, n=26, p=0.035). The median NIHSS score at 90 days was more favorable in the HFO group than in the RO group (6, IQR [1-18] vs 8, IQR [1-20], p=0.005).

CONCLUSION

The study suggests that high-flow oxygen therapy after mechanical thrombectomy under general anesthesia with tracheal intubation may lessen the need for reintubation and tracheotomy, potentially leading to improved long-term prognosis.

Neurological outcomes and mortality of hyperoxaemia in patients with acute brain injury: protocol for a systematic review and meta-analysis

INTRODUCTION

Oxygen is frequently prescribed in neurocritical care units. Avoiding hypoxaemia is a key objective in patients with acute brain injury (ABI). However, several studies suggest that hyperoxaemia may also be related to higher mortality and poor neurological outcomes in these patients. The evidence in this direction is still controversial due to the limited number of prospective studies, the lack of a common definition for hyperoxaemia, the heterogeneity in experimental designs and the different causes of ABI. To explore the correlation between hyperoxaemia and poor neurological outcomes and mortality in hospitalised adult patients with ABI, we will conduct a systematic review and meta-analysis of observational studies and RCTs.

METHODS AND ANALYSIS

The systematic review methods have been defined according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and follow the PRISMA-Protocols structure. Studies published until June 2024 will be identified in the electronic databases MEDLINE, Embase, Scopus, Web of Science, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature and ClinicalTrials.gov. Retrieved records will be independently screened by four authors working in pairs, and the selected variables will be extracted from studies reporting data on the effect of 'hyperoxaemia' versus 'no hyperoxaemia on neurological outcomes and mortality in hospitalised patients with ABI. We will use covariate-adjusted ORs as outcome measures when reported since they account for potential cofounders and provide a more accurate estimate of the association between hyperoxaemia and outcomes; when not available, we will use univariate ORs. If the study presents the results as relative risks, it will be considered equivalent to the OR as long as the prevalence of the condition is close to 10%. Pooled estimates of both outcomes will be calculated applying random-effects meta-analysis. Interstudy heterogeneity will be assessed using the I2 statistic; risk of bias will be assessed through Risk Of Bias In Non-Randomised Studies of Interventions, Newcastle-Ottawa or RoB2 tools. Depending on data availability, we plan to conduct subgroup analyses by ABI type (traumatic brain injury, postcardiac arrest, subarachnoid haemorrhage, intracerebral haemorrhage and ischaemic stroke), arterial partial pressure of oxygen values, study quality, study time, neurological scores and other selected clinical variables of interest.

ETHICS AND DISSEMINATION

Specific ethics approval consent is not required as this is a review of previously published anonymised data. Results of the study will be shared with the scientific community via publication in a peer-reviewed journal and presentation at relevant conferences and workshops. It will also be shared key stakeholders, such as national or international health authorities, healthcare professionals and the general population, via scientific outreach journals and research institutes' newsletters.

Prospective randomized controlled trial on the safety and neuroprotective efficacy of remote administration of hypothermia over spleen during acute ischemic stroke with mechanical thrombectomy: rationale, design, and protocol

Background

Brain inflammation plays a key role in ischemia/reperfusion (I/R) injury and is the main cause of "ineffective or futile recanalization" after successful mechanical thrombectomy (MT) in acute ischemic stroke (AIS). One of the primary sources of inflammatory cells after AIS are derived from the spleen. As an innovative and potential neuroprotective strategy after stroke, Remote Administration of Hypothermia (RAH) temporarily suppresses immune activities in the spleen, reduces the release of inflammatory cells and cytokines into blood, and thus reversibly diminishes inflammatory injury in the brain.

Methods

This single-center, prospective, randomized controlled study (RCT) is proposed for AIS patients with anterior circulation large vessel occlusion (LVO). Subjects will be randomly assigned to either the control or intervention groups in a 1:1 ratio (n = 40). Participants allocated to the intervention group will receive RAH on the abdomen above the spleen prior to recanalization until 6 h after thrombectomy. All enrolled patients will receive standard stroke Guideline care. The main adverse events associated with RAH are focal cold intolerance and abdominal pain. The primary outcome will assess safety as it pertains to RAH application. The secondary outcomes include the efficacy of RAH on spleen, determined by spleen volumes, blood inflammatory factor (cells and cytokines), and on brain injury, determined by infarction volumes and poststroke functional outcomes.

Discussion

This study aims to examine the safety and preliminary effectiveness of RAH over the spleen during endovascular therapy in AIS patients. The results of this study are expected to facilitate larger randomized clinical trials and hopefully prove RAH administration confers adjuvant neuroprotective properties in AIS treated with MT.

Clinical trial registration

https://www.chictr.org.cn/. Identifier ChiCTR 2300077052.

The neuroprotective effects of normobaric oxygen therapy after stroke

BACKGROUND

Stroke, including ischemic and hemorrhagic stroke, is a severe and prevalent acute cerebrovascular disease. The development of hypoxia following stroke can trigger a cascade of pathological events, including mitochondrial dysfunction, energy deficiency, oxidative stress, neuroinflammation, and excitotoxicity, all of which are often associated with unfavorable prognosis. Nonetheless, a noninvasive intervention, referred to as normobaric hyperoxia (NBO), is known to have neuroprotective effects against stroke.

RESULTS

NBO can exert neuroprotective effects through various mechanisms, such as the rescue of hypoxic tissues, preservation of the blood-brain barrier, reduction of brain edema, alleviation of neuroinflammation, improvement of mitochondrial function, mitigation of oxidative stress, reduction of excitotoxicity, and inhibition of apoptosis. These mechanisms may help improve the prognosis of stroke patients.

CONCLUSIONS

This review summarizes the mechanism by which hypoxia causes brain injury and how NBO can act as a neuroprotective therapy to treat stroke. We conclude that NBO has significant potential for treating stroke and may represent a novel therapeutic strategy.

The Role of the Complement System in Synaptic Pruning after Stroke

Stroke is a serious disease that can lead to local neurological dysfunction and cause great harm to the patient's health due to blood cerebral circulation disorder. Synaptic pruning is critical for the normal development of the human brain, which makes the synaptic circuit completer and more efficient by removing redundant synapses. The complement system is considered a key player in synaptic loss and cognitive impairment in neurodegenerative disease. After stroke, the complement system is over-activated and complement proteins can be labeled on synapses. Microglia and astrocytes can recognize and engulf synapses through corresponding complement receptors. Complement-mediated excessive synaptic pruning can cause post-stroke cognitive impairment (PSCI) and secondary brain damage. This review summarizes the latest progress of complement-mediated synaptic pruning after stroke and the potential mechanisms. Targeting complement-mediated synaptic pruning may be essential for exploring therapeutic strategies for secondary brain injury (SBI) and neurological dysfunction after stroke.

Normobaric Hyperoxia Combined With Endovascular Treatment Based on Temporal Gradient: A Dose-Escalation Study

BACKGROUND

Normobaric hyperoxia (NBO) has neuroprotective effects in acute ischemic stroke. Thus, we aimed to identify the optimal NBO treatment duration combined with endovascular treatment.

METHODS

This is a single-center, randomized controlled, open-label, blinded-end point dose-escalation clinical trial. Patients with acute ischemic stroke who had an indication for endovascular treatment at Tianjin Huanhu Hospital were randomly assigned to 4 groups (1:1 ratio) based on NBO therapy duration: (1) control group (1 L/min oxygen for 4 hours); (2) NBO-2h group (10 L/min for 2 hours); (3) NBO-4h group (10 L/min for 4 hours); and (4) NBO-6h group (10 L/min for 6 hours). The primary outcome was cerebral infarction volume at 72 hours after randomization using an intention-to-treat analysis model. The primary safety outcome was the 90-day mortality rate.

RESULTS

Between June 2022 and September 2023, 100 patients were randomly assigned to the following groups: control group (n=25), NBO-2h group (n=25), NBO-4h group (n=25), and NBO-6h group (n=25). The 72-hour cerebral infarct volumes were 39.4±34.3 mL, 30.6±30.1 mL, 19.7±15.4 mL, and 22.6±22.4 mL, respectively (P=0.013). The NBO-4h and NBO-6h groups both showed statistically significant differences (adjusted P values: 0.011 and 0.027, respectively) compared with the control group. Compared with the control group, both the NBO-4h and NBO-6h groups showed significant differences (P<0.05) in the National Institutes of Health Stroke Scale scores at 24 hours, 72 hours, and 7 days, as well as in the change of the National Institutes of Health Stroke Scale scores from baseline to 24 hours. Additionally, there were no significant differences among the 4 groups in terms of 90-day mortality rate, symptomatic intracranial hemorrhage, early neurological deterioration, or severe adverse events.

CONCLUSIONS

The effectiveness of NBO therapy was associated with oxygen administration duration. Among patients with acute ischemic stroke who underwent endovascular treatment, NBO therapy for 4 and 6 hours was found to be more effective. Larger-scale multicenter studies are needed to validate these findings.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05404373.

Effect of a helium and oxygen mixture on physiological parameters of rats with cerebral arterial air embolism

Introduction: Cerebral arterial air embolism (CAE) is a serious and potentially dangerous condition that can interrupt the blood supply to the brain and cause stroke. One of the promising gas mixtures for emergency treatment of air embolism is an oxygen-helium mixture. Methods: We modeled CAE in awake rats by injecting air into the common carotid artery. Immediately after CAE, animals were either untreated or underwent hyperbaria, oxygen inhalation, heated air inhalation, or helium-oxygen mixture inhalation. Body temperature, locomotor activity, respiratory and cardiovascular parameters were monitored in the animals before CAE modeling, and 3 and 24 h after CAE modeling. Results: After 3 hours of CAE modeling in awake rats, depression of the nervous, cardiovascular and respiratory systems, as well as decreased body temperature were observed. 24 h after CAE modeling multifocal cerebral ischemia was observed. Normobaric helium-oxygen mixture inhalation, on par with hyperbaric treatment, restored body temperature, locomotor activity, respiratory volume, respiratory rate, and blood pressure 3 hours after CAE, and prevented the formation of ischemic brain damage lesions 24 h after CAE. Discussion: Thus, inhalation of a heated oxygen-helium gas mixture (O2 30% and He 70%) immediately after CAE improves the physiological condition of the animals and prevents the foci of ischemic brain damage formation.

Neuroprotection during Thrombectomy for Acute Ischemic Stroke: A Review of Future Therapies

Stroke is a major cause of death and disability worldwide. Endovascular thrombectomy has been impactful in decreasing mortality. However, many clinical results continue to show suboptimal functional outcomes despite high recanalization rates. This gap in recanalization and symptomatic improvement suggests a need for adjunctive therapies in post-thrombectomy care. With greater insight into ischemia-reperfusion injury, recent preclinical testing of neuroprotective agents has shifted towards preventing oxidative stress through upregulation of antioxidants and downstream effectors, with positive results. Advances in multiple neuroprotective therapies, including uric acid, activated protein C, nerinetide, otaplimastat, imatinib, verapamil, butylphthalide, edaravone, nelonemdaz, ApTOLL, regional hypothermia, remote ischemic conditioning, normobaric oxygen, and especially nuclear factor erythroid 2-related factor 2, have promising evidence for improving stroke care. Sedation and blood pressure management in endovascular thrombectomy also play crucial roles in improved stroke outcomes. A hand-in-hand approach with both endovascular therapy and neuroprotection may be the key to targeting disability due to stroke.

Penumbral Rescue by normobaric O = O administration in patients with ischemic stroke and target mismatch proFile (PROOF): Study protocol of a phase IIb trial

RATIONALE

Oxygen is essential for cellular energy metabolism. Neurons are particularly vulnerable to hypoxia. Increasing oxygen supply shortly after stroke onset could preserve the ischemic penumbra until revascularization occurs.

AIMS

PROOF investigates the use of normobaric oxygen (NBO) therapy within 6 h of symptom onset/notice for brain-protective bridging until endovascular revascularization of acute intracranial anterior-circulation occlusion.

METHODS AND DESIGN

Randomized (1:1), standard treatment-controlled, open-label, blinded endpoint, multicenter adaptive phase IIb trial.

STUDY OUTCOMES

Primary outcome is ischemic core growth (mL) from baseline to 24 h (intention-to-treat analysis). Secondary efficacy outcomes include change in NIHSS from baseline to 24 h, mRS at 90 days, cognitive and emotional function, and quality of life. Safety outcomes include mortality, intracranial hemorrhage, and respiratory failure. Exploratory analyses of imaging and blood biomarkers will be conducted.

SAMPLE SIZE

Using an adaptive design with interim analysis at 80 patients per arm, up to 456 participants (228 per arm) would be needed for 80% power (one-sided alpha 0.05) to detect a mean reduction of ischemic core growth by 6.68 mL, assuming 21.4 mL standard deviation.

DISCUSSION

By enrolling endovascular thrombectomy candidates in an early time window, the trial replicates insights from preclinical studies in which NBO showed beneficial effects, namely early initiation of near 100% inspired oxygen during short temporary ischemia. Primary outcome assessment at 24 h on follow-up imaging reduces variability due to withdrawal of care and early clinical confounders such as delayed extubation and aspiration pneumonia.

TRIAL REGISTRATIONS

ClinicalTrials.gov: NCT03500939; EudraCT: 2017-001355-31.

Normobaric Hyperoxia (NBHO): An Adjunctive Therapy to Cerebrovascular Recanalization in Ischemic Stroke

Acute ischemic stroke (AIS) is a serious neurological disease. Normobaric hyperoxia (NBHO) is both a non-invasive and easy method that seems to be able to improve outcomes after cerebral ischemia/reperfusion. In clinical trials, normal low-flow oxygen has been shown to be ineffective, but NBHO has been shown to have a transient brain-protective effect. Today, NBHO combined with recanalization is the best treatment available. NBHO combined with thrombolysis is considered to improve neurological scores and long-term outcomes. Large randomized controlled trials (RCTs), however, are still needed to determine the role they will have in stroke treatment. RCTs of NBHO combined with thrombectomy have both improved infarct volume at 24 hours and the long-term prognosis. These two mechanisms most likely play key roles in the neuroprotective actions of NBHO after recanalization, including the increase in penumbra oxygen supply and the integrity of the blood-brain barrier (BBB). Considering the mechanism of action of NBHO, oxygen should be given as early as possible to increase the duration of oxygen therapy before recanalization is initiated. NBHO can further prolong the existence time of penumbra, so that more patients may benefit from it. Overall, however, recanalization therapy is still essential.

Arterial Glyceryl Trinitrate in Acute Ischemic Stroke After Thrombectomy for Neuroprotection (AGAIN): A Pilot Randomized Controlled Trial

Although endovascular therapy demonstrates robust clinical efficacy in acute ischemic stroke (AIS), not all stroke patients benefit from successful reperfusion. This study aimed to evaluate the safety, feasibility, and preliminary efficacy of intra-arterial administration of glyceryl trinitrate (GTN) after endovascular recanalization for neuroprotection. This is a prospective randomized controlled study. Eligible patients were randomized to receive 800 μg GTN or the same volume of normal saline through the catheter after recanalization. The primary outcome was symptomatic intracranial hemorrhage (ICH), while secondary outcomes included mortality, functional outcome, infarction volume, complications, and blood nitrate index (NOx). A total of 40 patients were enrolled and randomized with no participants being lost to follow-up. There was no significant difference in the proportion of sICH between GTN and control groups. Additionally, no significant difference was observed in mortality or rates of neurological deterioration and other complications. Favorable trends, while non-significant, were noted in both outcome and imaging for functional independence at 90 days and reduction in final infarct volume (75.0% vs 65.0%; 33.2 vs 38.9 ml) for the GTN group. Moreover, the concentration of blood NOx in the GTN group was significantly higher than in the control group at 2 h after GTN administration (26.2 vs 18.0 μmol/l, p < 0.05). The AGAIN study suggests intra-arterial administration of GTN post-endovascular therapy is safe and feasible and GTN successfully raised NOx levels over controls at 2 h. A multi-center randomized controlled trial with a larger sample size is warranted to determine GTN neoadjuvant efficacy.

Higher versus lower fractions of inspired oxygen or targets of arterial oxygenation for adults admitted to the intensive care unit

BACKGROUND

This is an updated review concerning 'Higher versus lower fractions of inspired oxygen or targets of arterial oxygenation for adults admitted to the intensive care unit'. Supplementary oxygen is provided to most patients in intensive care units (ICUs) to prevent global and organ hypoxia (inadequate oxygen levels). Oxygen has been administered liberally, resulting in high proportions of patients with hyperoxemia (exposure of tissues to abnormally high concentrations of oxygen). This has been associated with increased mortality and morbidity in some settings, but not in others. Thus far, only limited data have been available to inform clinical practice guidelines, and the optimum oxygenation target for ICU patients is uncertain. Because of the publication of new trial evidence, we have updated this review.

OBJECTIVES

To update the assessment of benefits and harms of higher versus lower fractions of inspired oxygen (FiO2) or targets of arterial oxygenation for adults admitted to the ICU.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, BIOSIS Previews, and LILACS. We searched for ongoing or unpublished trials in clinical trial registers and scanned the reference lists and citations of included trials. Literature searches for this updated review were conducted in November 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared higher versus lower FiO2 or targets of arterial oxygenation (partial pressure of oxygen (PaO2), peripheral or arterial oxygen saturation (SpO2 or SaO2)) for adults admitted to the ICU. We included trials irrespective of publication type, publication status, and language. We excluded trials randomising participants to hypoxaemia (FiO2 below 0.21, SaO2/SpO2 below 80%, or PaO2 below 6 kPa) or to hyperbaric oxygen, and cross-over trials and quasi-randomised trials.

DATA COLLECTION AND ANALYSIS

Four review authors independently, and in pairs, screened the references identified in the literature searches and extracted the data. Our primary outcomes were all-cause mortality, the proportion of participants with one or more serious adverse events (SAEs), and quality of life. We analysed all outcomes at maximum follow-up. Only three trials reported the proportion of participants with one or more SAEs as a composite outcome. However, most trials reported on events categorised as SAEs according to the International Conference on Harmonisation Good Clinical Practice (ICH-GCP) criteria. We, therefore, conducted two analyses of the effect of higher versus lower oxygenation strategies using 1) the single SAE with the highest reported proportion in each trial, and 2) the cumulated proportion of participants with an SAE in each trial. Two trials reported on quality of life. Secondary outcomes were lung injury, myocardial infarction, stroke, and sepsis. No trial reported on lung injury as a composite outcome, but four trials reported on the occurrence of acute respiratory distress syndrome (ARDS) and five on pneumonia. We, therefore, conducted two analyses of the effect of higher versus lower oxygenation strategies using 1) the single lung injury event with the highest reported proportion in each trial, and 2) the cumulated proportion of participants with ARDS or pneumonia in each trial. We assessed the risk of systematic errors by evaluating the risk of bias in the included trials using the Risk of Bias 2 tool. We used the GRADEpro tool to assess the overall certainty of the evidence. We also evaluated the risk of publication bias for outcomes reported by 10b or more trials.

MAIN RESULTS

We included 19 RCTs (10,385 participants), of which 17 reported relevant outcomes for this review (10,248 participants). For all-cause mortality, 10 trials were judged to be at overall low risk of bias, and six at overall high risk of bias. For the reported SAEs, 10 trials were judged to be at overall low risk of bias, and seven at overall high risk of bias. Two trials reported on quality of life, of which one was judged to be at overall low risk of bias and one at high risk of bias for this outcome. Meta-analysis of all trials, regardless of risk of bias, indicated no significant difference from higher or lower oxygenation strategies at maximum follow-up with regard to mortality (risk ratio (RR) 1.01, 95% confidence interval (C)I 0.96 to 1.06; I2 = 14%; 16 trials; 9408 participants; very low-certainty evidence); occurrence of SAEs: the highest proportion of any specific SAE in each trial RR 1.01 (95% CI 0.96 to 1.06; I2 = 36%; 9466 participants; 17 trials; very low-certainty evidence), or quality of life (mean difference (MD) 0.5 points in participants assigned to higher oxygenation strategies (95% CI -2.75 to 1.75; I2 = 34%, 1649 participants; 2 trials; very low-certainty evidence)). Meta-analysis of the cumulated number of SAEs suggested benefit of a lower oxygenation strategy (RR 1.04 (95% CI 1.02 to 1.07; I2 = 74%; 9489 participants; 17 trials; very low certainty evidence)). However, trial sequential analyses, with correction for sparse data and repetitive testing, could reject a relative risk increase or reduction of 10% for mortality and the highest proportion of SAEs, and 20% for both the cumulated number of SAEs and quality of life. Given the very low-certainty of evidence, it is necessary to interpret these findings with caution. Meta-analysis of all trials indicated no statistically significant evidence of a difference between higher or lower oxygenation strategies on the occurrence of lung injuries at maximum follow-up (the highest reported proportion of lung injury RR 1.08, 95% CI 0.85 to 1.38; I2 = 0%; 2048 participants; 8 trials; very low-certainty evidence). Meta-analysis of all trials indicated harm from higher oxygenation strategies as compared with lower on the occurrence of sepsis at maximum follow-up (RR 1.85, 95% CI 1.17 to 2.93; I2 = 0%; 752 participants; 3 trials; very low-certainty evidence). Meta-analysis indicated no differences regarding the occurrences of myocardial infarction or stroke.

AUTHORS' CONCLUSIONS

In adult ICU patients, it is still not possible to draw clear conclusions about the effects of higher versus lower oxygenation strategies on all-cause mortality, SAEs, quality of life, lung injuries, myocardial infarction, stroke, and sepsis at maximum follow-up. This is due to low or very low-certainty evidence.

Ventilation Targets for Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke: A Systematic Review

Mechanical thrombectomy (MT) has become a standard treatment for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). Recent evidence suggests that general anesthesia (GA) and mechanical ventilation do not lead to inferior neurologic outcomes if compared to non-GA. However, the guidelines lack specific recommendations for ventilation targets during MT under GA. This systematic review aims to identify ventilation strategies correlating with better neurological outcomes in AIS patients undergoing MT, particularly focusing on oxygenation and carbon dioxide (CO2) targets. A systematic search of multiple databases was conducted to identify human studies reporting the correlation between ventilation strategies and neurological outcomes in MT for AIS. Eligible studies included clinical trials, observational studies, and case-control studies. Out of 157 studies assessed, 11 met the inclusion criteria. Five studies investigated oxygenation targets, while six studies explored CO2 targets. The published studies highlighted the controversial role of supplemental normobaric oxygen therapy and its potential association with worse outcomes. Regarding CO2 targets, the studies identified a potential association between end tidal CO2 levels and functional outcomes, with hypocapnia being unfavorable. This systematic review demonstrates that the current available evidence still lacks strength to suggest specific ventilation targets, but it highlights the potential risks of hyperoxia and hypocapnia in this specific cohort of patients.

Vertebrobasilar artery cooling infusion in acute ischemic stroke for posterior circulation following thrombectomy: Rationale, design and protocol for a prospective randomized controlled trial

BACKGROUND

Although endovascular mechanical thrombectomy demonstrates clinical efficacy in posterior circulation acute ischemic stroke (AIS), only one third of these patients attain functional independence with a third of patients' expiring despite vascular recanalization. Neuroprotection strategies, such as therapeutic hypothermia (TH) have been considered a promising adjunctive treatment in AIS. We propose the following rationale, design and protocol for a prospective randomized controlled trial (RCT) aimed to determine whether Vertebrobasilar Artery Cooling Infusion (VACI) improves functional outcomes in posterior circulation AIS patients post mechanical thrombectomy.

METHODS

Subjects in the study will be assigned randomly to either the cooling infusion or the control group in a 1:1 ratio (n = 40). Patients allocated to the cooling infusion group will receive 300 ml cool saline at 4C through the catheter (30 ml/min) into vertebral artery after thrombectomy. The control group will receive the same volume of 37C saline. All patients enrolled will receive standard care according to current guidelines for stroke management. The primary outcome is symptomatic intracranial hemorrhage (ICH), whereas the secondary outcomes include functional outcome score, infarction volume, mortality, ICH, fatal ICH, cerebral vasospasm, coagulation abnormality, pneumonia and urinary infection.

DISCUSSIONS

This study will determine the preliminary safety, feasibility, and neuroprotective benefits of VACI in posterior circulation AIS patients with reperfusion therapy. The results of this study may provide evidence for VACI as a new therapy in posterior circulation AIS.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, ChiCTR2200065806, registered on November 15, 2022.

Arterial Glyceryl Trinitrate in Acute Ischemic Stroke after Thrombectomy for Neuroprotection (AGAIN): Rationale, design and protocol for a prospective randomized controlled trial

BACKGROUND

Although endovascular recanalization therapy demonstrates robust clinical efficacy in acute ischemic stroke (AIS), not all victims of these cerebrovascular accidents can benefit from it and achieve a favorable prognosis after successful reperfusion. Therefore, alternative neuroprotective strategies are urgently needed for AIS patients after vessel recanalization. Nitric oxide (NO) levels are low after AIS and NO donor drugs may be neuroprotective against cerebral ischemia-reperfusion injury. Glyceryl trinitrate (GTN), often used in the clinic as a NO donor, may provide a novel neuroprotective strategy. This rationale, design, and protocol for a prospective pilot study plans to explore the preliminary safety, feasibility, and neuroprotective benefits of Arterial Glyceryl Trinitrate in Acute Ischemic Stroke after Thrombectomy for Neuroprotection (AGAIN).

METHODS

AGAIN, a prospective RCT, is proposed for AIS patients after mechanical thrombectomy. Subjects will be randomly assigned in a 1:1 fashion (n = 40) to either the control group or the intervention group. Participants assigned to the intervention group will be administered 800 μg GTN in the catheter immediately after recanalization, whereas those in the control group will be administered the same volume of normal saline. All participants from either group will be given concurrent treatment with standard of care therapies in accordance with the current guidelines for stroke management. The primary outcome is safety [symptomatic intracranial hemorrhage (ICH), hypotension, neurological deterioration, ICH, fatal ICH, as well as headache, tachycardia, emesis, and seizures], whereas secondary outcomes included changes in poststroke functional outcomes, infarction volumes, and blood nitrate index detection.

DISCUSSIONS

This study is a prospective randomized controlled trial to test the safety and efficacy of intra-arterial GTN in AIS patients after endovascular therapy. The results from this study will give insight for future GTN studies and new neuroprotective strategies for future AIS treatment strategies.

TRIAL REGISTRATION NUMBER

ChiCTR2100045254. Registered on March 21, 2021.

Influence of neutrophil-to-lymphocyte ratio and mean platelet volume on severity and short-term prognosis of acute ischemic stroke

OBJECTIVE

To investigate the influence of neutrophil-to-lymphocyte ratio (NLR) and mean platelet volume (MPV) on the severity and short-term prognosis of acute ischemic stroke (AIS).

METHODS

A retrospective analysis was made on 188 AIS patients treated in our hospital from June 2019 to June 2021. They were divided into mild stroke group and severe stroke group based on NIHSS score. In view of the modified Rankin score (mRS) on 14th day after stroke, patients were divided into good prognosis group and bad prognosis group. The clinical data, NLR and MPV data of each group were compared, and the independent risk factors of short-term poor prognosis of AIS patients were analyzed by multivariate Logistic regression.

RESULTS

NLR and MPV in patients with mild stroke were lower than those with severe stroke (P<0.05). In addition, NLR and MPV of patients with good prognosis were lower than those with poor prognosis (P<0.05). Regression analysis revealed that high NLR and MPV were independent predictors of short-term poor prognosis of AIS patients. The AUC of NLR in predicting the poor prognosis of patients after 14 days of stroke was 0.904, and the specificity and sensitivity were 70.55% and 97.62%. A. AUC of MPV was 0.904, and the specificity and sensitivity were 92.47% and 85.71%. B. Pearson correlation analysis revealed that NLR was positively correlated with MPV (r=0.452, P<0.001).

CONCLUSION

The elevation of NLR and MPV may be independent risk factors of AIS, but it is related to the severity of stroke and short-term prognosis.

Systematic Review - Combining Neuroprotection With Reperfusion in Acute Ischemic Stroke

Background

Clinical trials of neuroprotection in acute ischemic stroke (AIS) have provided disappointing results. Reperfusion may be a necessary condition for positive effects of neuroprotective treatments. This systematic review provides an overview of efficacy of neuroprotective agents in combination with reperfusion therapy in AIS.

Methods

A literature search was performed on the following databases, namely PubMed, Embase, Web of Science, Cochrane Library, Emcare. All databases were searched up to September 23rd 2021. All randomized controlled trials in which patients were treated with neuroprotective strategies within 12 h of stroke onset in combination with intravenous thrombolysis (IVT), endovascular therapy (EVT), or both were included.

Results

We screened 1,764 titles/abstracts and included 30 full reports of unique studies with a total of 16,160 patients. In 15 studies neuroprotectants were tested for clinical efficacy, where all patients had to receive reperfusion therapies, either IVT and/or EVT. Heterogeneity in reported outcome measures was observed. Treatment was associated with improved clinical outcome for: 1) uric acid in patients treated with EVT and IVT, 2) nerinetide in patients who underwent EVT without IVT, 3) imatinib in stroke patients treated with IVT with or without EVT, 4) remote ischemic perconditioning and IVT, and 5) high-flow normobaric oxygen treatment after EVT, with or without IVT.

Conclusion

Studies specifically testing effects of neuroprotective agents in addition to IVT and/or EVT are scarce. Future neuroprotection studies should report standardized functional outcome measures and combine neuroprotective agents with reperfusion therapies in AIS or aim to include prespecified subgroup analyses for treatment with IVT and/or EVT.

Normobaric Oxygen (NBO) Therapy Reduces Cerebral Ischemia/Reperfusion Injury through Inhibition of Early Autophagy

Objectives

Normobaric oxygen (NBO) therapy has great clinical potential in the treatment of ischemic stroke, but its underlying mechanism is unknown. Our study aimed to investigate the role of autophagy during the application of NBO on cerebral ischemia/reperfusion injury.

Methods

Male Sprague Dawley rats received 2 hours of middle cerebral artery occlusion (MCAO), followed by 2, 6, or 24 hours of reperfusion. At the beginning of reperfusion, rats were randomly given NBO (95% O₂) or room air (21% O₂) for 2 hours. In some animals, 3-methyladenine (3-MA, autophagy inhibitor) was administered 10 minutes before reperfusion. The severity of the ischemic injury was determined by infarct volume, neurological deficit, and apoptotic cell death. Western blotting was used to determine the protein expression of autophagy and apoptosis, while mRNA expression of apoptotic molecules was detected by real-time PCR.

Results

NBO treatment after ischemia/reperfusion significantly decreased infarct volume and neurobehavioral defects. The increased expression of the autophagy markers, including microtubule-associated protein 1A light chain 3 (LC3) and Beclin 1, after ischemia/reperfusion was reversed by NBO, while promoting Sequestosome 1 (p62/SQSTM1) expression. In addition, NBO reduced cerebral apoptosis in association with alleviated BAX expression and increased BCL-2 expression. 3-MA reduced autophagy and apoptotic death but did not further improve NBO-attenuated ischemic damage.

Conclusion

NBO induced remarkable neuroprotection from ischemic injury, which was correlated with blocked autophagy activity.