Remote ischaemic conditioning (RIC) refers to a process whereby periods of intermittent ischaemia, typically via the cyclical application of a blood pressure cuff to a limb at above systolic pressure, confers systemic protection against ischaemia in spatially distinct vascular territories. The mechanisms underlying this have not been characterised fully but have been shown to involve neural, hormonal and systemic inflammatory signalling cascades. Preclinical and early clinical studies have been promising and suggest beneficial effects of RIC in acute ischaemic stroke, symptomatic intracranial stenosis and vascular cognitive impairment. Through systematic searches of several clinical trials databases we identified 48 active clinical trials of RIC in ischaemic stroke, intracerebral haemorrhage and subarachnoid haemorrhage. We summarise the different RIC protocols and outcome measures studied in ongoing clinical trials and highlight which studies are most likely to elucidate the underlying biological mechanisms of RIC and characterise its efficacy in the near future. We discuss the uncertainties of RIC including the optimal frequency and duration of therapy, target patient groups, cost-effectiveness, the confounding impact of medications and the absence of a clinically meaningful biomarker of the conditioning response. With several large clinical trials of RIC expected to report their outcomes within the next 2 years, this review aims to highlight the most important studies and unanswered questions that will need to be addressed before this potentially widely accessible and low-cost intervention can be used in clinical practice.

中文翻译：

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中风的远程缺血调节：未解决的问题和未来方向

远程缺血调节 (RIC) 是指间歇性缺血的过程，通常通过在高于收缩压的肢体上循环应用血压袖带，在空间上不同的血管区域提供针对缺血的全身保护。其背后的机制尚未完全表征，但已显示涉及神经、激素和全身炎症信号级联。临床前和早期临床研究很有希望，并表明 RIC 在急性缺血性中风、症状性颅内狭窄和血管性认知障碍中的有益作用。通过对几个临床试验数据库的系统搜索，我们确定了 48 项 RIC 在缺血性中风、脑出血和蛛网膜下腔出血中的活跃临床试验。我们总结了正在进行的临床试验中研究的不同 RIC 方案和结果测量，并强调哪些研究最有可能阐明 RIC 的潜在生物学机制并在不久的将来描述其疗效。我们讨论了 RIC 的不确定性，包括最佳治疗频率和持续时间、目标患者群体、成本效益、药物的混杂影响以及缺乏具有临床意义的调节反应生物标志物。RIC 的几项大型临床试验预计将在未来 2 年内报告其结果，本综述旨在强调最重要的研究和未回答的问题，在这种潜在的广泛可及的低成本干预措施可用于临床实践。