The protective effects of dexmedetomidine on ischemic brain injury: A meta-analysis

Intracranial lesions, trauma or surgery-related damage activate immune inflammation and neuroendocrine responses, causing ischemic brain injury. Studies have shown that inflammatory cascade mediated by neuroendocrine hormones and proinflammatory mediators is implicated in the pathophysiology of ischemic brain injury. Alpha2-adrenoceptor agonists, dexmedetomidine, is widely used as neuroprotectants in anesthesia practice. However, it is still lack of a comprehensive meta-analysis to evaluate the neuroprotection of dexmedetomidine against ischemic brain injury via suppressing these two physiological responses. Searched the Cochrane Library, Pub-Med, EMBASE, EBSCO, Ovid, Chinese biological and medical database (CBM). Related literatures published in English or Chinese before January 2017 were enrolled. We assessed the quality of eligible studies and synthesized predefined outcomes with a random-effects model or fixed-effects model. Nineteen Randomized Controlled Trials including 879 patients were included. Findings for meta-analysis of various outcomes were summarised. Primary results shown that compared with placebo, dexmedetomidine reduced a surge of TNF-α [SMD = − 2.34, 95%CI (− 3.25, − 1.44)], IL-6 [SMD = − 2.44, 95%CI (− 3.40, − 1.47)], S100-β [SMD = − 2.73, 95%CI (− 3.65, − 1.82)], NSE [SMD = − 1.69, 95%CI (− 2.77, − 0.61)], cortisol [SMD = − 2.48, 95%CI (− 3.38, − 1.58)] and glucose [SMD = − 1.44, 95%CI (− 1.85, − 1.04)]; maintained the level of SOD [SMD = 1.36, 95%CI (0.62, 2.10)]; decreased the rise in CRP level at postoperative one day. In response to stress reaction, dexmedetomidine attenuated the stress-related increasing of MAP, HR and intracranial pressure without significant effects on cerebral oxygen metabolism. Alpha2-adrenoceptor agonists, dexmedetomidine, could reduce the release of inflammatory mediators and neuroendocrine hormones as well as maintain intracranial homoeostasis, alleviating ischemic brain injury and exerting an effect on brain protection.