Impact of inhalational anesthetics on postoperative cognitive function: Study protocol of a systematic review and meta-analysis

BACKGROUND: Conflict findings of the impact of inhalational anesthetics on postoperative cognitive function are reported. No systematic review has been performed to solve the problem. The aim of the study was to assess the effect of different inhalational anesthetics on postoperative cognitive function in a network meta-analysis. METHODS: We will search MEDLINE, EMBASE, the Central Register of Controlled Trials in the Cochrane library, and CINAHL for randomized controlled trials or cohort studies assessing the short-term or long-term cognitive function of elderly patients (over 60 years) receiving major surgeries and inhalational anesthetics (desflurane, isoflurane, sevoflurane, halothane, and nitrous oxide) during surgery. Two reviewers will independently screen study eligibility, extract information from eligible studies, and appraise study quality. The impact of inhalational anesthetics will be assessed through: incidence of postoperative cognitive dysfunction at 1 week, 3 months, 1 year, and over 1 year after surgery; incidence of post-operative delirium; test of postoperative cognitive function. RESULTS: The results of this systematic review and meta-analysis will be published in a peer-reviewed journal. CONCLUSION: To our knowledge, this systematic review will be the first to evaluate existing research on the incidence of postoperative cognitive function after inhalational anesthetics. Our study will assess the effect of different inhalational anesthetics on postoperative cognitive function. ETHICS AND DISSEMINATION: The review will be finished in December 2017, and the result will be published in a peer-reviewed journal or disseminated through conference posters or abstracts. REVIEW REGISTRATION NUMBER: CRD42017056675 (www.crd.york.ac.uk/PROSPERO).