The efficacy and safety of pre-emptive methoxamine infusion in preventing hypotension by in elderly patients receiving spinal anesthesia: A PRISMA-compliant protocol for systematic review and meta-analysis

Hypotension is frequent after spinal anesthesia, especially in elderly patients. Whether pre-emptive methoxamine infusion is effective and safe to prevent spinal anesthesia-induced hypotension is still a controversial issue, to dress this knowledge lack, we performed a systemic review and meta-analysis to evaluated it. PARTICIPANTS: Elderly patients undergoing spinal anesthesia. INTERVENTIONS: Administration of methoxamine prior to spinal anesthesia. METHODS: We searched PUBMED, Cochrane Library, EMBASE, China National Knowledge Infrastructure, Wanfang Database, and VIP Database, Chinese BioMedical Literature & Retrieval System from January 1(st) 1978 to February 28(th) 2022. Primary outcomes of interests included hemodynamic parameters, such as systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate. Secondary outcomes of interests included the incidence of intraoperative hypotension, bradycardia, nausea and vomiting, vasopressors requirement, intraoperative blood loss. For continuous or dichotomous variables, treatment effects were calculated as weighted mean difference or odds ratio, respectively. RESULTS: Our search yielded 8 randomized controlled trials including 480 patients, and 240 patients were allocated into methoxamine group and 240 into control group. Meta-analysis demonstrated that pre-emptive methoxamine infusion in preventing hypotension by in elderly patients receiving spinal anesthesia had higher blood pressures, lower heart rates. Compared with the control group, the incidence of perioperative hypotension in elderly patients was lower, and elderly patients had less requirement for vasopressor in methoxamine group. CONCLUSION: This meta-analysis demonstrated that pre-emptive methoxamine infusion in elderly patients receiving spinal anesthesia can improve blood pressure, slow down heart rate, reduce the incidence of hypotension and requirement for vasopressor. However, these findings should be interpreted rigorously. Further well-conducted trials are required to confirm this.