The Use of Metaraminol as a Vasopressor in Critically Unwell Patients: A Narrative Review and a Survey of UK Practice.

Background: Major international guidelines state that norepinephrine should be used as the first-line vasopressor to achieve adequate blood pressure in patients with hypotension or shock. However, recent observational studies report that in the United Kingdom and Australia, metaraminol is often used as second line medication for cardiovascular support. Aim of the study: The aim of this study was to carry out a systematic review of metaraminol use for management of shock in critically unwell patients and carry out a survey evaluating whether UK critical care units use metaraminol and under which circumstances. Methods: A systematic review literature search was conducted. A short telephone survey consisting of 6 questions regarding metaraminol use was conducted across 30 UK critical care units which included a mix of tertiary and district general intensive care units. Results: Twenty-six of thirty contacted centres responded to our survey. Metaraminol was used in 88% of them in various settings and circumstances (emergency department, theatres, medical emergencies on medical wards), with 67% reporting use of metaraminol infusions in the critical care setting. The systematic literature review revealed several case reports and only two studies conducted in the last 20 years investigating the effect of metaraminol as a stand-alone vasopressor. Both studies focused on different aspects of metaraminol use and the data was incomparable, hence we decided not to perform a meta-analysis. Conclusions: Metaraminol is widely used as a vasopressor inside and outside of the critical care setting in the UK despite limited evidence supporting its safety and efficacy for treating shock. Further service evaluation, observational studies and prospective randomised controlled trials are warranted to validate the role and safety profile of metaraminol in the treatment of the critically unwell patient.