Comparison of metaraminol versus no metaraminol on time to resolution of shock in critically ill patients

Safety and efficacy of peripheral metaraminol infusion in patients with neurological conditions: a single-center retrospective observational study

Introduction

Metaraminol is a sympathomimetic amine vasopressor that can be administrated through a peripheral venous access. However, limited evidence restricts its application in critically ill patients. This study aimed to investigate the safety and efficacy of peripheral metaraminol infusion in patients with neurological conditions.

Methods

Patients who received peripheral metaraminol infusion between May 2019 and April 2022 were recruited. Data on baseline characteristics, clinical parameters, and infusion-related complications were retrospectively collected and analyzed.

Results

273 patients who received metaraminol were enrolled. Of these, 35 (12.8%) patients required central venous catheter insertion due to inability in achieving hemodynamic stability following peripheral metaraminol monotherapy. In 29,574.2 hours of vasopressor infusion, metaraminol infusion resulted achievement of the target blood pressure 73.4% of the time. Meanwhile, adverse events occurred in 5 patients and resolved after local tissue treatment.

Discussion

Metaraminol could provide hemodynamic support and avoid complications associated with a central venous catheter and delay in vasopressor administration. Through careful and close monitoring, peripheral metaraminol infusion is safe and feasible for patients with neurological conditions. Future large-scale, prospective, multicenter studies are needed to evaluate the safety and efficacy of metaraminol infusion through a peripheral intravenous catheter.

Dose equivalence for metaraminol and noradrenaline - A retrospective analysis

BACKGROUND

Noradrenaline and metaraminol are commonly used vasopressors in critically ill patients. However, little is known of their dose equivalence.

METHODS

We conducted a single centre retrospective cohort study of all ICU patients who transitioned from metaraminol to noradrenaline infusions between August 26, 2016 and December 31, 2020. Patients receiving additional vasoactive drug infusion were excluded. Dose equivalence was calculated based on the last hour metaraminol dose (in μg/min) and the first hour noradrenaline dose (in μg/min) with the closest matched mean arterial pressure (MAP). Sensitivity analyses were performed on patients with acute kidney injury (AKI), sepsis and mechanical ventilation.

RESULTS

We studied 195 patients. The median conversion ratio of metaraminol to noradrenaline was 12.5:1 (IQR 7.5-20.0) for the overall cohort. However, the coefficient of variation was 77% and standard deviation was 11.8. Conversion ratios were unaffected by sepsis or mechanical ventilation but increased (14:1) with AKI. One in five patients had a MAP decrease of >10 mmHg during the transition period from metaraminol to noradrenaline. Post-transition noradrenaline dose (p < 0.001) and AKI (p = 0.045) were independently associated with metaraminol dose. The proportion of variation in noradrenaline dose predicted from metaraminol dose was low (R2 = 0.545).

CONCLUSIONS

The median dose equivalence for metaraminol and noradrenaline in this study was 12.5:1. However, there was significant variance in dose equivalence, only half the proportion of variation in noradrenaline infusion dose was predicted by metaraminol dose, and conversion-associated hypotension was common.

International pharmacy survey of peripheral vasopressor infusions in critical care (INFUSE)

PURPOSE

The primary objective was to determine the proportion of hospitals that administered norepinephrine peripheral vasopressor infusions (PVIs) in critically ill adult patients. Secondary objectives were to describe how norepinephrine is used such as the maximum duration, infusion rate and concentration, and to determine the most common first-line PVI used by country.

MATERIALS AND METHODS

An international multi-centre cross-sectional survey study was conducted in adult intensive care units in Australia, US, UK, Canada, and Saudi Arabia.

RESULTS

Critical care pharmacists from 132 institutions responded to the survey. Norepinephrine PVIs were utilised in 86% of institutions (n = 113/132). The median maximum duration of norepinephrine PVIs was 24 h (IQR 24-24) (n = 57/113). The most common maximum norepinephrine PVI rate was between 11 and 20 μg/min (n = 16/113). The most common maximum norepinephrine PVI concentration was 16 μg/mL (n = 60/113). Half of the institutions had a preference to administer another PVI over norepinephrine as a first-line agent (n = 66/132). The most common alternative PVI used by country was: US (phenylephrine 41%, n = 37/90), Canada (dopamine 31%, n = 5/16), UK (metaraminol 82%, n = 9/11), and Australia (metaraminol 89%, n = 8/9).

CONCLUSIONS

There is variability in clinical practice regarding PVI administration in critically ill adult patients dependent on drug availability and local institutional recommendations.

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.