Characteristics and outcomes of intensive care patients receiving metaraminol infusion-a retrospective observational cohort study.

There is limited published data on metaraminol dosing, duration of therapy and clinical outcomes for critically ill patients. We conducted a retrospective cohort study across two tertiary intensive care units (ICUs) and included all patients who received a metaraminol infusion between 26 August 2016 and 31 December 2021. The primary outcome of this study was to describe the characteristics and outcomes of patients who receive metaraminol in ICU. Secondary outcomes included a range of pharmacological and physiological measures. We studied 1261 patients, which represented 6.7% of ICU admissions during the study period. Most (85.4%) patients were unplanned admissions and less than 40% required mechanical ventilation. ICU and hospital mortality were low (7.4% and 12.4% respectively). Median total infusion duration for metaraminol was 10 (interquartile range, 3-24) h. Median dose range was 1 mg/h (16 µg/min) to 6 mg/h (100 µg/min). Almost three-fifths of these patients subsequently transitioned to norepinephrine (noradrenaline), which commenced at a median time of 7 h after initiation of metaraminol. Hourly heart rate, mean arterial pressure and respiratory rate remained very stable during infusion of metaraminol and median urine output remained greater than 30 ml/h for the first 24 h. In conclusion, patients who received metaraminol by infusion in the ICU had a low severity of illness and risk of mortality. Dosing of metaraminol was conservative and clinicians frequently transitioned to norepinephrine early despite the low doses infused. Metaraminol effectively maintained blood pressure with no associated tachycardia or significant drop in urine output and no clinical evidence of tachyphylaxis.