Micro- and Macrocirculatory effects of norepinephrine on anaesthesia- induced hypotension

Abstract

Abstract Purpose: Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity and mortality. Norepinephrine is often use to treat IOH. However, the question regarding the mode of administration in either a bolus or continuous infusion (CI) remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a CI of norepinephrine to treat IOH.Methods: We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissue CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a CI of 200 µg/h of norepinephrine.Results: Thirty-six patients were included, with 41 boluses and 33 CI.Bolus and CI induced an increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, CI was associated with a smaller decrease in CO and stroke volume (p<0.05).For microcirculatory parameters, a more favourable response was observed when CI was used. Perfusion index (-12 vs. +12%, p=0,008), microvascular flow index (-0,1 vs. + 0,3, p=0,03), total vessel density (-0,2 vs. +2,3 mm2/mm2, p=0,002), and perfusion vessel density (-0,36 vs. +1,44 mm2/mm2, p=0,01) showed opposite variations with bolus and CI, respectively.Conclusions: These results on macro- and microcirculation could reveal the need for the preferential use of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.Trial registration : (NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204).