• Marieke Poterman, Jaap Jan Vos, Hugo E M Vereecke, Michel M R F Struys, Henk Vanoverschelde, Thomas W L Scheeren, and Alain F Kalmar.
• From the Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands (MP, JJV, HEMV, TWLS, AFK, MMRFS), Department of Anesthesia, Ghent University (MMRFS), and Department of Anesthesia and Intensive Care Medicine, Maria Middelares Hospital, Ghent, Belgium (HV, AFK).
• Eur J Anaesthesiol. 2015 Aug 1; 32 (8): 571-80.

BackgroundPhenylephrine and norepinephrine are two vasopressors commonly used to counteract anaesthesia-induced hypotension. Their dissimilar working mechanisms may differentially affect the macro and microcirculation, and ultimately tissue oxygenation.ObjectivesWe investigated the differential effect of phenylephrine and norepinephrine on the heart rate (HR), stroke volume (SV), cardiac index (CI), cerebral tissue oxygenation (SctO2) and peripheral tissue oxygenation (SptO2), and rate-pressure product (RPP).DesignA randomised controlled study.SettingSingle-centre, University Medical Center Groningen, The Netherlands.PatientsSixty normovolaemic patients under balanced propofol/remifentanil anaesthesia.InterventionsIf the mean arterial pressure (MAP) dropped below 80% of the awake state value, phenylephrine (100 μg + 0.5 μg kg(-1) min(-1)) or norepinephrine (10 μg + 0.05 μg kg(-1) min(-1)) was administered in a randomised fashion.Main Outcome MeasuresMAP, HR, SV, CI, SctO2, SptO2 and rate-pressure product (RPP) analysed from 30 s before drug administration until 240 s thereafter.ResultsPhenylephrine and norepinephrine caused an equivalent increase in MAP [Δ = 13 (8 to 22) and Δ = 13 (9 to 19) mmHg, respectively] and SV [Δ = 6 ± 6 and Δ = 5 ± 7 ml, respectively], combined with a significant equivalent decrease in HR (both Δ = -8 ± 6 bpm), CI (both Δ = -0.2 ± 0.3 l min(-1) m(-2)) and SctO2 and an unchanged RPP (Δ = 345 ± 876 and Δ = 537 ± 1076 mmHg min(-1)). However, SptO2 was slightly but statistically significantly (P < 0.05) decreased after norepinephrine [Δ  = -3 (-6 to 0)%] but not after phenylephrine administration [Δ = 0 (-1 to 1)%]. In both groups, SptO2 after vasopressor was still higher than the awake value.ConclusionIn normovolaemic patients under balanced propofol/remifentanil anaesthesia, phenylephrine and norepinephrine produced similar clinical effects when used to counteract anaesthesia-induced hypotension. After norepinephrine, a fall in peripheral tissue oxygenation was statistically significant, but its magnitude was not clinically relevant.

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