Effect of phenylephrine and ephedrine bolus treatment on cerebral oxygenation in anaesthetized patients

BACKGROUND: How phenylephrine and ephedrine treatments affect global and regional haemodynamics is of major clinical relevance. Cerebral tissue oxygen saturation ([Image: see text])-guided management may improve postoperative outcome. The physiological variables responsible for [Image: see text] changes induced by phenylephrine and ephedrine bolus treatment in anaesthetized patients need to be defined. METHODS: A randomized two-treatment cross-over trial was conducted: one bolus dose of phenylephrine (100–200 µg) and one bolus dose of ephedrine (5–20 mg) were given to 29 ASA I–III patients anaesthetized with propofol and remifentanil. [Image: see text], mean arterial pressure (MAP), cardiac output (CO), and other physiological variables were recorded before and after treatments. The associations of changes were analysed using linear-mixed models. RESULTS: The CO decreased significantly after phenylephrine treatment [▵CO=−2.1 (1.4) litre min(−1), P<0.001], but was preserved after ephedrine treatment [▵CO=0.5 (1.4) litre min(−1), P>0.05]. The [Image: see text] was significantly decreased after phenylephrine treatment [▵[Image: see text]=−3.2 (3.0)%, P<0.01] but preserved after ephedrine treatment [▵[Image: see text]=0.04 (1.9)%, P>0.05]. CO was identified to have the most significant association with [Image: see text] (P<0.001). After taking CO into consideration, the other physiological variables, including MAP, were not significantly associated with [Image: see text] (P>0.05). CONCLUSIONS: Associated with changes in CO, [Image: see text] decreased after phenylephrine treatment, but remained unchanged after ephedrine treatment. The significant correlation between CO and [Image: see text] implies a cause–effect relationship between global and regional haemodynamics