Effect of Bolus Treatment on Cerebral Oxygenation
Effect of Bolus Treatment on Cerebral Oxygenation
Background How phenylephrine and ephedrine treatments affect global and regional haemodynamics is of major clinical relevance. Cerebral tissue oxygen saturation (
)-guided management may improve postoperative outcome. The physiological variables responsible for
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.
, 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, P<0.001], but was preserved after ephedrine treatment [▵CO=0.5 (1.4) litre min, P>0.05]. The
was significantly decreased after phenylephrine treatment [▵
=−3.2 (3.0)%, P<0.01] but preserved after ephedrine treatment [▵
=0.04 (1.9)%, P>0.05]. CO was identified to have the most significant association with
(P<0.001). After taking CO into consideration, the other physiological variables, including MAP, were not significantly associated with
(P>0.05).
Conclusions Associated with changes in CO,
decreased after phenylephrine treatment, but remained unchanged after ephedrine treatment. The significant correlation between CO and
implies a cause–effect relationship between global and regional haemodynamics.
Phenylephrine and ephedrine are routinely used in the perioperative setting to treat anaesthesia-related hypotension in order to maintain mean arterial pressure (MAP) and cerebral perfusion pressure. However, phenylephrine and ephedrine have very different pharmacological effects: phenylephrine is a pure α1-agonist, whereas ephedrine is a mixed-acting agent with positive inotropic and chronotropic effects. Indeed, the distinctive effects of phenylephrine and ephedrine on global haemodynamics (such as cardiac output, CO) and regional haemodynamics (such as cerebral tissue oxygen saturation,
) have been demonstrated.
Recently published studies show that near-infrared spectroscopy (NIRS)-guided brain protection protocols in cardiac surgery might lead to reduced neurocognitive complications and improved postoperative outcomes. Because the endpoint of haemodynamic optimization is to improve oxygen delivery, monitoring cerebral oxygenation may help to elucidate the effects of various clinical interventions on global and regional haemodynamics. Moreover, several studies have demonstrated that changes in
correlate with changes in cerebral blood flow (CBF) when cerebral metabolic rate of oxygen (CMRO2) and arterial blood oxygen content are kept constant. Understanding how the administration of phenylephrine and ephedrine affects cerebral perfusion and oxygenation is of major clinical relevance because both agents are routinely used to treat anaesthesia-related hypotension in surgical patients.
Consequently, the aims of our study were (i) to investigate the effect of phenylephrine and ephedrine bolus administration on cerebral oxygenation in anaesthetized patients and (ii) to identify the physiological variables [MAP, CO, heart rate (HR), stroke volume (SV), end-tidal CO2 (
), oxygen saturation via pulse oximetry (
), and bispectral index (BIS)] which are responsible for the changes in
induced by phenylephrine and ephedrine treatments.
Abstract and Introduction
Abstract
Background How phenylephrine and ephedrine treatments affect global and regional haemodynamics is of major clinical relevance. Cerebral tissue oxygen saturation (
)-guided management may improve postoperative outcome. The physiological variables responsible for
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.
, 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, P<0.001], but was preserved after ephedrine treatment [▵CO=0.5 (1.4) litre min, P>0.05]. The
was significantly decreased after phenylephrine treatment [▵
=−3.2 (3.0)%, P<0.01] but preserved after ephedrine treatment [▵
=0.04 (1.9)%, P>0.05]. CO was identified to have the most significant association with
(P<0.001). After taking CO into consideration, the other physiological variables, including MAP, were not significantly associated with
(P>0.05).
Conclusions Associated with changes in CO,
decreased after phenylephrine treatment, but remained unchanged after ephedrine treatment. The significant correlation between CO and
implies a cause–effect relationship between global and regional haemodynamics.
Introduction
Phenylephrine and ephedrine are routinely used in the perioperative setting to treat anaesthesia-related hypotension in order to maintain mean arterial pressure (MAP) and cerebral perfusion pressure. However, phenylephrine and ephedrine have very different pharmacological effects: phenylephrine is a pure α1-agonist, whereas ephedrine is a mixed-acting agent with positive inotropic and chronotropic effects. Indeed, the distinctive effects of phenylephrine and ephedrine on global haemodynamics (such as cardiac output, CO) and regional haemodynamics (such as cerebral tissue oxygen saturation,
) have been demonstrated.
Recently published studies show that near-infrared spectroscopy (NIRS)-guided brain protection protocols in cardiac surgery might lead to reduced neurocognitive complications and improved postoperative outcomes. Because the endpoint of haemodynamic optimization is to improve oxygen delivery, monitoring cerebral oxygenation may help to elucidate the effects of various clinical interventions on global and regional haemodynamics. Moreover, several studies have demonstrated that changes in
correlate with changes in cerebral blood flow (CBF) when cerebral metabolic rate of oxygen (CMRO2) and arterial blood oxygen content are kept constant. Understanding how the administration of phenylephrine and ephedrine affects cerebral perfusion and oxygenation is of major clinical relevance because both agents are routinely used to treat anaesthesia-related hypotension in surgical patients.
Consequently, the aims of our study were (i) to investigate the effect of phenylephrine and ephedrine bolus administration on cerebral oxygenation in anaesthetized patients and (ii) to identify the physiological variables [MAP, CO, heart rate (HR), stroke volume (SV), end-tidal CO2 (
), oxygen saturation via pulse oximetry (
), and bispectral index (BIS)] which are responsible for the changes in
induced by phenylephrine and ephedrine treatments.
