Abstract

Background. We studied the effects of a parallel phenylephrine infusion during bispectral index guided anaesthesia induction with propofol on haemodynamic parameters. We hypothesised that mean arterial pressure and cardiac index would be better maintained in the group of patients receiving the phenylephrine infusion during induction.

Methods. We studied ASA I-III patients scheduled for oncological abdominal surgery. Forty patients randomly received either a 0.9% NaCl or a phenylephrine (0.5 μg/kg/min) infusion during the induction of anaesthesia with propofol to a bispectral index value of 60. Mean arterial pressure, stroke volume index and systemic vascular resistance index were recorded, starting at one minute before induction for 20 minutes, at one-minute intervals.

Results. After induction of anaesthesia before intubation mean arterial pressure and stroke volume index decreased significantly compared to baseline in both groups, while the systemic vascular resistance index increased slightly. At the end of measurements, mean arterial pressure (66 11 vs. 94 14 mmHg; 0.9% NaCl vs. phenylephrine group p<0.01) and stroke volume index (34.2 9.1 vs. 44.0 9.7 ml/m2; 0.9% NaCl vs. phenylephrine group p<0.01) were lower in both groups in comparison to baseline values, but were better maintained in the phenylephrine group, whereas systemic vascular resistance index was higher than at baseline (2308 656 vs. 3198 825 dynes s/cm5/m2; 0.9% NaCl vs. phenylephrine group p<0.01) with significant differences between groups.

Conclusion. Our study shows that a continuous phenylephrine infusion can attenuate the drop in mean arterial pressure and stroke volume index during anaesthesia induction with propofol.

Key words: anaesthetics, propofol, monitoring, depth of anaesthesia, consciousness monitors, bispectral index, sympathetic nervous system, phenylephrine, measurement techniques, cardiac output

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