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Signa Vitae

Journal of Intensive Care and Emergency Medicine

Haemodynamic stability during anaesthesia induction with propofol – impact of phenylephrine. A double-blind, randomised clinical trial.

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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Multimodal monitoring (MMM) in the perioperative period

Abstract

Routine anaesthesia monitoring until the mid-1980s often consisted of just a finger on the pulse, primitive ECG and intermittent blood pressure (MAP) measurement using a cuff and aneroid gauge or mechanical oscillotonometer. Then in quick succession an explosion of new monitors was introduced including pulse oximetry (SpO2), end tidal carbon dioxide (EtCO2) and anaesthetic agent monitoring as well as automated non-invasive blood pressure (NIBP) machines. These were all routinely in place in many hospitals by the late 1980’s, but then progress came to a halt with no advances in routine anaesthetic monitoring for over 25 years.

This paper concentrates on three classes of non- or minimally invasive monitors which have become additionally available in the last 10 to 15 years and if used in combination their potential impact on improving outcome following surgery in high risk patients:

  1. Monitors which calculate stroke volume (SV, and thus cardiac output, CO) from a standard radial arterial line (e.g. LiDCO, UK), oesophageal probe (Deltex, UK), ECG pads or even from the finger
  2. Monitors which assess the degree of cortical suppression (e.g. BIS, Medtronic, USA) produced by anaesthetics thus potentially allowing the administrator to “fine tune” anaesthesia for individual patients
  3. Monitors which assess tissue oxygenation, usually of the brain (e.g. Invos, Medtronic, USA)

If used together they provide complementary information which should improve perioperative haemodynamic management and outcome and form part of a multi-modal monitoring (MMM) strategy which is the subject of this article.

Key words: cardiac output, minimally invasive, tissue oxygenation, depth of anaesthesia, multi-modal monitoring

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