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Haemodynamic Effects of Effect-site Propofol Induction in Cardiac Surgical Patients

R. Chapman, ¹ M. Higgins, ¹ S. Hickey, ¹ K. Anderson, ¹ R. Smith, ¹

G.N.C. Kenny. ²

1  Dept of Anaesthesia, Glasgow Royal Infirmary, Glasgow, UK

2 University Dept of Anaesthesia, Glasgow Royal Infirmary, Glasgow, UK

Infusion devices that deliver effect-site controlled target controlled infusions (TCI) are now widely available; however there is limited experience with them in cardiac surgical patients. Previous work in cardiac surgical patients has used small stepwise increments in effect-site propofol concentration¹. The aim of this study was to assess the haemodynamic effects of effect-site TCI compared to plasma TCI in cardiac surgical patients.

Methods

Following consent patients scheduled for elective coronary artery bypass surgery were randomized to receive either effect-site (Marsh model with a t-half Keo of 2.6 min with a 285% plasma overshoot) or plasma driven (standard Marsh) TCI induction. Based on previous work by our group a target effect-site concentration of 2mcg/ml was chosen. Following loss of consciousness (defined as loss of verbal contact), bispectral index, mean arterial pressure (MAP), heart rate and cardiac output (measured by LidCO) were recorded for 10 minutes.

Results

At present 20 patients have been recruited. The mean age of patients in the plasma group was 68 (52-79; S.D. 8.6) and 64 (46-82; S.D. 13.4). All patients had preserved left ventricular function as assessed by preoperative echocardiogram. The mean maximal drop in MAP for the effect group was 22mmHg (S.D. 12.8) and 23.3 (S.D. 9.9) for the plasma group. This gives a difference of only 1.3 (P= 0.818)

Discussion

Although we have studied a relatively small number of patients this work would indicate that effect-site driven TCI Propofol is heamodynamically safe in cardiac surgical patients. As with plasma control infusions this stability will only be achieved if the operator selects a target effect-site concentration appropriate to the individual patient.

Acknowledgements

We would like to thank the Cardiac theatre staff of Glasgow Royal Infirmary for their help and support with this research.

References

1. Macquaire V. Target-controlled infusion of propofol induction with or without plasma constraint in high-risk adult patients undergoing cardiac surgery. ACTA Anaesthesiologica Scandinavica 2002; 46: 1010-1016.