An interventional study of Propofol and Propofol in Target Controlled Infusion of Propofol, sponsored by Golden Jubilee National Hospital. Completed at 1 site in United Kingdom. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2017-08-14.
Sponsored by Golden Jubilee National Hospital · Not applicable, Interventional, and Other
Anaesthesia for surgical procedures can be provided using a continuous infusion of intravenous drug. The most commonly used drug for this technique is propofol. Infusion devices programmed with pharmacokinetic models can be used to infuse propofol to achieve a target blood concentration. These pharmacokinetic models predict the rate of distribution of propofol within the body and also the rate at which it is cleared. In practice, the anaesthetist enters patient details such as age, sex and weight as well as a target blood concentration of propofol. The infusion device then infuses propofol at the appropriate rate to achieve this concentration.
White and colleagues recently published the Covariates Model for propofol. It is anticipated that this model will have reduced bias and inaccuracy compared to the models in current clinical use. The VaSCoM study has three objectives:
To achieve the above objectives, patients over 18 years of age and undergoing elective non-cardiac surgery will be recruited to the study. Anaesthesia will be delivered using a target controlled infusion device programmed with the Covariates Model for propofol. The target blood concentrations will be set according to a pre-determined schedule and all measurements will be made prior to the start of surgery.
Prospective validation of the Covariates Model will be done by comparing blood concentration of propofol predicted by the model to those actually measured. These results will then be compared to the predictions made using the models in current clinical practice.
Modelling of the effect site means predicting the concentration of propofol in the brain for a given blood concentration. This will involve using depth of anaesthesia monitors (such as bispectral index) as surrogate markers of brain concentration and comparing this to the predicted and measured blood concentrations of propofol.
Finally, important information on the distribution and clearance of propofol can be gained through the comparison of venous and arterial blood samples. In this study, simultaneous sampling of venous and arterial blood will facilitate this comparison.
Golden Jubilee National Hospital is the lead sponsor of 28 studies on the registry; 4 are open to participants now.
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Exclusion Criteria:
Patients in the low-high-low group will receive an infusion of propofol with an initial blood target concentration of 2 mcg/ml. After 15 minutes the target will be increased to 5 mcg/ml and after a further 15 minutes the target will be reduced back to 2 mcg/ml for a further 15 to 30 minutes.
Drug: Propofol
Patients in the high-low-high group will receive an infusion of propofol with an initial blood target concentration of 5 mcg/ml. After 15 minutes the target will be reduced to 2 mcg/ml and after a further 15 minutes the target will be increased back to 5 mcg/ml for a further 15 to 30 minutes.
Drug: Propofol
Patients in the low-high-low group will receive an infusion of propofol with an initial blood target concentration of 2 mcg/ml. After 15 minutes the target will be increased to 5 mcg/ml and after a further 15 minutes the target will be reduced back to 2 mcg/ml for a further 15 to 30 minutes.
Patients in the high-low-high group will receive an infusion of propofol with an initial blood target concentration of 5 mcg/ml. After 15 minutes the target will be reduced to 2 mcg/ml and after a further 15 minutes the target will be increased back to 5 mcg/ml for a further 15 to 30 minutes.
Performance error of predicted blood propofol concentration (venous blood samples)
Performance error is calculated as: ((Measured blood concentration - Predicted blood concentration)/ Predicted blood concentration) x 100 The median performance error and the absolute performance error can then be calculated as measures of bias and inaccuracy respectively.
Time frame: 1.5, 5, 16.5, 20, 31.5, 35, 45-60 minutes post infusion start time
Depth of anaesthesia
Depth of anaesthesia (as measured by bispectral index and index of consciousness) will be used as a surrogate marker of propofol effect site concentration. By using complex statistical analysis to compare depth of anaesthesia to measured and predicted blood concentrations, we aim to determine the Keo. This is the rate constant for elimination of propofol from the effect site compartment and will be incorporated to the Covariates Model to predict brain concentration for a given blood concentration of propofol.
Time frame: 0 to 45-60 minutes post infusion start time
Comparison of performance errors calculated from venous blood samples to performance errors calculated from arterial blood samples
Performance error is calculated as: ((Measured blood concentration - Predicted blood concentration)/ Predicted blood concentration) x 100
Time frame: 1.5, 5, 16.5, 20, 31.5, 35, 45-60 minutes post infusion start time
This study is completed, as verified in Aug 2017. You cannot join it, but the record below documents what was studied.
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Golden Jubilee National Hospital