Hemodynamic Changes and Propofol Pharmacokinetic Variation During Anesthesia Induction and Knee-chest Positioning

Study Overview
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Brief Summary
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Induction of anesthesia and the knee-chest position are associated with hemodynamic changes that may impact patient outcomes. Changes from baseline in cardiac output and other hemodynamic variables following induction of anesthesia and knee-chest positioning were compared. Propofol plasma concentrations were also measured after induction of anesthesia and after the knee-chest position. The aim of this study was to assess whether planned reductions in target-controlled infusion propofol concentrations attenuate the hemodynamic changes associated with anesthesia induction and knee-chest position. The secondary aim was to quantify the variation in propofol measured plasma concentrations (Cm), both after induction and after KC positioning, and correlate them with predicted concentrations (Cp) by the Schnider Pk model.

Detailed Description
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A total of 20 patients scheduled for elective lumbar spinal surgery in the knee-chest position were included. In addition to standard anesthesia monitoring, bispectral index and noninvasive cardiac output monitoring were undertaken. The study was carried out in 2 parts. In phase 1, target-controlled infusion propofol anesthesia was adjusted to maintain BIS 40 to 60. In phase 2, there were 2 planned reductions in propofol target concentration: (1) immediately after loss of consciousness: reduction calculated using a predefined formula, and (2) before positioning: reduction equal to the average percentage decrease in CO after knee-chest position in phase 1.

Official Title
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Relationship Between Hemodynamic Changes and Propofol Pharmacokinetic Variation During Anesthesia Induction and Knee-chest Positioning in Propofol TCI Guided Anesthesia

Conditions
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Hemodynamic Instability, Anesthesia, Surgery

Intervention / Treatment
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* Drug: Propofol reduction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: • Lumbar spinal condition for surgical treatment in knee-chest position Exclusion Criteria: Severe ischemic heart disease Congestive heart failure Atrial fibrillation or flutter Body mass index > 35 kg/m2 Glasgow Coma Scale < 15 Dementia disease History of drug abuse or addiction Consumption of opioid medication Pre-operative administration of midazolam

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Non-Randomized
Intervention Model: Sequential Assignment
Interventional Model Description: In phase 1, target-controlled infusion propofol anesthesia was adjusted to maintain BIS 40 to 60. In phase 2, there were 2 planned reductions in propofol target concentration: (1) immediately after loss of consciousness - reduction calculated using a predefined formula, and (2) before positioning - reduction equal to the average percentage decrease in CO after knee-chest position in phase 1.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: No protocolled propofol reduction<br>In phase 1, target-controlled infusion propofol anesthesia was adjusted to maintain BIS 40 to 60. | |
| Experimental: Two protocolled propofol reductions<br>In phase 2, there were 2 planned reductions in propofol target concentration: (1) immediately after loss of consciousness-reduction calculated using a predefined formula, and (2) before positioning-reduction equal to the average percentage decrease in CO after knee-chest position in phase | Drug: Propofol reduction<br>* Reduction of propofol target concentration<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hemodynamic changes | Changes from baseline in cardiac output and comparison of the changes between both groups. | Baseline (moment 0), 10 minutes after induction of anesthesia (moment 1), 10 minutes after knee-chest positioning (moment 2) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pharmacokinetic changes | Correlation between propofol measured plasma concentrations and predicted plasma concentrations (Cp) by the Schnider Pk model. | Baseline (moment 0), 10 minutes after induction of anesthesia (moment 1), 10 minutes after knee-chest positioning (moment 2) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hemodynamics, Knee-Chest Position, Propofol, Anesthesia, General, Anesthetics, Intravenous, pharmacokinetics