Anesthesia, Hemodynamic Instability, Surgery
Conditions
Keywords
Hemodynamics, Knee-Chest Position, Propofol, Anesthesia, General, Anesthetics, Intravenous, pharmacokinetics
Brief summary
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
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.
Interventions
DRUGPropofol reduction
Reduction of propofol target concentration
Sponsors
Centro Hospitalar do Porto
University of Salamanca
Study design
Allocation
NON_RANDOMIZED
Intervention model
SEQUENTIAL
Primary purpose
PREVENTION
Masking
NONE
Intervention 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.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Hemodynamic changes | Baseline (moment 0), 10 minutes after induction of anesthesia (moment 1), 10 minutes after knee-chest positioning (moment 2) | Changes from baseline in cardiac output and comparison of the changes between both groups. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Pharmacokinetic changes | Baseline (moment 0), 10 minutes after induction of anesthesia (moment 1), 10 minutes after knee-chest positioning (moment 2) | Correlation between propofol measured plasma concentrations and predicted plasma concentrations (Cp) by the Schnider Pk model. |
Countries
Portugal
Outcome results
None listed