Reevaluation Prediction of the Effect Site Propofol Eleveld Model Using Slow and Fast Induction

Patients ASA1-2, 18 to 70 years old, scheduled for elective surgery with personal conset to participate, will be randomised into two groups using different induction mode. TCI effect site mode induction or TCI plasma mode induction both using the Elevelt PKPD propofol model. Standard monitoring (EKG, SaO2, PCo2et, NIAP), and Conox/ and or BIS EEG monitor to evaluate the prediction. The model's prediction will be compared with values provided by the Conox/BIS index for both groups and between them. The study will be conducted during the 20 minutes after Loss of responsiveness.

Patients aged 18 to 70 years will be included. Patients allergic to propofol are excluded. Eleveld's PKPD model for propofol includes covariates for adjustment in administration with target-controlled infusion pumps. Induction to the site of effect will be performed using EC60 for each age, while slow induction will use the target plasma modality, starting at a target of 3 ug/ml and increasing by 0.5 ug/ml every 3 minutes until loss of consciousness. This is defined as the loss of response to voice and shoulder tap. The 20 minutes following loss of consciousness will be evaluated. Biometric and gender characteristics of both groups, concomitant pathologies, and surgical times will be compared. The temporal evolution of the propofol effect site predicted by the Eleveld model will be compared between the two types of induction using EEG (CONOX or BIS). To obtain the EEG index prediction by Eleveld it will be use the Tiva trainer software 2.0, simulating the evolution of the kinetics and effect site calculated by Eleveld in the infudion TCI pumps. It is estimated that 20 patients per group are required to find a 20% difference in predicted versus actual EEG index with 90% power. Statistical methods: 1. Data analysis tool: Stata 10 software 2. Statistics * Summary: Mean (central tendency) and standard deviation (dispersion) * Association: Student's t-test for continuous quantitative variables and Fisher's exact test for dichotomous variables.