The goal of this prospective observational study is to identify effect site concentrations (CET) of propofol using the Eleveld model for different levels of procedural sedation.

The main question it aims to answer is to identify CET propofol using the Eleveld model for different levels of procedural sedation as measured by the modified observer's assessment of alertness and sedation score (MOAAS) and EEG monitoring.

Participants vital signs will be monitored according to the departmental protocol. Sedation will be administered using Target-Controlled Infusion (TCI) of propofol (administered by effect-site TCI using the Eleveld model) and remifentanil (administered by effect site TCI using the Eleveld model). Target controlled infusion of propofol and remifentanil is according to the departmental protocol. The MOAAS score will be noted every 5 minutes or when the target effect site concentration of propofol is altered. Depth of sedation will also be monitored using a non-invasive BIS® monitor.

Since 2012 procedural sedation practices in Dutch hospitals has taken a huge flight. Propofol is the preferred drug of choice for moderate to deep sedation. This can be titrated by using pharmacokinetic (PK) and pharmacodynamic (PD) models programmed in infusion pumps for target controlled infusion (TCI). Several pharmacokinetic-pharmacodynamic (PKPD) models for TCI propofol are available. While most TCI systems incorporate PK or PKPD models for specific patient groups such as adults, children or older patients, the Eleveld model has been developed for TCI of propofol for general anesthesia and sedation in a broad range of patients. In 2021 Vellinga et al published a study on the validation of the Eleveld model in patients undergoing general anesthesia. So far, the Eleveld model has not been externally validated for the use of procedural sedation in adult patients.

The aim of this study is to identify effect-site target concentrations of propofol for the Eleveld model that are associated with moderate to deep sedation levels, MOAAS 3-1 and the associated bispectral index ( BIS) levels in adult patients.

The secondary outcomes are: time to introduction of the endoscope and the time to reach MOAAS 5 after having stopped TCI propofol. The use of vasopressors such as ephedrine, phenylephrine or norepinephrine. The need for airway maneuvers such as chin lift, jaw thrust or nasopharyngeal airway.

The purpose of this investigation is to produce normalizing graphs of propofol drug infusion and TCI target concentrations for clinical sedation using the Eleveld TCI model. It mirrors the validation study of the Eleveld model. The sample size estimation of that study was determined by estimation bounds of the model-based drug concentration prediction accuracy. That study used 25 individuals for four groups: children, non-obese, elderly, and obese adults. Aside from the determination of prediction accuracy of the Eleveld model, an important secondary result was normalizing graphs of target concentrations, drug infusion, and drug effects in clinical practice.

The intention of the current investigation is to reproduce the normalizing graphs of TCI targets, drug infusion and effects similar to the Eleveld propofol TCI model validation study, but targeted to sedation rather than anesthesia. The current investigation uses no blood samples so sample size estimation cannot be based on model-based drug concentration prediction accuracy. We determined that a sample size similar to the validation study is appropriate and propose allocating 25 patients per group and three groups: non-obese, elderly and obese adults, for a total of 75 individuals.

Inclusion Criteria:

• Adult patients for procedural sedation in the UMCG between 01-01-2024 and 01-01-2025.

Exclusion Criteria:

• Age <18 years; use of esketamine during the procedure, use of benzodiazepines prior or during the procedure, hearing disability, BIS quality index < 50

Three groups of 25 adult patients each, undergoing a diagnostic of interventional procedure at the endoscopy suite under procedural sedation.