Surgical Intervention in Deep Sedation: No Pain or no Memory

Prior to enrollment, upon arrival in the operating room and after being properly positioned on the operating table, patients will undergo standard intraoperative monitoring with pulse oximetry (SpO2), 3-lead electrocardiography (ECG), non-invasive brachial blood pressure monitoring (BP), a sensor for the Bispectral Index (BIS), and a nociception sensor (NOL) will also be placed.

Patients will be pre-oxygenated with a face mask with inspired oxygen fraction (FiO2) at 100% for 3 minutes.

The induction phase of deep sedation anesthesia will be conducted with a single bolus of Fentanyl 1 mcg/kg and total intravenous anaesthesia - target controlled infusion (TIVA-TCI) Propofol with an effect site concentration (Cε) of 4.0 mcg/mL.

Once the sedation level shows a Bispectral Index between 40 and 60, observation of the NOL Index will begin.

Subsequently, the laryngeal mask can be positioned, mechanical ventilation started, and the surgical procedure commenced.

During this phase, the maintenance of the anesthetic plan will be ensured by the infusion of Propofol in TIVA-TCI (with a Cε that keeps the BIS between 40 and 60) and the administration of Paracetamol 1 g, Ketorolac 30 mg, and Dexamethasone 4 mg.

At the end of the surgical procedure, the observation of the NOL Index will conclude.

Upon awakening, patients will be taken to the Post-Anesthesia Care Unit (PACU), where they will remain until their vital parameters are stabilized. At this point, 15 minutes post-operatively, the intensity of pain will be recorded using the numeric pain rating scale (NRS) scale.

Subsequently, patients will be transferred to the ward, where, 2 hours post-operatively, they will be interviewed about the intensity of post-operative pain and whether they need any rescue analgesic doses.

Data collection and management will be handled by the investigator and/or the designated study staff.

Data will be collected directly into a digital file (spreadsheet - MS Excel - Microsoft, Redmond, CA) without the use of paper forms.

Data will be collected anonymously without identifying codes that could link to the patient's medical record and identity. The correspondence list between demographic data and the patients' identification codes will be kept at the enrolling center and will only be accessible to the study staff.

The data to be collected include the following:

• Anthropometric Data:

• Sex
• Age
• Weight
• Height
• Body Mass Index (BMI)
• American Society of Anesthesiologists (ASA) Physical Status
• Clinical Data

• Surgical Procedure Performed
• Heart Rate (HR)
• Non-Invasive Blood Pressure (BP)
• Pulse Oximetry (SpO2)
• Bispectral Index (BIS)
• NOL Index
• NRS Pain Scale

Continuous variables will be presented as mean and standard deviation or as median and interquartile range depending on their distribution. Normal distribution will be assessed using the Kolmogorov-Smirnov test. Any sub-analyses and comparisons between sub-groups will be conducted using the Student's t-test for parametric data, while the Mann-Whitney test will be used for non-parametric data. Categorical variables will be presented as absolute numbers and percentages of the total sample. Any sub-analyses and comparisons between sub-groups will be conducted using the Chi-square test or Fisher's exact test, depending on the size of the sub-groups. In all cases, the null hypothesis will be rejected for α values <0.05. The software used for data analysis and sample size calculation is MedCalc v. 22.013 (MedCalc Software, Ostend, Belgium).

Inclusion criteria

• Adult patient
• ASA Physical Status I - II - III

Exclusion criteria

• ASA Physical Status IV
• Pregnant and breastfeeding patients
• Pre-existing cardiac arrhythmias
• Patients with neuromuscular diseases
• Patients with psychiatric syndromes under pharmacological treatment
• Patients with chronic use of analgesics
• Patients with a history of drug abuse
• Allergy to one or more drugs used in the protocol
• Refusal to consent