Anesthesia Depth Monitoring

This randomized prospective study aims to compare the effects of two target-controlled infusion models, the Schnider and Eleveld models, on anesthetic depth and hemodynamic responses during anesthesia induction in adult patients undergoing spinal surgery. Patients scheduled for spinal surgery will be randomized into either the Schnider or Eleveld group. Before induction, standard monitoring will be applied, including electrocardiography, peripheral oxygen saturation, invasive arterial blood pressure monitoring, heart rate monitoring, and bispectral index monitoring. Anesthesia induction will be performed with fentanyl 2 mcg/kg, rocuronium 0.6 mg/kg, and propofol administered by target-controlled infusion with an effect-site target concentration of 3 mcg/mL according to the allocated pharmacokinetic model. Hemodynamic parameters and bispectral index values will be recorded before induction and at the 1st, 3rd, 5th, and 10th minutes after induction. Additional parameters, including time to BIS below 40, time to delta activity, burst suppression duration, total propofol dose during the first 5 minutes, need for additional propofol, hemodynamic response to intubation, vasopressor requirement within the first 10 minutes, and use of esmolol, will also be documented. The primary aim is to evaluate whether the Schnider and Eleveld models differ in terms of induction-related hemodynamic stability and anesthetic depth during the early induction period.

Many older people can experience confusion, memory problems, or a decline in their thinking after major surgery. These problems are sometimes called 'postoperative neurocognitive disorders' or PND and can affect recovery and a person's ability to live independently. The investigators want to find out the best way to study these problems in older patients undergoing surgery. This is a 'feasibility study', which means we are testing the research methods. The investigators want to see if it is possible to ask participants to do memory tests and give blood samples before and after their operation. The investigators are hoping to include around 40 patients over 2 years in this study. The investigators will compare performance in memory (cognitive assessment) findings before and after surgery and link this to data taken from the anaesthetic, including the types of drugs used, duration, brain features from processed electroencephalogram monitoring and standard recommended monitoring. In addition the investigators will link this to blood sample markers of brain health and function (biomarkers). The results of this study will help the investigators plan a much larger study in the future, with the ultimate goal of making surgery safer for the brain.

The aim of this study is to evaluate the effect of using the non-invasive Conox monitor on intraoperative opioid consumption. Additionally, the study aims to assess the impact of Conox monitoring on recovery time, postoperative agitation rate, and pain scores, and to investigate the correlation between qCON and qNOX values and conventional hemodynamic parameters.

Post-hospitalization behavioral changes are common in children after surgery and general anesthesia and may persist for varying durations depending on individual and perioperative factors. The Post-Hospitalization Behavior Questionnaire (PHBQ) is a well-validated instrument widely used to evaluate negative postoperative behavioral changes in pediatric patients following hospitalization or surgical procedures. Although early postoperative behavioral disturbances have been extensively studied, most research has focused on short-term outcomes within the first weeks after surgery, while long-term behavioral outcomes remain insufficiently investigated. Processed electroencephalography (pEEG) monitoring provides an objective method for assessing anesthetic depth during surgery. Parameters such as the Patient State Index (PSI) and Spectral Edge Frequency 95 (SEF95) allow dynamic evaluation of cortical activity and may help optimize anesthetic administration by preventing excessively deep or inadequate anesthesia. Improved anesthetic depth management may theoretically influence postoperative recovery and behavioral outcomes. In the initial randomized study, early postoperative behavioral assessments were obtained within the first postoperative month using the Post-Hospitalization Behavior Questionnaire (PHBQ). In the present follow-up study, children will be contacted again 12-24 months after surgery to evaluate long-term behavioral outcomes. PHBQ scores at long-term follow-up will be compared between children who previously received EEG-guided anesthesia and those managed with standard anesthesia without processed EEG monitoring. By examining both early and long-term behavioral outcomes, this study aims to determine whether intraoperative EEG-guided anesthesia management influences postoperative behavioral changes in the pediatric population.

The goal of this observational study is to determine whether macrophage/monocyte mediated inflammatory signaling contributes to reduced anesthetic requirements in older adults undergoing major abdominal surgery. The main questions it aims to answer are: * Is there a difference in anesthetic dosing requirements (minimum effective dose) between young and older patients undergoing major abdominal surgery? * How do electroencephalographic (EEG) signatures under anesthesia correlate with age and systemic inflammatory markers? * Is there an association between age, levels of circulating inflammatory cytokines, and monocyte/macrophage phenotypes with anesthetic requirements? If there is a comparison group: Researchers will compare older adult patients undergoing major abdominal surgery to younger adult patients undergoing major abdominal surgery to see if macrophage/monocyte-mediated inflammatory signaling influences anesthetic sensitivity and the risk of postoperative neurocognitive complications in the older population. Participants will: * Receive general anesthesia for major abdominal surgery, with continuous recording of anesthetic dose requirements. * Undergo electroencephalographic (EEG) monitoring during the anesthetic period. * Provide blood samples for the measurement of circulating inflammatory cytokines and the assessment of monocyte phenotypes. * Provide peritoneal tissue samples (collected during surgery) to evaluate tissue macrophage populations. * Provide cerebrospinal fluid (CSF) samples to assess biomarkers of blood-brain barrier permeability.

Perioperative assessment of adequate depth of anesthesia and analgesia is currently a recommended part of routine anesthesia practice for all surgical procedures. In most cases, it is performed by monitoring and evaluating physiological parameters, which is insufficient, especially for the depth of anesthesia. The depth of anesthesia, when measured with the Conox device, is indicated by the qCON index, the recommended value for anesthesia management is between 40-60. Shallow (above 60) anesthesia may be associated with an increased incidence of perioperative wakefulness episodes, and deeper (below 40) anesthesia may lead to a more frequent occurrence of adverse effects of anesthesia, including emergent delirium in the postoperative period. In addition to assessing the depth of anesthesia, the Conox device also allows for instrumental assessment of analgesia. Inadequate analgesia increases postoperative discomfort and may contribute to an increased incidence of complications in anesthesia and during the postoperative period. Instrumental monitoring of the depth of anesthesia and analgesia increases the safety of anesthesia care. During perioperative care, periods with significant painful stimulation include not only the surgical procedure itself but also airway management during induction of general anesthesia, especially intubation. The hypothesis is - due to the significant painful stimulation during airway management during induction of anesthesia, adequate depth of anesthesia and analgesia may be insufficient and is associated with the patient's clinical response, which may be associated with the occurrence of postoperative delirium.