Postoperative delirium is a frequent complication in children undergoing general anesthesia. It has been suggested that inflammation and oxidative stress contribute to the pathophysiology of delirium. The aim of this prospective observational study was to investigate the relationship between inflammatory markers, and delirium. The main questions it aimed to answer were:

• Is there a realtionship between delirium and neutrophil-to-lymphocyte ratio?
• Is there a realtionship between delirium and platelet volume?
• Is there a realtionship between delirium and platelet distribution width?
• What is the incidence of postoperative delirium in the study group?

Postoperative delirium is a frequent complication in children undergoing general anesthesia. It has been suggested that inflammation and oxidative stress contribute to the pathophysiology of delirium. The aim of our study was to investigate the relationship between inflammatory markers, and delirium.

This single-center, prospective, and observational study included 221 children aged 3 to 9 years in the ASA 1-3 risk group who underwent adenoidectomy, tonsillectomy, and/or ventilation tube placement. Consent was obtained from the parents, and patients were either premedicated with oral midazolam in the preoperative period or taken to surgery without premedication, depending on the anesthesiologist's preference. After induction with sevoflurane, intravenous access was established, and fentanyl (1 µg.kg-1) and rocuronium (0.6 mg.kg-1) were administered. Following intubation, maintenance was achieved with sevoflurane, 50% oxygen, 50% air, and a remifentanil infusion at 0.1-0.15 µg.kg-1.min-1. Additionally, all children received intravenous paracetamol (15 mg.kg-1), methylprednisolone (1 mg.kg-1), and ondansetron (0.1 mg.kg-1). At the end of the operation, the muscle relaxant effect was reversed with sugammadex at 2 mg.kg-1. Following extubation, patients were transferred to the post-anesthesia recovery unit and monitored for 30 minutes in the presence of their parents. In the postoperative period, patients' pain was assessed using the Face, Legs, Activity, Cry, and Consolability (FLACC) Scale, and the presence of delirium was evaluated with the Pediatric Anesthesia Emergence Delirium (PAED) Scale.

The FLACC Scale is used to assess the intensity of postoperative pain in young children, infants, or those unable to communicate. Each parameter is assessed on a scale from 0 to 2, with the total score interpreted as follows: 0 = relaxed and comfortable, 1-3 = mild discomfort, 4-6 = moderate pain, and 7-10 = severe discomfort/pain. A score greater than 3 indicates a need for analgesics In our study, ibuprofen was administered to patients experiencing pain within the first 30 minutes of the postoperative period.

The Pediatric Anesthesia Emergence Delirium (PAED) Scale is the only validated tool for measuring delirium and agitation in the postoperative period. The PAED score is used to assess delirium after the patient awakens and prior to the administration of medication, in order to differentiate pain from delirium. Accordingly, the PAED score is determined by evaluating each category-eye contact, purposeful movements, awareness of surroundings, restlessness, and inconsolability-on a scale from 0 to 4. A total score equal to or greater than 10 indicates the presence of delirium. In our study, all patients were assessed using the PAED scoring system in the postoperative period, and those with a score of 10 or higher were considered to have delirium.

Complete blood count values that are routinely measured in the preoperative period were recorded for all patients.

Statistical analysis Data analysis was performed using the R Studio package program (RStudio Team (2020), Integrated Development for R. RStudio, PBC, Boston, MA, http://www.rstudio.com/ ). In our descriptive analyses, quantitative data were expressed as mean and standard deviation, while qualitative categorical variables were presented as case numbers and percentages (%). In the analysis of NLR levels in patients classified as having delirium, tests for normal distribution and homogeneity of variance were conducted to ensure the assumptions for the Student's t-test were met. Shapiro-Wilk normality tests were performed for the "Yes" and "No" groups. The Student's t-test was used to compare the mean NLR levels between the two groups. The association between the need for analgesics and the presence of delirium in children was evaluated using the Pearson chi-square test with Yates continuity correction.

Inclusion Criteria:

• ASA I-III risk group
• Planned to have adenoidectomy, tonsillectomy, and/or ventilation tube placement.

Exclusion Criteria:

• Children under 3 years old
• Children over 9 years old

This single-center study, took place in Ankara Bilkent City Hospital's operating rooms and postoperative care unit. Children undergoing adenoidectomy, tonsillectomy, and/or ventilation tube placement were followed up.

Data will be shared after publication of the study. Study protocol, statistical analysis, study report will be shared if required by a researcher.

Beginning right after publication and ending 2 years after the publication of results

Data required for researches will be shared