Cerebral Hypoxia Clinical Trials

The goal of this observational cohort study is to evaluate whether the COPD Assessment Test (CAT) score can predict the risk of perioperative respiratory complications in patients aged 40 to 70 years with diagnosed Chronic Obstructive Pulmonary Disease (COPD), undergoing elective surgical procedures lasting no longer than 150 minutes. The main questions it aims to answer are: * Is there a statistically significant association between preoperative CAT scores and the incidence of intraoperative and early postoperative respiratory complications in COPD patients? * Can the CAT score be effectively used as a preoperative risk stratification tool to guide anesthetic and surgical decision-making? Researchers will compare two patient groups based on CAT scores: those with CAT \<10 and those with CAT ≥10 to determine whether higher CAT scores are associated with an increased incidence of perioperative respiratory complications. Participants will: * Complete the CAT questionnaire during the preoperative evaluation * Undergo elective surgery with an expected duration of ≤150 minutes * Be monitored intraoperatively for bronchospasm, oxygen desaturation, and ventilation difficulty * Be monitored postoperatively (within the first 72 hours) for hypoxemia, reintubation, bronchospasm episodes, postoperative pneumonia, intensive care unit (ICU) admission, and length of hospital stay * Have perioperative clinical data collected and analyzed for comparative outcomes between CAT score subgroups