Electrical impedance tomography (EIT) to evaluate the effect of different concentrations of ropivacaine on pulmonary ventilation function during intercostal nerve blockade

This study aims to find out how different strengths of the anesthetic drug ropivacaine affect lung breathing function when used in intercostal nerve block (a type of local anesthesia) for breast quadrantectomy surgery. Researchers will use a non-invasive imaging technique called electrical impedance tomography (EIT) to monitor lung ventilation in real time. Why is this study being done? Intercostal nerve block is a common anesthesia method for breast surgeries, but the ideal strength of ropivacaine that balances effective pain relief with safety for lung function is not fully clear. EIT can help measure how each drug strength affects breathing by showing changes in lung airflow. What will happen in the study? Participants: 72 adults scheduled for breast quadrantectomy, aged 18-80, will be randomly assigned to receive one of three ropivacaine strengths (0.25%, 0.375%, or 0.5%) during intercostal nerve block. Procedures: After anesthesia, EIT will monitor lung ventilation before and after the block. Researchers will measure: How much each lung side contributes to breathing during quiet and deep breaths. How quickly the anesthesia works, pain levels during surgery, and any side effects (like difficulty breathing or allergic reactions). Who can join? Adults having elective breast quadrantectomy. ASA physical status I-II (generally healthy to mildly ill). BMI \<35 kg/m². No history of nerve block allergies, breathing problems, or certain lung diseases. What are the possible benefits? The study may help doctors choose the best ropivacaine strength to ensure good pain control while minimizing risks to lung function, especially for same-day surgery patients. What are the risks? Potential risks include rare side effects from the anesthetic (like allergic reactions or low blood pressure) or temporary breathing changes, which will be closely monitored. How is the study designed? This is a double-blind, randomized trial (neither patients nor doctors know which drug strength is used) at Fudan University Shanghai Cancer Center.