EIT Evaluation of Pulmonary Ventilation With Different Ropivacaine Concentrations in Intercostal Nerve Blockade

Intercostal Nerve Block, Pulmonary Ventilation, Anesthesia, Local, Breast Neoplasms, Surgical Procedures, Operative

Ropivacaine, Intercostal Nerve Block, Pulmonary Ventilation Function, Electrical Impedance Tomography, Anesthetic Concentration, Breast Neoplasms

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.

The purpose of this study is to explore the impact of different concentrations of ropivacaine on pulmonary ventilation function and anesthetic efficacy during intercostal nerve block, so as to provide a reference for clinical medication selection. This is a single-center, prospective, randomized controlled trial, with the research subjects being patients scheduled to undergo breast quadrant resection under intercostal nerve block anesthesia. Eligible patients will be randomly assigned to three groups, receiving 0.25%, 0.375%, or 0.5% ropivacaine for intercostal nerve block respectively (4ml injected into each intercostal space, blocking the 2nd to 6th intercostal nerves). The procedure will be performed by experienced anesthesiologists under ultrasound guidance, with a double-blind design where neither the anesthesiologists nor the patients are aware of the grouping and drug concentration information. In the study, Electrical Impedance Tomography (EIT) will be used for real-time, non-invasive monitoring of changes in patients' pulmonary ventilation function before and after the block. Meanwhile, indicators related to anesthetic efficacy such as the onset time of anesthesia and block success rate will be evaluated. The entire research process includes preoperative screening, intraoperative intervention, and postoperative follow-up, aiming to clarify the relationship between ropivacaine concentration, its impact on pulmonary ventilation function, and anesthetic efficacy, so as to provide a basis for optimizing the clinical application of ropivacaine in intercostal nerve block.

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