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.
Patients scheduled for elective breast quadrantectomy;
Aged 18-80 years;
American Society of Anesthesiologists (ASA) physical status I-II;
Body mass index (BMI) <35 kg/m².
Contraindications for nerve block: infection at the puncture site, local anesthetic allergy, coagulation dysfunction or bleeding risk;
Patients with unilateral diaphragmatic paralysis;
Patients with severe ventilatory or gas exchange dysfunction;
Complicated with acute or chronic pulmonary and bronchial diseases, sleep apnea syndrome;
Parallel
0.25% ropivacaine
DrugDuring breast quadrantectomy, intercostal nerve block is performed at the 2nd to 6th intercostal spaces along the posterior axillary line using an in-plane technique. 4ml of 0.25% ropivacaine (prepared from Naropin, 10ml:75mg) is injected into each intercostal space. Under ultrasound guidance, the needle tip is ensured to reach the space between the internal intercostal muscle (intercostal endomysium) and the innermost intercostal muscle below the rib margin. After aspiration shows no blood, the drug is injected, and anechoic fluid can be seen diffusing below the internal intercostal muscle, with the local parietal pleura gradually descending as the injected fluid volume increases.
0.375% Ropivacaine
DrugDuring breast quadrantectomy, intercostal nerve block is performed at the 2nd to 6th intercostal spaces along the posterior axillary line using an in-plane technique. 4ml of 0.375% ropivacaine (prepared from Naropin, 10ml:75mg) is injected into each intercostal space. Under ultrasound guidance, the needle tip is ensured to reach the space between the internal intercostal muscle (intercostal endomysium) and the innermost intercostal muscle below the rib margin. After aspiration shows no blood, the drug is injected, and anechoic fluid can be seen diffusing below the internal intercostal muscle, with the local parietal pleura gradually descending as the injected fluid volume increases.
0.5% Ropivacaine
DrugDuring breast quadrantectomy, intercostal nerve block is performed at the 2nd to 6th intercostal spaces along the posterior axillary line using an in-plane technique. 4ml of 0.5% ropivacaine (prepared from Naropin, 10ml:75mg) is injected into each intercostal space. Under ultrasound guidance, the needle tip is ensured to reach the space between the internal intercostal muscle (intercostal endomysium) and the innermost intercostal muscle below the rib margin. After aspiration shows no blood, the drug is injected, and anechoic fluid can be seen diffusing below the internal intercostal muscle, with the local parietal pleura gradually descending as the injected fluid volume increases.
The percentage decrease (/L) of the surgical side lung ventilation to total lung ventilation after blockade
The patient was placed in a supine position, and an EIT electrode strip was placed along the 4th intercostal space on the chest. Continuous monitoring of EIT (Drager Infinity C500, Germany) was performed, and tidal resistance changes during quiet breathing and deep breathing over at least 5 consecutive respiratory cycles were collected to construct lung ventilation distribution images. The main focus is to compare the changes in ROI% in different regions before and after the block, with comparisons made in 4 quadrants: "left upper, right upper, left lower, right lower".
Block success rate
The patient was able to undergo the surgery successfully without the need for additional rescue anesthesia measures.
Adverse events
The number of cases with adverse events, adverse reactions, and serious adverse events (to be specified) such as local anesthetic toxicity, Horner's syndrome, and pneumothorax.
Pain-related assessment
The Numerical Rating Scale (NRS) was used to assess the patient's pain score via telephone.
Pain-related assessment
The Numerical Rating Scale (NRS) was used to assess the patient's pain score via telephone.
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