Breast cancer is the malignant neoplasm with the highest incidence in women in Brazil, with the exception of non-melanoma skin tumors. Breast cancer surgery is an important part of treatment and post-operative pain needs to be adequately prevented and treated. This prospective, randomized, double-blind clinical study aims to evaluate the efficacy of interfascial pectoral nerve block (PECS II) compared to local anesthetic infiltration at the surgical site in patients undergoing breast cancer surgery in terms of pain and nausea. Data collection will be carried out at the Nossa Senhora das Dores Hospital with 133 patients, who will be divided into two groups: the PEC group will undergo PECS II blockade and the LOC group will undergo local anesthetic infiltration at the surgical site. Both interventions will be performed after the induction of opioid-free/sparing balanced general anesthesia. At the end of surgery, the patients will be taken to the post-anesthetic recovery room (PACU), where post-operative pain will be monitored on arrival and at 30-minute intervals up to two hours after surgery, and before the patient is discharged the following day. A visual analog scale (VAS) will be used, and PONVs will also be recorded. After a 2-hour stay in the PACU, they will be transferred to the ward, and after 24 hours, they will be reassessed using the same parameters. Opioid consumption will be recorded in the PACU and during hospitalization, as well as the occurrence of nausea or vomiting and compared between the groups, and side effects and complications will be monitored.

Introduction:

Breast cancer is the most prevalent malignant neoplasm among women in Brazil, and oncologic surgery is an essential part of its treatment. Postoperative pain is a significant challenge, especially in approaches with general anesthesia. Methods such as PECS II blockade and infiltration of local anesthetics have been used for pain management and reduction of opioid consumption.

Objective:

The study aims to evaluate the effectiveness of the PECS II interfascial block in comparison with local anesthetic infiltration in controlling postoperative pain in patients undergoing breast oncology surgery under general anesthesia with minimal use of opioids (opioid-free/sparing).

Methodology:

This is a prospective, randomized, double-blind clinical trial involving 133 patients. They will be divided into two groups:

PEC group: will receive the PECS II block; LOC group: will be treated with local anesthetic infiltration at the surgical site.

Both interventions will take place after induction of anesthesia. The outcomes assessed include postoperative pain (using a visual analog scale - VAS), occurrence of nausea and vomiting (PONV), opioid consumption and side effects during 24 hours after surgery.

Conclusion:

The study aims to verify which anesthetic group provides less post-operative pain, less opioid consumption and greater patient well-being by not causing vomiting and nausea.

Inclusion Criteria:Female patients aged between 18 and 80 years, ASA physical status I, II or III and undergoing unilateral surgery.

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Exclusion Criteria: pregnant women, morbidly obese (BMI>40 kg/m²), patients with cognitive impairment or inability to communicate with the evaluator, coagulopathies, history of allergy to local anesthetics and patients with a history of chronic pain or drug addiction.

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Double-blind

- both the researcher and those taking part in the study do not know which intervention each participant is receiving is receiving