INTRODUCTION: The axillary lymphadenectomy procedure is known to be associated with late postoperative complications, such as chronic pain and changes in shoulder mobility. Recently, several thoracic ultrasound guided interfascial blocks have been described, including serratus plane block. These blocks were associated with reduced postoperative pain scores in breast surgeries but were never evaluated in axillary dissection. The safety and feasibility of performing axillary dissection under local anesthesia and tumescent anesthesia associated with sedation has been demonstrated in case series, although it is not already the standard technique.

DISCUSSION: This project aims to investigate the feasibility of the serratus plane block associated with intra-venous sedation in a prospective case series including 15 patients submitted to axillary dissection, by scoring patient and surgeon satisfaction with the technique, pain, quality of life with EORTC QLQ-C30 questionnaire, and quality of recovery with QoR-40 questionnaire in the first 30 postoperative days.

This study is a prospective case series. All patients should go through a preoperative evaluation with an anesthesiologist. At that time the eligibility for the study will be evaluated and if the patient consent to participate in the study.

The following parameters shall be evaluated in the ambulatory evaluation:

• Age
• Anthropometric data (weight and height);
• Presence of comorbidities;
• Revised cardiac index (LEE);
• Estimation of functional capacity in metabolic equivalents (METs) by history;
• Performance Status by the scale of Eastern Cooperative Oncology Group (ECOG);
• Determination of the physical status by the American Society of Anesthesiologists (ASA) classification;
• QoR-40 recovery quality scale, validated for Brazilian Portuguese;
• Quality of life EORTC QLQ-C30 questionnaire, validated for Brazilian Portuguese.

During the anesthetic procedure, the following standard technique should be applied: peripheral venous access, dipyrone 30 mg/kg, antibiotic according to the institutional protocol, moderate sedation with intravenous propofol in continuous infusion in the absence of any contraindication. Midazolam will be used in case of contraindication to propofol or during the execution of the block according to preference of the researcher who will perform the block. Associated with propofol infusion, the alpha agonist dexmedetomidine may be used in continuous infusion associated with fentanyl, tramadol, dextroketamine, magnesium sulfate, dipyrone and tenoxicam, whose uses will be evaluated on a case-by-case basis and will be recorded in the database.

In case of conversion to general anesthesia, the airway control should be carried out preferably with laryngeal mask, with the orotracheal intubation as an alternative option. The maintenance of anesthesia will be in this case using propofol continuous infusion in the absence of contraindications, otherwise sevoflurane will be used. Postoperative nausea and vomiting prophylaxis will be done with four milligrams of dexamethasone and ondansetron.

Patients will be submitted serratus plane block according to the technique described in Blanco. The patients will be positioned in a supine position. The transducer of the ultrasound device is protected with sterile cover. The ultrasound probe is positioned in the mid clavicular region of the thoracic wall in a sagittal plane. Using a nether-lateral path with the probe, will be counted the ribs, until the fifth rib is identified in the mid axillary line. In this position, over the fifth rib, the latissimus dorsi muscle superficially and the serratus muscle deeper and lower can be easily observed. The identification of the thoracodorsal artery with use of doppler imaging assists in identifying the superficial plane to the serratus muscle. Once identified the structures, the needle is introduced in the plane of the transducer positioning its tip on the surface of the serratus muscle. Then 40 ml of solution with 1% lidocaine, adrenaline 1:200,000 and ropivacaine 0.5% are injected in patients above 50kg and 32ml of the same solution in patients with body weight between 40 and 50kg aiming to respect the maximum dose of local anesthetic recommended.

At the end of the surgical procedure the patient will be referred to the anesthetic recovery unit. The extension of the blockade will be then evaluated. They will be discharged to ward as soon as they get the discharge criteria.

The surgical time, time for execution of the blockage (counted from the placement of the sterile field until the removal of the needle), the surgical room time, estimated bleeding, presence of surgical complications or anesthetic and number of lymph nodes extracted will be registered. At the end of the surgery the surgeon will be asked to fill out a range of Likert 5 points on his opinion on the quality of anesthesia (extremely satisfied, satisfied, not satisfied or dissatisfied, dissatisfied, extremely dissatisfied) and to compare the quality of anesthesia with general anesthesia on a 3-point scale (indistinguishable from general anesthesia, sufficient to perform the procedure, extremely challenging/inadequate).

On the first day of postoperative the standard analgesia will be carried out with dipyrone 30 mg/kg IV every 4 hours, associated with tenoxicam 20mg every 12 hours. In case of contraindication to dipyrone, will be administered paracetamol 500 mg VO every 6 hours. As a rescue therapy the default option is tramadol 50mg IV up to every 4 hours (daily maximum dose of 300mg/day and morphine 4 mg each hour (in case of allergy or intolerance to tramadol and rescue the tramadol). If necessary more than 24 hours of hospitalization, postoperative analgesia will be performed as option of the assistant team. The use of postoperative painkillers will be recorded in the database.

All patients should be evaluated on the first postoperative day with record of the verbal numerical scale for the evaluation of pain at rest, cough and abduction of 90 Degrees of the member and the presence of adverse effects. They be asked to fill the scale of Likert of 5 points with his opinion on the quality of anesthesia (extremely satisfied, satisfied, neither satisfied nor dissatisfied, dissatisfied, extremely dissatisfied) and the scale of recovery quality QoR-40. Between the twenty-eighth and the thirtieth-fifth postoperative day All patients will be reassessed, occasion where the scale of recovery quality QoR-40 and the scale of quality of life EORTC QLQ-C30, presence of surgical wound infection will be applied, cutaneous necrosis, seroma, lymphedema, lymphatic fistula and date of drain removal.

Inclusion Criteria:

• Undergo axillary dissection due to metastatic skin or soft tissue cancer;
• ASA physical status classification between I and III;
• have signed the informed consent.

Exclusion Criteria:

• weight less than 40 kilograms;
• tumor affecting topography to be blocked;
• presence of ulcerated lesion in the axilla;
• presence of coagulopathy.