Two regional anesthesia techniques already in use in common clinical practice -paravertebral block and pectoral nerve block (PECS block) are compared in a randomized, double-blind, multicenter, controlled, non-inferiority trial, in order to compare their success rate in patients udergoing breast surgery.

Aim of the study is to compare paravertebral block and PECS block success rate in patients undergoing elective breast surgery (mastectomy or quadrantectomy) with a combined anesthesia technique.

Primary outcome is block success rate defined as a VAS score of 30 or less in PACU and at 6, 12 and 24 hours after surgery. Secondary outcomes are: rescue opioids requirement; incidence of procedure related complications; incidence of postoperative side-effects; patients' quality of life level during the first 24 postoperative hours; patients' satisfaction.

A prospective, randomized, controlled, double-blinded, non-inferiority trial was designed in order to compare paravertebral block and PECS block with regard to block success over the first 24 hours postoperatively in patients undergoing mastectomy or quadrantectomy procedures with a combined anesthesia technique.

Inclusion criteria: adult patients, ASA class 1 to 3, scheduled for elective mastectomy or quadrantectomy. Exclusion criteria: patients refusal, contraindication to regional anaesthesia (coagulopathies, concurrent anticoagulant therapy, allergy to local anaesthetics, infection at puncture site).

After written informed consent, patients will be randomized into two cohorts, the first being treated with a paravertebral block, while the second with a PECS block. Both procedures will be standardized with regard to injection technique, local anaesthetic drug and volume and performed under ultrasound real-time guidance. Both groups will undergo the regional anesthesia technique after induction of general anaesthesia to be blinded with regard to the type of block. This will be standardized as well, according to our centers current clinical practice. Postoperative pain will be than measured on a validated visual analogue scale (VAS 0-100) in the recovery room and periodically after discharge to the ward until 24 hours postoperatively. Rescue opioids requirement will be recorded. Eventual procedural complications occurred will be recorded as well as postoperative side effects. A questionnaire about patients' satisfaction and quality of life during the first 24 postoperative hours will be filled in for every patient. Data collected will be initially inserted in a form and subsequently collected, pooled and anonymously registered in an electronic data base.

A sample size calculation has been preliminary performed with regard to the primary outcome. A 20% difference in the blocks success rate (defined as a postoperative pain on VAS scale of 30 or less) will be considered as clinically significant.

In our practice, paravertebral block is the current gold standard and it is associated on average to a 50% mean value on VAS scale during the first 48 postoperative hours. PECS block will be thus compared to this standard of care. A total of 39 patients per arm will be required (95% confidence interval). Accounting for a 10% drop-out rate, we will include 43 patients per arm.

Pain levels will be measured as medians and interquartile ranges. Statistical analysis will be performed using Student t-test for normally distributed variables while Mann-Whitney test was applied to non-normally distributed variables.

This study will be conducted in compliance with the protocol, the current version of the Declaration of Helsinki, the ICH-GCP or ISO EN 14155 (as far as applicable) as well as all national legal and regulatory requirements.

Inclusion Criteria:

• adult patients
• ASA class 1 to 3 patients
• patients scheduled for elective breast mastectomy or quadrantectomy

Exclusion Criteria:

• patients' refusal
• contraindication to regional anaesthesia (coagulopathies, concurrent anticoagulant therapy, allergy to local anaesthetics, infection at puncture site)