This study addresses articles and studies related to the erector spinae plane (ESP) block and its technique, advantages and disadvantages, applicability, among others. It aims to provide more information about this block, which is relatively new, and how it can be explored in the anesthesiologist's routine, mainly inserted in the anesthesia scenario for cardiac surgery with a focus on postoperative analgesia.

All patients who meet the inclusion criteria will be submitted to ESP block after anesthetic induction. This will be performed with fentanyl (up to 5 micrograms/Kg), etomidate (2 milligrams/Kg) and cisatracurium at a dose of two DE95. Then the operator will perform the esp block, at the level of the fourth thoracic vertebra, being blinded as to the content of the solution, if local anesthetic (25 ml of 0.375% Ropivacaine in each side, respecting the toxic dose) or placebo (25 ml of 0.9% NaCl on each side). There will be randomization as to the inclusion in each group, using software. After puncture and infusion of the initial dose, a catheter (Contiplex C,Bbraun) will be inserted on each side, also under ultrasound guidance and connected to a patient-controlled analgesia pump (PCA), with a corresponding solution of ropivacaine or 0.9% NaCl programmed with a maintenance dose a 4ml / Hr and 06ml bolus with trigger. Anesthetic maintenance with halogenated (sevoflurane), cisatracurium in a continuous infusion pump (CIP) of 1-3 micrograms/Kg/min and if necessary remifentanil 0.1-0.3 microgram/Kg/min.

All patients will be submitted to the institution's standard management: multimodal analgesia with common analgesic (dipyrone 4 to 8 g / day or paracetamol 1500 to 2250 mg / day, tramadol 200 to 400 mg / day) in addition to rescue analgesia if necessary. (morphine 02 mg). PCA withdrawal will be on the fifth postoperative day .

Inclusion Criteria:

• Consent to the free and informed consent term.
• Patient undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB).
• Preserved left ventricular global function (LVEF > 50%).

Exclusion Criteria:

• Moderate or severe valvular dysfunction.
• Previous anterior sternotomy.
• Known allergy to the study drugs.
• Complications during catheter insertion or block placement.
• Pre-existing diagnosed chronic pain under treatment.
• Concomitant use of drugs with a long half-life (induction and anesthetic maintenance doses will be standardized; patients taking medications with a long half-life are excluded to prevent bias in outcome assessment).
• Concomitant administration of Magnesium Sulfate.

The blinding of the intervention for patients, anesthesiologists, cardiac surgeons, intensivists, nurses, outcome assessors and investigators will be guaranteed by a central randomization, the preparation and solution of the protocol will be carried out by the study's non-blind team, randomization will be 1: 1. There will be randomization as to the inclusion in each group, using software.