The purpose of this study is to determine whether the addition of the superficial parasternal intercostal plane (SPIP) block alone (30cc of 0.25% bupivacaine) or plus Magnesium (200mg of magnesium sulfate) or plus Magnesium + Buprenorphine (300mcg) as adjuvants can improve post-operative pain in patients undergoing cardiothoracic surgery, specifically, coronary artery bypass grafting (CABG)

Postoperative pain management remains an important clinical challenge in cardiothoracic surgery. Inadequate postoperative pain control can have adverse pathophysiologic consequences, including increased myocardial oxygen demand, hypoventilation, suboptimal clearance of pulmonary secretions, acute respiratory failure, and decreased mobility, with associated increased risks for formation of clots in a blood vessels (thromboembolism). These adverse events may result in greater perioperative morbidity and mortality. Despite several multimodal approaches to postoperative pain control, optimal pain management after cardiothoracic procedures remains an issue.

Regional anesthesia is used to block sensation in a specific part of body during and after surgery. It offers numerous advantages over conventional general anesthesia, including faster recovery time, fewer side effects, no need for an airway device during surgery, and a dramatic reduction in post-surgical pain and reduction in opioid use following surgery. The use of local anesthetic peripheral nerve blocks for surgical anesthesia and postoperative pain management has increased significantly with the advent of ultrasound-guided techniques.

Ultrasound has revolutionized regional anesthesia by allowing real-time visualization of anatomical structures, needle advancement and local anesthetic (LA) spread. This has led not only to refinement of existing techniques, but also the introduction of new ones.

In particular, ultrasound has been critical in the development of fascial plane blocks, in which local anesthetic (LA) is injected into a tissue plane rather than directly around nerves. These blocks are believed to work via passive spread of LA to nerves traveling within that tissue plane, or to adjacent tissue compartments containing nerves.

Although research into these techniques is still at an early stage, the available evidence indicates that they are effective in reducing opioid requirements and improving the pain experience in a wide range of clinical settings. They are best employed as part of multimodal analgesia with other systemic analgesics, rather than as sole anesthetic techniques. Catheters may be beneficial in situations where moderate-severe pain is expected for >12 hours, although the optimal dosing regimen requires further investigation.

In this study the investigators will focus on the superficial parasternal-intercostal plane (SPIP) block, which is among the anteromedial chest wall (near sternum) blocks and was first performed by Raza et al. and Ohgoshi et al.

The investigators will be assessing whether the addition of SPIP block (alone or plus adjuvants) will decrease the visual analog scale (VAS) pain scores in the first 24 hours after surgery, decrease post-operative total opioid consumption (oral morphine equivalents), decrease total acetaminophen and ketorolac consumption, decrease post-operative nausea and vomiting (PONV), decrease length of the ICU stay, decrease time to extubation, and decrease length of hospital stay in comparison to when SPIP block is not administered.

Inclusion Criteria:

• Patients undergoing primary coronary artery bypass grafting

Exclusion Criteria:

• Patients with significant genetic or acquired clotting/bleeding disorders (hemophilia, DIC, etc.)
• Patients with significant platelet dysfunction
• Infection at site for regional anesthesia
• Allergy to local anesthetics
• Severe aortic stenosis
• Severe mitral stenosis
• Sepsis