ABC Blocks for Cardiac Surgery

This randomized blinded trial aims to evaluate the effect of parasternal intercostal and rectus sheath blocks ("anterior blocks for cardiac surgery" or ABC blocks) on postoperative recovery in patients undergoing median sternotomy for cardiac surgery. Subjects will be randomized to receive either local anesthetic (liposomal bupivacaine plus bupivacaine 0.25%) or saline sham block.

Subjects will be randomized on the morning of surgery to receive either "anterior blocks for cardiac surgery" or "ABC blocks" using 60 mL of local anesthetic mixture (20 mL of liposomal bupivacaine plus 40 mL of 0.25% bupivacaine) or a sham saline ABC block (60 mL). All subjects will receive standard of care anesthetic regimen for their cardiac surgery at the discretion of his/her attending anesthesiologist. 40 mL of the solution will be administered in the parasternal intercostal space, and 20 mL will be placed in the rectus sheath in the epigastric region.

For the parasternal blocks, a linear high frequency ultrasound probe will be placed parasagitally at the T2-3 level approximately 3cm lateral to the mid-sternum, and all relevant structures will be identified, including the pectoralis major muscle, internal intercostal muscle, ribs, pleura, and any vasculature, including the internal mammary artery and vein. Color Doppler will be used confirm the location of vasculature.

After skin local anesthetic infiltration, a 10 cm 21G insulated block needle (Sonoplex, Pajunk Medical Systems, Norcross, GA) will be inserted from the inferior aspect of the ultrasound probe in a caudal to cranial direction and aligned with the ultrasound scanning plane (in-plane approach). In this way, both the needle shaft and tip can be visualized as the needle approaches the plane between the pectus major and intercostal muscles. The needle will be redirected as needed. Once satisfactory position of the needle time is confirmed and after frequent negative aspiration, 10 mL of study solution will be slowly injected. This injection will be repeated at the T4-5 interspace. Spread of local anesthetic will be documented in the appropriate plane in real time. This procedure will be performed bilaterally.

For the rectus sheath blocks, a linear high frequency ultrasound probe will be placed in a transverse position in the midline, just inferior to the xiphoid process. The probe will be moved laterally to visualize the lateral edge of the rectus abdominis muscle. A 10 cm 21G insulated block needle will be inserted from the lateral aspect of the ultrasound probe in a lateral to medial direction until visualized deep to the muscle immediately adjacent to the posterior rectus sheath. After negative aspiration, 10 mL of study solution will be slowly injected into this plane. This procedure will then be repeated on the contralateral side

All nerve blocks will be performed by a trainee supervised by an anesthesiologist experienced in regional anesthesia. The anesthesiology team and in the OR will be blinded to group allocation.

Subjects will receive a general anesthetic consistent with standard of care for cardiac surgeries at the discretion of his/her attending anesthesiologist. At the conclusion of the case, subjects will be extubated and/or transported to the ICU intubated. The decision to extubate the subject in the OR will be made at the discretion of the attending anesthesiologist.

Evaluation of acute postoperative pain intensity using a 0-10 visual analog scale (VAS) and opioid consumption will be undertaken at the following time points:

* 24 hours postoperatively
* 48 hours postoperatively Review of the medical chart will be made post-operatively to gather other data, including total intraoperative oral morphine equivalent consumption, cumulative opioid consumption at 48 hours, time to tracheal extubation, ICU length of stay, hospital length of stay, and time to first session with physical therapy. Occurrences of any adverse events reported by the subject or medical team will also be collected.

Eligibility Criteria:
Inclusion Criteria:

* Subjects scheduled for elective cardiac surgery involving primary median sternotomy
* Age 18-85 years of age
* BMI 18-50 kg/m2

Exclusion Criteria:

* Left ventricular ejection fraction (LVEF) \< 30%
* Preoperative, intraoperative, or immediate post-operative placement of intra-aortic balloon pump or deployment of extra-corporeal membrane oxygenation (ECMO)
* Inability to understand or speak English
* Allergy to amide local anesthetic
* Contraindication to peripheral nerve block (e.g. local infection, previous trauma to the block site)
* Chronic opioid consumption (daily oral morphine equivalent of \>20 mg) in the past three months
* Severe pulmonary disease
* Neurological deficit or disorder
* Suspected or known addition to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past two years
* Uncontrolled anxiety, schizophrenia, or other severe psychiatric disorder