One of the most painful aspects of open heart surgery is the incision made through the skin and the sternum to access the heart (a "sternotomy"). Post-sternotomy pain is a potentially debilitating complication of surgery that slows recovery immediately after surgery and can lead to issues with chronic pain. Previous research has shown that by injecting local anesthesia in the pecto inter-fascial plane, the space between the pectoralis major and the intercostal muscles, pain relief can be provided. The investigators aim to assess if repeated injections of local anesthesia via catheters is a useful adjunct compared to routine care.

Justification:

Post-sternotomy pain after cardiac surgery can be debilitating, with associated risks of decreased respiratory function and chronic pain. Severe acute sternal pain after cardiac surgery occurs in 49% of patients at rest and 78% of patients during coughing. Post-sternotomy pain is worst during the first two days and improves thereafter.

The sternum is innervated by the medial division of the anterior cutaneous branches of the T2-6 intercostal nerves, which may be targeted by several regional anesthetic techniques. Concerns of rare epidural hematoma and possible case cancellations with a bloody tap, in the context of systemic heparinization for cardiac surgery, deters many from utilizing neuraxial analgesia for post-sternotomy pain. Contrarily, parasternal regional blocks such as pecto-intercostal fascial plane block (PIFB) provide a low-risk alternative that targets the anterior cutaneous branches of intercostal nerves, and PIFB has been shown to be effective in improving acute post-sternotomy pain.

Nevertheless, single-shot PIFB is limited by its short duration of action, whereas sternotomy pain can remain severe for two postoperative days. Hence, continuous local anesthetic infusion via bilateral PIFB catheters for 48 hours may improve patient pain experience and related outcomes over single shot PIFB.

Objective:

This study aims to evaluate whether, in addition to single shot PIFB, continuous local anesthetic infusion (compared with placebo infusion) through bilateral PIFB catheters reduces acute sternal pain at 24 hours after cardiac surgery with complete median sternotomy. The 24-hour time point was chosen as it represents a time where both the post-sternotomy pain is rated as severe, especially with movement and coughing, and the patient is required to start actively participating in the postoperative rehabilitative process.

Hypotheses:

This study hypothesize that, in addition to single shot PIFB, continuous ropivacaine infusion through bilateral PIFB catheters will be more effective than placebo infusion in reducing sternal pain score on standardized coughing at 24 hours after cardiac surgery with complete median sternotomy.

Study Design:

This will be a prospective, randomized, triple-blinded, placebo-controlled trial in which patients will be randomly allocated to two study groups on a 1:1 basis into:

1) Treatment Group: 20 mL of ropivacaine 0.2% will be deposited via parasternal multi-orifice catheters on each side, followed by infusion of 3 mL/h for 48 hours.

2) Control Group: 20 mL of ropivacaine 0.2% will be deposited via parasternal multi-orifice catheters on each side, followed by a saline infusion of 3 mL/h for 48 hours.

Inclusion Criteria:

• Scheduled cardiac surgery patients
• Complete median sternotomy
• Adult (19 years old or older)
• English-speaking

Exclusion Criteria:

1. Preoperative Exclusion Criteria:

   • Patient refusal

   • Emergent surgery

   • Inability to provide consent

   • Expected inability to follow up via telephone

   • Known preoperative coagulopathy

     i) Congenital coagulopathy ii) Congenital platelet disorders iii) Platelet count < 50 x 10^9 iv) International normalized ratio (INR) or activated partial thromboplastin time (aPTT) exceeding the upper range of normal in the absence of anticoagulant use v) Does not include active anticoagulant or antiplatelet use

   • Known predicted post-operative therapeutic anticoagulation within 48 hours.

   • Known skin disease over block insertion site that would prevent catheter securement

   • Known Immunodeficiency including uncontrolled diabetes, as defined by HbA1C of 7.8% or more

   • Known preoperative advanced liver failure (as defined by Child-Pugh B or C)

   • Known preoperative advanced renal failure (as defined by Estimated Glomerular Filtration Rate (eGFR) < 30 mL/min/1.73 m2)

   • Known opioid tolerance (as defined by morphine oral equivalent >60mg for a period of 7 days or longer pre-operatively)

   • Known allergy to local anesthetic, acetaminophen, or hydromorphone

   • Known weight less than 60 kg

   • Any known technical or physical barrier to block catheter placement (i.e., deep brain stimulation pulse generator or other devices, breast or other implants)

2. Postoperative Exclusion Criteria:

   • Postoperative bleeding at time of randomization as defined by:

     i) initial chest tube loss of >350 mL ii) >200 mL per hour loss iii) > 2 mL/kg/hour loss for 2 consecutive hours iv) or requiring return to the operating room for surgical management

   • Hemodynamic instability, as determined by Cardiac Surgery Intensive Care Unit (CSICU) attending anesthesiologist

   • Anticipated mechanical ventilation of more than 24 hours

   • Anesthesiologist unavailable to insert Pecto-Intercostal Fascial Plane Block (PIFB) catheter within 4 hours of CSICU arrival

   • Any known technical or physical barrier to block catheter placement (i.e., deep brain stimulation pulse generator or other devices, breast or other implants)

Individual participant data (IPD) will not be shared with other researchers.

Patient Masking: Patients will be informed that they will receive one of two solutions (ropivacaine or saline) for infusion, without disclosing which group they are allocated to.

Anesthesiologists, cardiac surgeons, Cardiac Surgery Intensive Care Unit (CSICU) nurses, ward nurses, nurse practitioners, and acute pain service team Masking: blinded/masked to assignments.

Assessors Masking: Assessment of patients, data collection, and follow-up will be conducted by team members (i.e. research assistant, anesthesiologist, CSICU nurses, and ward nurses, acute pain service team) will be blinded/masked to group allocation of a patient participant.

Data Analyst Masking: The data analysts will be provided a table with two groups of the unique numbers, but which group corresponds with ropivacaine and which corresponds with normal saline will not be revealed until the data analysis has been fully completed.