Sternotomies and PectoIntercostal Fascia Blocks in Fast-Track Cardiac Anesthesiology (SPIFFY)

This study is looking to see if a regional block placed on each side of the incision after surgery helps with pain relief. Ultrasound-guided pectointercostal fascia blocks will be placed at the conclusion of surgery following application of dressings. Patients will be in the supine position with the surgical drapes in place. The blocks are performed using a high frequency linear transducer with aseptic technique. The investigators hypothesize that placement of PIF blocks and catheters will decrease acute postoperative pain from midline sternotomy in fast track cardiac surgery patients compared to the current standard of care. A physician will place an ultrasound guided pecto-intercostal fascial plane blocks bilaterally at the conclusion of surgery. They will also leave a catheter, similar to a small IV, between the muscle layers where the freezing medication goes. This will let the investigators give more freezing medication over the first 24 hours after surgery. The freezing medication blocks the pain signals from travelling to your brain from your incision, which might help participants need fewer narcotics after surgery. Some of the research on this block shows a trend toward reduced pain, but the use of a catheter to allow repeat doses of freezing medication has not been studied. The investigators hope to show that this regional block means participants need less opioids (narcotics) in the first 2 days after their heart surgery. In order to see whether the regional block is helpful there will be two groups of study participants. Both groups will receive infusion catheters covered with opaque bandages however one group will receive the study drug (ropivacaine) and the other will not (placebo). To reduce the risks to placebo group participants, those participants will have a catheter taped to their skin surface under an opaque dressing. This will give the illusion of block placement without the risks of a needle poking through skin. Both groups will still be given pain medications by IV or by mouth as needed after the surgery.

Acute postoperative pain at median sternotomy sites is common in cardiac surgery patients. Inadequate control of acute pain can lead to sympathetic activation, hemodynamic sequelae, respiratory compromise, delirium and contributes to the development of chronic pain. Parental opioids have long been at the forefront of perioperative pain management for cardiac surgery patients, historically in large intravenous doses. With the onset of fast-track cardiac anesthesia (FTCA) which emphasizes reduced periods of post-operative mechanical ventilation, intensive care unit stay and overall health care cost; new strategies for managing post-operative pain in cardiac surgery patients are required. Opioid focused strategies contribute to many side effects including sedation, confusion, apnea, nausea, emesis, and ileusF , which can prevent effective fast tracking of these patients. FTCA has highlighted the potential for regional anesthetic techniques to revolutionize post-operative cardiac surgery care. Though thoracic epidural analgesia offers excellent analgesia for post-sternotomy pain, the small but catastrophic risk of epidural hematoma in heparinized patients has hindered it from becoming standard of care. Over the last decade, various thoracic wall blocks have been developed and shown to benefit patients presenting for thoracic or breast surgeries, and sternotomies. Of these, fascial plane thoracic wall blocks offer the advantages of being simple to perform ultrasound equipment and having low complications rates. One such block is the pectointercostal fascia (PIF) block which was first described in 2014 as an analgesic adjunct for breast procedures. In this block the fascial plane between the pectoralis major and internal intercostal muscles is infiltrated with local anesthetic with the aim of anesthetizing the anterior cutaneous branches of the intercostal nerves, thereby providing analgesia to the anterior chest wall from T2 to T6 with a single injection. The block can be placed with ultrasound guidance with the patient in the supine position - making it easy to place in the operating room or as a rescue block in CVICU. Despite the higher volumes of local anesthetic required for a plane block of this nature, previous studies have shown that the serum levels of local anesthetic remain well below the toxic rangeI,J. Injection into the fascial plane allows for excellent spread of local anesthetic along multiple rib spaces, precluding the need for multiple injections. It also opens up a space for placement of a catheter thus providing the option of longer term analgesia in postoperative patients. While PIF blocks avoid the hemodynamic side effects and risk of neuraxial complications associated with thoracic epidurals and paravertebral catheters they are not without risk. These risks include potential hemothorax, pneumothorax, chest wall hematoma, local anesthetic systemic toxicity and surgical site infection.

sternotomy, regional anesthesia, pectointercoastal fascia block, fast-track cardiac surgery, post-operative pain, truncal nerve block, cardiac surgery, cardiac anesthesia

the physicians placing the nerve blocks will not be blinded to the treatment group. The post-operative care team including the nurses doing pain assessments and management will be blinded to group allocation.

The control group patients will receive the same intraoperative analgesia management. A PIF block will not be performed, instead, a peripheral nerve block catheter will be secured to the skin surface and connected to a CADD™ pump. As the catheter is taped to the skin surface the control group patients will not be exposed to the risks of peripheral nerve block placement.

PIF blocks will be placed at the conclusion of surgery with the surgical drapes in place. The blocks are performed using a high frequency linear transducer with aseptic technique. The ultrasound probe is placed longitudinally 3 cm from the sternum at the level of the 4th-6th intercostal space. Using an in-plane approach, an echogenic needle will be advanced into the fascial plane between pectoralis major and the external intercostal muscles. Peripheral nerve block catheters will then be inserted and secured to the skin surface with tegaderm. For patients weighing over 70 kg, 20 mL of 0.5% ropivacaine will be administered. This will be reduced to 15mL per side for patients weighing less than 70 kg. A CADD™ pump will be connected to each catheter and programmed to deliver 20 mL boluses of ropivacaine 0.2% starting at postoperative hour 2. The boluses will be staggered every 2 hours on alternate sides until hour 24. The catheters will be removed 24 hours post-operatively.

The control group patients will receive the same intraoperative analgesia management. A PIF block will not be performed, instead, a peripheral nerve block catheter will be secured to the skin surface and connected to a CADD™ pump. As the catheter is taped to the skin surface the control group patients will not be exposed to the risks of peripheral nerve block placement.

Inclusion Criteria: adult patients presenting to the Mazankowski Heart Institute for operations via full midline sternotomy, i.e.: coronary artery bypass grafting, and/or single valve repair or single valve replacement who are expected to be fast track candidates post-operatively. patients scheduled for cardiac bypass grafting and/or single valve surgery requiring cardiopulmonary bypass. Exclusion Criteria: Unstable or fluctuating cardiac condition (acute MI, HF, tamponade, type A dissection, ongoing refractory arrhythmia, LVEF <40%, massive transfusion protocol, reinstitution of CPB or other mechanical support) Alternative surgical approach (e.g. thoracotomy, mini sternotomy) Repeat sternotomy or emergency surgery Pregnancy or lactation Age <18 Chronic pain Tolerance to opioids Active alcohol misuse disorder, IVDU or cannabis use >1g/d Allergy to local anesthetics Inability to provide informed consent High doses of steroids pre-operatively (>10 mg prednisone/day)

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