Erector Spinae Catheter for Open Heart Surgery

Methodology With the Approval of Ethical committee of VinMec Healthcare and after Patient's information and consent from guardian or parents, adults will be randomized via a random number generator into one of two treatment groups by the person who obtained consent which is prescribed in the nurse preparation file".

Group 1: will receive a single shot dose of local anesthetic Ropivacaine throw ESP catheters and 6 hours after continuous infusion of Iso saline with a rescue analgesia in case of pain according to the bellow protocol Group 2 :will received a single shot dose of local anesthetic Ropivacaine throw ESP catheters and 6 hours after a continuous infusion of Ropivacaine with a rescue analgesia if needed according to the bellow protocol Catheter Performance The anesthesia team will perform to all patients without exclusion criteria (Group I \& II) for open heart surgery after the anesthesia induction a bilateral insertion of an Erector Spinae Plane Block catheter under ultrasound guidance.

Patient in right lateral decubitus. The anesthesiologist will use an Ultrasound linear probe at T4 level and identify the T4 transverse process. By hydro-dissection he will identify the inter-fascial space between the Inter-transverse ligament anteriorly and the Erector Spinae Muscle posteriorly to insert under ultrasound vision a catheter . The tip of the catheter should be at T5 Transverse level seen by ultrasound. The anesthesiologist check the right position of the catheter with a dextrose 5% injection = 1 to 3 mL under ultrasound vision and see the spread of the dextrose in the inter-fascial space which sign that the catheter is not intra-vascular. This procedure will be bilateral. The catheter will have a yellow label on the Huer®-Lock connector to identify clearly that it is regional analgesia catheter to prevent any errors of miss injection. (Yellow is the international identification of regional anesthesia analgesia lines).

After this control an induction low dose is injected. Table 1 Induction dose Patient 30 - 40 kg = 6 mL of Ropivacaine 0.5% / side Patient 40 - 50 kg = 8 mL of Ropivacaine 0.5% / side Patient 50 - 60 kg = 10 mL of Ropivacaine 0.5% / side Patient 60 - 70 kg = 12 mL of Ropivacaine 0.5% / side Patient > 70 kg = 14 mL of Ropivacaine 0.5% / side 5h after, the ESP catheter induction, prepare the solution in the pump The clinical research nurse specially trained for this study will proceed to the randomization of the patient according to the randomization table and prepare the solution in the pump as per attached protocol. They will put the number of patient's randomization on the pump. The nurse receives instruction to keep strictly confidential the content of the pumps. They will deliver the prepared pumps to the anesthesiologist and anesthesia nurse in charge of the patient. They will connect the pumps to the patient and start the infusion 6 hours after as per protocol.

Group 1 \& Group 2 will have the blinded solution in the pump ♣ Table 2 Intermittent Automatic bolus For post operative ESP catheter infusion Patient 30 - 40 kg = 6 mL of Ropivacaine 0.5% / side/ 6h Patient 40 - 50 kg = 8 mL of Ropivacaine 0.5% / side/ 6h Patient 50 - 60 kg = 10 mL of Ropivacaine 0.5% / side/ 6h Patient 60 - 70 kg = 12 mL of Ropivacaine 0.5% / side/ 6h Patient > 70 kg = 14 mL of Ropivacaine 0.5% / side/ 6h (The bolus on the second catheter will be delayed by 1 hour).

• Assess Pain Level All the participants to this studies were trained to the protocol last January 2018 and the nurse trained to random performance and data collection. For all groups . The nurse will assess pain level at rest and mob after extubation and also the Localization of the pain
• Sternum
• Back pain
• Drains If pain FLACC > 3 or VAS at rest or at Mob >4
• If Extension problem increase IAB 2 mL/catheter of the solution inside the pump (DOUBLE BLINDED neither the patient, the physician in charge of the patient and the investigator know what is in the pump .on the side concerned (by increasing the volume we will increase the extension of the analgesia block. This volume increasing will be limited to only one increase. If still pain after the anesthesiologist is not allowed to increase again the volume and should shift to rescue analgesia described below)
• IF Not the patient will receive a dose of morphine as follow :

Morphin 50 mcg/kg/min if patient is still intubated

Morphine PCA mode rescue : if patient extubation:

• Concentration : 50 mg/50 ml
• Loading dose: 1mg
• PCA dose demand: 1 mg/dose
• Lockout: 10 min
• Continuous rate (basal): 0 Dose limit (hr): 6mg/hour Pain Re-assessment 1 hour after settings changes of the pump
• if the FLACC < 3 or VAS inferior to 4 : continue ESP catheters and paracetamol+ ibuprofen /6h
• if the FLACC >3 VAS > 4= poor analgesia +> Rescue analgesia by opioids as before this technique and commonly used in open heart surgeries. Morphine 30 mcg/kg/h.
• Catheter Removal A Bi-daily inspection of the catheters insertion points will be done. If redness around puncture point the catheters will be removed and shift to classical IV analgesia to prevent any infection. It will be declared as a minor incident in the study.

ESP catheters will be removed 2 hours after drain removal maximum 56h after insertion.

2 h. after Drain removal and ESP catheter removed the analgesia in both group will be with the following antalgics:

• Paracetamol Systematically 1g/6h
• Ketorolac 30 mg IV every 8h ♣ Scales evaluate the pain:
• Before extubation FLACC scale at rest
• After extubation and still drains will remain we will use VAS Scale at rest and at Mob (sitting in bed rotation of the thorax) Localization of the pain
• Sternum
• Back pain
• Drains ¬ After drains removal we will use FLACC Scale rest and Mob ( sitting in bed rotation of the thorax) and pain localization A check list anesthesia protocol will be provided for each patient and check list for the pump solution will be provided for the nurse in charge of randomization and preparation of the pump ♣ Statistical analysis and sample size calculation Based on our prior institutional unpublished retrospective data of maximal pain scores from 24 - 48 hours post-surgery in patients who received Single shot ESP bl0cks who underwent open heart surgeries (mean 3 with standard deviation 2.2) We determine that a total of 18 patients per arm will be needed to achieve A decrease in mean pain of 1.5 with 80% power with 5% alpha. We will assume up to 10% lost to follow up and 10% of patients would be non-compliant so we will enroll 25 patients in each group.