This clinical trial focuses on an elaborate, propensity-matched, non-inferiority comparison of NOL-guided Superficial Parasternal Intercostal Plane Block (SPIPB) and Erector Spinae Plane Block (ESPB) within the context of open-heart surgery with cardiopulmonary bypass.

A. Ethics

Local Ethics Committee approval and Informed Consent from patient or next-of-kin are obtained prior to study enrollment.

B. Study enrollment

Forty consecutive adult patients scheduled for elective open cardiac surgery under general anesthesia are to receive general anesthesia plus SPIPB. This prospective group of patients will be matched one-to-one to a historical group of 55 patients that underwent open cardiac surgery under general anesthesia combined with ESPB.

C. Methods

C1. Preinduction

• 16-G peripheral intravenous cannula and radial artery catheter.
• Five-lead ECG, pulse oximetry, non-invasive and invasive blood pressure monitoring.
• Analgesia monitor - the NoL index (PMD200TM, Medasense) finger probe will be connected to the index finger of the non-cannulated hand.
• Surgical antibiotic prophylaxis (Cefuroxime 1.5g).
• Stress ulcer prophylaxis (omeprazole 40 mg).

C2. Superficial Parasternal Intercostal Plane Block (SPIPB)

After induction, skin asepsis with chlorhexidine 2% is performed on the anterior chest wall. A high-frequency linear ultrasound probe is positioned parasagittally, 2 cm from midline, bilaterally, at the level of the 4th rib. A 25-G echogenic block needle is inserted at a 20⁰-30⁰ angle in a caudal-to-cephalad direction until the tip of the needle reaches the interfascial plane between the pectoralis major muscle and the internal intercostal muscle. Correct hydrodissection is first certified using normal saline. Subsequently, ropivacaine 0.5% with dexamethasone 8mg/20ml is used and maximum spread is attained by slowly advancing the needle as the interfascial plane splits up ahead. A maximum dose of 3mg/kg ropivacaine is used, corresponding to 1.5 mg/kg per side (e.g., 20 ml ropivacaine 0.5% / side for a 70kg adult).

C3. General anaesthesia

Monitoring

• End tidal CO2 (ETCO2).
• Bispectral index (BIS) monitoring (target 40-60).
• The nociception monitor (PMD200TM, Medasense) is started before induction.
• CVP insertion into the right internal jugular vein under ultrasound guidance.
• Urinary catheter, rectal temperature probe placement.

Induction

• Propofol 1-1.5 mg/kg or Etomidate 0.2-0.3 mg/kg.
• Fentanyl 5 mcg/kg.
• Atracurium 0.5 mg/kg.

Maintenance of anaesthesia

• Sevoflurane in O2 during periods of preserved pulmonary blood flow and mechanical ventilation.
• Propofol infusion during periods of extracorporeal support.
• Atracurium 0.2-0.3 mg/kg/h for adequate neuromuscular blockade.

Analgesia

1. Analgesic drugs

   • Fentanyl: bolus 1.5 mcg/kg.
   • Paracetamol: 1-gram following induction of general anaesthesia.

2. Analgesia monitoring

   • NoL index provides a multiderivative assessment of nociception before cardiopulmonary bypass (CPB) initiation. Optimal analgesia is defined as a NoL index of 10-25.
   • Mean arterial blood pressure (MAP) provides post-CPB decision loop: targets are within ± 15% of MAP recorded during optimum NOL.

C4. Postoperative

Extubation criteria

• Normothermia (T◦ ≥ 36◦C).
• No clinical bleeding.
• Wakefulness.
• Hemodynamic stability (MAP ≥ 60 mmHg and lactate ≤ 2 mmol/L) with minimal vasoactive support (dobutamine < 5 µg/kg/min and norepinephrine < 100 ng/kg/min).
• Adequate gas exchange:
• Tidal volume ≥ 5 ml/kg.
• Adequate airway reflex to handle secretions.

Analgesia

• Paracetamol 1g iv every 6 hours.
• Morphine bolus 0.03 mg/kg for NRS > 3.

Inclusion Criteria:

1. Informed Consent.
2. Elective heart surgery with sternotomy and bypass.
3. Hemodynamic stability prior to induction.
4. Sinus rhythm.

Exclusion Criteria:

1. Known allergy to any of the medications used in the study.
2. BMI > 35.
3. Patient refusal to participate in the study.
4. Coagulopathy (INR > 1.5, APTT > 45, Fibrinogen < 150 mg/dl).
5. Non-elective/emergent and/or redo surgery.
6. ASA ≥ 4.
7. Any preoperative hemodynamic support (mechanical or pharmaceutical).
8. Severe LV dysfunction (LVEF ≤ 30%).
9. Severe RV dysfunction.