2.2. Anesthesia
stress ulcer, NRS, ESPB
STRESS ULCER
Detailed methods were previously reported [Before the induction of anesthesia, a single investigator performed all the blocks (i.e., bilateral single-shot US-guided ESPB) with the patient in the sitting position, using an in-plane, caudocranial needle insertion in the fascial plane between the erector spinae muscle and the T5-T6 transverse process. Ropivacaine 0.5% 1.5 mg/kg and dexamethasone 8 mg/20 mL were administered on each side after correct positioning was confirmed by hydrolocation.The induction of anesthesia was standardized, consisting of propofol 1.5 mg/kg, fentanyl 5 µg/kg, and rocuronium 0.6 mg/kg, followed by protective mechanical ventilation, antimicrobial prophylaxis, and stress ulcer prophylaxis.Anesthesia was maintained either with sevoflurane before and after CPB or propofol during CPB. The NOL index was continuously monitored and available for decision-making only from the induction of anesthesia until CPB initiation. This restriction is inherent to the photoplethysmographic nature of the input signal that renders the output (i.e., the NOL index) ineffective during CPB and potentially faulty after CPB discontinuation due to temporary cardiac pacing. In both groups, intraoperative fentanyl administration followed a standard protocol to attain optimum NAN balance defined as a NOL index between 10 and 25 (i.e., 10 ≤ target NOL index ≤ 25) on a scale from 0 (i.e., absence of nociception) to 100 (i.e., extreme nociception). The original NAN protocol is reiterated herein [Postoperatively, all the patients were admitted to the intensive care unit and extubated when a minimum set of weaning criteria was met. Analgesia included intravenous paracetamol 1 g every 6 h and morphine 0.03 mg/kg to achieve numeric rating scale (NRS) scores lower than 4 (i.e., NRS ≤ 3).