Different Peribulbar Blocks With SPI-guided Anaesthesia for VRS (P&MSPIVRS)

The aim of this randomized trial is to assess the efficacy of preventive analgesia using different peribulbar blocks (PBB) under SPI-guided anaesthesia for vitreoretinal surgery (VRS), presence of PONV (postoperative nausea and vomiting) and oculocardiac reflex (OCR) and compare Numerical Rating Scale (NRS) with Surgical Pleth Index (SPI) for monitoring pain perception postoperatively. Patients will receive general anaesthesia combined with either preventive PBB using either lidocaine with bupivacaine or bupivacaine or ropivacaine

Monitoring depth of anaesthesia using spectral entropy (SE) and quality of neuromuscular block are routine in modern anaesthesia, whereas monitoring of analgesia still requires further studies. Recently, the Surgical Pleth Index (SPI) was added as a surrogate variable showing the nociception-antinociception balance into abovementioned parameters constituting a novel approach in monitoring patients intraoperatively, known as adequacy of anaesthesia (AoA) or tailor-made anaesthesia. Different options of local anesthetic mixtures used for peribulbar block result in different analgetic potency. PBB is supposed to reduce requirement for intraoperative narcotic analgesics when used together with general anaesthesia and therefore may reduce the rate of PONV, OCR and perception of postoperative pain. The aim of the study is to investigate the influence of different PBBs on abovementioned outcomes.