Adequacy of Anesthesia Guidance Combined with Peribulbar Blocks Shows Potential Benefit in High-Risk PONV Patients Undergoing Vitreoretinal Surgeries

<b>Background/Objectives</b>: Postoperative nausea and vomiting (PONV) are common after general anesthesia (GA) and, in patients undergoing vitreoretinal surgery, may be triggered by the oculocardiac reflex (OCR) leading to the oculoemetic reflex (OER). Inadequate dosing of intravenous rescue opioid analgesics may further provoke OCR. Adequacy of Anesthesia (AoA) monitoring enables optimized titration of intravenous rescue opioid analgesics, while preemptive intravenous or peribulbar analgesia may reduce opioid use. This study evaluated the impact of preemptive paracetamol or peribulbar block (PBB) combined with AoA-guided GA on the incidence of PONV, OCR, and OER in patients undergoing vitreoretinal surgery. <b>Methods</b>: A total of 185 patients were randomized to four groups: GA with AoA-guided intraoperative rescue opioid analgesia plus a single intravenous dose of paracetamol 1 g, or PBB using 1% ropivacaine, 0.5% bupivacaine, or a 1:1 mixture of 0.5% bupivacaine/2% lidocaine. Data from 175 patients were analyzed. <b>Results</b>: AoA-guided GA yielded an OCR incidence of 11.4% and PONV incidence of 4%. PBB, regardless of anesthetic solution, did not significantly reduce intraoperative rescue opioid analgesia requirements or the incidence of PONV, OCR, or OER compared with intravenous paracetamol. Notably, no PONV occurred in patients with three Apfel risk factors (predicted risk ≈ 61%) who received PBB. <b>Conclusions</b>: No overall advantage of PBB over intravenous paracetamol was observed. It may, however, benefit patients at high PONV risk.