Ultrasound Guided Sacral Erector Spinae Plane Block in vNOTES Surgery

Vaginal natural orifice transendoscopic surgery (vNOTES) has emerged as a minimally invasive surgical approach in gynecological procedures. By utilizing the vaginal passage as a natural orifice, vNOTES eliminates abdominal incisions and has been associated with less postoperative pain, shorter hospital stays, and faster recovery compared to conventional laparoscopic surgery. Despite these advantages, patients undergoing vNOTES may still experience significant perioperative pain due to visceral pelvic manipulation, colpotomy, and uterine traction during the procedure. Effective perioperative analgesia is crucial for optimizing recovery after gynecological surgery and improving patient satisfaction. Opioids remain the primary method for intraoperative analgesia; however, their use is associated with well-known side effects such as postoperative nausea and vomiting, respiratory depression, and delayed recovery. Therefore, multimodal analgesic strategies incorporating regional anesthesia techniques to reduce perioperative opioid consumption are increasingly being investigated. Erector spinae plane (ESP) block is a relatively new fascial plane block, first described in 2016 and since then applied in a wide variety of thoracic and abdominal surgical procedures. By injecting a local anesthetic deep beneath the erector spinae muscle, the block can spread along the fascial plane, potentially affecting both dorsal and ventral branches and providing somatic and possibly visceral analgesia. Recently, a sacral modification of the ESP block has been described as a promising technique for surgeries involving the sacral and perineal regions. Ultrasound-guided sacral ESP block has demonstrated beneficial postoperative analgesic effects in procedures such as pilonidal sinus surgery and other perineal operations. However, the potential role of sacral ESP block in gynecological procedures, particularly vNOTES surgery, has not yet been sufficiently explored. Pelvic organs receive complex autonomic and somatic innervation, primarily originating from sacral segments (S2-S4), including the pelvic splanchnic nerves and pudendal nerve. Targeting these nerve pathways with sacral ESP block can provide effective analgesia for both visceral and somatic components of pain associated with vNOTES procedures. Therefore, this prospective randomized study aimed to evaluate the effect of ultrasound-guided sacral erector spinae plane block on intraoperative opioid consumption in patients undergoing vNOTES surgery. We hypothesized that adding sacral ESP block to general anesthesia would reduce intraoperative remifentanil requirements and lower postoperative pain scores. The primary objective of this study was to investigate the effects of sacral ESP block on intraoperative opioid consumption in challenging vNOTES; the secondary objective was to determine its effects on postoperative pain scores. Since sacral ESP block is routinely used in the operating room, this study poses no risk to the patient or healthcare professionals. This study will include patients scheduled for elective vNOTES surgery at the oncology tower of Ankara Etlik City Hospital. Patients will be randomly assigned to two groups in the operating room during the preoperative period. Patients will be randomly assigned to two groups in a 1:1 ratio using a computer-generated randomization sequence. Allocation concealment will be ensured using sequentially numbered, opaque, and sealed envelopes. The group undergoing the block will receive a bilateral S2-3 level sacral ESP block under ultrasound guidance. A total of 20 ml of block solution will be administered to one side, consisting of 10 ml of 0.5% bupivacaine, 5 ml of 2% lidocaine, and 5 ml of saline. Intraoperative remifentanil consumption will be recorded after standard general anesthesia induction. If heart rate and mean arterial pressure change by more than 20% compared to the baseline value, the remifentanil dose will be increased or decreased by 0.02-0.03 mcg/kg/min (Stepwise remifentanil titration protocol). Heart rate and mean arterial pressure values will be recorded during colpotomy and uterine traction phases of the patients. All patients will receive a standard analgesia protocol: 1 gram of paracetamol every 8 hours, 1 mg/kg of diclofenac every 12 hours, and 50 mg of tramadol as rescue analgesia if VAS > 4. The total tramadol dose consumed will be recorded. Postoperative NRS scores at 0, 2, 6, 12, and 24 hours will be recorded (0: No pain, 10: Unbearable pain). Postoperative nausea, vomiting, and adverse events will also be recorded. The time of discharge of the patients will also be recorded. All patients will be thoroughly informed before the study, and those who volunteer will be included. Patients who do not wish to participate in the study will be excluded. Patients excluded from the study will not be deprived of any treatment. Routine treatment and analgesia procedures will be applied.

Inclusion criteria

• Ages 18-65
• Planned for elective vNOTES surgery
• ASA 1-3
• BMI <35

Exclusion criteria

• ASA 4
• Planned emergency surgery
• Pregnant patients
• Persons with coagulopathy
• Persons with allergy to local anesthetics
• Persons with neurological disease
• Persons with infection in the area where the block will be performed
• Persons who refuse to participate in the study for any reason