The study is a prospective, randomised, controlled double-blind clinical trial. The primary aim was to evaluate the efficacy of caudal block and ilioinguinal-iliohypogastric nerve block with PI and PVI in pediatric inguinal hernia operations under general anesthesia. The secondary aim is to evaluate postoperative analgesic agent consumption and to evaluate the correlation of PI and PVI values with hemodynamic parameters. Pediatric patients between the ages of 2-8 years who are planned to undergo elective inguinal hernia operation will be included in the study.

ASA III-IV patients, patients with peripheral vascular disease, patients with diabetes mellitus, patients with neuromuscular disease, patients with bleeding disorders, patients with infection at the site of the block, patients with infection at the site of perfusion index probe adhesion, patients with bilateral inguinal hernia operation, patients with inguinal hernia operation with circumcision, patients with emergency operation, patients with mental retardation, patients who do not speak Turkish, patients with local anesthetic allergy, patients who do not give consent to participate in the study will not be included.

After the patients scheduled for inguinal hernia surgery are admitted to the operating room, routine monitoring will be performed as performed in the clinic. In addition to routine monitoring, a Radical-97TM Pulse CO-OximeterTM (Masimo Corp, Irvine, CA, USA) probe will be attached to the toe to monitor PI and PVI and covered with gauze to prevent exposure to ambient light. Patients will be given anaesthetic drugs as routinely administered (propofol 1-3mg/kg, fentanyl 1-2mcg/kg), followed by placement of an appropriately sized supraglottic airway device (LMA) and maintenance of anaesthesia with oxygen, air and sevoflurane. After LMA by randomisation by closed envelope method, caudal or ilioinguinal-iliohypogastric nerve block will be performed by an experienced anaesthetist as the investigators routinely perform in patients other than the control group. Caudal block is performed in the left lateral decubitus position after sterile conditions are provided, the sacral cornuas are palpated and a 25 gauge caudal needle (egemen international brand 25g 30 mm) is advanced at an angle of 45 degrees. After the needle hits the sacrum, the angle is reduced by retreating a few millimetres and the epidural area is reached in the sacral canal. After controlling the absence of blood and cerebrospinal fluid by negative aspiration, Buvasin® will be administered at a dose of 0.25%, 0.5 ml/kg. Ilioinguinal-iliohypogastric nerve block will be performed by placing the linear probe transversely-obliquely in the direction of the line connecting the spina iliaca anterior superior and the umbilicus under ultrasound guidance after sterile conditions are provided while the patient is in the supine position. The block needle (braun brand stimplex ultra 360 block needle) is inserted with in-plane technique in the same plane with the ultrasound probe. External and Internal Oblique Muscle and Transversus Abdominus Muscle layers and nerves are determined, needle tip localisation is determined, aspirated at frequent intervals and 0.25% Buvasin® 0.5ml/kg is given to the neurofascial plan. PI, PVI, pulse, saturation, noninvasive arterial pressure values will be recorded before induction, after induction, after LMA, before applied block, after applied block (after surgical incision) at 0, 5, 10, 15, 20, 25 and 30 minutes and at the end of anaesthesia. All patients will be given paracetamol 10mg/kg iv, which is a routine intravenous (iv) analgesic, at the end of surgery. In case of perioperative complications, the complications will be recorded.

Flacc pain scale (Face, Legs, Activity, Cry, Consolability) will be applied at 0, 2, 6 hours postoperatively. Postoperative analgesic use and discharge time will be recorded. Flacc pain scale will be performed by an anaesthetist blinded to the study.