Ultrasound Guided Retrolaminar Block for Pediatric Inguinal Hernia

Regional analgesia for inguinal hernia repair in children has attracted increasing interest over the past few years. Caudal block, lumbar epidural block and wound infiltration using a variety of local anesthetic drugs and adjuncts have been used with varying success. Ilio-inguinal nerve blockade has been widely used in this context and despite being generally safe, complications may occurr. The duration of ilio-inguinal nerve block is also limited to the early postoperative period. Paravertebral blockade has been shown to produce long lasting postoperative analgesia when used in combination with general anaesthesia in paediatric herniorrhaphy, and has also been proposed as an alternative to general anaesthesia in adult inguinal hernia repair. Ultrasound-guided retrolaminar block is one of the newer and technically simpler alternatives to the traditional PV block. The first case report of a landmark lamina technique was followed by a study in mastectomy patients where this "blind" technique was used to inject local anesthetic between the thoracic laminae and the deep paraspinous muscles. This technique would logically decrease the chances of pleural injury, while the risk of inadvertent neuraxial injection remains. ultrasound guidance has improved the lamina technique, defining the site of injection as "retrolaminar" by real-time sonographic identification of the lamina and the needle tip-lamina contact, thus minimizing the risk of epidural injection associated with the blind technique. This was immediately followed by a report by the same group describing their first experiences with the retrolaminar technique in patients with multiple rib fractures.To our knowledge, no studies have demonstrated the efficacy and safety of ultrasound guided retro-laminar block in pediatric patients. Therefore, this study will be conducted to evaluate the efficacy and safety of retrolaminar block and compare it with the ilioinguinal nerve block in pediatric patients undergoing unilateral inguinal hernia repair. The study will include 60 patients who will be scheduled for elective outpatient inguinal herniorrhaphy. Patients will be randomly allocated using computer generated random numbers to one of two treatment groups: ultrasound guided ilio-inguinal nerve block (INB Group, n =30) or ultrasound guided retrolaminar block (RLB Group, n =30) using the sealed opaque envelope technique. The eligible patients for this study will be preoperatively evaluated regarding their medical history, clinical examination, laboratory results (complete blood picture, coagulation profile). The day before the surgery, the study protocol will be explained to parents of all patients in the study who will be kept fasting prior to surgery. General anaesthesia will be induced with 8% sevoflurane in oxygen via a facemask. After establishing venous access, a laryngeal mask will be placed and anaesthesia was maintained with 1 MAC sevoflurane and oxygen. Intraoperative monitoring included ECG, heart rate, pulse oximetry, non-invasive blood pressure and end tidal carbon dioxide concentration.During the operation, any haemodynamic changes in excess of 15% from baseline values resulted in a step-wise increase or decrease of the sevoflurane concentration. 0.3 ml.kg of 0.25% bupivacaine will be injected at the level of L1 lamina in RLB group. 0.3 ml.kg of 0.25% bupivacaine will be injected between the transversus abdominis and internal oblique toward the ilioinguinal nerve in INB group. Systolic blood pressure and heart rate will be recorded immediately prior to skin incision (baseline), 60 s after skin incision, during sac traction and on closure of the wound. Pain levels will be assessed post operatively using FLACC (face, legs, activity, cry, consolability) scale at 30 minutes and at 1, 2, 4, 6, 12, 24 hours by trained nurses and second anesthesist who will be blinded to group allocation. When the FLACC score is more than 2 and less than or equal to 5, 15 mg/kg acetaminophen IV will be administered. When the FLACC score is more than 5, 0.5μg/kg fentanyl IV will be coadministered with acetaminophen in the recovery room. Parents will be informed about the pain evaluation, and when patients have pain at home, parents will give 7 mg/kg oral ibuprofen. The anesthesiologist will record data received from the parents over the phone. Parental satisfaction after surgery will be recorded. Satisfaction levels of the parents will be given verbally as a level from 1 to 10, with the lowest level of satisfaction at a value of 1 and the highest level at 10.