Study Type: Prospective, Randomized, Observational Clinical Study

Primary Purpose:

The primary objective of this study is to compare the analgesic efficacy of caudal block (CB) and quadratus lumborum block (QLB) in children undergoing lower abdominal surgery using objective pain monitoring methods.

Key Questions Addressed:

Does the quadratus lumborum block provide superior intraoperative and postoperative analgesia compared to the caudal block, as measured by the Pain Monitor (PAM) and the FLACC scale?

Is the PAM monitor a reliable tool for objectively assessing nociception and pain in children who are unable to verbally express pain?

Which regional anesthesia technique more effectively delays the time to first postoperative analgesic requirement and reduces total analgesic consumption?

Which method is associated with higher parental satisfaction and fewer postoperative side effects, such as postoperative nausea and vomiting?

Comparison Groups:

Children receiving ultrasound-guided quadratus lumborum block will be compared with those receiving caudal block.

Intervention Group:

Bilateral quadratus lumborum block with 0.5 mL/kg of 0.25% bupivacaine.

Active Comparator Group:

Caudal block with 1 mL/kg of 0.125% bupivacaine.

Participant Population:

A total of 68 children, aged 2 months to 6 years, with ASA physical status I-II, scheduled for elective lower abdominal surgeries (e.g., inguinal hernia repair, orchiopexy, hydrocele).

What Participants Will Do:

Participants will receive the assigned regional block as part of standard anesthetic care. Observational data will be collected as follows:

Intraoperative: Continuous nociception monitoring using the PAM device at predefined time points (during laryngeal mask airway insertion, block performance, surgical incision, 20 minutes after block performance, and extubation).

Postoperative: Pain assessment using the FLACC scale at 1, 2, and 4 hours in the post-anesthesia care unit.

Rescue analgesia (intravenous paracetamol) will be administered if the FLACC score is ≥4. Time to first analgesic administration and total analgesic consumption will be recorded.

Additional outcomes include postoperative nausea and vomiting (PONV) scores, Steward recovery scores, and parental satisfaction scores assessed using the Pediatric Parental Satisfaction Scale (PPPS).

Primary Outcome:

Intraoperative PAM index scores.

Secondary Outcomes:

Postoperative FLACC scores, time to first analgesic requirement, total postoperative analgesic consumption, incidence and severity of PONV, Steward recovery scores, and parental satisfaction (PPPS) scores.

Study Title:

Comparison of the Analgesic Efficacy of Caudal and Quadratus Lumborum Blocks Using a Pain Monitor in Children Undergoing Lower Abdominal Surgery

Study Objectives

Primary Objective:

To compare the analgesic efficacy of caudal block and quadratus lumborum block (QLB) using an objective pain monitoring device (Pain Monitor; PAM).

Secondary Objectives:

To evaluate the postoperative analgesic efficacy of caudal block and QLB in lower abdominal surgeries.

To compare postoperative analgesia duration and analgesic requirements between the two groups.

To assess postoperative side effects associated with each regional anesthesia technique.

To evaluate postoperative parental satisfaction.

Materials and Methods

Children aged 2 months to 6 years with ASA physical status I-II, scheduled for elective lower abdominal surgeries (e.g., inguinal hernia repair, orchiopexy, hydrocele) performed by the pediatric surgery unit at Etlik City Hospital, will be included.

Participants will be randomized using the Research Randomizer program (https://www.randomizer.org/

) into either the caudal block group or the quadratus lumborum block group. A total of 68 participants will be enrolled, with 34 participants in each group.

Both regional anesthesia techniques and the use of the PAM device for intraoperative nociception monitoring are established components of standard clinical practice at the study institution. Therefore, all participants will receive these interventions as part of routine perioperative care, independent of study participation. The study design is prospective and observational, with no deviation from standard anesthetic management.

Demographic data, anesthesia duration, and surgical duration will be recorded. Written informed consent will be obtained from parents or legal guardians preoperatively.

Participants may receive routine oral premedication with midazolam (0.5 mg/kg) in the preoperative area. In the operating room, standard monitoring (SpO₂, ECG, non-invasive blood pressure) will be applied, followed by placement of the PAM monitor. A pediatric probe will be placed on the foot in children younger than 3 years, and an adult probe will be placed on the hand in children aged 3 years or older.

Standard anesthesia induction and maintenance will be performed (oxygen/air mixture, sevoflurane, propofol, laryngeal mask airway). Under ultrasound guidance, either a caudal block with 1 mL/kg of 0.125% bupivacaine (maximum 20 mL) or a bilateral quadratus lumborum block with 0.5 mL/kg of 0.25% bupivacaine (maximum 20 mL) will be administered.

Intraoperative PAM index values will be recorded at five predefined time points:

During laryngeal mask airway insertion

During block performance

At the first surgical incision

20 minutes after block performance

During extubation

Following emergence from anesthesia, the PAM monitor will be removed, and participants will be observed for up to 4 hours postoperatively.

Postoperative assessments will include:

FLACC pain scores

PONV scores

Steward recovery scores

Parental satisfaction scores (PPPS)

These assessments will be performed at 1, 2, and 4 hours postoperatively.

Rescue analgesia with intravenous paracetamol (15 mg/kg) will be administered if the FLACC score is ≥4, and the time to first administration will be recorded. Postoperative complications will also be documented.

Inclusion Criteria:

1. Pediatric patients between 2 months and 6 years of age
2. Pediatric patients undergoing lower abdominal surgery
3. Family consent must be obtained
4. No contraindications to block (infection at the block site), coagulopathy (INR <1.4, platelets >100,000), local anesthetic allergy)
5. ASA I-II patients

Exclusion Criteria:

1. Severe systemic disease (ASA ≥III)
2. Infection at the block site
3. Coagulopathy (INR >1.4, platelets <100,000)
4. Local anesthetic allergy
5. Parental refusal
6. Children aged <2 months or >6 years

Children aged 2 months to 6 years with ASA I-II status undergoing lower abdominal surgeries (e.g., inguinal hernia, orchiopexy, hydrocele) performed by the pediatric surgery unit at Etlik City Hospital will be included.

Because it was not specified in the ethics committee.