SII Levels Following PENG Block in Pediatric Hip Surgery

Pericapsular Nerve Group Block Mitigates Surgical Stress and Enhances Analgesia in Pediatric Hip Surgery: A Randomized Controlled Trial

This study is a prospective, randomized, double-blind clinical trial. Its aim is to evaluate whether adding a pericapsular nerve group (PENG) block to spinal anesthesia can reduce the inflammatory response after hip surgery in children.

Hip surgery in children can cause a strong stress and inflammatory reaction, which may affect pain after surgery, the need for opioid medications, and recovery.

Children aged 3 to 8 years will be randomly assigned to one of two groups: spinal anesthesia alone or spinal anesthesia combined with a PENG block. The main goal is to compare changes in the Systemic Immune-Inflammation Index (SII), a blood-based marker of inflammation, measured before surgery and 24 hours after surgery.

Additional outcomes include other inflammatory markers, postoperative pain, opioid use, time to first rescue pain medication, and side effects.

Hip surgery in children is associated with a significant inflammatory and physiological stress response, which may contribute to postoperative pain, increased opioid requirements, and delayed recovery. Composite inflammatory indices derived from routine blood tests are increasingly used as accessible markers of systemic inflammation.

The Systemic Immune-Inflammation Index (SII), calculated as platelet count × neutrophil count / lymphocyte count, reflects the balance between inflammatory and immune responses and has been proposed as a sensitive indicator of surgical stress.

The pericapsular nerve group (PENG) block is a regional anesthesia technique used in hip surgery that provides effective analgesia with minimal motor impairment. Its potential effect on systemic inflammatory response remains insufficiently characterized.

The study is designed as a prospective, randomized, double-blind, single-center controlled trial with two parallel groups. Pediatric patients undergoing elective hip surgery will be allocated in a 1:1 ratio to receive spinal anesthesia alone or spinal anesthesia combined with ultrasound-guided PENG block. A sham procedure will be performed in the control group to maintain blinding.

Standardized perioperative management and postoperative analgesia will be applied in all participants.

The primary endpoint is the change in SII between the preoperative baseline and 24 hours after surgery. Secondary endpoints include additional inflammatory indices, C-reactive protein levels, postoperative pain intensity, opioid consumption, time to first rescue analgesia, and incidence of adverse events.

Blood samples will be collected at predefined time points for the assessment of inflammatory markers.

Inclusion Criteria:

• Age 3-8 years
• Scheduled for elective unilateral hip surgery
• American Society of Anesthesiologists (ASA) physical status I-III
• Written informed consent from the parent or legal guardian

Exclusion Criteria:

• Contraindications to spinal anesthesia or PENG block
• Infection at the planned needle insertion site
• Coagulation disorders
• Chronic immunosuppressive therapy or chronic steroid use
• Active infection or inflammatory disease
• Ongoing oncological treatment
• Known allergy to local anesthetics or study-related medications
• Conversion to general anesthesia
• Refusal to participate