Effective pain control during pediatric cardiac surgery remains a major clinical challenge, particularly in procedures involving median sternotomy, which is associated with intense nociceptive stimulation. Inadequate intraoperative analgesia may lead to increased opioid requirements, hemodynamic instability, delayed extubation, and prolonged intensive care unit stay. Objective monitoring of nociception may provide valuable information beyond conventional hemodynamic parameters in this vulnerable population.

This prospective randomized controlled study aims to evaluate the effect of ultrasound-guided parasternal plane block on intraoperative nociception in pediatric patients undergoing cardiac surgery with median sternotomy. Intraoperative nociception will be objectively assessed using the Pain Index Monitor (PAM), based on skin conductance measurements.

The results of this study are expected to provide objective evidence regarding the efficacy of parasternal plane block in attenuating nociceptive responses during pediatric cardiac surgery and to support the integration of regional anesthesia techniques and objective nociception monitoring into perioperative pain management strategies for children.

Inclusion Criteria:

• Age between 6 months and 7 years
• Scheduled for elective congenital cardiac surgery
• Planned median sternotomy
• American Society of Anesthesiologists (ASA) physical status II-III
• Hemodynamically stable preoperative condition
• Written informed consent obtained from a parent or legal guardian

Exclusion Criteria:

• Emergency surgery or redo sternotomy
• Age <6 months or >7 years
• ASA physical status I or >III
• Severe neurological disorders preventing reliable application of behavioral pain scales
• Failure to obtain written informed consent from a parent or legal guardian